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Midtronics, Inc. v. Aurora Performance Products LLC

July 11, 2008


The opinion of the court was delivered by: Milton I. Shadur Senior United States District Judge


Midtronics, Inc. ("Midtronics") claims that Aurora Performance Products LLC d/b/a Argus Analyzers ("Argus") and BPPower, Inc. ("BPPower") have infringed its United States Patent 5,821,756 (the "'756 Patent"), entitled Electronic Battery Tester with Tailored Compensation for Low State-Of Charge.*fn1 Having reached an impasse as to the meaning of certain of the claim terms, the parties now look to this Court for aid in claim construction.*fn2 This opinion conducts a Markman analysis to construe language contained in various claims of the '756 Patent.

Tenets of Claim Construction

In an action claiming patent infringement, the court must resolve any disputed issues of claim construction before moving to the infringement claim (Apex Inc. v. Raritan Computer, Inc., 325 F.3d 1364, 1370 (Fed. Cir. 2003)). Construction of a patent claim presents a question of law through which the court determines the scope and meaning of the claim (Markman v. Westview Instruments, Inc., 517 U.S. 370, 372 (1996)).

To that end claim terms should be given their ordinary and customary meaning as understood by a person of ordinary skill in the art as of the effective filing date of the patent application (Phillips v. AWH Corp., 415 F.3d 1303, 1313 (Fed. Cir. 2005) (en banc)). Claim language is the most important indicator of the meaning of the claim and should therefore be the central focus of the analysis (Middleton, Inc. v. Minn. Mining & Mfg. Co., 311 F.3d 1384, 1387 (Fed. Cir. 2002); Phillips, 415 F.3d at 1312). Beyond the claim language, a construing court should look primarily to other intrinsic evidence: other claims within the same patent, the patent's specification and the prosecution history (Hockerson-Halberstadt, Inc. v. Avia Group Int'l, Inc., 222 F.3d 951, 955 (Fed. Cir. 2000)). But as helpful as a patent's specification may be in claim construction (Phillips, 415 F.3d at 1315), a court must be mindful to avoid importing limitations from the specification into the claims (id. at 1323).

If ambiguity lingers after the application of intrinsic evidence, a construing court may then turn to extrinsic evidence to supplement its interpretive efforts (Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1583-84 (Fed. Cir. 1996)). For example, judges may consult and rely on dictionary definitions, although extrinsic in nature, so long as the definitions do not contradict claim terms (id. at 1584 n.6). But when the patentee dons a lexicographer's cap and crafts special definitions, those specially defined meanings trump ordinary usage--and so dictionary definitions are not then a proper resource (id. at 1582; Phillips, 415 F.3d at 1316).

Patent Subject Matter

Midtronics's patent claims an improvement on previous battery testers ('756 Patent abstract). Dr. Keith Champlin ("Champlin"), one of the three co-inventors of the '756 Patent, has amassed numerous patents relating to battery testers since the 1970s (M. Mem. 2; A-B Mem. 3), essentially creating an alternative to previous battery testers that had employed "discharge testing" (M. Mem. 3; A-B Mem. 2).

Discharge testing (also known as load testing) subjects the battery to a direct current load having a predetermined value for a prescribed period of time (M. Mem. 3; A-B Mem. 2). That process has several disadvantages. Among those, it causes the battery to lose considerable energy immediately after the test and is not repeatable because it creates changes in the battery's chemistry (M. Mem. 3-4).

Champlin invented "dynamic testing" in the 1970s by measuring what he calls the dynamic conductance of the battery (M. Mem. 4-5). Dynamic testing (which utilizes a low energy small signal) is repeatable and does not alter the battery under test (M. Mem. 5-6). Because not all battery types are designed in the same way,*fn3 the accuracy of the test can be compromised unless the type of battery being tested is taken into account (M. Mem. 7). In that respect the '756 Patent claims an improvement over previous dynamic testers by adjusting for different battery types to create more accurate test results (M. Mem. 7).

Disputed Claim Terms

Midtronics offers four claim terms for construction:

(1) dynamic battery parameter, (2) dynamic resistance, (3) dynamic conductance and (4) intermediate dynamic parameter (M. Mem. 1). Argus and BPPower state that the only claim term in need of construction is "dynamic," and they offer "measured using an alternating current signal" as their proposed meaning (A-B Mem. 1).

At the outset it is helpful to review some basic electrical terms. "Current" is the movement of an electric charge through an electrical element (think of a charge moving through a copper wire) (M. R. Mem. 3 n.2). "Conductance" is the measure (in "mhos") of the ability of a circuit to conduct electricity (McGraw-Hill Dictionary of Scientific and Technical Terms [hereafter simply "Scientific Dictionary"] 434 (5th ed. 1994)). "Resistance" is the measure (in "ohms") of the opposition of a circuit to the flow of electrical current (as such, it is the inverse of resistance*fn4 ) (McGraw-Hill Encyclopedia of Physics 328 (2d ed. 1993)). "Polarity" is the ...

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