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Prosecution History Estops Patentee from Asserting Claims Against Conventional Technique

August 09, 2001

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Last Month at the Federal Circuit - September 2001

Judges: Clevenger (author), Schall, and Gajarsa

In Day International, Inc. v. Reeves Bros., No. 00-1505 (Fed. Cir. Aug. 9, 2001), the Federal Circuit affirmed a SJ of noninfringement after affirming the district court’s claim construction on U.S. Patent No. 4,770,928 (“the ‘928 patent”) directed to an improved method of manufacturing compressible printing blankets used to transfer ink from a printing plate to paper. In particular, the ‘928 patent is directed to an improved method in which a compressible layer is cured in a way that avoids an agglomeration problem experienced in prior art processes.

Reeves Brothers (“Reeves”) manufactures compressible printing blankets using a method in which the compressible layer is initially cured at conventional vulcanization temperatures, i.e., above 270ºF. The infringement dispute concerned the claim limitation that the compressible layer be cured at a “temperature below the melting point of [the] microcapsules.” Reeves argued that the scope of the invention should be limited to processes that involve an initial curing step at low temperatures, namely at 110-170ºF, and filed a corresponding motion for SJ. A magistrate judge found that arguments made by the patentee during the prosecution history limited the scope of the invention as argued by Reeves.

The Federal Circuit agreed that the comments in the prosecution history were made to distinguish prior art and to disavow curing steps performed at higher, conventional curing temperatures. With this claim construction, the Court affirmed the district court’s SJ of noninfringement, given that Reeves had never cured the compressible layer in its printing blankets at a temperature below 270ºF.