ITW GSE APS & ANR. vs DABICO AIRPORT SOLUTIONS PVT LTD & ORS.

2024-07-04 Information

* IN THE HIGH COURT OF DELHI AT NEW DELHI

% Reserved on: 14thMay, 2024
Pronounced on: 4th July, 2024

+ CS(COMM) 628/2023 CC(COMM) 1/2024, I.A. 17218/2023, I.A. 17219/2023, I.A. 18297/2023, I.A. 5765/2024, I.A. 9850/2024, I.A. 9851/2024, I.A. 9852/2024 & I.A. 10717/2024.

ITW GSE APS & ANR. ….. Plaintiffs
Through: Mr. Pravin Anand, Ms. Vaishali R. Mittal, Mr. Siddhant Chamola and Mr. Gursimran Singh Narula, Advs.
versus
DABICO AIRPORT SOLUTIONS PVT LTD & ORS….. Defendants
Through: Mr. Saikrishna Rajagopal, Mr. Himanshu Bagai, Ms. Garima Sahney, Mr. Kushal Gupta, Ms. Deepshikha Sarkar and Ms. Bhanu, Advs. for D-1 to 3.
Ms. Bitika Sharma, Mr. Sudeep Chatterjee, Mr. Rohan Swarup, Mr. George Vithayathil and Mr. Rakesh Karela, Advs. for D-4.
CORAM:
HON’BLE MR. JUSTICE ANISH DAYAL

JUDGMENT
%
TABLE OF CONTENTS
A. Introduction 2
B. Brief Facts 3
C. Alleged infringing activities 7
D. Proceedings so far 8
E. Submissions on behalf of plaintiffs 11
F. Submissions on behalf of defendants 21
G. Submissions in rejoinder 25
H. Analysis 28
(i) Claim Construction 33
(ii) Invalidity of the Suit Patent and credible challenge 44
a. Lack of an inventive step 44
Prior Art D2 (US 4835977 (6/6/1989) 57
Prior Art D6 WO/1986/000977 (13/02/1986) 58
Prior Art D14 (US 7207183) 60
Finding on Lack of Inventive Step 61
b. Double Patenting 62
(iii) Infringement of the Suit Patent 63
a. Claim Mapping 65
I. Relief 70

I.A. 17216/2023 (Application under Order XXXIX Rule 1 and 2 CPC)

A. INTRODUCTION
1. This application under Order XXXIX Rules 1 and 2 of Code of Civil Procedure, 1908 (CPC) has been filed by plaintiffs as part of the suit seeking permanent injunction restraining defendants, and other persons acting for and on their behalf, from dealing with the impugned products manufactured by defendants and sold to airport authorities, either on an exclusive or on a principal to principal basis, as also from the act of using, making, selling, distributing, advertising, exporting, offering for sale, importing or in any other manner, directly or indirectly, dealing in any product that infringes the subject matter of the plaintiffs registered patent bearing number IN 330145 (IN 145/ suit patent) and other attendant relief.
B. BRIEF FACTS
2. Plaintiff no.1, ITW GSE ApS, also known as AXA Power ApS is a Danish affiliate company of ITW and is the assignee of IN 145. It claims to be the leading supplier of Ground Power Units, Pre-Conditioned Air (PCA) units, Cables and Hoses, as also claims to have delivered more than 90,000 units to customers in over 100 countries. Plaintiff No. 1 also claims to have manufactured and supplied PCA units, which are installed under the passenger boarding bridge or mounted on the apron at airports.
3. Plaintiff No.1 is the subsidiary of Plaintiff no. 2, Illinois Tool Works Inc., a corporation founded in 1912, and existing and functioning under the laws of the United States of America. Plaintiff No. 2 also claims to be an American Fortune 200 company. According to the plaint, plaintiff No. 2 is listed at the New York Stock Exchange and has a market capitalization of around US $ 70 Billion, while plaintiff No.1s business falls under the specialty products category, which comprises about 11% of plaintiff No. 2s business.
4. Plaintiffs claim to employ about 46,000 people across 51 countries, as also to have 19,000 granted and/ or pending patents across the globe.
5. Plaintiffs global revenue, as claimed, is as under:
Year
Revenue (in Millions of USD)
2022
15, 932
2021
14, 455
2020
12, 574
2019
14, 109
2018
14, 768
2017
14, 314
2016
13, 599
2015
13, 405
2014
14, 484

6. The subject matter of the present dispute relates to IN 145 titled A Preconditioned Air Unit with Variable Frequency Driving, registered in the name of AXA Power ApS. The suit patent relates to a PCA unit supplying preconditioned air, i.e., heated or cooled air, to an aircraft parked on the ground. IN 145 is directed to a PCA unit which has a variable frequency driver (VFD). The suit patent has been nationalized in India via a PCT application, and according to the plaintiffs, had been granted in major jurisdictions, such as EPO, USA, and Japan.
7. The bibliographic details of the suit patent are as follows:
Patent No.
330145
Patent Application No.
7032/DELNP/2011
Title of the Invention
A preconditioned air unit with variable frequency driving
PCT Publication No.
WO/2010/106520
International Filing Date
March 18, 2010
Date of publication (S.
11A)
December 21, 2012
Date of priority
March 20, 2009
Date of grant
January 24, 2020
Date of publication of
grant (S. 43)
January 24, 2010
Date of expiry
March 18, 2030

8. The suit patent was granted on 24th January, 2020. The main independent claim of the suit patent, according to the plaintiff, is claim 1 and the suit patent, claims the following principal subject matter:
a. The invention discloses a compressor with a VFD in each of at least two refrigeration systems of a PCA unit and each VFD is configured for variations of the power of the respective compressor.
b. This configuration is such that the PCA can adjust cooling performed by the PCA unit based on the type of aircraft, ambient temperature, humidity, cabin temperature, outgoing temperature, and outgoing airflow from the PCA.
c. PCAs are known in the art to save parked aircrafts from operating their Auxiliary Power Unit (APU) Engine.
d. This invention discloses a PCA that is more flexible and more efficient by operating compressors in multiple refrigeration systems through variable frequency control which reduces costs and increases serviceability.
9. According to the plaintiffs, patents corresponding to the suit patent have been granted in favour of the plaintiffs in at least five other jurisdictions across the world, including in the US and the EU.
10. The US and EP patents corresponding to the suit patent are US 9771169 and EP 2408669 respectively. The family of patents corresponding to the suit patent claims priority from the Danish patent application bearing number PA 2009 00392 dated 20th March, 2009, and its member patents are all based, according to the plaintiff, on essentially the same subject matter i.e. a preconditioned air unit with variable frequency driving.
11. According to the plaintiffs, PCA units manufactured using the suit patent are installed at airports and the plaintiffs have earned a revenue of more than USD 100 million since 2010. Recently, plaintiffs have installed PCA units at the Doha Airport in Qatar. Plaintiffs have further installed several PCA units in India, particularly at airports in Mumbai and Bengaluru.
12. Plaintiffs have also secured another patent bearing number IN 310952 (IN 952) in relation to another invention pertaining to PCA units. IN 952 has the same priority date as the suit patent, i.e. 20th March, 2009. According to the plaint, the scope of the suit patent and IN 952 are different, in that the latter focuses on modularity, which is not the subject matter of the suit patent (a fact highly contested between the parties).
13. Defendant No. 1, Dabico Airport Solutions Pvt. Ltd. is a company incorporated under the laws of India. Dabico Netherlands Holding BV, Defendant No. 2 is a subscriber in defendant No.1 company. In 2008, defendant No. 1 was acquired by Cavotec SA (Cavotec), a Swiss company; and in 2022, defendant No.1 was acquired from Cavotec by defendant No. 3, Fernweh Group LLC. Defendant No. 4 manufactures the allegedly infringing PCA units for defendant Nos. 1 to 3.
C. ALLEGED INFRINGING ACTIVITIES
14. The grievance of the plaintiff is that since 2020 and in subsequent years, the defendants have bid in tenders floated by Government for installation of PCA units and have won tenders at Goa, Hyderabad and Delhi Airports. The technical specifications of these PCA units offered by defendants, according to plaintiffs, correspond with the claims of the plaintiffs suit patent.
15. Plaintiffs claim to have put the defendants to notice of the infringement of the suit patent in UK and in India since 2020. On 8thJune 2020, ITW first initiated written correspondence with Cavotec indicating that the PCA unit described on Cavotecs website has all the features of Claim 1 of EP 669, the suit patents corresponding European patent. According to the plaintiffs, the defendants in their correspondence continued to evade questions on how their PCA units infringe the suit patent.
16. In March, 2023, the plaintiffs also initiated pre-litigation mediation with defendants; however, due to absence of any progress on this front, mediation failed on 4th September, 2023.
D. PROCEEDINGS SO FAR
17. Summons were issued in the suit on 06th September, 2023.Since the defendants chose not to disclose their products, plaintiffs filed an application being I.A. 17217/2023 seeking inspection of defendants PCA units through a Local Commissioner, which was refused by this Court by order dated 01st November, 2023. In this order, defendants submission that their operation & instruction manuals and the Government tenders specifications are sufficient for adjudication for infringement was noted by the Court. The Court recorded the defendants statement in para 34 that they would stand by their own manuals, to which the plaintiffs seek to map their claim. The relevant paragraph is produced as under:
34. Mr. Saikrishna Rajagopal also points out, in this context, that his client stands by the specifications and features of the defendants’ PCAs as contained in the documents on the basis of which the plaintiffs claim to have undertaken its claim-mapping exercise. That being so, he claimed to soliloquize (or, as he put it, “ask himself) as to the justification for the plaintiffs seeking a physical inspection based mapping by a local commissioner. He submits that, once the plaintiffs have themselves claimed to have adduced sufficient evidence to establish infringement of the suit patent by the defendants’ PCAs, and the document and material on which the said mapping was done was not denied by the defendants, there is no justification, whatsoever, for the prayers in this application.

35. I entirely agree.

18. A Counter Claim has also been filed by defendants, inter alia, seeking revocation of IN 145.
19. Mr. Pravin Anand, counsel for plaintiffs, drew attention to a tabulation provided in their replication, giving a feature-wise breakdown of claim number 1 of the suit patent, which is extracted as under:
Feature 1.1

A preconditioned air unit (10) for supplying preconditioned air to an aircraft parked on the ground, the preconditioned air unit comprising:

Feature 1.2

a housing (12) accommodating a flow duct (20) with an air inlet for ambient air and an air outlet for connection to the parked aircraft

Feature 1.3

a blower (30) connected with the flow duct (20) for generation of an air flow from the air inlet (22) toward the air outlet (25)

Feature 1.4

a plurality of refrigeration systems (36),

wherein each refrigeration system comprises:
at least one compressor (38);
at least one condenser (40);
at least one expansion valve (42); at least one evaporator (44) connected in a flow circuit containing a refrigerant, and
wherein the at least one evaporator (44) interacts with the air flow in the flow duct (20); and at least one variable frequency driver (46, 54, 56) for power supply of the at least one compressor (38); and

Feature 1.5

the housing (12) further accommodates a central controller (60) that is configured for controlling operation of the preconditioned air unit (10) including the variable frequency drivers (46, 54, 56) of the plurality of refrigeration systems (36), characterized in that

Feature 1.6

at least one variable frequency driver (46, 54, 56) has a controller that is configured for variation of the output frequency of the at least one variable frequency driver (46, 54, 56)

Feature 1.7

and the central controller (60) is connected to at least one controller of the at least one variable frequency driver (46, 54, 56).

Feature 1.8

wherein the central controller (60) automatically adjusts the cooling performed by the preconditioned air unit (10) to at least one of: the selected type of aircraft, the ambient temperature, the humidity, the cabin temperature, the outgoing temperature and the outgoing airflow from the preconditioned air unit (10).

E. SUBMISSIONS ON BEHALF OF PLAINTIFFS
20. Mr. Pravin Anand expanded on the basic features of the suit patent, with a presentation to support his submissions. The relevant aspects of his submissions are as under:
21. The PCA units are used to introduce fresh conditioned air into an aircraft cabin while the aircraft is parked at a gate for maintenance. The air is filtered, heated or cooled, and moisture is removed before delivery to the aircraft.
22. Conventionally, aircrafts used their own auxiliary power units to power jet fuel driven air conditioning equipment which were not cost effective nor environmentally friendly. The PCA unit is the replacement of the APU when the aircraft is on the ground.
23. The PCA unit draws air from ambient temperature on the airfield and cools it down. Based on the temperature profile of each airport, the PCA unit is engaged from the time the passengers disembark from an aircraft and the aircraft is serviced, till the embarkation of the passengers on the aircraft.
24. The objective of the suit patent was to design a PCA unit that is able to automatically adjust cooling performance, according to at least one of the following conditions: type of aircraft, ambient temperature, humidity, cabin temperature.
25. The crux of the suit patent was to supply preconditioned air using ambient air through multiple refrigeration systems controlled through a central controller, which manages the VFDs attached to the compressor. The job of the central controller was to automatically adjust the cooling of the PCA depending on the type of aircraft, the ambient temperature, humidity, cabin temperature etc.
26. The components of a PCA unit and its housing are represented as under:

27. The 3D diagram for illustrative purposes has been provided by plaintiffs and extracted as under:

28. Each refrigeration unit in the PCA comprises of an evaporator, compressor, expansion valve, condenser, air flow duct and VFD. The 3D diagram specifying these components in a refrigeration unit have been supplied by plaintiffs and extracted as under:

29. The refrigeration circuit involves the regular refrigeration cycle, but the refrigerant passes through a circuit involving these components, and it changes the temperature of the refrigerant to produce cooling or heating.
30. The compressor, which is the heart and soul of a refrigeration unit, was traditionally directly connected to the main power supply in conventional PCA units and, therefore, was limited by the supply. In the suit patent, the compressor is driven by the VFD which automatically adjusts the compressors operating speed to match the production of the compressed air. VFD essentially varies the frequency and voltage of the power supply. This allows the VFD to control the cooling requirements.
31. The VFD has a controller, configured for variation of the output frequency of the VFD, which in turn is connected to the central controller, which automatically adjusts the performance of each compressor, depending on the surrounding conditions.
32. In this background, Mr. Anand submitted, that the technical contribution of the suit patent, was a PCA unit, having at least two refrigeration systems, each system having a VFD controlled compressor, connected to a central controller. This allowed the individual compressors to run at different speeds, and therefore, managing the best and most efficient compressor speed mode. Without the suit patent, multiple refrigeration circuits will operate as per fixed capacity irrespective of their requirement, which could range from extreme hot in airports like Dubai to extreme cold in airports like Finland or seasonal variations in airports like India. It also allows management of cooling in the event there is failure of any one refrigeration circuit, by varying the capacity of other circuits.
33. Plaintiffs counsel submitted that while the suit patent (IN 145) was neutral to modularity, the plaintiffs other patent (IN 952) was a modular arrangement in which the refrigeration modules could be removed and readjusted in a modular process. The infringement claimed was qua the suit patent IN 145, and not IN 952.
34. Plaintiffs counsel claimed infringement of the suit patent by mapping it on various pieces of information of the defendants PCA unit as could be gleaned from:
a) Brochure of defendants PCA units when defendant No.1 to 3 used to trade under the brand Cavotec;
b) Brochure and datasheets of defendant No.4, which is the manufacturer of Cavotec branded PCA units which are installed at various airports in India by defendant No.1.
c) Operation, Maintenance & Trouble Shooting Manual for PCA unit (Model number PDX 60IS), which sets out details and specification of the defendants PCA units.
d) Tender documents (request for proposal) released on behalf of the airport authority at Goa, delineating the specification of the PCA unit. The defendants bid under the tender was successful.
35. Plaintiffs further asserted that amongst the abovementioned documents, claim mapping with the Operation, Maintenance & Trouble Shooting Manual for PCA unit (Model number PDX 60IS) demonstrates the infringement of the suit patent unequivocally.
36. This was in context, as noted above, that defendant had not disclosed the product and plaintiffs application for inspection by Local Commissioner, as noted above, was rejected by this Court.
37. The following aspects were highlighted by plaintiffs counsel in relation to the claim for infringement, by giving a comparison of each feature of plaintiffs PCA unit as shown in the tabulation at paragraph 19 above and relevant parts of the defendants documents, especially the :
i. The operation and maintenance manual of the defendants product specified that the product was a PCA unit.
ii. The tender documents filed by the defendants would show that the PCA unit was in a housing which would map with feature 1.2.
iii. Defendants operation and maintenance manual would show that they used a blower which would map with feature 1.3.
iv. The defendants unit would show a plurality of refrigeration systems in the operation and maintenance manual which would map with feature 1.4 of the plaintiff’s product.
v. The defendants operation and maintenance manual would show at least one variable frequency driver for power supply of at least one compressor with each refrigerant circuit having a compressor which was VFD controlled. This would map with feature 1.4 of the plaintiffs unit.
vi. The defendants operation and maintenance manual in the equipment description and cooling mode sections mentioned that the refrigeration circuits were connected to unit controls based upon a control architecture which could control how many circuits would operate and at what level depending upon the ambient and outlet air temperature sensors. This would map with feature 1.5 of the plaintiffs unit.
vii. Defendants operation and maintenance manual while mentioning the variable frequency driver states that it controls and protects the compressor and its capacity based on the load requirement for maintaining output air temperature. This, according to the plaintiffs, maps to feature 1.6 of the plaintiffs unit.
viii. The automatic controls in the defendants unit would determine how many circuits would operate and at what level, depending on input from ambient and air temperature sensors which maps to feature 1.7 of the plaintiffs unit. The same would also map to feature 1.8 of the plaintiffs unit.
38. Similar mapping was done by the plaintiffs of their unit features with the RFP for Goa Airport, as the defendants were successful in winning the tender.
39. It was asserted by Mr. Anand that their PCA unit allowed each refrigeration system to operate at different operating conditions, enhancing its ability to deal with air having different air pressure and humidity. The VFD, therefore, achieved this purpose by being connected to each compressor in serial stages.
40. Plaintiffs had not intended to limit the scope of the claims to modularity and this was evident from the following: firstly, from independent claim 1 of the suit patent, which does not mention modularity and; secondly, since the complete specification of the patent merely elaborated on modular embodiment as an example, but does not disclaim a non-modular embodiment. Paragraph 74 of the complete specification was pointed out to state that no modular PCA units were part of the claims and the same is extracted as under:
[74] Other preconditioned air units may be provided within the scope of the appended claims. For example, other preconditioned air units may be provided that are not modular. Also, preconditioned air units may be provided with different numbers of refrigeration systems, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 etc. refrigeration systems.

41. On the issue of limitation, plaintiffs counsel relied upon various authorities which are enumerated as under, to essentially point out that it was improper to import a or read-in a limitation from the general discussion in specifications, embodiments and examples:
i. Donald S. Chisum, Chisum on Patents, A Treatise on the Law of Patentability, Validity and Infringement, Volume 5A
ii. Conmark Communications, Inc. vs. Harris Corp, 156 F.3d, 1182 (Fed. Cir. 1998)
iii. Teleflex, Inc. vs. Ficosa N. America Corp. and Ors., 299 F. 3d 1313, 1327 (Fed Cir. 2002)
iv. Terell on the Law of Patents, 17th Edition
v. Glaverbel SA vs. British Coal Corp. and Another, [1995] R.P.C. 255.
42. Plaintiffs counsel, inter alia, also pointed out various decisions of this Court to assert that patent rights in respect of claims are broader than the embodiments and that the reading of the claim should not be restrictive and limited, but should be read purposively. These decisions are enumerated below:
i. Ace Technologies Corp and Ors. vs. Communications Components Antenna Inc., 2023 SCC OnLine Del 2082 (decision of the Division Bench)
ii. F. Hoffman-La Roche Ltd. vs. Cipla, 2015 SCC OnLine Del 13619 (decision of the Division Bench)
iii. Communication Components Antenna Inc. vs. Ace Technology Corp. and Ors., 2019: DHC: 3323 (decision of the Single Judge)
iv. Bayer Pharma Aktiengesellschaft vs. The Controller General of Patents and Designs, 2024: DHC: 2395 (decision of the Single Judge)
43. Without prejudice to the submission by plaintiffs counsel that the suit patent related to a non-modular PCA unit, it was further stated that the categorization was irrelevant as claims of the suit patent would be infringed both by a modular as well as a non-modular PCA unit.
44. It was submitted that plaintiffs have suffered irreparable harm having lost contracts for providing PCA units at several airports in India, including in Hyderabad, Goa and Delhi, claiming a loss of about US $ 6 million in sales revenue.
45. Defendants had chosen not to secure patents in India but secured US2014/0102125 A1 in foreign jurisdictions through sister concerns such as Ipalco B.V., wherein the control unit performed a function similar to the suit patent. Moreover, balance of convenience was in favour of the plaintiffs since defendants failed to comment on claim chart mapping which should, therefore, be presumed to be correct.
46. Defendants have also withheld details of the infringing products from the Court and have not explained why the PCA units do not infringe the suit patent. The defence of non-modularity was raised only in the written statement. Defendant no.4, which is the manufacturer of the defendants PCA units, has not advanced any arguments and therefore would also have to be restrained in this regard.

F. SUBMISSIONS ON BEHALF OF DEFENDANTS
47. Mr. Saikrishna Rajagopal, counsel for defendants, effectively focused his submissions on the fact that despite the plaintiffs claim that their suit patent was non-modular, the essential features of the claim related to modularity, which feature is not present in the defendants unit, which is integrated and not modular. He highlighted the following aspects:
48. A PCA unit effectively uses the same mechanism as that of conventional air conditioning system using the conventional refrigeration cycle which has been known since 1800s. It is, therefore, incapable of being patented under Section 3(d) and Section 3(f) of the Patent Act, as it is using the very same technology in a different environment. The claim itself mirrored a conventional air conditioning unit.
49. What is claimed by the plaintiffs as the principal inventive step is only the VFD controlled by a central monitoring unit used for optimization.
50. PCA however was not an inventive step as compared to earlier prior arts like an HVAC, and was a new name for an already existing technology.
51. There were four essential elements of a PCA unit – plurality, modularity, refrigeration units and controller. The modularity of refrigeration systems was well known in the prior art. Modularity was an essential aspect, which the defendants did not implement. The refrigeration units involved compressors, which is the basic component in a refrigeration cycle. Furthermore, VFD controllers were well known before the priority date and were employed in multiple systems.
52. On modularity, prior art WO/1986/000977 (13/2/1986) [D6] was relied upon, which mentions both modular constructions permitting additional slave modules to be added to increase the capacity and the ability to manage shutdown of one module using a control circuit. The modularity enabled plug and play type operation of individual refrigeration systems. In a modular system, malfunctioning refrigeration unit could be replaced without the need to shut down the entire system, while in a non-modular system the entire unit has to be shut down for repair and maintenance. Plaintiffs earlier patent IN 952 had modularity and the suit patent is also essentially modular in its scope.
53. VFD compressors were well known before the priority date of the suit patent and were employed in multiple refrigeration systems. For this, defendants counsel relied upon Prior Art US7207183 [D14].
54. To assert its claim around modularity of the plaintiffs unit, defendants counsel highlighted parts of the specifications of the suit patent that clearly mentioned that the plurality of refrigeration systems were implemented in a modular fashion; the said extracts are as under:
[47] Each of the self-contained cooling modules 36 can be installed in the housing 12 of the main unit without interfering with the refrigeration system of the module 36 so that assembly and possible disassembly of self-contained cooling modules 36 in the pre-conditioned air unit housing 12 can be performed by persons without specific skills in the field of refrigeration systems. The self-contained cooling modules 36 may be manufactured at one site particularly suitable for manufacturing of refrigeration systems for subsequent integration with housings 12 of the main unit at a separate site particularly suitable for manufacturing flexibility and decreasing manufacturing cost of the preconditioned air unit without having to perform the cumbersome task of emptying the preconditioned air unit for refrigerant is made possible.

55. Defendants counsel relied upon the decision in Allergan Inc. vs. The Controller of Patents, C.A (Comm IPD-PAT) 22/2021 to assert that the claims would have to be read in the light of specifications and the claims and accompanying specifications could not be dichotomized. In this regard, other decisions relied upon were: Edward H. Philips vs. AWH Corporation, Hopeman Brothers, Inc. and Lofton Corporation, 415 F. 3d 1303; Nature Simulation Systems Inc vs. Autodesk, Inc., 23 F.4th 1334; Nautilus Inc. vs. Biosig Instruments, Inc., 572 U.S 898 (2014).
56. It was also highlighted that, as for the plaintiffs, the problems in the prior art were cost, efficiency, flexibility and serviceability. In order for the suit patent to provide an answer to these problems, it had to be a modular PCA unit with a VFD compressor and a central controller and therefore, the plaintiff’s argument that the claims of the suit patent were non-modular is not sustainable.
57. It was further argued that the suit patent is invalid on the following grounds: firstly, obviousness and lack of inventive step under Section 64 (1)(f); secondly, double patenting under Section 64 (1)(j) as also under Section 53(4); thirdly, non-compliance of Section as per Section 64 (1)(m) was placed; and fourthly, it was submitted that the suit patent is not patentable under Section 64 (1)(k) read with Section 3(d) and 3(f) of the Patents Act.
58. Defendants counsel submitted that the PCA units were well discovered in the prior arts and reliance was placed on prior arts: US4835977 (6/6/1989) [D2] and US7461516B2.
59. Multiple and modular refrigeration systems were present in prior art D6 well as DE202008002015U1 (29/05/2008) [D20].
60. To the plaintiffs contention that the prior arts were non-analogous, defendants counsel relied on the KSR International Company v Teleflex Inc. Et Al., 550 U.S. 398 (2007).
61. It was submitted that the suit patent was a new use of a known apparatus which was not patentable under Section 3(d) of the Patent Act or was merely an arrangement of known devices and, therefore, was not patentable under Section 3(f) of the Patent Act.
62. Defendants also alleged that plaintiffs engaged in double patenting, since they filed two patent applications, one resulting in IN 952 and the second in the suit patent. According to the defendants, the specifications of the two patents were similar, and they essentially dealt with the same invention, same implementation, and providing the same solution to the same problem. Diagrammatic figures used for the two patents were also similar, as also the working statements. It was submitted that only one stray line of modularity has been added to the suit patent, which is to be disregarded, since the specifications do not teach non-modularity. It was alleged that the plaintiffs misrepresented the Patent Office and, therefore, the suit patent was liable to be revoked under Section 64. Reliance for this was placed on decisions in F. Hoffman-LA Roche Ltd. and Anr. vs. Cipla Ltd., 2009 (110) DRJ 452 (DB), Glaverbel S.A. vs. Dave Rose & Ors., 2010 SCC OnLine Del 308, and Sotefin SA vs. Indraprastha Cancer Society and Research Center & Ors., 2024: DHC: 2154. It was submitted that double patenting makes the patent vulnerable and invalid.
G. SUBMISSIONS IN REJOINDER
63. Mr. Anand submitted in rejoinder that the main problem which was being solved by the suit patent was not serviceability, but of control and management of the life of the compressor and ability to adjust cooling, depending on ambient conditions.
64. It was stated that the invention in the suit patent was neutral to the issue of modularity (reference was made to paragraph [74] of the specifications), and it was only the cooling modules that were self-contained. Further, it was submitted that since the claim did not limit itself to modularity, it essentially covered all options of modularity and non-modularity.
65. Plaintiff’s counsel also stated that the challenge to the validity of the suit patent by the defendants was fanciful and not credible, since weightage had to be given to the Patent Office having granted the patent after scrutiny.
66. Reliance was placed on the decision of Division Bench of the Court in Intex Technologies vs. Telefonaktiebolaget LM Ericsson, 2023: DHC: 2243 in particular on para 129 thereof.
67. On the issue that there was lack of inventive step in the suit patent, the plaintiffs counsel relied upon the decision in Avery Dennison Corporation vs. Controller of Patents and Designs, 2022 SCC OnLine Del 3659, which summarizes various principles and approaches for determining whether a patent lacks an inventive step, as also on the extract from a book on patent law authored by Justice Prathiba M. Singh. it was argued that the starting point of an inventive step analysis is to determine the state of the art at the time the invention was conceived, and whether on the priority date of the plaintiffs patent, a person skilled in the art would have thought it was obvious, given the technology prevalent and the common general knowledge, to have a central controller regulate multiple VFD run compressors on each refrigeration system.
68. It was submitted that the defendants defence on obviousness or lack of inventive step, therefore, had to fail as: firstly, the defendant had to combine 20 prior arts of different technical fields to state that the suit patent lacked inventive step, which was contrary to the principle enunciated in Prism Cement Limited vs. Controller of Patents and Designs, 2020 SCC OnLine IPAB 25, where in para 32, it was observed that greater the number of documents which must be combined to reach the invention, higher is the likelihood that it has an inventive step; secondly, defendants failed to identify a person skilled in the art; thirdly, defendants claim that conventional air conditioning was already covered is not borne out since PCA and HVAC units are not comparable; fourthly, defendants could not justify as to how its own sister concern Ipalco B.V. filed the US patent US2014/0102125 A1 (wherein the control unit performed a function similar to the suit patent.) 2 years after the priority date of the suit patent and was granted protection in the United States on 2nd February, 2020 (later assigned in the name of defendant no. 2.)
69. On mosaicing, Mr. Saikrishna Rajagopal, counsel for plaintiffs, countered by stating that it was legitimate to establish prior art through mosaicing, to which Mr. Anand stated that mosaic applies if one prior art links to another prior art.
70. Furthermore, it was submitted that reference to an old prior art of conventional refrigeration system cannot lead to an inference that it was obvious. The passage of at least 23 years since the prior art D6 shows that the invention was not obvious and reliance was placed on Avery Dennison (supra) for this assertion.
71. It was stated that in the prior art US7207183 (13/10/2005) the VFD was linked to a compressor in parallel whereas in the plaintiffs case the VFD was connected to all the compressors.
72. On the issue of double patenting raised by defendants, it was submitted that there is no mention of the same in the Patents Act. However, the closest reflection of the concept would be in Section 64 (1)(a) and Section 13 (1)(b). It was further submitted that the scope of independent claim 1 was significantly different and covered different aspects of the PCA units. IN 952 covered mechanical arrangements of refrigeration systems, that is, compartments and configuration of the compartments in the PCA unit. Furthermore, the two patents have the same priority date, and therefore, plaintiffs cannot be accused of evergreening.
73. Moreover, the First Examination Report issued by the Controller on 16th October, 2017 indicated that there were separate examination reports of both the inventions on the same date and therefore, there was no misrepresentation or suppression by the plaintiffs, the Patent Office being clearly aware of both the inventions which had been independently secured.
74. Lastly, plaintiffs counsel submitted that defendants contention that invalidity would also be on account of Section 3(d) and 3(f) of the Patent Act was not sustainable since the patent was not a process claim and also it was not a mere arrangement or rearrangement or duplication of devices functioning independently in a known way.
H. ANALYSIS

75. Heard counsel for parties, and perused the material on record.
76. Plaintiffs claim that defendants PCA unit infringes the plaintiffs suit patent IN I45, which is for a PCA unit with at least one VFD, supervised by a controller that is configured for variation of the output frequency. Plaintiffs specifically assert that they are not claiming monopoly over PCA units, which were known in the art, and that it is the presence of VFDs for at least two compressors which distinguishes the suit patent. Therefore, plaintiffs relief for infringement is based on this distinguishing feature.
77. For the purposes of further analysis, independent claim no.1 of the suit patent is extracted below (with parts of characterization underscored since it forms the crux of the invention; reference may be made to Guala Closures SPA v. AGI Greenpac Limited, 2024 SCC OnLine Del 3510, a decision rendered by Justice Prathiba M Singh on 8th May 2024):
A preconditioned air unit (10) for supplying preconditioned air to an aircraft parked on the ground, the preconditioned air unit comprising:
a housing (12) accommodating a flow duct (20) with an air inlet for ambient air and an air outlet for connection to the parked aircraft;
a blower (30) connected with the flow duct (20) for generation of an air flow from the air inlet (22) toward the air outlet (25);
a plurality of refrigeration systems (36), wherein each refrigeration system comprises:
at least one compressor (38);
at least one condenser (40);
at least one expansion valve (42);
at least one evaporator (44) connected in a flow circuit containing a refrigerant, and wherein the at least one evaporator (44) interacts with the air flow in the flow duct (20); and
at least one variable frequency driver (46, 54, 56) for power supply of the at least one compressor (38); and
the housing (12) further accommodates a central controller (60) that is configured for controlling operation of the preconditioned air unit (10) including the variable frequency drivers (46, 54, 56) of the plurality of refrigeration systems (36), characterized in that:
the at least one variable frequency driver (46, 54, 56) has a controller that is configured for variation of the output frequency of the at least one variable frequency driver (46, 54, 56); and
the central controller (60) is connected to at least one controller of the at least one variable frequency driver (46, 54, 56); wherein the central controller (60) automatically adjusts the cooling performed by the preconditioned air unit (10) to at least one of: the selected type of aircraft, the ambient temperature, the humidity, the cabin temperature, the outgoing temperature and the outgoing airflow from the preconditioner air unit (10).

78. The essential feature-wise breakdown of claim 1 as provided by plaintiffs is again reproduced as under for ease of reference:
Feature 1.1

A preconditioned air unit (10) for supplying preconditioned air to an aircraft parked on the ground, the preconditioned air unit comprising:

Feature 1.2

a housing (12) accommodating a flow duct(20) with an air inlet for ambient air and an air outlet for connection to the parked aircraft.

Feature 1.3

a blower (30) connected with the flow duct (20) for generation of an air flow from the air inlet (22) toward the air outlet (25).

Feature 1.4

a plurality of refrigeration systems (36),

Feature 1.5

Feature 1.6

at least one variable frequency driver (46;54;56) has a controller that is configured for variation of the output frequency of the at least one variable frequency driver (46, 54, 56)

Feature 1.7

and the central controller (60) is connected to at least one controller of the at least one variable frequency driver (46;54;56).

Feature 1.8

79. The crux of the suit patent was to supply preconditioned air using ambient air through multiple refrigeration systems, controlled through a central controller, which manages the VFDs attached to the compressor. The job of the central controller was to automatically adjust the cooling of the PCA unit depending on the type of aircraft, the ambient temperature, humidity, cabin temperature etc.
80. This was an improvement on a conventional PCA unit which was directly connected to the main power supply and was therefore, limited by it. Per the suit patent, the compressor, which is the heart and soul of a refrigeration unit, was driven by the VFD, allowing adjustment to the compressors operating speed, depending on the variable cooling requirements. While the VFD controlled a compressor, the VFDs in turn were connected to a central controller, which would do the job of management of various refrigeration units, allowing each of the refrigeration units to function independently at varying capacities to adjust to the external requirements.
81. The plaintiffs claimed that defendants have been selling PCA units, which infringe the suit patent and have bid in tenders floated by the government, since 2020, including on tenders floated for airports at Goa, Hyderabad and Delhi.
82. According to plaintiffs, defendants were put to notice of the infringement of the plaintiffs patent in UK, and in India. However, defendants remained evasive in their response. Subsequently, in March 2023, pre-litigation mediation was initiated by the plaintiffs. As the attempt at mediation was unsuccessful, plaintiffs filed the present suit. Therefore, the instant application for interim relief has been pressed by plaintiffs.
83. For the purposes of claiming infringement, first the claims are to be constructed and, thereafter, the claims are to be compared with the defendants product.
84. For construction of claims, various judicial tests have been adopted to interpret the patent specifications and claims, inter alia the pith and marrow test, the test of purposive construction etc. This aspect will be adverted to a bit later.
85. As regards the second step of comparison, if substantive elements of claims can be found in the defendants product through direct comparison or other methods, the defendants product would be deemed to infringe the patent. Essentially, the defendant’s product has to be compared with the claims of the patent to establish infringement. For the purposes of comparison, trivial variations do not matter. The Court has to make an assessment that the defendant’s product is producing the same effect (reference be made to RX Prism Health Systems Private Limited v Canva Private Limited and Others, 2023 SCC Online Del 4186).
(i) Claim Construction
86. Let us first deal with the first issue of claim construction.
87. The rival contentions on claim construction hinge on the issue of modularity of the PCA units. On one hand, defendants submit that the claims ought not to be constructed in isolation from the specifications; and when constructed through the prism of the specifications, the claims of the suit patent import an essential element of modularity to the invention, and therefore, at the very threshold, there is no infringement, since the defendants product is non-modular. To this, plaintiffs counsel asserts that the claims have to be given their ordinary and plain meaning, and that reading-in a limitation into the claim through the specifications is impermissible. Plaintiffs contend that nowhere in the claims, read as they are, is there a claim of modularity, and the claims when read with the specifications are agnostic to the concept of non-modularity.
88. As per the plaintiff, the essential feature of the suit patent is the ability of the PCA unit to automatically adjust cooling performance, according to at least one of the conditions i.e. type of aircraft, ambient temperature, humidity, cabin temperature, outgoing temperature, and outgoing airflow from the PCA unit. This was achieved by driving the compressor through a VFD, and in turn controlling the various compressors with VFDs by a central controller.
89. A bare perusal of claim 1 of the suit patent shows that the claim is for a PCA unit comprising a housing, with a blower, and a plurality of refrigeration systems. Each of the refrigeration systems comprises at least one compressor, at least one condenser, at least one expansion valve, at least one evaporator, and at least one VFD, which in turn is controlled by a central controller.
90. In itself, claim 1 does not speak of modularity. Modularity essentially involves using a modular system, in that, sets of components can be attached or detached, without disturbing the other components. Importantly, the other patent granted to the plaintiffs, being IN 952, with the same priority date, seems to in fact specifically advert to modularity.
91. The suit patent, on the other hand, focuses on the aspect of the VFD attached to the compressor and the management of various VFDs through a central controller. The comparative between claim no. 1 of the two patents is provided by plaintiff and extracted as under:
Claims of IN 145

1. A preconditioned air unit (10) for supplying preconditioned air to an air to an aircraft parked on the ground, the preconditioned air unit comprising:
a housing (12) accommodating a flow duct (20) with an air inlet for ambient air and air outlet for connection to the parked aircraft;
a blower (30) connected with a flow duct (20) for generation of an air flow from the air inlet (22) toward the air outlet (25);
a plurality of refrigeration systems (36), wherein each refrigeration system comprises:
at least one compressor (38);
at least one condenser (40);
at least one expansion valve (42);
at least one evaporator (44)
connected in a flow circuit containing a refrigerant, and wherein the at least one evaporator (44) interacts with the air flow duct (20); and
at least one variable frequency driver (46, 54, 56) for power supply of the at least one compressor (38); and
the housing (12) further accommodates a central controller 60 that is configured for controlling operation of the preconditioned air unit (10) including the variable frequency drivers (46, 54, 56) of the plurality of refrigeration systems (36), characterized in that:

the at least one variable frequency driver (46, 54, 56) has a controller that is configured for variation of the output frequency of the at least one variable frequency driver (46, 54, 56); and

the central controller (60) is connected to at least one controller of the at least one variable frequency driver (46, 54, 56); wherein the central controller (60) automatically adjusts the cooling performed by the preconditioned air unit (10) to at least one of: the selected type of aircraft, the ambient temperature, the humidity, the cabin temperature, the outgoing temperature and the outgoing airflow from the preconditioned air unit (10).

Claims of IN 952

1. A preconditioned air unit (10) for supplying preconditioned air to an aircraft parked on the ground, the preconditioned air unit (10) comprising a main unit with a housing (12) accommodating
a flow duct (20) with an air inlet (22) for ambient air an and an air outlet (25) for connection to the parked aircraft, a blower (30) connected with the flow duct (20) for generation of an air flow from the air inlet (22) toward the air outlet (25) and
a plurality of compartments (34), each of which is configured for accommodation of a self-contained cooling module (36) comprising:
at least one refrigeration system,
each of which includes at least one
compressor (38), at least one
condenser (40), at least one
expansion valve (42), and at least one
evaporator (44) connected in a flow
circuit containing a refrigerant, and
wherein
each compartment is configured so that the at least one evaporator (44) interacts with the air flow in the flow duct (20) when the self-contained
cooling module (36) is installed in the compartment, and wherein at least one self-contained cooling module (36) is installed in the plurality of compartments (34).

92. Ex facie, it seems that while IN 952 focuses on the mechanical arrangement i.e. modularity, the suit patent relates to the electrical and functional aspects of a PCA unit. Prima facie this Court is agreeable with the plaintiff on this assessment. However, defendants submission that the specifications of the suit patent essentially point to modularity and claims have to be construed in that light, needs to be examined in some detail.
93. Defendants point out to the use of the phrase plurality of refrigeration systems in claim 1 and submit that the reference numeral 36 used in the claim has been referred to as a self-contained cooling module throughout the specifications. In particular, attention has been drawn towards specifications [47], [49], and [51], which are extracted as under:
[47] Each of the self-contained cooling modules 36 can be installed in the housing 12 of the main unit without interfering with the refrigeration system of the module 36 so that assembly and possible disassembly of self-contained cooling modules 36 in the pre- conditioned air unit housing 12 can be performed by persons without specific skills in the field of refrigeration systems. The self-contained cooling modules 36 may be manufactured at one site particularly suitable for manufacturing of refrigeration systems for subsequent integration with housings 12 of the main unit at a separate site particularly suitable for manufacturing of airport ground equipment in general thereby increasing manufacturing flexibility and decreasing manufacturing cost of the preconditioned air unit 10. Further, the self-contained cooling module 36 may be stored as a spare part including the refrigerant, whereby repair of a preconditioned air unit without having to perform the cumbersome task of emptying the preconditioned air unit for refrigerant is made possible.
[49] Preferably, the self-contained cooling modules 36 are removably installed in the housing 12 of the main unit facilitating separation of an installed self-contained cooling module from the housing 12, e.g. utilizing screws, nuts and bolts for fastening each of the self-contained cooling modules 36 to the housing 12 and utilizing electrical connectors (not shown) to establish the required electrical interconnections between the cooling module and the housing 12 when the cooling module 36 is inserted in the housing 12 of the main unit 10.
[51] The removability of the modules 36 enhances the serviceability of the preconditioned air unit 10 since a possible malfunctioning self-contained cooling module can be separated from the housing 12 of the main unit 10 and replaced with a functioning module 36 with a minimum of down time of the preconditioned air unit 10. One cooling module 36 can be replaced in approximately 20 minutes. In the event that a functioning cooling module 36 is not available for substitution of the malfunctioning cooling module 36, the preconditioned air unit 10 will continue operation with the remaining cooling modules 36 i.e. the preconditioned air unit 10 remains fully operational, however with a lowered cooling capacity. Further, the malfunctioning module 36 can be moved for repair at a separate site particularly suitable for repair of refrigeration systems. Also, the possible requirement of dismounting and moving the entire preconditioned air unit for repair of a cooling circuit is hereby reduced.
Preferably, the self-contained cooling module 36 has physical dimensions suitable for movement by a fork lift truck 47 as illustrated in Fig. 4 facilitating transportation of the module 36, e.g. for storage, assembly into a preconditioned air unit 10, and service. For example, a malfunctioning module 36 can be removed from the housing 12 with a fork lift truck 47 and a properly functioning module 36 can be installed in the housing 12 with a fork lift truck 47.
94. To this, plaintiffs counsel has drawn attention to paragraph [74] of the specifications, which specifically provides that other preconditioned air units may be provided in the scope of the appended claims, including ones which are not modular. On this basis, the plaintiffs claim that the complete specification merely elaborates a modular embodiment as an example, but does not disclaim a non-modular embodiment. Paragraph [74] of the specifications is extracted below:
[74] Other preconditioned air units may be provided within the scope of the appended claims. For example, other preconditioned air units may be provided that are not modular. Also, preconditioned air units may be provided with different numbers of refrigeration systems, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 etc. refrigeration systems.
(emphasis added)

95. The additional argument of the defendants is relatable to paragraph [4] of the specifications wherein the problem stated to be solved by the invention is of cost, efficiency, flexibility and serviceability of PCA units. This, the defendants submit, can only be resolved by an apparatus which is modular in nature. Paragraph [4] of the specifications is extracted below:
[4] Cost, efficiency, flexibility, and serviceability remain an issue in known preconditioned air units.

96. Even though, various specifications do refer to the PCA containing a self-contained cooling module in their respective compartments (see for example specification [18], [33], [46], [48], [49], [51], reference may also be made to specification [41] where it is stated that the invention can be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Paragraph [41] of the specifications is produced below:
[41] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments were provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
(emphasis added)

97. It is also apparent from the reading of the specifications that the predominant aspect of the suit patent is of a compressor being driven by a VFD and details various aspects of how a VFD would control the respective compressors, as well as the central controller configured for controlling the operation. In this regard, reference may be made to specifications [8] – [12], [15]-[17],[21]-[23],[25], [55]-[58], [60]-[62], [67]-[69].
98. Plaintiffs counsels submission that the fundamental principle is not to read in or import structural and functional limitations in the claim, or cut down or extend the clear meaning or language of the claim by reference to the body of specifications, and the reliance on Chisum on Patents, Terrell on the Law of Patents, 17th Edition, and Glaverbel SA vs. British Coal Corp (supra) appeals to this Court.
99. Chisum on Patents categorically proscribes the importation of limitations from the general discussion, embodiments and examples in the specifications. In this regard, the following extract is relevant:
[A] Reading In or Importing Structural and Functional Limitations Into a Claim. The first caveat is that it is improper to import (i.e. read in) a limitation from the specifications general discussion, embodiments and examples. Further, [g]eneral descriptive terms will ordinarily be given their full meaning; modifiers will not be added to broad terms standing alone. This caveat bars the reading in of functional or process limitations as well as structural ones. Thus, it has been held improper to read a limitation on how an apparatus was used into a claim to the apparatus. Or a limitation on how a claimed structure was manufactured. On the other hand, an express structural limitation on a claim may be properly defined by reference to functional characteristics.
100. Terrell on the Law of Patents echoes the same principle when it comes to claim construction, and states that it is not legitimate to cut down or extend the clear meaning of the claim. In coming to this conclusion, reliance was placed on the decision in Glaverbel SA vs. British Coal Corp (supra) where the Court held that a patent is to be construed objectively, through the eyes of a skilled addressee. The Court also held that the whole document must be read together, the body of specifications with the claims. But if the claim is clear, the monopoly sought by the patentee cannot be extended or cut down by reference to the rest of the specifications and the subsequent conduct is not available to aid the interpretation of a written document.
101. These aspects have also been recognized by the Division Bench of this Court in Ace Technologies (supra), when it observes that patent rights are in respect of the claims and are broader than the preferred embodiments in the following paragraph:
42. In our view, the said contentions are not destructive of the other. We agree with the contention that the embodiments cannot be read to expand the scope of the Claims. The question whether the appellants have raised a credible challenge to the Suit Patent is required to be considered in context of the Claims because the patent rights are in respect of the Claims and are broader than the preferred embodiments. However, the description of the Suit Patent and the preferred embodiments are relevant to interpret and understand the Claims.

43. In Bishwanath Prasad Radhey Shyam v. Hindustan Metal Industries (supra), the Supreme Court had observed as under:
43. As pointed out in Arnold v. Bradbury, [[1871] 6 Ch. App. 706] the proper way to construe a specification is not to read the claims first and then see what the full description of the invention is, but first to read the description of the invention, in order that the mind may be prepared for what it is, that the invention is to be claimed, for the patentee cannot claim more than he desires to patent. In Parkinson v. Simon, [(1894) 11 RPC 483] Lord Esher, M.R. enumerated that as far as possible the claims must be so construed as to give an effective meaning to each of them, but the specification and the claims must be looked at and construed together.
44. The claims cannot be read in isolation. It is necessary that the same be read in the context of specifications and the description of the patent. There is no dispute that the specifications and description of the patent are necessary for interpreting and understanding the claims. However, the specifications cannot broaden the claim. As stated above, the monopoly that the Patents Act grants is in respect of the specific claims and not the preferred embodiments.
(emphasis added)
102. A clear enunciation of the nuanced assessment required during claim construction is provided by the United States Court of Appeals (Federal Circuit) in Conmark Communications (supra) where it was stated as part of the discussion that: we recognize that there is sometimes a fine line between reading a claim in light of the specification, and reading a limitation into the claim from the specification.
103. The defendants attempt to distinguish these authorities and decisions, are unmerited. It was essentially asserted that a purposive construction of the claim must be adopted, and that such construction of the claim would result in interpreting the claimed term plurality of refrigeration systems to be modularly interpreted, as that is the only embodiment sufficiently disclosed and enabled in the specification, while the non-modular embodiment was not enabled. However, this argument may not be sustainable. As stated above, the claim along with the specifications, seem to focus on the application of the VFD to the compressor, the variable controlling factor, and the overall central controller. The plurality of refrigeration systems as claimed, does not in itself assert modularity and, therefore, the claims would have to be seen as granted and it would be improper to read a critical limitation into the claims. As noted above, the difference with IN 952 is also dispositive in this regard, where modularity has been specifically claimed.
104. In any case, defendants have been unable to present any evidence of the fact that their PCA unit is non-modular in nature. The only submission canvassed before the Court was that the suit for infringement was not filed in relation to plaintiffs patent IN 952 because defendants PCA unit was non-modular in nature. However, no prima facie evidence has been presented in this regard.
(ii) Invalidity of the Suit Patent and credible challenge

a. Lack of an inventive step
105. Having accepted prima facie, the plaintiffs position that the claims are agnostic to modularity and focus only on the VFD plus central controller, the defendants primary challenge then, as categorically submitted, is that the suit patent ought to be revoked for being invalid due to lack of an inventive step and for being obvious in light of the prior art.
106. In this context, relying upon the decisions in Glaverbel S.A. vs. Dave Rose &Ors., 2010 SCC OnLine Del 308, and F. Hoffman LA Roche Ltd. & Anr. vs. Cipla Ltd., 2009 (110) DRJ 452 (DB), and Sulphur Mills Limited vs. Shree Ram Agro India & Ors. 2024: DHC: 2154, defendants argue that if there exists a credible challenge to the validity of the suit patent, interim injunction cannot be granted in favour of the plaintiff.
107. Relying upon the decision in F. Hoffman LA Roche (supra), another Division Bench of this Court in Natco Pharma vs. Novartis AG and Another, 2024 SCC OnLine Del 3064, recently expounded the law on this subject. According to the said decision, in order to raise a credible challenge to the validity of the suit patent, the defendant needs to merely show that the patent is vulnerable to being invalidated. Unless such credible challenge is made, the question as to validity of the suit patent is required to be determined at the stage of trial. Relevant observations in Natco Pharma (supra) are extracted below:
43. Unless there is no real prospect of the defendant to succeed in its challenge and an appropriate application to allow the action is made prior to framing of issues, the questions as to the validity of the patent asserted, are required to be determined at the trial. However, at the stage of interim relief, the defendant has to establish its assertion that its defence is not insubstantial and sets out a credible challenge to the validity of the patent. The defendant is not required to establish that the patent is invalid, it has to merely show that the patent is vulnerable. If the challenge raised to the validity is substantial, the threshold standard for resisting an interim injunction in this regard – subject to other relevant considerations-would be met. In this context, it is relevant to refer to the decision of the Division Bench of this Court in F. Hoffmann-LA Roche Ltd. v. Cipla Ltd.7. In the said case, the Division Bench had rejected the contention that the defendant had a heavy burden to discharge and would have to establish a stronger prima facie case than the plaintiff. The Division Bench had also not accepted the contention that since there is a multi-level examination of opposition to the grant of patent, it ought to be accorded the highest weightage. The relevant extract of the said decision is set out below:

53. The plea of the plaintiff that since there is a multilayered, multi-level examination of the opposition to the grant of patent it should accorded the highest weightag