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Courts Not Free to Excuse Patentee from Consequences of Its Own Word Choice

02-1414
March 18, 2004

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Last Month at the Federal Circuit - April 2004

Judges: Linn (author), Newman, and Prost

In International Rectifier Corp. v. IXYS Corp., No. 02-1414 (Fed. Cir. Mar. 18, 2004), the Federal Circuit reversed the district court’s claim construction rulings, reversed-in-part and vacated-in-part a SJ that IXYS Corporation (“IXYS”) had infringed two patents held by International Rectifier Corporation (“IR”), and remanded the case back to the district court for entry of judgment in IXYS’s favor regarding certain claims found noninfringed as a matter of law and for further proceedings regarding other claims where factual issues remained.

This opinion reviewed rulings on three patents held by IR: U.S. Patent Nos. 4,959,699 (“the ‘699 patent”), 5,008,725 (“the ‘725 patent”), and 5,130,767 (“the ‘767 patent”). These patents relate to VPPM transistor devices manufactured by diffusing impurities into semiconductor wafers. The opinion focuses on the construction of three different claim terms: “polygonal,” “annular,” and “adjoining,” and whether the district court’s construction of these terms was overbroad. The district court construed all three claim terms and found IXYS liable for infringement of all asserted claims. The Federal Circuit reviewed the intrinsic evidence and found the district court’s construction of all three claim terms to be erroneous.

The Federal Circuit determined that the district court’s construction of the term “polygonal” was incorrect because it went beyond the ordinary dictionary definition of the term when there was no support in the written description for such a construction. IR argued that one skilled in the art would understand “polygonal” to encompass shapes with curved corners because the “polygonal base regions” recited in the claims are formed by the diffusion process, which blurs the outline of the regions. The Federal Circuit rejected this argument and found that although claim terms must be considered from the perspective of one skilled in the art, recognition of these diffusion effects did not warrant redefinition of the term. Because the patentee was aware of the diffusion effects, yet still chose the word “polygonal” without modification or qualification, the patentee was held to the ordinary definition of the term.

The Federal Circuit also found the district court’s construction of the term “annular” to be overbroad because it went beyond the definition provided by the patentee in the written description. The Court found that although the patentee had trumped the ordinary meaning of the term by acting as his own lexicographer, the patentee was held to the meaning provided in the written description.

Finally, the Federal Circuit found the district court’s construction of the term “adjoining” to be overbroad because the district court adopted the definition of the synonym “adjacent.” The dictionary cited by the district court makes an express distinction between the terms “adjoining” and “adjacent,” and the Federal Circuit found that the district court was not free to disregard this distinction. The Federal Circuit pointed out that had the patentee meant “adjacent,” he could have used that word. Instead, the patentee chose “adjoining,” and the patentee was held to his word choice.

The Federal Circuit reversed the SJ of infringement regarding the claims containing the term “adjoining” and remanded the case for entry of judgment in IXYS’s favor, because it found that no reasonable jury could find these claims infringed based on the facts stipulated to by the parties. The Federal Circuit, however, vacated the SJ of infringement regarding the claims containing the terms “polygonal” and “annular,” and remanded the case for further proceedings because it found that although the structure of the accused device was undisputed, a factual issue remained as to how the new claim construction applies to these claims.