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Nesscap Co., Ltd. v. Maxwell Technologies

December 5, 2007


The opinion of the court was delivered by: Honorable Janis L. Sammartino United States District Judge


This action alleges infringement of Nesscap Co., Ltd.'s ("Nesscap" or "plaintiff") Patent No. 6,743,544 ("patent") by Maxwell Technologies, Inc. ("Maxwell" or "defendant"). The patent claims an electric energy storage device that reduces internal electric resistance between electrodes and their terminals. (Patent, at 1:8-9.) In its preliminary infringement contentions, plaintiff asserted that defendant's line of Medium Cell Boostcap Ultracapacitors infringed claim 1 of the patent. (Sharp Decla. ISO Motion, Exhibit F, at 67.) In claim 1, the patent claims, inter alia, "a pressure adjusting means inserted between the housing and the anode and cathode terminals so as to maintain a predetermined constant pressure between the electrode body and the anode and cathode terminals" and "a metal layer formed on surfaces of the first and second protrusions" of the electrodes. (Patent, at 8:58-63.)

Defendant moves for summary judgment of non-infringement because its ultracapacitors allegedly lack "pressure adjusting means" and a "metal layer." (Doc. No. 21.) For the reasons stated below, the Court denies the motion. The denial is without prejudice.


A. Factual Background

An electric energy storage device provides electric energy to some external source. (Patent, at 1:13-17.) The storage device consists of an "electrode body," i.e., an anode electrode and cathode electrode, along with insulating film that separates the electrodes. (Id. at 3:45-55.) The storage device also includes an anode and cathode terminal, such that each electrode contacts its respective terminal (i.e., anode electrode to anode terminal, cathode to cathode). (Id. at 3:55-60.) The terminals are connected to the electrode body mechanically. (Id. at 7:59-64.) The electrode body is installed within a housing made of, e.g., metal or molding resin. (Id. at 6:45-46.)

The storage device can provide more energy if there is less internal resistance between the electrodes and terminals. (Id. at 1:17-20.) The internal resistance is less if the electrodes are shorter and/or have contact with the terminals over a larger surface area. (Id. at 2:65-67.) The patent claims an invention that reduces internal resistance by increasing the contact area in three ways. First, the electrodes are aligned in an offset manner, such that one end of each electrode protrudes out of the electrode body. (Id. at 5:24-27.) Second, the portion of the terminal that contacts the electrode is designed with an uneven surface of screw threads. (Id. at 5:60--6:12.) Third, a metal layer is added onto the electrodes by, e.g., applying a metal spray. (Id. at 8:9-12.)

The pressure adjusting means controls the contact pressure that the terminals apply to the electrode body. The contact pressure varies based on, inter alia, gases produced during operation, increases in temperature, or simply long-term use. (Id. at 6:54-62.) The pressure adjusting means, typically made of an elastic rubber packing, is located between the housing and the terminals. (Id. at 6:46-52.)

The initial patent application contained no claim with a "pressure adjusting means" limitation and included the "metal layer" limitation only in a dependent claim. (Sharp Decla. ISO Motion, Exhibit A, at 18-19.) The United States Patent Office initially rejected this application and an amendment, but finally accepted the inventor's submission of an independent claim containing limitations for both the "pressure adjusting means" and the "metal layer". (Id., Exhibits B & D.)

In defendant's ultracapacitors, the anode and cathode terminals are welded to the anode and cathode ends of the electrode body. (Gallay Decla. ¶¶ 11-12.) The electrode body is inserted into a metal housing or "can", and the housing is then "necked", or compressed, around the electrode body to form shoulders. (Id. ¶¶ 8-9 & Fig. 4.) The anode terminal forms the base of the housing and is welded directly onto the anode electrode. (Id. ¶ 11 & Fig. 6.) The cathode terminal forms part of the cap of the housing for the ultracapacitor. (Id. ¶ 12.) To connect the cathode electrode to the cap/cathode terminal (so that electrical current can flow through both), the ultracapacitor includes an aluminum conductor*fn1 welded to the cathode electrode. (Id. & Fig. 7.) The aluminum conductor is then folded so the cap can be moved down to seal the housing. (Id. ¶ 14 & Fig. 9.)

B. Procedural Background

On December 14, 2006, plaintiff initiated the present action against defendant for patent infringement in the United States District Court for the District of Delaware. On January 3, 2007 defendant answered the complaint and filed counterclaims for declaratory judgments of invalidity and non-infringement. The action was transferred to this Court by Order dated April 13, 2007.

On June 27, 2007, defendant filed the present motion for summary judgment. (Doc. No. 21.) Plaintiff filed its opposition on August 27, 2007 (Doc. No. 22), and plaintiff replied on August 31, 2007 (Doc. No. 23).*fn2 The Court heard oral argument on the ...

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