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Prosecution Disclaimer Must Be Unambiguous

July 07, 2003
May, Timothy J.

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Last Month at the Federal Circuit - August 2003

Judges: Clevenger (author), Michel, and Schall

In Omega Engineering, Inc. v. Raytek Corp., No. 01-1546 (Fed. Cir. July 7, 2003), the Federal Circuit rejected the district court’s claim construction and reversed the district court’s SJ of noninfringement. The Federal Circuit remanded the case with a broader claim construction for further proceedings.

Omega Engineering, Inc. (“Omega”) owns U.S. Patent Nos. 5,727,880 (“the ’880 patent”), 5,823,678 (“the ‘678 patent”), and 5,823,679 (“the ‘679 patent”), which are based on a common priority application and relate to a lasersighting system for use on infrared thermometers.

Claim limitations relating to the outline or periphery of the energy zone measured by the thermometer became the focus of the appeal. The district court had construed the phrases “to outline the energy zone,” “outline visibly” the energy zone, “to outline visibly the periphery,” and equivalent phrases as excluding a laser beam directed inside the energy zone.

The Federal Circuit concluded that the district court’s claim constructions wrongly incorporated the negative limitation that the claims may not cover a device directing a laser beam inside the energy zone. The Court began its analysis with claim 1 of the ‘880 patent, which requires a “means for causing” at least one laser beam “to strike the periphery of the energy zone for visibly outlining said energy zone.” The Federal Circuit disagreed with the trial court’s finding that directing light inside the energy zone would contradict the stated purpose of “visibly outlining said entire energy zone” and concluded that the trial court had incorrectly assumed that a laser beam directed inside the energy zone could not at the same time outline that zone. The plain words of the claims permissively require “at least one laser beam,” indicating that the “means for causing” may act on another laser beam to strike inside the zone. Further, the claims do not require that the laser beam be both outside and inside the periphery at the same time.

The Federal Circuit also rejected Raytek Corporation’s (“Raytek”) arguments that Omega had disclaimed during prosecution a laser-sighting system directing a laser inside the energy zone. During prosecution, Omega had repeatedly insisted that its invention differed from the prior art by precluding appreciable heat from entering the energy zone and affecting the temperature of the energy zone. While these statements narrowed the construction of the phrase “to visibly outline,” they did not preclude projection of light into the interior of the energy zone. Thus, the disclaimer was not as comprehensive as Raytek had argued.

The Federal Circuit also found that the disclaimer made in the ‘880 patent extended to the ‘678 and ‘679 patents, which are continuations-in-part of the ‘880 patent.

With respect to claim 16 of the ‘880 patent, which requires a “means for causing” the laser beam to identify the periphery and center of the energy zone, the district court had required that the laser beam strike those points sequentially. The Federal Circuit disagreed, finding that neither the claims nor the written description supported adding the limitation “sequentially.” The district court justified its addition of the sequential limitation by first identifying corresponding structure in the disclosure of the ‘880 patent. The Federal Circuit concluded, however, that starting with a structure and defining the function in light of that structure, the lower court had essentially turned the rule of construction for means-plus-function claims upside down.

Because Omega and Raytek disputed whether the laser beam in the center of the energy zone adds any appreciable heat, and given its new construction of the claims, the Court found that triable issues of fact remain and, therefore, reversed the SJ of noninfringement of claims 1 and 16 of the ‘880 patent and the asserted claims of the ‘678 and ‘679 patents.