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Multiplying Is Not Dividing

May 21, 2001
Levine, Howard W.

Decision icon Decision

Last Month at the Federal Circuit - June 2001

Judges: Clevenger (author), Plager, and Schall

In AccuScan, Inc. v. Xerox Corp., No. 00-1316 (Fed. Cir. May 21, 2001) (nonprecedential decision), the Federal Circuit reversed a jury verdict of infringement based on arguments made during the prosecution history of U.S. Patent No. 3,952,144 (“the ‘144 patent”). The ‘144 patent claims a circuit for calibrating a facsimile machine. At trial a jury had found that each of Xerox Corporation’s (“Xerox”) products, the DocuTech publishing system, the 5775 color copier, the SA4 scanner, and the 7017/20/21 facsimile machines, infringed the ‘144 patent and awarded AccuScan, Inc. (“AccuScan”) damages close to ten million dollars.

On appeal, Xerox argued that the claims at issue could not cover the four accused products, either literally or under the DOE, based on positions AccuScan advocated during prosecution. The Federal Circuit agreed, concluding that arguments and amendments made during the prosecution of the ‘144 patent limited the interpretation of the claim terms so as to exclude any interpretation that was disclaimed during prosecution.

To overcome prior art, AccuScan had argued during prosecution that while the prior art multiplied a corrected signal by a gain value, the claimed invention used a divide circuit. Because it was uncontested that the Xerox DocuTech publishing system and the 5775 copier do not use a divide circuit, but instead either multiply the corrected signal by a gain value or subtract logarithms, these two devices could not fall within the scope of the properly interpreted claims either literally or under the DOE. AccuScan, however, contended that multiplication by a reciprocal (as is performed by the DocuTech) is in fact the same thing as division. The Federal Circuit stated that while AccuScan’s contention was mathematically correct, AccuScan had explicitly disclaimed such an interpretation during prosecution. Therefore, there can be no infringement with respect to either the DocuTech or the 5775 copier.

AccuScan had also argued during prosecution that its claimed invention separately stored a sample of white light throughout the complete scan of the document page and continuously used this white sample to calibrate the video signal. AccuScan advanced this argument to overcome a reference that its invention did not store a white sample during the whole scan, but instead used the white sample value to calculate a gain value. Based on this argument during prosecution, and since it was uncontested that all of Xerox’s products only store the white sample value temporarily, the Federal Circuit held that none of Xerox’s accused products infringe the properly interpreted claims literally or under the DOE.

Xerox also argued that the ‘144 patent was invalid based on a prior publication and an offer for sale. As to the prior publication, the Federal Circuit explained that the claims at issue are means-plusfunction claims. Therefore, the claims must be interpreted in light of the structures set forth in the specification. As the specification only disclosed one embodiment of the claimed device, the Federal Circuit limited the scope of the claims to that specific embodiment. Accordingly, as the prior art reference raised by Xerox did not disclose the same formula utilized by the embodiment described in the specification, the Federal Circuit held that there was no anticipation by the prior publication.

As to the offer for sale, the Federal Circuit found that there were disputed factual issues as to whether the offer for sale included the invention claimed by the ‘144 patent and that there was substantial evidence supporting the jury’s verdict. Accordingly, the Federal Circuit affirmed the jury’s verdict on validity.

[Don Dunner, Bob Yoches, John Alison, and Howard Levine of our firm represented Xerox successfully on appeal.]