Whether the trial court erred in holding that Cardinal's device read on a means-plus-function clause in claim 11 of Chiuminatta's '499 patent.
Yes. The trial court did not apply the proper, narrower test of infringement of a means-plus-function clause.
Chiuminatta owns U.S. Patent No. 5,056,499. Claim 11 of the patent reads as follows:
"A saw for cutting concrete even before the concrete has hardened to its typical, rock-like hardness, comprising: …means connected to the saw for supporting the surface of the concrete adjacent the leading edge of the cutting blade to inhibit chipping, spalling, or cracking of the concrete surface during cutting…."
The district court erred in construing the means limitation in claim 11 to include every conceivable support surface. Under a proper analysis, the means limitation should be construed as corresponding only to the disclosed skid plate in the specification of the '499 patent, and its equivalents. Furthermore, the proper test for determining an equivalent is whether the differences in the accused device and any disclosed in the specification are insubstantial. The Federal Circuit decided that although the wheels in Cardinal's device perform some of the same functions as the skid plate, the wheel is sufficiently different from the skid plate disclosed in Chiuminatta's patent to avoid infringement.