Corresponding Structure Varies with Function in Means Plus Function Claims

DESA IP, LLC v. EML Technologies, LLC, [06-1168](January 4, 2007)[MICHEL, Plager and Rader]
BRIEF: DESA appeals from a stipulated judgment of non-infringement, and the Federal Circuit reversed and remanded because of errors in claim construction. The Federal Circuit agrees that “sensor means” and “control circuit means” were means plus function claims under 35 U.S.C. §112, but rejected the district courts determination of the corresponding structure. The Federal Circuit found that the specification specifically identified the sensors, and indicates that the additional structure included by the district court was part of the detector circuit, not the sensor. The Federal Circuit rejected appellee’s argument that control circuit means had to include a pulse counting feature because the patentee distinguished certain prior art because of this feature. Instead, the Federal Circuit said that the corresponding structure varied from claim to claim with the recited function. Finally the Federal Circuit corrected the district court’s interpretation of “switching means” which include structure for actuating the switching means. Thus the Federal Circuit remanded for proceedings consistent with the corrected claim construction.