Enercon India Ltd. vs Aloys Wobben

S. Chandrasekaran, Technical Member

This is an original application for revocation filed under Section 64 read with Section 117 D of the Patents Act 1970 ( herein after referred to as the

Act) for revoking the patent No. 197949 dated 2.11.1998 granted to the Respondent a German citizen.

The impugned Patent was filed on 2.11.1998 claiming the priority date 3.11.1997 and the Patent was granted on 19.5.2006 by the Patent Office

after due examination of the Patent application having the title ""Pulse inverter with variable pulse frequency and a wind power installation having a

pulse inverter"". The applicant is a Company registered under the Companies Act 1956, a subsidiary of ENERCON GmbH. Germany applied for the

revocation of the Patent on the following grounds.

a. The subject matter of the Patent is obvious and does not involve any inventive step [Section 64 (1)( f)];

b. The claims do not clearly define the scope of the invention. [Section 64 (1) (i)].

c. The complete specification does not sufficiently and fairly describe the invention.[Section 64(1)(h)];

The applicant stated that they are one of the foremost leaders in the wind energy sectors in India and they manufacture and install wind turbines all

over India and thus they are an interested person within the meaning of the Section 64 of the Act.

The Respondent challenged the competency of the signatory to the application for revocation and the same was heard by this Appellate Board and

passed an order disposing the matter to be decided along with the main matter. Aggrieved by this order, the Respondent appealed in the Madras High

Court, which was heard and disposed of by the Hon'ble High Court directing this Appellate Board to consider and dispose of this preliminary issue

along with the main matter. The Miscellaneous petition was again heard as per the directions of the High Court.

On completion of the pleadings, the matter was listed for final hearing on 15.09.2010 before this Bench. Shri. R. Parthasarathy, Advocate appeared

for the Applicant and the Respondent was represented by Shri. S. Herold Daniel, Advocate.

On 15-9-2010, Respondent submitted a M.P proposing amendments to the claims in the granted patent. As the M.P was filed only on the date of

hearing the Registry could not scrutinize the application and number the same and therefore was not listed before us. The applicant's counsel pointed

out, that the M.P was signed on an earlier date 13-9-2010 and has also been notarised, but the same was not submitted till the commencement of the

hearing. Consequently the same was not entertained.

The Respondent filed a M.P. No. 82/2010 on 2-3-2010 questioning the locus standi of the applicant to maintain the present revocation application.

Therefore this has to be considered first and disposed of. Before considering this question of locus of the signatory, let us look into the facts and

background of the case as to its origin briefly.

(a)The applicant is a joint venture company. The applicant is involved in the manufacturing of wind turbine generators and setting up of wind farms on

a turnkey basis. There are two shareholder groups of the applicant company, viz., Enercon GmbH, a company incorporated under German law owns

56% of the shareholding of the applicant company as a first shareholder. The members of the Mehra family own the remaining 44% of the

shareholding of the applicant company as a remaining shareholder.

(b)There are four members on the board of the Petitioner,

• Two representatives of Enercon GmbH

•Two representatives of the Mehra family

•The Chairman of the board is Dr. Aloys Wobben and the Managing Director of the applicant company is Mr. Yogesh Mehra.

•The actual day to day management of the affairs of the applicant company is to be carried out by the Managing Director of the company in India.

(c)In 2007, Enercon GmbH filed a petition under the Companies Act, 1956 in the Company Law Board, Principal Bench, New Delhi alleging

oppression and mismanagement of the affairs of the applicant company by the Mehra group members. On 29.10.2007 the Company Law Board

passed an interim order which directed ....""Status quo with regard to all the issues pending in the proceeding should be maintained and no action in

relation to the same shall be taken"" (emphasis supplied). CLB further directed that ......""No changes shall be brought about in the managerial set up

and their responsibilities."" On 19.5.2008 the CLB passed a further order stating that no further board meetings of the applicant company should be

convened without the leave of the Company Law Board thus freezing all the meetings except the day to day activities of the applicant company.

(d) The said revocation applications have been filed from January 2009. They were filed in the name of the applicant company and were signed by

Mr. Yogesh Mehra, the Managing Director of the applicant company. The counter statements were filed nearly after a year later by the Respondent.

Along with the counter statement, miscellaneous applications were also filed questioning the locus standi of Mr. Yogesh Mehra to sign the said

revocation applications for and on behalf of the applicant company. Mr. Yogesh Mehra has signed the revocation applications on the strength of a

Board resolution dated 26.4. 2007 which is quite evidently prior to the orders passed by the CLB dated 29-10-2007.

(e) The main arguments of the Respondent are as follows:

•The Board resolution dated 26.4. 2007, by which Mr. Yogesh Mehra is authorized to file proceedings on behalf of the applicant company is bad in

law since it falls foul of the orders dated 29.10.2007 and 19.5.2008 passed by the CLB;

•The Board resolution only authorizes Mr. Yogesh Mehra to manage day to day activities of the applicant company and under the general powers,

to defend the Company and file suits on behalf of the company on matters that may arise out of contractual laws, corporate laws, taxation laws or

any other statutory acts"" but not to initiate these revocation proceedings;

•Mr. Yogesh Mehra having filed a suit in a derivative capacity in the Bombay High Court could not now file this proceeding on behalf of the

applicant company;

•That the validity of the Board resolution has been challenged before the Company Law Board.

•This Appellate Board having been formed substituting for the High Court as regards finalizing the applications for revocation of patents, this

Appellate Board like the High Court has the full powers to decide on all the matters of law and those connected matters of legal disputes under CPC;

(f) The aforesaid contentions have been refuted by the applicant. The applicant's senior counsel referred to the Supreme Court of India case in ""Patel

Roadways Ltd. v. Birla Yamaha Ltd., (2000) 4 SCC 91"" to show how the Hon'ble Supreme Court of India has decided about ""a suit"".

(g) On perusing the entire details available in the records, it is seen that Mr. Mehra was authorized by the Board resolution dated 26-4-2007 to sign the

pleadings i.e the revocation applications. The present revocation applications have been signed by Mr. Mehra by virtue of the said Board resolution

dated 26.4.2007 which empowers Mr. Mehra to do so as is clear from the contents of the resolution produced before us. This Appellate Board cannot

decide upon the validity, legality and propriety of this Board resolution dated 26.4.2007 and this Appellate Board, in the absence of any judgment or

order of a competent Court of Law declaring the resolution to be null and void or staying the resolution, has to proceed on the footing and directions

given therein and assume that the said resolution dated 26.4.2007 is perfectly valid and legal. Counsel for the Respondent during the course of

arguments sought to urge grounds in support of the proposition that the resolution dated 26.4.2007 was not proper and legal. However as stated

hereinbefore the legality and/or validity of the Board resolution dated 26.4.2007 cannot be questioned in the present proceedings which are instituted

under the provisions of Section 64 of the Act. The jurisdiction to test the validity and legality of the Board resolution does not rest with this Appellate

Board. If that be so, then the obvious conclusion is that Mr. Mehra by virtue of the resolution dated 26.4.2007 is fully empowered to sign the suits /

pleadings including all these revocation applications. As such there is no substance in the contention of the Respondent that Mr. Mehra has no

authority to sign the pleadings. Further the contention of the Respondent is wrong that the applicant company cannot maintain the present revocation

applications.

(h) It was further contended by the counsel for the Respondent that the present proceeding is not a suit and as such the resolution dated 26.4.2007

cannot be taken to have empowered Mr. Mehra to sign the same. This argument too is without any substance. It cannot be said that the present

proceeding is not a suit especially in the light of the arguments of the counsel of the Respondent made already, that this Appellate Board is a Court for

all practical purposes, having regard to the nature of the powers and jurisdiction vested in it by statute, which appears that the Respondent is

contradicting his own arguments made already before us. Reliance can be placed in this regard on the law laid down by the Supreme Court of India in

Patel Roadways Ltd. v. Birla Yamaha Ltd.,: (2000) 4 SCC 91. The Hon'ble Supreme Court at paragraph 48 and 49 observed as follows:

(i) Suit, Action - 'Suit' is a term of wider signification than action; it may include proceedings on a petition.

From the above it is clear that the terms ""suit"" is a generic term taking within its sweep all proceedings initiated by a part for realization of a right

vested in him under law. The meaning of the term ""suit"" also depends on the context of its user which in turn, amongst other things, depends on the

Act or the rule in which it is used. No doubt the proceeding before a National Commission is ordinarily a summary proceeding and in an appropriate

case where the Commission feels that the issues raised by the parties are too contentions to be decided in a summary proceeding it may refer the

parties to a civil court... A proceeding before the National Commission, in our considered view, comes within the term ""suit.

(j) Therefore, as can be seen from the Supreme Court ruling, the term ""suit"" is not to be strictly construed but construed in the manner in which it is

used. The term ""suit"" has been used in the Board resolution in the context of 'initiation of proceedings' and has to be liberally construed. That apart, the

above mentioned Supreme Court decision, and particularly the admission of the counsel for the Respondent that this Appellate Board is a Court,

clearly establishes that the proceedings before this Appellate Board would also be in the nature of a suit and as such it is clear that Mr. Mehra is

competent to sign the present revocation applications.

(k) As regards the derivative action, the circumstances in which the same were filed have no bearing on the present proceedings. The mere filing of a

derivative action cannot and does not act as estoppel of Mr. Yogesh Mehra from filing these revocation applications. The argument of the counsel for

the Respondent in this regard is therefore completely irrelevant and not germane to the issue as to whether Mr. Mehra has the authority to sign the

present proceedings.

(l) It was next contended that Enercon GmbH has filed an application before the Company Law Board, New Delhi praying for a stay of the operation

of the Board resolution dated 26.4.2007. The said application was filed on 5.10. 2010. The said application came up for admission on 19.10. 2010

wherein a stay of the operation of the resolution was sought. The Company Law Board has however not granted any interim order. Therefore, as on

date, the Board resolution is valid and subsisting. It has not been set aside or stayed by any court / judicial body. Under these circumstances, it cannot

be said that Mr. Mehra has no locus or authority to sign the revocation applications on the strength of the resolution dated 26.4.2007. As such it cannot

also be held that the applicant company is not a person within the meaning of Sections 2(1)(s) or 64 of the Act.

(m) Lastly, reliance by the Respondent on the interim orders passed by the CLB dated 29.10.2007 and 19.5.2008 is completely misconceived and

misconstrued for the sole reason that these orders have been passed after the resolution dated 26.4.2007 and cannot in any manner have any

relevance on the issue as to whether Mr. Mehra has the authority to sign the revocation applications in the present case, particularly when this Board

resolution has not been made null and void. The Miscellaneous Petition No. 64/2010 is therefore dismissed.

Basics and objects of the invention to understand the background and nomenclature in respect of ""Pulse inverter and a wind power installation

having the same"" are: -

The synchronous generator with the intermediate DC circuit incurred high costs and had poor level of electrical efficiency as the output flows by way

of a converter, whose efficiency was much lower than the efficiency of the variable speed generators. These generators use the converters in the

rotor circuit, but the modern technology uses the rectifiers and converters, which are cost effective, having the overall electrical efficiency equivalent

to that of the generators and this has seen the application of this invention in the wind power installation technology, particularly, this type of modern

inverters use pulse width modulation technique to eliminate the harmonics. These known PWM inverters use the constant switching frequency or

pulse duty cycle, which is also referred to as pulse frequency or pulse repetition rate for producing a sinusoidal alternating current wherein the pulse

frequency variation is dependent on the configuration of the alternating current to be produced, and the pulse frequency is at a minimum, with the

switching frequency being at maximum in the region of passage through the zero of the alternating current produced and the switching frequency is at

a minimum, with the pulse frequency being at maximum in the region of the maximum amplitude of the alternating current.

Further in this case there are few words, such as inverter, pulse width modulation and the like, the meaning of which should be clearly understood

first, along with its function and with this view, certain technical information about these phrases have been slightly elucidated here for reference.

Wind turbines are designed to produce electrical energy. They are designed so that they yield maximum power output at wind speeds around 15 mps.

(30 knots). In case of stronger winds it is necessary to waste part of the excess wind energy in order to avoid damage to the wind turbine. All wind

turbines therefore come with some sort of power control. There are different ways of doing this safely on modern wind turbines.

In wind power generation system the grid-connected inverter is an important section for energy conversion and transmission, of which the

performance has a direct influence on the entire wind power generation system. Inverter is the device which converts the constant voltage into the

alternating voltage of constant frequency. For instance 24 or 48 Volts of DC voltage is converted into AC voltage 220 Volts of 50 Hz frequency and

this arrangement of circuit is called as inverter circuit, but generally categorized under converter circuits. The process is based on the cutting extra

voltage and further generating pulses of constant frequency.

The different inverters have voltage conversion process as follows:

1 Rectangular alternating pulse. Such inverters are the most inexpensive and can be used for power supply of the most appliances. However some

devices (like drill) will be warming while operation.

2 Quasi-sinusoid. Such pulse is similar to the normal sinusoid but has some small ""teeth"". These devices are not expensive, but allow supplying almost

all known electric appliances excluding some high technological measuring and other scientific equipment, etc.

3 Sinusoid. These devices are expensive, but only used in industry for power supply of high sensitive equipment.

Wind generator voltage control methods are well known so as to efficiently utilize the wind power which is prone to fluctuation every moment.

Boost chopper circuit with a single switching device is the choice for power control that provides an improved efficiency. Since the wind power

fluctuates with wind velocity, the generator output voltage and frequency vary continuously. This varying AC voltage is rectified into DC using a diode

bridge rectifier and the DC voltage is then regulated to obtain constant voltage by controlling the duty ratio of a DC/DC boost converter. The DC

voltage is inverted to get the desired AC voltage and frequency employing a PWM inverter as shown below in fig.1:

Fig.1. PWM inverter

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Boost Chopper. The conversion of rectified DC voltage to any specified DC output voltage can be carried out employing a DC-DC Converter or

chopper circuit.

PWM Inverter: For providing electric power to industrial applications in the form of AC, the DC output of Boost Chopper is inverted in a three

phase inverter. Gating signals for PWM Inverter devices are generated employing a Sinusoidal Pulse Width Modulation Technique (SPWM), by

comparing a sinusoidal reference signal with a triangular carrier wave. The frequency of reference signal 'f r' determines the inverter output

frequency 'f O' and its peak amplitude controls the modulation index 'M' and this in turn the RMS output voltage, VO.

The following figures show the boost chopper output voltage for different values of wind velocity. The chopper output voltage seen here is

508volts constant. This is given to SPWM inverter and its output voltage form is shown below as an example.

Fig.2. Boost Chopper Output Voltage

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required.)

Fig.3. SPWM Inverter Output Voltage is shown below:

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required.)

Fig.4. Sinusoidal Output Voltage of SPWM Inverter shown below:

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required.)

Figs. 3 & 4 show the inverter output voltage of 415Volt AC for different values of wind velocity, and this is the constant ac voltage that is given to

load.

So we notice that as the wind velocity varies the output voltage of PMSG also varies. The varying voltage is rectified into DC and is stepped up in

a boost chopper producing a constant DC voltage irrespective of wind velocities. The constant DC voltage from the chopper is inverted in a Sinusoidal

Pulse Width Modulated (SPWM) Inverter to obtain an AC output of constant voltage and constant frequency which is then fed to the grid for use by

different load units according to the need.

Changing the square wave as described above is an example of pulse-width modulation (PWM). Modulating, or regulating the width of a square-

wave pulse is often used as a method of regulating or adjusting an inverter's output voltage. When voltage control is not required, a fixed pulse width

can be selected to reduce or eliminate selected harmonics. Harmonic elimination techniques are generally applied to the lowest harmonics because

filtering is more effective at high frequencies than at low frequencies. Multiple pulse-width or carrier based PWM control schemes produce

waveforms that are composed of many narrow pulses. The frequency represented by the number of narrow pulses per second is called the switching

frequency or carrier frequency. These control schemes are often used in variable-frequency motor control inverters because they allow a wide range

of output voltage and frequency adjustment while also improving the quality of the waveform. With these background of knowledge, let us look at the

arguments of the applicant and that of the Respondent.

Arguments by applicants

The counsel for the Applicant started his argument inviting our attention to the definition of the ""patent"" as under Section 2(1)(m), ""invention"" as under

Section 2(1)(j), ""inventive step"" as under Section 2(1)(ja), respectively of the Act. The counsel submitted that how the applicant satisfies the condition

of ""person interested"" and what is the definition of ""person interested"" as given in Section 2(1)(t) of the Act. Then the counsel submitted that inventive

step being one of the ground, its definition and analysis with respect to the claims, particularly the scope of definition of the claims, from which the

feature regarding the technical advance or economic significance or both and that makes the invention not obvious to a person skilled in the Article

Then the counsel submitted his arguments as followed:

A. Claims of the patent lack inventive step:

(a) A Patent is granted for a single invention only. Accordingly the claims and the complete specification shall relate to a single inventive concept.

(b) The question as to whether the invention as claimed, is obvious has to be judged from the view point of the person skilled in the Article

(c) Power is generated from various sources like hydroelectric power stations, thermal power stations etc, from which the power is fed into the grid or

household which operates in India at an Ac voltage of 220 volts and 50 Hz alternating current.

(d) Higher the wind speed, higher the rotor speed of the wind turbine and similarly, higher the rotor speed, higher the power output, but subject to the

limits beyond which the power will be constant. The varying power cannot be fed into the grid because it will be at a different or varying frequency

and not at 50 Hz.

(e) One way is that irrespective of the wind speed, the wind turbine will operate or rotate at the constant speed and generate the constant output at

50Hz. There is wastage of extra wind energy going unutilized. Another way is that instead of wasting the wind energy, wind turbine is operated at

varying speeds and electronic means are used to optimise the wind energy and ultimately to feed constant power.

(f) The variable frequency output being variable alternating current is rectified into direct current, which is again converted by inverter into fixed

frequency AC to be fed into the grid.

(g) The DC into AC conversion in the above step is done by using PWM technique to have the AC output with fixed frequency for feeding into the

grid.

(h) The invention is directed towards an improved PWM inverter having its application in the field of wind turbine generators, whereas this PWM

technique is known in the art, which has been acknowledged by the Respondent as given in the pages 2 & 3 of the specification.

(i) Known inverters with constant switching frequency has power loss up to 2% of the total power generated, whereas with reduction in switching

frequency, power loss can be minimised, but simultaneously increases troublesome harmonics in the output. With increase in the switching frequency,

power loss rises, but there is reduction in the harmonics.

(j) Making the switching frequency variable in dependence on the configuration of the alternating current to be generated, wherein the switching

frequency is at maximum in the region of passage through the zero of the alternating current produced and the switching frequency is at a minimum, in

the region of maximum amplitude of alternating current.

The applicant's counsel continued his arguments next based on the grounds relied in the revocation application and submitted as follows;

(a) The question as to whether the invention as claimed, is obvious has to be judged from the view point of the person skilled in the Article The subject

matter of the claims relates to power conversion involving an inverter with the variable switching frequency having a specific pattern in which the

frequency is varied using the controllers, in accordance with the AC to be produced. So an electrical engineer with the knowledge of power

converters like inverters will be the person skilled in the Article

(b) The features claimed in the claim 1 are:

i. Pulse frequency varies in response to the AC to be produced.

ii. The switching frequency is higher at the region of passage through the zero of the alternating current produced than the switching frequency at the

minimum, in the region of the maximum amplitude of the alternating current.

iii. The switching frequency is a multiple greater in the region of passage through the zero of the alternating current produced than the switching

frequency at the maximum amplitude region of the alternating current to be produced.

iv. The lowest switching frequency in the maximum amplitude region of AC is at least some 100 Hz.

(c) The specification clearly states from fig.2 that ""making the switching frequency variable"" more specifically in dependence on the alternating

current to be generated. Further the switching frequency is at a maximum in the region of passage through the zero of the alternating current

produced than the switching frequency is at a minimum, in the region of the maximum amplitude of the alternating current.

(d) The above reference from the specification clearly shows that the real inventive step lies in the step or the feature mentioned in para 'b'(i) & (ii)

above, which is actually responsible for the optimisation of the power and reduction in troublesome harmonics, that being the object of the invention.

(e) On page 5 of the patent specification (page 17 of the revocation application) last paragraph, the Respondent has merely stated the additional

features at 'b' (iii) & (iv) above from claim 1, in the statement of invention (to be in conformity with the claim 1, in view of the omnibus claim 6) but

otherwise, there is no supporting description in the said specification to state that these additional features given in the 'b'(iii)(iv) contribute to the

inventive step in the claim to achieve the object of the invention claimed in the impugned patent. It was argued by the counsel, that if one frequency is

greater than the other as disclosed in the prior art, the expression, 'multiple' thereof is covered in the disclosure automatically. Therefore the features

'b'(iii) & (iv) will not form part of the inventive step or concept as evident in the impugned specification. It does not teach or show any supporting

description and does not involve any technical advance and in any case these features of the invention would be obvious to the person skilled in the art

having normal skills. Hence the claim 1 as worded does not involve any inventive step. The invention is obvious.

(f) The counsel submitted that to prove the ground of obviousness, it is to be clearly shown that the features do not teach or show any technical

advance and in any case these features of the invention would be obvious to the person skilled in the art having normal skills. The counsel also

referred to the US patent 4,520,437 (hereinafter referred to as US '437 patent). This US patent relates to a pulse width modulated inverter for

conversion of DC into sinusoidal AC signal (Col.1 lines 7 to 12). This US patent also describes about the problems faced in the prior Article (Col. 1

lines 25 to 40).

(g) In order to overcome this disadvantage, the prior art inverter also employs variable pulse switching frequency for the inverter switches to generate

the sinusoidal waveform as given in the impugned patent. (Col.1 lines 44 to 60).

(h) This US '437 patent discloses about the time intervals at successive positive and negative pulses generated by the synthesiser are selected so that

the frequency of the carrier varies from a high frequency at the zero crossings of the generated sinusoid to a lower frequency at the peak value of the

generated sinusoid.(Col.1 lines 54 to 60.)

(i) The description in Col.3 lines 41 to 57 of this US '437 patent, shows, while referring to waveform of fig. 2, the switched waveform is both pulse

width modulated in response to the timing signals supplied by the microcomputer drive circuit 30.

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(j) The carrier frequency is varied each half cycle from some maximum value at the zero crossing 301 of the derived sine wave 300, as shown in fig.3

to a minimum value as the sine wave approaches its peak value 302. These modulation techniques advantageously minimize the low frequency

harmonic content and reduce the amplitude of the harmonics in the vicinity of the carrier frequency by distributing them over a range of frequencies,

rather than a single frequency and permit the use of smaller output filter components 29. The synthesiser waveform 300, as shown in fig.3 is

approximately a sinusoidal waveform with the effects of distortion due to pulse filtering. From this description as well as the details available in fig. 2

& 3 of the US '437 patent it is very clearly seen that there is variation of pulse frequency with respect to configuration of sinusoid AC. Further it is

also evident that the pulse frequencies in fig. 2 are maximum, corresponding to points 301 in fig.3. The pulse frequencies in fig.2 are minimum

corresponding to 302 in fig.3. Lastly it is also to be noted from Col.8 lines 28 to 34 of the US '437 description, it is seen that, the carrier frequency of

the pulse signal is varied from a maximum value at the zero crossing point of the synthesized sinusoid to a minimum value as the sine wave

approaches its peak value, to advantageously and significantly reduce the harmonic distortion occurring at the output of the synthesizer output filter.

From these description it is very clear that the US '437 patent teaches that it is advantageous to move from constant to variable switching frequency

and that too in a manner that frequency is maximum at zero crossings (same as the passage through zero in the impugned patent) of the generated

sinusoid (AC) and minimum at the peak value (which is same as maximum amplitude region in the impugned patent) of the generated sinusoid (AC).

This shows that the variation of switching frequency is in dependence to the shape or configuration of the AC to be generated as well as the regions

where the switching frequency will be maximum and minimum are well known. This is nothing but the features at para 'b' (i) & (ii) above of the claim

1 which are clearly present in the US '437 patent. Therefore the claim 1 does not involve an inventive step in view of the US '437 patent alone as

there is no technical advance in the claimed invention compared to the existing knowledge in the US '437 patent and hence for this reason alone the

patent is liable to be revoked.

(k) It was submitted earlier that the features 'b' (iii) & (iv) above do not contribute towards the inventive step or concept in the impugned specification.

As such these features do not teach or show any technical advance to the state of the art features available. For a moment assuming that these

features do contribute towards the inventive step, the said features are known in US 5,559,419 patent (hereinafter referred to as US '419 patent). This

patent is dated 24-9-1996 (filed in 1994) which is very much before the priority date of the impugned invention. This prior art discloses the inverter

apparatus for induction machines relating to the inverter which can be controlled in a pulse width modulated manner(Col.2 lines 32 to 35) and the

principal claim of the impugned patent is also directed to the pulse inverter. This US '419 discloses that, ""switching frequencies of 20 kHz or greater

are desirable to reduce acoustic noise and to obtain high current regulation bandwidth. Soft switched inverters such as the resonant dc link converter

operate at considerably higher switching frequencies. (Col.10 lines 64 to 67 and Col.11 lines 1 to 4). A balanced polyphase 1 to 2 kHz signal with low

harmonic distortion can be readily synthesized in addition to the fundamental excitation when using 5 kHz to 20 kHz switching, in the manner as

described above and illustrated in fig. 4 & 5 accompanying the US '419 patent. Preferably, the inverter switching frequency should be at least 5 to 10

times the signal frequency. Further the signal frequency should be at least 5 to 10 times the fundamental frequency of the drive power provided to the

motor. (Col.11 lines 5 to 13). This shows that if the signal frequency to be generated is 50Hz the preferred minimum switching frequency is 5 to 10

times i.e. 250 Hz or 500Hz which is nothing but ""at least some 100Hz. Thus said feature of 'b' (iii) above claimed in claim 1is present in US '419 patent

which discloses that: ""in larger drive systems(>100KW), inverter switching frequencies of upto frequencies of 60Hz or higher, synthesis of a sufficiently high signal frequency via the inverter may not be possible. In such cases additional

dedicated circuitry may be desirable to generate the signals at frequencies sufficiently higher than the inverter switching e. g 5 to 10 K Hz. The above

information and reference clearly indicates that for larger drive systems inverters may have switching frequencies greater i.e. 5 to 10 kHz. This is

definitely a multiple greater than 250 or 500Hz. Thus on or before the priority date of the invention, a skilled person in the art would have easily

known, using the information available in the US '419 patent as to what are the switching frequency ranges in which a pulse inverter may operate and

he does not have to do any inventive work to find or say or show even, that the said frequency at zero crossing points of the AC is a multiple greater

than 250 to 500Hz. Thus it is also possible for a skilled person in the art, to easily combine the teachings of the US '437 patent and the US '419 patent

and find to arrive at this invention point and also to prove that claim 1 does not show any technical advance over the existing knowledge in the said

prior art seen in the said US patents.

Hence the counsel submitted that the claim 1 as worded does not involve any inventive step and the invention is obvious.

(l) The counsel then referred to the Windsurfing International Inc v. Tabur Marine (Great Britain) Ltd 1985 RPC 59 and said that the question of

obviousness will have to considered taking the following four steps, namely,

i. Identifying the inventive concept;

ii. What is the common general knowledge that is known to the skilled person in the art;

iii. Identifying the differences between the cited matter and alleged invention;

iv. To decide that these steps or differences would become an obvious invention to the skilled person in the art, without having any knowledge of the

present invention.

(m) Applying these principles to the case in hand the counsel submitted:

i. Inventive concept is moving from constant switching frequency to variable switching frequency and that too in a manner that the switching

frequency varied is maximum at the passage through zero points of the generated sinusoid waveform (AC) and minimum at the maximum amplitude

region of the generated sinusoid waveform (AC).

ii. The prior art (in US '437 patent) clearly discloses as has been shown earlier, that at the priority date of the patent, the skilled person knew as part of

the knowledge existing since 1985, the inventive concept shown in step (i) above (Col.3 lines41 to 57; Col.8 lines 28 to 38).

iii. There being no difference between the inventive concept and the existing knowledge, which indicates that there is no technical advance in the

impugned patent.

iv. In view of the fact that there is no difference between the inventive concept and the existing knowledge in the prior art, there is no need to go to

the step (iv), as the skilled person in the art, would arrive at this invention using the existing knowledge in the available prior art and find this invention

obvious, without even having any knowledge of the present invention.

(n) A patent is granted for a single invention only. Accordingly the claims and the complete specification shall relate to a single inventive concept. In

this case then there shall be only one common inventive step/concept pervading all the claims. Since that step or the concept claimed in claim 1 has

been shown to be obvious, all the dependent claims which only add minor methods of variations will not impart any inventive step to the dependent

claims. Hence the counsel contended that the impugned patent has to be revoked on this ground alone.

(o) The counsel submitted that the Respondent has reiterated in the counter statement that from the specification it is very clearly shown that the real

inventive step lies in the step or the feature mentioned in para 'b'(i) & (ii) above, which is actually responsible for the optimisation of the power and

reduction in troublesome harmonics, that being the object of the invention, whereas the features in 'b' (iii) & (iv) above in the claim 1 do not contribute

towards the inventive step or concept in the impugned specification. As such these features do not seem to be teaching or showing any technical

advance to the state of the art features available.

(p) The counsel submitted that the Respondent stated that US '437 patent has already been considered by the US and European patent offices before

granting the equivalent of the impugned patent in India and the claims granted in EPO and US are narrower than the granted claims in India.

(q) USPTO and EPO did not consider the cited US '419 patent relied by the applicant herein, as the statutory test of inventive step is quite different in

EPO and US from India. The provisions regarding inventive step in US PTO and EPO is not like the provisions contained in the Section 2(1)(ja) of the

Act which requires, ""technical advance over the existing knowledge"" before going into the question whether the invention would be obvious to a skilled

person in the Article Hence the fact that the patent is granted in US PTO and EPO is not relevant to determine the validity of the impugned patent in

India.

(r) The counsel submitted that the Respondent has reiterated in the counter statement that from the specification it is very clearly shown that the real

inventive step lies in the step or the feature mentioned in para 'b'(i) & (ii) above, which is actually responsible for the optimisation of the power and

reduction in troublesome harmonics, that being the object of the invention and whereas the features in 'b' (iii) & (iv) above in the claim 1 do not to

contribute towards the inventive step or concept in the impugned specification. This again reinforces the contention of the applicant as to the lack of

inventive step, since the features at 'b' (i) (ii) are disclosed in US'437 patent and simultaneously the US'419 patent also discloses the features of 'b' (iii)

and (iv). Thus it is possible for a skilled person in the art, to easily combine the teachings of US '437 patent and US '419 patent and find to arrive at

this invention point to prove that claim 1 does not show any technical advance over the existing knowledge in the said prior art seen in the said US

patents. Hence the claim 1 as worded does not involve any inventive step. The invention is obvious.

(s) The counsel submitted that the Respondent has stated in the counter statement that US '437 patent does not show the feature F4 according to para

5.4 of the counter statement, wherein the F4 is about the feature regarding ""the lowest pulse frequency in the region of the maximum amplitude is at

least some 100 Hz."" Here the Respondent has stated that there is the main difference that the impugned patent varies the switching frequency

according to the output current whereas in the US '437 patent the invention is about varying according to the voltage. Here again the counsel argued

that this difference does not matter to the person skilled in the art, because both voltage and current have sinusoidal form and operate, for a given load

at a frequency of 50 Hz. Thus the expression variation according to the configuration of the alternating current will hold good for voltage also. Even if

the current varies according to the load, the variation will be in amplitude i.e. height of the peak of the curve and not in frequency or shape of the

curve (sinusoidal). This fact is very well known to the person skilled in the art and he would find such a difference absolutely obvious to him. Further

the counsel argued that neither in the specification nor in the counter statement, the Respondent has ever stated that, because the switching was

occurring according to the current and not voltage, the invention in achieving the object of reducing the harmonics and the power losses, then the

objection of the Respondent is totally incorrect and baseless.

(t) It was submitted that the Respondent had stated in the counterstatement, that, a sinusoidal alternating current was obtained, because of current

control and not voltage control and in the event of a short circuit, this is obtained by an appropriate control by varying the pulse frequency as defined in

the claim 1. Again this fact is pointed out, that, there is no supporting description or even a hint for current control or short circuit situation in the

specification. Hence there is an insufficiency in the description regarding the invention. It was argued that the Respondent cannot take such a

defence, in the absence of any clear and absolute supporting description in the specification for the above feature.

(u) It was submitted that the stand taken by the Respondent that modulation in US '437 patent is performed by a micro controller and also performs a

series of other functions, which allegedly leads to the conclusion that it produces sinusoidal voltage and not sinusoidal current is not correct. In fact

that the impugned patent uses a micro controller, because it is not manually possible to perform modulation for a pulse inverter.

(v) The counsel submitted that Respondent stated that in contrast to the teaching of the US '437 patent, the variation of the pulse frequency according

to the subject matter of claim 1 is dependent on the configuration of the alternating current and it is only by this configuration it is possible to greatly

reduce power loss as well as any harmonics. The applicant's counsel submitted that this statement in the counter statement is different from what is

stated in the specification. The expression ""only by this configuration does not appear anywhere in the specification. The counsel submitted that if this

statement is true, the whole inventive concept according to the impugned patent might have changed. As it has not happened like that, the

Respondent's contention is incorrect and totally without any support. Hence the description is insufficient and the whole specification suffers from

insufficiency of description.

(w) The counsel relied on both the experts affidavits submitted in evidence to which no evidence or affidavit in reply was filed by the Respondent.

(x) A miscellaneous petition has been filed on 15th September 2010 with revised set of claims amending the claims as granted. It was also pointed out

that the amendments claims now filed are the same as granted in EPO by limiting the scope of the claims which are narrower than the claims as

granted in India. Prayer is made by Respondent to Hon'ble Board to consider these revised and amended claims as filed under Section 58 of the Act,

in case the Hon'ble Board decides to conclude that the granted claims cannot be held valid and revoking the entire patent.

(y) Particular emphasis was laid on the affidavit of Dr. B.E. Kushare who cited a US patent 3376490 (here after referred to as '490 patent) to state

that the features of the claim 1 in the impugned patent is not novel. The deponent has tried to show as to how the claim 1 is anticipated and is obvious

in view of the fact the US '490 patent clearly showing in its fig.3 about the variation of pulse frequency being dependent on the configuration of the

AC output (Col.3 lines24 to 41 read with fig.3).

(z) The counsel referred to ""Titanium Metals Corp. Of America V. Donald B. Banner 778 F.2d 775, where the Court of Appeals laid down that it is

also an elementary principle of patent law that when, as by a recitation of ranges or otherwise, claim covers several compositions, the claim is

anticipated"" if one of them is in the prior Article It was submitted that the claim 2 involves a particular range of switching frequency i.e. 14 -18 kHz in

the passage through zero range and 500 Hz - 2kHz at the maximum amplitude region of the AC to be produced. There is no supportive description in

the specification which suggests that these ranges particularly contribute in any way towards the inventive step. The US '490 patent discloses 2kHz as

the low range frequency (at the maximum amplitude region) and passage through zero point, the US '490 patent discloses there is no limitation on the

frequency of the pulses at the beginning or at the end of each wave train. Preferable value for higher range is 10 kHz (Col.3, lines 34 -41). These

claimed ranges were also disclosed in US '419 patent as was also supported by the expert Dr. Kushare in his affidavit. Therefore there is no inventive

step in the claim 2.

Further, it was pointed out that despite being given time extensively, the Respondent has not produced any affidavit of an expert to counter the

expert affidavits submitted in favour of the applicant for revocation. In this respect counsel for the Respondent confirmed that they will not be

submitting or relying on any expert affidavit / evidence.

The counsel for the Respondent started his arguments first referring to the M.P No. 64 of 2010, where the Respondent had challenged Mr.

Yogesh Mehra's competency to depose an affidavit and has no locus standi to initiate revocation application on behalf of Enercon (India) Limited. The

counsel said that the matter was heard and decided that this matter would be disposed off along with the main application. When they appealed

against this order, the Hon'ble Madras High Court had also directed the Appellate Board to consider this issue in the miscellaneous petition along with

the other matters in the main application. Hence the request was made to decide the locus standi issue along with other grounds of the revocation

application.

Without prejudice to the above issue, the counsel submitted as follows:

(a) At the very outset, the Respondent submitted that the applicant's contentions are based on conjectures and surmises and are misleading in nature

and denied in toto. Further the applicant based on some prior art to erroneously conclude that the subject invention is obvious and does not involve an

inventive step and also the description in the specification is insufficient. In this connection the applicants counsel cited the fact that in many countries

the patent has been granted for the subject invention and also questioned that if it is not a real invention, how a patent would have been granted in so

many countries.

(b) The present patent is directed to pulse inverter. A pulse inverter with variable pulse frequency for producing a sinusoidal AC current,

characterised in that,

i. pulse frequency variation is dependent on the configuration of the AC current to be produced;

ii. the pulse frequency at the passages through zero of the alternating current to be produced is a multiple greater than in the region of the maximum

amplitude of the alternating current and iii. the lowest pulse frequency in the region of the maximum amplitude of the alternating current is at least

some 100Hz.

(c) The Respondent filed the counter statement and referred to the novelty and inventive step of the claims 1 to 5 of the impugned patent against the

cited patents US '437 and US '419 patent. It was further submitted that the invention claimed in the claims 1 to 5 of the impugned patent is based on

the idea of not using the static switching frequency in the pulse inverter, but to provide a variable switching frequency which can be increased to be

able to provide a more accurate sinusoidal alternating output current and can be reduced in those areas where it is actually needed. So the invention

does not become obvious to a person skilled in the Article

(d) The counsel for the Respondent stated that US '437 patent has already been considered by the US and European patent offices before granting

the equivalent of the impugned patent in India and the claims allowed in EPO and US are narrower than the granted claims in India. Even in India the

Patent Office considered these citations and after a strict examination procedure only the patent was granted. Similarly USPTO granted the US

patent 6256212 and the EPO granted the EP patent 1027767 but after the initial application was opposed and upheld with amended claims. The

Respondent submits that the filing of the revocation application by the applicant is more of a strategic move apart from being frivolous and vexatious

and hence requested to take cognizance of the above submissions while deciding on the issue of the locus standi of the applicant.

(e) The Respondent pointed out that the applicant has not relied on the grounds of the novelty of the subject patent and so it is admitted that the

subject patent does not lack novelty thereof.

Inventive step

1 It was submitted by the Respondent that the invention claimed in the claims 1 to 5 of the impugned patent is based on the idea of not using the static

switching frequency in the pulse inverter, but to provide a variable switching frequency which can be increased to be able to provide a more accurate

sinusoidal alternating output current and can be reduced in those areas where it is actually needed. Therefore it is very clear that the inventive concept

is moving from constant switching frequency to variable switching frequency and further that the switching frequency varied is maximum at the

passage through zero points of the generated AC current and minimum at the maximum amplitude region of the generated AC current. Therefore all

the averments made by the applicant are denied.

2 The counsel submitted that the US '437 patent relates to a power conversion circuit for synthesising a sine wave with programmed amplitude

control. The counsel also pointed out that the US '437 patent has already been considered by the US and European patent offices before granting the

equivalent of the impugned patent in India and even in India the Patent Office considered these citations and after a strict examination procedure only,

the patent was granted. It was further pointed out that a sinusoidal alternating current was obtained from the said pulse inverter circuit, whereas the

US '437 patent is directed to the production or generation of a sinusoidal voltage, which is main difference, so as to say, that not the voltage is

controlled but the current is controlled to obtain the sinusoidal AC current and because of current control (and not voltage control) in the event of a

short circuit, this is obtained by an appropriate control by varying the pulse frequency as defined in the claim 1. Therefore the biggest advantage is

providing the highest possible power and much more power than an inverter known in the Article

3 According to the teachings of US '437 patent the modulation is performed by a micro controller and also performs a series of other functions, which

allegedly leads to produce a sinusoidal voltage and not sinusoidal current. In fact, the impugned patent uses a micro controller, because it is not

manually possible to perform modulation for a pulse inverter. So the variation of pulse frequency according to the subject matter of claim 1 is

dependent on the configuration of the alternating current and it is only by this configuration it is possible to greatly reduce power loss as well as any

harmonics in the output current.

Further the counsel submitted that the output voltage and the output current do not always correspond to each other, which becomes very apparent

in case of a short circuit on the output side. Consequently the US '437 patent needs to have a shutdown of the inverter completely or for a longer

period of time, which amounts to loss of power. But in the impugned case, in case of a short circuit, the output alternating current will also be limited

as the variation of the pulse frequency is dependent on the output alternating current. Therefore the pulse inverter can react to any false or short

circuits in the loads connected to the inverter.

5 The Respondent submitted that US 5559419 patent (here after referred to as US '419 patent) relates to a method and apparatus for transducerless

flux estimation in drives for induction machines. The drive system includes an inverter which is controlled in a pulse width modulated manner to

provide output voltage to the stator windings at the fundamental frequency and at the signal frequency. The inverter may also be controlled to provide

only the fundamental driver frequency power to the stator and a separate signal generator may be connected to inject the high frequency signal to the

stator winding (Col.2 lines 31 to 39). From this it is very clear that the inverter provides an output voltage at its output and it is therefore neither

producing a sinusoidal AC current nor is any pulse frequency variation dependent on the configuration of the output AC current. In the citations of

Col.11 lines 5 to 9 and lines 14 and 15 as well as in the entire teaching of the US '419 patent, there is absolutely no hint or indication that the pulse

frequency can be variable pulse frequency and that the pulse frequency at the passages through zero are a multiple of the frequency produced in the

region of the maximum amplitude of the alternating current. The counsel submitted that when the US '419 patent only teaches to provide a constant

pulse frequency, it is highly questionable as to why a person skilled in the art who is trying to improve a pulse inverter should consider the teaching of

the US '419 patent as being a prior Article Therefore the counsel questioned as to how even a skilled person in the art will ever consider a

combination of the teachings of the US '437 patent and US '419 patent, as such a combination can never lead to the subject matter of claim 1 as in

none of the two documents, a pulse inverter is described for producing a sinusoidal AC current. Furthermore, neither the US '437 patent nor the US

'419 patent discloses that a variation in the pulse frequency is dependent on the configuration of the alternating current. Hence the claim 1 is novel and

inventive.

6 Claim 2 is dependent on claim 1 and in turn relates to a pulse inverter. Neither the US '437 patent nor the US '419 patent discloses the features

mentioned in the claim 1. As the claim 1 is novel and has inventive step, the claim 2 is also novel.

7 Claim 3 relates to wind power installation with a pulse inverter and also to be noted that neither the US '437 patent nor the US '419 patent discloses

the features mentioned in the claim 1. Claim 3 is dependent on claims 1 and 2. As the claim 1 is novel and has inventive step, the claim 3 is also novel.

8 The Respondent submitted that the applicant has referred to the US patent No. 5225712 which relates to a wind turbine power converter which

smooths the output power from a variable speed wind turbine to reduce or to eliminate substantial power fluctuations on the output line. This US '712

patent does not relate to providing a pulse inverter with variable frequency as recited in the claim 1 of the subject patent. Claim 4 relates to an

arrangement of a plurality of wind power installations with a pulse inverter which are connected in mutually parallel relationship and claim 4 in turn is

dependent on claim 3 which in turn is dependent on claims 1or 2. So as the claims 1 to 3 is novel and inventive, the claim 4 is also novel and inventive.

9 Claim 5 is dependent on preceding claims 1and 2 and as the claims 1 and 2 are novel and inventive, claim 5 is also novel and inventive.

Scope of the claim1

The expression used ""some 100Hz"" is not just that but it is ""at least some 100 Hz"" which relates to a value which is larger than 100 Hz and it is more

so as the phrase ""at least some 100Hz"" contain the phrase ""at least"". Also the corresponding US patent granted has the same exact wording.

Sufficiency of description

The Respondent submitted that it is very clear for any person in the art how the feature ""multiple greater than"" can be understood. There shall be no

question that a person in the art is enabled to perform the invention as exact phrasing have been used in the impugned patent and the US patent

6256212 and the wordings are one and the same. On page 7, second paragraph of the impugned patent an example of the frequency in the region of

the maximum amplitude of the alternating current is given, namely, between 1kHz and 16 kHz. Therefore the person skilled in the art would have no

problem to determine what is multiple greater than this region, thus showing the description of the invention to be fully clear and fair to the person

skilled in the Article Thus the counsel finally prayed that the application for revocation be dismissed, simultaneously upholding the grant and declaring it

valid.

Reply to Respondent's arguments

a. The counsel submitted that the Respondent was giving the interpretations to the claim 1 by borrowing limitations and language which are neither

part of the claim nor of the specification.

b. It was submitted that the Respondent stated that the inverter in the US '437 patent generates voltage while the inverter in the impugned patent

generates alternating current, but it is to be understood clearly, that the voltage and current are so interlinked that what is produced is power output

and power is a function of voltage and current, whereas current is not produced sans voltage by inverter and vice-versa.

c. As regards the US '419 patent, the Respondent stated that it has motor as its load and as regards the US '437 patent, it does not talk about the wind

turbine. If this is the condition or line of argument, the counsel for the applicant reiterated, that, the principal claim 1 does not talk as to where from the

input is coming or in other way, does the claim 1 talk anything about where the output is going to or to be used and for what purpose? The only

claimed features are of a pulse inverter and how the circuit performs the switching function. Thus the words load or wind turbine, do not concern the

claim 1 at all.

d. When the Respondent stated that the US '437 patent is not a relevant citation document, it was pointed out that the same was marked and

considered as 'X' category document in the PCT International Search Report of the PCT application of the impugned patent, means it is a document

of particular relevance for anticipation and inventive step, taken alone. Thus the ISA, contrary to Respondent 's submission, considered the US '437

patent document as a relevant document for inventive step taken alone and this particular fact is known to the Respondent and aware of this report,

but purposefully chose not to disclose this information and tried to mislead the Hon'ble Board by saying that US '437 patent is not relevant.

e. In any case the applicant can rely on more than one prior art for proving obviousness and in that respect, the US '437 patent talks about synthesizing

a sine wave by conversion from DC to AC and there has been no mention as to where this output is fed into? But as far as the claim 1 is concerned, it

is discussing about an inverter only and not directing in the claim saying that the output of the inverter is fed into the grid or there are specific loads

connected to it, so as to differentiate the inverter in the impugned patent from the US '437 patent. Such limitations like grid or loads are neither present

in the claim 1 nor present in the specification. It is seen that the Respondent will not consider these limitations to claim 1 when it comes to a question

of infringement, but trying to bring in these limitations to avoid the invalidity of the patent when it is raised and / or questioned.

f. The Respondent has neither produced any affidavit to counter applicant's expert affidavit nor has given any response during oral arguments to the

contents of the said affidavits which were duly served on the Respondent along with the reply to the counterstatement and also referred to during the

arguments.

g. In the Windsurfing case the patentee tried to amend the claims at the last stage during the trial. The Court opined that claim amendment may be

made to overcome the objection of novelty. However if the impugned patent is lacking inventive step, no amendment can be made to include any

change in the inventive concept by such amendment. Unless there are surprising results such an amendment cannot be allowed. Moreover the

amendment cannot be used as a last minute tool to make the case survive the attack by converting a non-essential element into an essential element

by combining the dependent claims into the independent claims. Thus the amendment moved by the Respondent should not be allowed since there is

no inventive step in the impugned patent.

h. Finally the applicant's counsel ended his arguments with the prayer that as the impugned patent does not have any inventive step, the same may be

revoked.

We have heard the arguments of both the counsel and have gone through the pleadings and the documents filed in support thereof.

Person interested

In this case, the Respondent has raised a question of locus standi for the person who has filed the application for revocation for and on behalf of the

Petitioners that he is not authorized and is not ""the person interested"" to file a revocation petition. The Respondent has taken the ground that in terms

of the articles of association of the company, Mr. Yogesh Mehra, the Managing Director lacks the competence to file a revocation application for and

on behalf of the applicants for revoking the patent granted to the Respondent, as the reliance placed on the articles of association is wrong and the

power is not conferred on him to execute any such legal action, and more so when the matter is still pending before the company law board. The

applicant had stated that Mr. Yogesh Mehra, being the Managing Director has been authorized by the Board resolution dated 26th April 2007 to

defend and initiate suits and proceedings on behalf of the applicant and that in terms of the articles of association of the company, Mr. Yogesh Mehra,

being the Managing Director has the requisite locus standi to file and institute the revocation proceedings. Appellate Board has the power only to

check as to whether the applicant filing the revocation, namely the applicant company, herein M/s. Enercon (India) limited is a ""person interested"" or

not, according to the Act under which this proceeding has been initiated.

Now we wish to point out that this issue of locus standi of Mr. Mehra has already been discussed and decided earlier in Para 7(g) ante. The

Company Law Board having not granted any interim order after 29.10.2007 and 19.5.2008, as on date, the Board resolution is valid and subsisting. It

has not been set aside or stayed by any court / judicial body. Under these circumstances, it cannot be said that Mr. Mehra has no locus or authority to

sign the revocation applications on the strength of the resolution dated 26.4.2007. As such it cannot also be held that the applicant company is not a

person within the meaning of Sections 2(1)(s) or 64 of the Act.

Now we have to see whether the applicant is a person interested or not to file a revocation application. According to Section 2(1)(t) of the Act,

person interested"" is defined as below:

Person interested"" includes a person engaged in, or in promoting, research in the same field as that to which the invention relates;

The word or expression ""person interested"" appears under Sections 25 as well as 64 of the Act, dealing with opposition proceedings to the grant of

patent before the Controller and revocation proceedings before this Appellate Board. In fact the actions taking place in opposition proceeding is almost

analogous and similar to the revocation proceedings before this Appellate Board, excepting for the creation or constitution of an opposition Board

under Section 25(3) (b) of the Act, to examine and submit the recommendation to the Controller who is to hear the opposition parties. As per Patent

Law by P. Narayanan, it could be clearly seen or stated that there are three grounds upon which the opponent can establish his locus Standi to oppose

the grant of patent or to seek the revocation of the patent, which are mainly,

(1) possession of patents in the same field as the invention relates;

(2) manufacturing interest relating to a similar product being manufactured by the patentee; and

(3) trading interest..

In AIR 1983 DELHI 496 Ajay Industrial Corporation v. Shiro Kanao of Ibaraki city, para B in page 496, it was held that, ""person interested"" must

be a person who has a direct, present and tangible commercial interest which was injured or affected by the continuance of the patent on the register.

The applicant's counsel stated at the very beginning, that they are one of the foremost leaders in the wind energy sectors in India and they

manufacture and install wind turbines all over India and thus they are an interest person within the meaning of the Section 2(1)(t) as well as the

Section 64 of the Act. In view of this judgment, we have to check and find out whether this applicant is a person interested as per the requirement of

the Act under which these proceedings are taking place.

In Globe Industries Corporation's Patent (1977) R.P.C 563 in the Supreme Court of Judicature - Court of Appeal, Lord Justice Scarman observed

that, ""where the statute uses the words 'any person interested', the interest has to be genuine; the possibility of prejudice has to be genuine and in

addition, and quite independently, the Court must be satisfied that the opposition or the application for revocation, as the case may be, is not a frivolous,

vexatious or blackmailing operation.

And in the same case law, Globe Industries Corporation's Patent (1977) R.P.C 563 in the Supreme Court of Judicature - Court of Appeal, Lord

Justice Goff observed that, ""what an opponent on an application for revocation has got to establish is that there is genuine interest which may be

prejudiced; Of course, the prospect of prejudice must be real, not speculative or fanciful and it must be a prejudice to present a commercial interest.

In Mediline A.G's Patent (1973) R.P.C. 91 before the patents Appeal Tribunal, Mr. Justice Graham has held that, ""there must be a real, definite

and substantial interest to prove the commercial interest and that it must be a genuine interest. There must be the existence, or the likelihood of real

prejudice.

Therefore applying the same analogy here, we find that, as regards first ground, there is no evidence before us to show that the applicants are in

possession of any patents in the same field. As regards the second ground i.e., the manufacturing interest, the applicants are one of the foremost

leaders in the wind energy sectors in India and they manufacture and install wind turbines all over India and this establishes the manufacturing interest.

As regards the trading interest, looking at the ruling of the Solicitor General, Sir Thomas Inskip in Clavel's application 45 R.P.C. 222 and a previous

ruling by Sir Stanley Buckmaster in New Thing's application, 31 R.P.C. 40 that ""a trading interest to be effective, must be a real, definite and

substantial interest and must not arise from something that the opponent proposes to do"".

It is very clear that the applicants have been manufacturing and installing the wind turbines shows the trading interest of the product, too, as ""a

person interested"" in opposing the grant or revocation of the patent. Therefore what an applicant for revocation of patent, (the applicants herein) has

to establish is that there is a real and genuine interest together with a commercial interest, which may be prejudiced when such a patent is granted.

The applicants have shown that they have been manufacturing and installing wind turbines all over India and this shows that they have a real and

genuine interest together with a commercial interest in the product. In view of the above said findings, we find that undoubtedly locus Standi is

established by the applicants and they are ""the person interested"" in this case sufficiently meeting the requirement of Section 2(1)(t) of the Act.

Common general knowledge

Now we shall see as to whether a common knowledge on the date of the patentee's claim would amount to anticipation by way of public knowledge

destroying the novelty or affecting the inventive step. First we should see what is a common general knowledge?

""Criteria for ""Common General Knowledge

It is important to have a clear understanding of the meaning of the common general knowledge. It is the background technical knowledge available to

all in a particular trade while doing or carrying out a product development activity.

The common general knowledge as described by Laddie J in Raychem Corp's Patents 1998 RPC 31 at 40, ""The common general knowledge is the

technical background of the notional man in the art against which the prior art must be considered ... It includes all that material in the field he is

working in which he knows exists, which he would refer to as a matter of course if he cannot remember it and which he understands is generally

regarded as sufficiently reliable to use as a foundation for further work or to help understand the pleaded prior Article This does not mean that

everything on the shelf which is capable of being referred to without difficulty is common general knowledge nor does it mean that every word in a

common text book is either. In the case of standard textbooks, it is likely that all or most of the main text will be common general knowledge.

The law as to what constitutes common general knowledge is also set out in the decisions of the Court of Appeal in General Tire & Rubber Co v.

Firestone Tyre & Rubber Co Ltd 1972 RPC 457 at 482-483 and Beloit Technologies Inc v. Valmet Paper Machinery Inc 1997 RPC 489 ;

In General Tire v. Firestone 1972 RPC 457 : it is held, 'on the other hand, common general knowledge is a different concept [sc. from public

knowledge] derived from a commonsense approach to the practical question of what would in fact be known to an appropriately skilled addressee -

the sort of man, good at his job, that could be found in real life.'

In Beloit v. Valmet 1997 RPC 489 (CA). Aldous J held; ""At the same time, the skilled man should not be taken to represent some sort of lowest

common denominator of persons actually engaged in the field, possessed only of the knowledge and prejudices that all of them can be said to possess.

The common knowledge of different groups employed on the same tasks in different organizations is likely to be different, and It is unlikely that the

expert witnesses will be truly representative of the skilled person, as not only may they be too well qualified but they will come to the case with

personal prejudices or preferences that must be discounted:

Luxmoore J. in British Acoustic Films (53 R.P.C.221) stated: ""It is not sufficient to prove common general knowledge that a particular disclosure

is made in an article, or series of articles, in a scientific journal, no matter how wide the circulation of that journal may be, in the absence of any

evidence that the disclosure relates. A piece of particular knowledge as disclosed in a scientific paper does not become common general knowledge

merely because it is widely read, and still less because it is widely circulated. Such a piece of knowledge only becomes general knowledge when it is

generally known and accepted without question by the bulk of those who are engaged in the particular art; in other words, when it becomes part of

their common stock of knowledge relating to the Article

The correct explanation was given by the Court of Appeal in Beloit Technologies Inc v. Valmet Paper Machinery Inc (1997) RPC 489 at pages

494-495:-""The information in a patent specification is addressed to such a man and must contain sufficient details for him to understand and apply the

invention. It only lacks an inventive step if it is obvious to such a man. It follows that evidence that a fact is known or even well-known to a witness

does not establish that fact forms part of the common general knowledge. Neither does it follow that it will form part of the common general

knowledge if it is recorded in a document.

In ICI Chemicals & Polymers Ltd., v. Lubrizol Corps 45 IPR 577 Emmett J stated, ""the common general knowledge is the technical background to

the hypothetical skilled worker in the relevant art....but also includes the material in the field in which he is working which he knows exists and to

which he would refer as a matter of course.

Thus from the above cases, common general knowledge is the common knowledge in the field to which the invention relates. It is generally known

as common knowledge and regarded as a good basis for further research activity by those engaged in that art before it becomes part of their common

stock of knowledge relating to the art, and then becoming part of the common general knowledge. Therefore it means the information which at the

date of the patent in question is known and accepted without question by those who are engaged in the art or science to which the alleged invention

relates. It would also appear therefore, that when it is a question of common general knowledge i.e, knowledge available in a country for a long time,

which every skilled worker in that field is, expected to know. Then such knowledge would be sufficient to invalidate a patent. Again such knowledge

need not even be found in a particular document. In other words a patent application has to be accessed on the basis of not only what will be available

from prior documents but also from the common general knowledge on the subject, which may or may not be available in any such document. It can

be taken as a well settled principle, that the common general knowledge is a knowledge that must be attributed to a skilled person, without which he

may not be taken to be a skilled person in the Article Therefore it is a knowledge that every skilled person should acquire before he embarks on the

problem for which the patent provides the solution. A patent can therefore be taken to be addressed to the skilled addressee, someone skilled in the

subject matter of the invention. It is also important to differentiate between matter which was in the public domain at the priority date of the patent and

matter which can properly be regarded as common general knowledge. Evidence that a particular fact is known or even well-known to a witness does

not mean that it is common general knowledge. Likewise, a piece of information disclosed in a scientific paper does not become common general

knowledge merely because it is widely read. On the other hand, it is not necessary to show that the information is known in the sense that the skilled

person has memorized it. Material which is known to exist and to which the skilled person would refer as a matter of course if he cannot remember it

is clearly part of the common general knowledge.

Skilled person in the art

A patent specification is addressed to those likely to have a practical interest in the subject matter of the invention, and such persons are those with

practical knowledge and experience of the kind of work in which the invention is intended to be used. The addressee reads the specification with the

common general knowledge of persons skilled in the relevant Article He is unimaginative and has no inventive capacity. So a patent must be

considered through the eyes of the notional person skilled in the Article The 'notional skilled person' who is the addressee of the specification is

normally described in various ways for various purposes. The skilled person is essentially a legal construct, and not a mere lowest common order of all

the persons engaged in the art at a particular time.

The Patentee shall disclose all the features of the invention in the specification, without any ambiguity, in return to the exclusive monopoly right

which is granted to him. A patent can be granted only when all the three following criteria are satisfied or complied with. They are,

a. New and useful

b. Inventive step or non-obviousness

c. Capable of industrial application

The first criterion is the novelty of the product, which is to be patented. Novelty is not defined in the Indian law, but the 'invention' and ""inventive

step"" are defined as below under Section 2(1)(j) and 2(1) (ja) of the Act respectively;

(j) ""invention means a new product or process involving an inventive step and capable of industrial application;

(ja) ""inventive step"" means a feature of an invention that involves technical advance as compared to the existing knowledge or having economic

significance or both and that makes the invention not obvious to a person skilled in the art;

The applicants have argued by referring to US patents 4,520,437 & 5,559,419 in respect of obviousness and lack of inventive step and we consider

only those arguments made before us relying on the specific grounds taken by them.

The best-known statement of status and function of claims in a patent specification, is given by Lord Russell of Killowen in Electric and Musical

Industries Ltd v. Lissen Ltd (1938) 56 RPC 23, 39: ""The function of the claims is to define clearly and with precision the monopoly claimed, so that

others may know the exact boundary of the area within which they will be trespassers. Their primary object is to limit and not to extend the monopoly.

What is not claimed is disclaimed. The claims must undoubtedly be read as part of the entire document and not as a separate document; but the

forbidden field must be found in the language of the claims and not elsewhere.

Obviousness

We shall see the claims of the impugned patent with respect to obviousness or lack of inventive step. A patent will be invalid for lack of inventive step

if the invention claimed in it was obvious to a person skilled in the art having regard to the state of the art at the priority date. In fact on the date of the

patent, the US '437 patent and the US '419 patent are already known to the public knowledge and the person skilled in the art must be aware of the

said patents as the former patent forms part of the common general knowledge, being an old prior art of more than 12 years by then, and the later

patent being part of the latest developments in the field.

The test to ascertain whether an invention involves an inventive step is expressed in Halsbury Laws of England as: 'was it for practical purposes

obvious to the skilled worker, in the field concerned, in the state of knowledge existing at the date of the patent to be found in the literature then

available to him, that he should or would make the invention the subject of the claim concerned.' In other words, the question to be answered in

determining inventive step is 'Would a non-inventive mind have thought of the alleged invention?' If the answer is 'no', then the invention is non-

obvious. If the patent claimed merely includes the development of some existing trade, in the sense that it is a development as would suggest itself to

an ordinary person skilled in the art, it would fail the test of non-obviousness.

Let us analyze claim 1 first as regards its inventive features.

The main inventive features as claimed in claim1 are as below:

a. In the wind power installation, the rotor driven variable speed synchronous generator generates a variable frequency output being variable

alternating current;

i. Pulse frequency variation is dependent on the configuration of the alternating current to be produced.

ii. The switching frequency is a multiple greater in the region of passage through the zero of the alternating current produced than the switching

frequency at the maximum amplitude region of the alternating current to be produced.

iii. The lowest switching frequency in the maximum amplitude region of the AC is at least some 100 Hz.

b. This variable frequency output being variable alternating current is rectified into direct current, which is again converted by inverter into fixed

frequency AC to be fed into the grid;

c. The DC into AC conversion in the above step is done by using PWM technique to have the AC output with fixed frequency for feeding into the

grid.

This PWM inverter technique is known in the art, which has been acknowledged by the Respondent as given in the pages 2 & 3 of the

specification.

a. The learned Counsel referred to the US'437 patent. This US patent refers to a pulse width modulated inverter for converting DC into sinusoidal AC

(as seen in Col.1 lines 7 to 12). This US patent also describes about the problems normally faced in the prior art (vide Col.1 lines 25 to 40). In order to

overcome these problems, the prior art inverter employs variable pulse switching frequency for the inverter switches to generate the sinusoidal

waveform as shown in the impugned patent (as seen in Col.1 lines 54 to 60). In this US '437 patent ""the time intervals at successive positive and

negative pulses generated by the synthesiser are selected such that the frequency of the carrier varies from a high frequency at the zero crossings of

the generated sinusoid to a lower frequency at the peak value of the generated sinusoid (Col.1 lines 54 to 60). The description in Col.3 lines 41 to 57 of

this US '437 patent, shows, while referring to waveform of fig. 2, the switched waveform is pulse width modulated in response to the timing signals

supplied by the microcomputer 30. The carrier frequency is varied from maximum value at the zero crossing 301 of the derived sine wave 300, as

shown in fig.3 to a minimum value as the sine wave approaches its peak value 302. These modulation techniques minimize the low frequency

harmonic content and reduce the amplitude of the harmonics in the vicinity of the carrier frequency by distributing them over a range of frequencies,

rather than a single frequency and permit the use of smaller output filter components 29.

(Editor: The text of the vernacular matter has not been reproduced. Please write to contact@manupatra.com if the vernacular matter is

required.)

b. The synthesiser waveform 300, as shown in fig.3 is approximately a sinusoidal waveform with the effects of distortion due to pulse filtering. Even in

the impugned patent, as seen in the penultimate para on page 4 of the specification the Respondent has stated that invention makes use of an inverter

having switching frequency that has been made variable, more specifically in dependence on the alternating current to be generated.

(Editor: The text of the vernacular matter has not been reproduced. Please write to contact@manupatra.com if the vernacular matter is

required.)

c. From this description above as well as the details available in fig. 2 & 3 of the US '437 patent along with its description, it is very clearly seen that

there is variation of pulse frequency with respect to configuration of sinusoid AC.

d. Lastly it is also to be noted from Col.8 lines 28 to 34 of the US '437 description, that, the carrier frequency of the pulse signal is varied from a

maximum value at the zero crossing point of the synthesized sinusoid to a minimum value as the sine wave approaches its peak value, advantageously

and significantly reduce the harmonic distortion occurring at the output of the synthesizer output filter. These description show very clearly that the US

'437 patent teaches that it is advantageous to move from constant to variable switching frequency and that too in a manner that frequency is maximum

at zero crossings (same as the passage through zero in the impugned patent) of the generated sinusoid (AC) and minimum at the peak value (which is

same as maximum amplitude region in the impugned patent) of the generated sinusoid (AC). This shows that the variation of switching frequency is in

dependence of the shape or configuration of the AC to be generated as well as the regions where the switching frequency will be maximum and

minimum are well known. This is nothing but the features at para 1 'a' (i),(ii)&(iii) above of the claim 1, which are clearly present in the US '437

patent. Therefore the claim 1 does not involve any inventive step in view of the US '437 patent alone as there is no technical advance seen in the

claimed invention compared to the existing knowledge available in the US '437 patent.

3 It was stated in the specification that known inverters with constant switching frequency has power loss up to 2% of the total power generated,

whereas with reduction in switching frequency, power loss can be minimised, but simultaneously increases troublesome harmonics in the output. If the

switching frequency is increased, power loss rises, but then the harmonics are substantially eliminated.

4 It was also stated in the specification that with the previous known pulse inverters, a static switching frequency was accepted and attempts were

made to optimize matters in the region of the switching times of the switches in order to reduce the power loss and to minimize the harmonics content.

5 The invention in the impugned patent also proposed, optimizing or making the switching frequency variable in dependence on the configuration of the

alternating current to be generated, wherein the switching frequency is at maximum in the region of passage through the zero of the alternating current

produced and the switching frequency is at a minimum, in the region of the maximum amplitude of the alternating current which is to be fed into the

grid.

(Editor: The text of the vernacular matter has not been reproduced. Please write to contact@manupatra.com if the vernacular matter is

required.)

6 The applicant's counsel referred to another US '419 patent. This patent is dated 24-9-1996 (filed on 21st June 1994) which is very much before the

priority date of the impugned patent. This prior art discloses the inverter apparatus which can be controlled in a pulse width modulated manner (Col.2

lines 32 to 35) and the principal claim of the impugned patent is also directed to the pulse inverter. This US '419 discloses that, ""switching frequencies

of 20 kHz or greater are desirable to reduce acoustic noise and to obtain high current regulation bandwidth. Soft switched inverters such as the

resonant dc link converter operate at considerably higher switching frequencies. (Col.10 lines 64 to 67 and Col.11 lines 1 to 4). A balanced polyphase

1 to 2kHz signal with low harmonic distortion can be readily synthesized in addition to the fundamental excitation when using 5 kHz to 20 kHz

switching, in the manner as described above and illustrated in fig.4 & 5 accompanying the said US '419 patent. Preferably, the inverter switching

frequency should be at least 5 to 10 times the signal frequency. Further the signal frequency should be atleast 5 to 10 times the fundamental frequency

of the drive power provided to the motor. (Col.11 lines5 to 13).

This disclosure in the said US '419 patent clearly shows that if the signal frequency to be generated is 50Hz the preferred minimum switching

frequency shall be 5 to 10 times i.e. 250 Hz or 500Hz which is nothing but clearly as stated in the claim 1 i.e. ""at least some 100Hz"". Thus said feature

of 1 'a' (iii) above, claimed in claim 1 is present in US '419 patent which discloses that: ""in larger drive systems (>100KW), inverter switching

frequencies of frequency via the inverter may not be possible. In such cases additional dedicated circuitry may be desirable to generate the signals at frequencies

sufficiently higher than the inverter switching e. g 5 to 10 K Hz. The above information and reference clearly indicates that for larger drive systems

inverters may have switching frequencies greater i.e. 5 to 10 kHz. This is definitely a multiple greater than 250 or 500Hz. In the impugned patent, the

switching frequency is varied between 1 kHz and 16 kHz which is exactly similar to or in other words, is within the range covered in the US '419

patent. Thus on or before the priority date of the invention claimed in this patent, a skilled person in the art would have easily known or must be aware

of the latest developments in the relevant field, or otherwise, using the information available in the said US '419 patent as to what are the switching

frequency ranges in which a pulse inverter may operate so as to have lesser loss of power with optimum reduction in harmonics and he does not have

to do any inventive work to find or say or show even, that the said frequency at zero crossing points of the AC is a multiple greater than 250 to 500Hz.

Thus it is also possible for a skilled person in the art, to easily combine the teachings of the US '437 patent and the US '419 patent and find to

arrive at this invention point and also we find that the invention claimed in claim 1 does not show any technical advance over the existing knowledge in

the said prior arts seen in the said US patents. Hence the claim 1 as worded does not involve any inventive step. We find that the invention is found to

be obvious and any skilled person in the art with average knowledge of skills will be able to visualize the details of the invention. In view of this there is

no inventive step in the invention claimed in the impugned patent and the invention claimed is obvious to any skilled person in the Article

The contention of the Respondent is not correct, that, as the applicant argued, the grant of a patent in US and EPO is not relevant to the

proceedings here and further they have not considered the US '419 patent, though the US '437 patent has been considered, because the test for

obviousness or inventive step is quite different with respect to US and EPO from India, viz., the provision as defined in Section 2(1)(ja) of the Act,

which requires, ""technical advance over the existing knowledge"" before considering the fact as to whether the invention is obvious to the person skilled

in the Article Moreover the grant of patent in other countries does not give any assurance or a presumption as to the validity of grant of patent or even

investigation during revocation proceedings which is covered in Section 13(4) of the Act which lays down that there is no presumption as to the

validity to the grant of a patent.

The statement of the Respondent that the inverter in the US '437 patent generates voltage while the inverter in the impugned patent generates

alternating current, is quite irrelevant, but, it is to be understood clearly, that the voltage and current are so interlinked that what is produced is power

output and power is a function of voltage and current, whereas current is not produced sans voltage by inverter and vice-versa.

The Respondent's statement in the counter statement that US '437 patent does not show the feature regarding ""the lowest pulse frequency in the

region of the maximum amplitude is at least some 100 Hz"" and the other statement of the Respondent that the main difference being, that the

impugned patent varies the switching frequency according to the output current whereas in the US '437 patent the invention is about varying according

to the voltage. But these differences does not matter to the person skilled in the art, because both voltage and current have sinusoidal form and

operate, for a given load at a frequency of 50 Hz. Thus the expression variation according to the configuration of the alternating current will hold good

for voltage also and these basic information would form part of the common general knowledge which a person skilled in the art is generally aware of.

Further even it is presumed as per the contention of Respondent, it must be understood, first, that, if the current varies according to the load, the

variation will be in amplitude i.e. height of the peak of the curve and not in frequency or shape of the curve (sinusoidal). This fact is also very well

known to the person skilled in the art and he would find such a difference absolutely obvious to him.

As per the Act, all the claims in a complete specification will have one inventive step or making them to be having group of inventive features to

have a single inventive concept. Since that inventive step in claim 1 has been shown to be obvious, all the subsidiary claims dependent on the principal

claim 1, which tend to add only minor variations of features will not impart any inventive step to the dependent claims.

We shall now consider a few case laws as regards obviousness or inventive step and particular reference is made to M/s. Bishwanath Prasad

Radhey Shyam v. Hindustan Metal Industries, (1979) 2 SCC 511, where Sarkaria. J, has held that, ""was it for practical purposes obvious to a skilled

worker, in the field concerned, in the state of the knowledge existing at the date of the patent to be found in the literature then available to him, that he

would or should make the invention the subject of the claim concerned?

Buckley LJ in Valensi v. British Radio Corporation 1973 RPC 337, held that, "" The hypothetical addressee is not a person of exceptional skill and

knowledge, and he is not to be expected to exercise any invention nor any prolonged research, enquiry or experiment. He must, however, be prepared

to display a reasonable degree of skill and common knowledge of the art in making trials and to correct obvious errors in the specification if a means

of correcting them can readily be found and arrive at the result...

A patent will be invalid for lack of inventive step if the invention claimed in it was obvious to a person skilled in the art having regard to the state of

the art at the priority date. The familiar structured approach to the assessment of allegations of obviousness first articulated by the Court of Appeal in

Windsurfing International Inc v. Tabur Marine (Great Britain) Ltd 1985 RPC 59; It is convenient to address the question of obviousness by using the

structured approach as explained by the Court of Appeal in Pozzoli v. BDMO 2007 EWCA 588 : 2007 FSR 37. This involves the following steps:

1 Identify the notional 'person skilled in the art' and the relevant common general knowledge of that person

2 Identify the inventive concept of the claim in question or, if it cannot be done, construe it.

3 Identify if any the differences existing between the matters cited as forming state of the art and the inventive concept of the claim or the claim as

construed.

4 Ask whether, when viewed without any knowledge of the alleged invention as claimed: do those differences constitute steps which would have been

obvious to the person skilled in the art or do they require any degree of invention?

The first step is; ""who is the notional person skilled in the art in this field of wind power installation technology?

e. This is a person who is likely to have a practical interest in the subject matter of the invention. The relevant common general knowledge of that

person must be such as the knowledge of electrical engineering with a broad specialisation or requisite experience in the wind power technology. In

this case, both the applicant and the Respondent are the person skilled in the art or otherwise such person must have the knowledge of motors and

generators with knowledge of inverters using pulse width modulation technique to eliminate the harmonics applicable in wind power installations.

The second step is; ""Identify the inventive concept of the claim in question

The main inventive features as claimed in claim1 are:

a. In the wind power installation, the rotor driven variable speed synchronous generator generates a variable frequency output being variable

alternating current;

i. Pulse frequency variation is dependent on the configuration of the alternating current to be produced.

ii. The switching frequency is a multiple greater in the region of passage through the zero of the alternating current produced than the switching

frequency at the maximum amplitude region of the alternating current to be produced.

iii. The lowest switching frequency in the maximum amplitude region of the AC is at least some 100 Hz.

b. This variable frequency output being variable alternating current is rectified into direct current, which is again converted by inverter into fixed

frequency AC to be fed into the grid;

c. The DC into AC conversion in the above step is done by using PWM technique to have the AC output with fixed frequency for feeding into the

grid.

The third step is; ""Identify if any the differences existing between the matters cited as forming state of the art and the inventive concept of the

claim or the claim as construed"".

a. Inventive concept of the claim i. In the wind power installation, the rotor driven variable speed synchronous generator generates a variable

frequency output being variable alternating current, wherein the Pulse frequency variation is dependent on the configuration of the alternating current

to be produced; and the switching frequency is a multiple greater in the region of passage through the zero of the alternating current produced than the

switching frequency at the maximum amplitude region of the alternating current to be produced, wherein the lowest switching frequency in the

maximum amplitude region of the AC is at least some 100 Hz.

ii. This variable frequency output being variable alternating current is rectified into direct current, which is again converted by inverter into fixed

frequency AC to be fed into the grid;

iii. The DC into AC conversion in the above step is done by using PWM technique to have the AC output with fixed frequency for feeding into the

grid.

• US'437 patent refers to a PWM inverter for converting DC into sinusoidal AC employing variable pulse switching frequency for the inverter

switches to generate sinusoidal waveform wherein the frequency of the carrier varies from a high frequency at zero crossings of generated sinusoid to

a lower frequency at peak value of generated sinusoid. Switched waveform is pulse width modulated in response to timing signals supplied by

microcomputer. The carrier frequency is varied from maximum value at zero crossing of the derived sine wave to a minimum value as the sine wave

approaches its peak value. Such modulation techniques minimize low frequency harmonic content reducing the amplitude of the harmonics in the

vicinity of the carrier frequency by distributing them over a range of frequencies, rather than a single frequency moving from constant to variable

switching frequency. So frequency is maximum at zero crossings of generated sinusoid and minimum at peak value of generated sinusoid, shows

variation of switching frequency is dependent on the configuration of the AC to be generated.

• The US '419 patent discloses the inverter apparatus which is controlled in a pulse width modulated manner and ""switching frequencies of 20 kHz

or greater reduce acoustic noise to obtain high current regulation bandwidth. A balanced polyphase 1 to 2 kHz signal with low harmonic distortion was

synthesized in addition to the fundamental excitation when using 5 kHz to 20 kHz switching and the inverter switching frequency was at least 5 to 10

times the signal frequency, which in turn must be at least 5 to 10 times the fundamental frequency of the drive power provided to the motor. For

system operation up to frequencies of 60Hz or higher, generation of the signals at frequencies sufficiently higher than the inverter switching e. g 5 to

10 K Hz. needed for larger drive systems inverters to have switching frequencies greater i.e. 5 to 10 kHz.

• ""Now to identify if any the differences existing between the matters cited as forming the state of the art and the inventive concept of the claim or

the claim as construed"":-From the description as well as the details available in figs. 2 & 3 of the US '437 patent it is very clearly seen that there is

variation of pulse frequency with respect to configuration of sinusoid AC. This shows that the variation of switching frequency is in dependence of the

shape or configuration of the AC to be generated as well as the regions where the switching frequency will be maximum and minimum are well

known. This is nothing but the features at para 1 'a' (i),(ii)&(iii) above of the claim 1, which are clearly present in the US '437 patent. Therefore

neither ""differences exist between the matters cited as forming the state of the art and the inventive concept of the claim or the claim as construed

nor could they be identified.

• It was also seen that there is a statement in the impugned patent that known inverters with constant switching frequency has power loss up to 2%

of the total power generated, whereas with reduction in switching frequency, power loss can be minimised, but simultaneously increases troublesome

harmonics in the output. If the switching frequency is increased, power loss rises, but then the harmonics are substantially eliminated. It was also

stated in the impugned patent that with the previous known pulse inverters, a static switching frequency was accepted and attempts were made to

optimize matters in the region of the switching times of the switches in order to reduce the power loss and to minimize the harmonics content, the

invention proposed, optimizing or making the switching frequency variable in dependence on the configuration of the alternating current to be

generated, wherein the switching frequency is at maximum in the region of passage through the zero of the alternating current produced and the

switching frequency is at a minimum, in the region of the maximum amplitude of the alternating current which is to be fed into the grid.

Now referring to other state of the art document, US '419 patent, which discloses an inverter apparatus that can be controlled in a pulse width

modulated manner(Col.2 lines 32 to 35) and the principal claim of the impugned patent is also directed to the pulse inverter. This US '419 patent also

discloses that, ""switching frequencies of 20 kHz or greater are desirable to reduce acoustic noise and to obtain high current regulation bandwidth. Soft

switched inverters such as the resonant dc link converter operate at considerably higher switching frequencies. (Col.10 lines 64 to 67 and Col.11 lines

1 to 4). So a balanced polyphase 1 to 2kHz signal with low harmonic distortion can be readily synthesized in addition to the fundamental excitation

when using 5 kHz to 20 kHz switching, in the manner as described above and illustrated in figs.4 & 5 accompanying the said US '419 patent.

Preferably, the inverter switching frequency should be at least 5 to 10 times the signal frequency. Further the signal frequency should be at least 5 to

10 times the fundamental frequency of the drive power provided to the motor. (Col.11 lines 5 to 13).

This disclosure in the said US '419 patent clearly shows that if the signal frequency to be generated is 50Hz the preferred minimum switching

frequency shall be 5 to 10 times i.e. 250 Hz or 500Hz which is nothing but clearly as stated in the claim 1 i.e. ""at least some 100Hz"". Thus said feature

of 1 'a' (iii) mentioned above, and also claimed in claim 1 of the impugned patent is present in the US '419 patent which discloses that: ""in larger drive

systems (100KW), inverter switching frequencies of 1 to 2 K Hz are common. If the system is to be operated upto frequencies of 60Hz or higher,

synthesis of a sufficiently high signal frequency via the inverter may not be possible. In such cases additional dedicated circuitry (as depicted in fig.6

accompanying the US '419 patent) may be desirable to generate the signals at frequencies sufficiently higher than the inverter switching e. g 5 to 10 K

Hz. The above information and reference clearly indicates that for larger drive systems inverters may have switching frequencies greater i.e. 5 to 10

kHz. This is definitely a multiple greater than 250 or 500Hz. Thus on or before the priority date of the invention claimed in the impugned patent, there

does not exist any difference between the state of the art shown and the features claimed in the impugned patent.

The last step is: ""ask whether, when viewed without any knowledge of the alleged invention as claimed: do those differences constitute steps

which would have been obvious to the person skilled in the art or do they require any degree of invention?

a. For the lack of inventive step in the invention claimed when it is obvious to a person skilled in the art having regard to the state of the art at the

priority date of the patent application, that patent will become invalid.

b. In the instant case, at the date of the patent, the US '437 patent and the US '419 patent are already known to the public knowledge and the person

skilled in the art is aware of the same and any skilled person in the art, though he is unaware of this patent, but with his average knowledge of skills in

the field of electrical technology and their application in the field of wind power installation technology, will certainly be able to visualize the details of

the invention or in other words, with his average and normal skill will be able to arrive at this invention, because of the fact that it is normal technical

knowledge, that in the field of wind power machines, to employ an inverter having variable pulse switching frequency for the inverter switches to

generate a sinusoidal waveform as shown in the impugned patent. Further the skilled person in the art understands that, the time intervals at

successive positive and negative pulses generated by the synthesizer are selected such that the frequency of the carrier varies from a high frequency

at the zero crossings of the generated sinusoid to a lower frequency at the peak value of the generated sinusoid. From the description in the US '437

patent, the skilled person in the art understands that, the switched waveform is pulse width modulated in response to the timing signals supplied by the

microcomputer. The carrier frequency is varied from maximum value at the zero crossing of the derived sine wave, to a minimum value as the sine

wave approaches its peak value. These modulation techniques minimize the low frequency harmonic content and reduce the amplitude of the

harmonics in the vicinity of the carrier frequency by distributing them over a range of frequencies, rather than a single frequency and permit the use of

smaller output filter components. Synthesizer waveform is approximately a sinusoidal waveform with the effects of distortion due to pulse filtering.

From this description as well as the details available in fig. 2 & 3 of the US '437 patent, the skilled person in the art understands that there is variation

of pulse frequency with respect to configuration of sinusoid AC. Further from the US '437 patent description, the skilled person comes to know that

the carrier frequency of the pulse signal is varied from a maximum value at the zero crossing point of the synthesized sinusoid to a minimum value as

the sine wave approaches its peak value, reducing the harmonic distortion occurring at the output of the synthesizer output filter. Also the skilled

person in the art understands that it is advantageous to move from constant to variable switching frequency and that too in a manner that frequency is

maximum at zero crossings of the generated sinusoid (AC) which is same as the passage through zero in the impugned patent and minimum at the

peak value of the generated sinusoid (AC) which is same as maximum amplitude region in the impugned patent and this shows that the variation of

switching frequency is in dependence of the shape or configuration of the AC to be generated as well as the regions where the switching frequency

will be maximum and minimum are well known. So the person in the art is very clear in his mind that the features at para 1 'a' (i),(ii)&(iii) above of the

claim 1, are clearly present in the US '437 patent and therefore the claim 1 does not involve an inventive step in view of the US '437 patent alone as

there is no technical advance in the claimed invention compared to the existing knowledge available in the US '437 patent. Considering the other US

'419 patent, the person in the art is very clear that this US '419 patent discloses the inverter apparatus that can be controlled in a pulse width

modulated manner and the principal claim of the impugned patent is also directed to the pulse inverter. Also this US '419 patent discloses that,

switching frequencies of 20 kHz or greater are desirable to reduce acoustic noise and to obtain high current regulation bandwidth and a balanced

polyphase 1 to 2kHz signal with low harmonic distortion can be readily synthesized in addition to the fundamental excitation when using 5 kHz to 20

kHz switching, in the manner as described above and as illustrated in fig.4 & 5 accompanying the said US '419 patent. He is also very clear that, the

inverter switching frequency should be at least 5 to 10 times the signal frequency, which in turn should be at least 5 to 10 times the fundamental

frequency of the drive power provided to the motor. Therefore he is aware that this disclosure in the said US '419 patent clearly shows that if the

signal frequency to be generated is 50Hz the preferred minimum switching frequency shall be 5 to 10 times i.e. 250 Hz or 500Hz which is nothing but

clearly as stated in the claim 1 i.e. ""at least some 100Hz"", which is the feature of 1 'a' (iii) above, claimed in claim 1 that is present in US '419 patent

which further discloses that: ""in larger drive systems (100KW), inverter switching frequencies of 1 to 2 K Hz are common. If the system is to be

operated up to frequencies of 60Hz or higher, synthesis of a sufficiently high signal frequency via the inverter being not possible, additional dedicated

circuitry is desirable to generate the signals at frequencies sufficiently higher than the inverter switching e. g 5 to 10 K Hz. Finally he is very clear that

the above information and reference clearly indicates that for larger drive systems inverters may have switching frequencies greater i.e. 5 to 10 kHz

and that is definitely a multiple greater than 250 or 500Hz. Therefore on or before the priority date of the invention claimed in this patent, a skilled

person in the art would have easily known or must be aware of the latest developments in the relevant field, or otherwise, using the information

available in the said US '419 patent as to what are the switching frequency ranges in which a pulse inverter may operate so as to have lesser loss of

power with optimum reduction in harmonics and he does not have to do any inventive work to find or say or show even, that the said frequency at

zero crossing points of the AC is a multiple greater than 250 to 500Hz. Thus it is also possible for a skilled person in the art, to easily combine the

teachings of the US '437 patent and the US '419 patent and find to arrive at this invention point and also to prove that the invention claimed in claim 1

does not show any technical advance over the existing knowledge in the said prior arts seen in the said US patents. Hence the claim 1 as worded does

not involve any inventive step. We also find that the invention is found to be obvious.

c. When the basic technology has already reached a particular, probably, a saturated level or point, for any optimization, then in any research made in

that field should have or show any technical advance to the present level. In the absence of any such technical advance in the work done, compared

to the knowledge present and available in the state of art, then that piece of work does not deserve the right of any monopoly.

d. In view of this analysis and the finding herein, it is very clear there is no inventive step in the invention claimed in the impugned patent and the

invention claimed is obvious to any skilled person in the Article

Therefore combining the said two cited US patents, a person skilled in the art can arrive at the invention claimed in the claim 1 of the impugned

patent. Hence the invention cannot be said to have any inventive step and the invention is obvious.

Insufficiency - Law A patent will be insufficient if the specification does not disclose the invention clearly enough and completely enough for it to

be performed by a person skilled in the Article The duty of the patentee is to provide the description which enables the skilled person in the art to

perform the invention with a will and to make the invention work. Such a person is not supposed to have exceptional skill and knowledge and he is not

expected to exercise any invention or any prolonged research, enquiry or experiment. He must have a reasonable degree of skill and common general

knowledge of the art in performing the trials and to correct the obvious mistakes if there is a way of correcting them is conceived.

Investigation for insufficiency of description of the invention is made at three stages under the Act;

• At the examination stage under Section 12(1) (a) read with Section 10(4) of the Act;

• In opposition proceedings under Section 25(1)(g) and Section 25(2) (g) of the Act;

• In revocation proceedings under Section 64(1) (h) of the Act.

It would appear from the wordings of these provisions that the standard of sufficiency to be applied varies according to the nature of the proceeding,

the standard to be applied in opposition proceeding being more rigorous than that applicable at the examination stage; and that applied in revocation

proceeding being still more rigorous.

Of course by virtue of Section 64 (1) (h) & (i) of the Act, a patent may be revoked if it ""does not disclose the invention clearly enough and

completely enough for it to be performed by a person skilled in the art"". It is fundamental to the validity of a patent that it not merely discloses a novel

product or process, but that the disclosure is ""enabling"".

The term 'sufficiency of disclosure' refers to adequacy of pertinent information to be provided in the complete specification to enable an average

skilled person in the art to perform the invention. It is stated in Halsbury's Law 3rd Edition, Vol.29. page 66, para 138 that insufficiency of description

has two branches,

1 The complete specification must describe an embodiment of the invention claimed in each of the claims and that the description must be sufficient to

enable those in the industry concerned to carry it into effect 'without their making further inventions' and

2 That the description must be fair i.e. it must not be unnecessarily difficult to follow.

In Press Metal Corporation limited v. Noshir Sorabji Pochkhannawallah (1982) PTC 256 Bom HC, it was held that, ""it is the duty of the patentee

to state clearly and distinctly, the nature and limits of the invention what he claims in his specification. If the language used by the patentee is obscure

and ambiguous, no patent can be granted and it is immaterial whether the obscurity in the language is due to design or carelessness or want of skill.

In Cyanamid v. Berk Pharmaceuticals 1976 RPC 231 at 234 J. Whitford held that ""it is not to be expected that every patent will be

comprehensible to everybody who picks it up, for patents are directed to persons who have skills in the particular fields with which each patent is

conceived - the so called skilled men in the Article The description of the invention has only to be a description sufficient to enable the notional skilled

man to put it into practice. Only those familiar in the field in question can be expected to make anything of the claims"".

In Mentor, at 1993 RPC 14 lines 28 to 45, Lloyd LJ said this: ""It was at first argued that the skilled man should not have to carry out any research,

enquiry or experiment at all, whether prolonged or otherwise.

Finally adopting the expression used by Lord Hoffmann in Biogen Inc. v. Medeva plc 1997 RPC 1 at 50 line 39, a patent would be insufficient on

either basis if it cannot ""deliver the goods"" or, If the claim is cast more widely than the teaching justifies, the claim will be Biogen insufficient; if the

claim on the face of it appears to be cast narrowly enough, it may nonetheless be classically insufficient if the teaching of the specification is not

enabling.

In Pottier's Appln.1967 RPC 170, Lloyd Jacob, J said, ""the purpose of a patent specification is to disclose how an alleged invention in its full width

may be put into practice and not to enable that width to be adjustable as subsequent practice develops.

Hence whenever the claim is drafted in wide or loosely worded terms, an ambiguity will arise to check whether the description in the specification

is sufficiently clear and definitive to enable a person of an ordinary skill to do or perform such an invention.

By way of highlighting the above issue, it is clearly noticeable from the patent specification, the Respondent has stated that because of current

control and not voltage control, a sinusoidal alternating current is always obtained and in the case of short circuit, this can be obtained by an

appropriate control by varying the pulse frequency as defined in the claim 1. This fact or argument does not have any support in the description or

even a hint as regards the current control protection in case of short circuit situation in the specification. Therefore we find here that Respondent has

taken a few stand or defences or made statements without disclosing them anywhere in the specification which amounts to insufficiency in description

about the various features of the invention.

Similarly the Respondent has stated that while distinguishing the features and the teaching of the US '437 patent, with that of the features in the

impugned patent, the variation of the pulse frequency according to the subject matter of claim 1 is dependent on the configuration of the alternating

current and emphasized that it is only by this configuration it is possible to greatly reduce power loss as well as any harmonics. The applicant has

pointed out that this statement in the counter statement is different from what is stated in the specification. We also find that the expression ""only by

this configuration does not appear anywhere in the specification and as per the submission of the applicant, that if this statement is true, then the whole

inventive concept according to the impugned patent might have changed and in the absence the Respondent's contention is incorrect and totally

without any support in the description. Hence the description is insufficient and the whole specification suffers from insufficiency of description.

In the light of the above case laws, let us see the wording of the principal claim of the patent specification. In claim 1 the claimed inverter uses

variable pulse frequencies wherein the said frequency at the passage through the zero points of the sinusoid current is a multiple greater than the

frequency in the region where the said current reaches maximum amplitude. The applicant argued that the expression 'multiple greater than' does not

have any support in the description. It is correct and clear from the description of the specification, there has been no mention anywhere in the full

specification that one frequency is a multiple greater than the other. The law is very clear, that the details of the invention be fully mentioned and

described in the best possible manner as to how the same invention can be performed, disclosing maximum information about the invention so as to

enable the skilled person in the art to perform the invention without any trial and experiments being conducted by him. In view of the lack of said

disclosure it cannot be said the claims are definitive and fully supported by necessary description; rather it would amount to insufficient or unfair

description as per Section 64(1)(h) of the Act. Similarly in the claim 2, specific ranges of the pulse frequencies at which the inverter claimed in claim 1

to operate have been claimed, whereas the description in the specification is fully silent to show the reason or describe as to why such specific ranges

have been chosen and the description is also silent as to how the skilled person in the art would be able to make use of these ranges with respect to

the inverter claimed in the claims, which amounts to an insufficiency of description about the features claimed in the claims as laid down in the Section

64(1)(h) of the Act.

Further it is necessary to record here that despite being given time and again since March 2010 this year and again in July and also on 9th August

2010 this year, the Respondent has not produced any affidavit of the expert to counter the expert affidavits of the applicant and on clarification by us

during the hearing, the Respondent's counsel submitted they will not be submitting or relying on any expert affidavit or evidence. In view of this and to

have equality of opportunity and also in view of natural justice to both the applicants and Respondents in this revocation application, we do not intend

to consider even the expert evidence produced by the applicant and only the revocation application, counter statement and rejoinder to the same and

the oral submissions of both the sides have been considered.

Conclusions

Obviousness

a. Comparing the inventive features in the US '437 patent and the inventive features as construed from the principal claim 1, no difference in the

invention claimed in the claim of the impugned patent could be perceived or noticed.

b. Invention claimed would be obvious to a person skilled in the art having regard to the state of the art, when no technical advance over the prior art,

is established, then the patent lacks inventive step and will become invalid.

c. In the instant case, at the date of the patent, the US '437 patent and the US'419 patent are already known to the public knowledge and the person

skilled in the art is aware of the same and any skilled person in the art, though he is unaware of this patent, but with his average knowledge and skills

in the field of relevant technology will certainly be able to visualize the details of the invention and will be able to arrive at this invention, as this a

known technical knowledge, that in the field of wind power machines, PWM inverter is used for converting DC into sinusoidal AC employing variable

pulse switching frequency for the inverter switches to generate sinusoidal waveform wherein the frequency of the carrier varies from a high

frequency at zero crossings of generated sinusoid to a lower frequency at peak value of generated sinusoid. Such modulation techniques minimize low

frequency harmonic content reducing the amplitude of the harmonics in the vicinity of the carrier frequency by distributing them over a range of

frequencies, rather than a single frequency moving from constant to variable switching frequency. Further it is known that the inverter apparatus

which is controlled in a pulse width modulated manner and ""switching frequencies of 20 kHz or greater reduce acoustic noise to obtain high current

regulation bandwidth. A balanced polyphase 1 to 2 kHz signal with low harmonic distortion can be synthesized in addition to the fundamental excitation

when using 5 kHz to 20 kHz switching and the inverter switching frequency is at least 5 to 10 times the signal frequency, which in turn must be at

least 5 to 10 times the fundamental frequency of the drive power provided to the motor. For system operation up to frequencies of 60Hz or higher,

generation of the signals at frequencies sufficiently higher than the inverter switching e. g 5 to 10 K Hz. needed for larger drive systems inverters to

have switching frequencies greater i.e. 5 to 10 kHz.

d. In view of this analysis and the finding herein, it is very clear there is no inventive step in the invention claimed in the impugned patent and the

invention claimed is obvious to any skilled person in the Article

As per the Act, all the claims in a complete specification will have one inventive step or making them to be having group of inventive features but to

have a single inventive concept. Since that inventive step in claim 1 has been shown to be obvious, all the subsidiary claims dependent on the principal

claim 1, which tend to add only minor variations of features will not impart any inventive step to the dependent claims.

Then the subordinate claims which are dependent on the principal claim1 would also become invalid and does not stand as a separate independent or

individual claim as no exclusive technical improvement in the feature could be shown therein.

Therefore combining the said two cited US patents, a person skilled in the art can arrive at the invention claimed in the claim 1 of the impugned

patent. Hence the invention cannot be said to have any inventive step and the invention is obvious.

Insufficiency

There has been no mention anywhere in the full specification regarding the expression 'multiple greater than' meaning that one frequency is a

multiple greater than the other. The law is very clear, that nondisclosure of the details of the invention or alternatively, maximum information about the

invention which would make the skilled person in the art to find it difficult to perform the invention without any trial and experiments would amount to

insufficient or unfair description as per Section 64(1)(h) of the Act.

5 In the claim 2, specific ranges of the pulse frequencies for the inverter operation have been claimed whereas the description in the specification is

fully silent to show the reason or describe as to why such specific ranges have been chosen amounts to an insufficiency of description about the

features claimed in the claims as laid down in the Section 64(1)(h) of the Act.

6 It is noticed that the Respondent has taken defences or made statements without any support or disclosure about them anywhere in the specification,

amounts to insufficiency in description about the various features of the invention.

Hence after taking into consideration of the above said case laws and findings and analysis made herein above, together with foregoing statements

in the conclusions, we hereby allow the application for the revocation of the patent. M.P. No. 20/2010 for stay has been dismissed as nothing remains

in the miscellaneous petition and also that the main application has been disposed of.M.P. No. 42/2010 for early hearing is dismissed as infructuous.

As per the directions of the Hon'ble High Court of Madras, all the miscellaneous petitions have been heard and decided along with the main

application. Consequently the patent granted to the Respondent is revoked and we direct the Controller of Patents to remove the patent No. 197949

from the register of patents. The parties shall bear their own costs.