Chamberlain Group, Inc. ("Chamberlain") owns U.S. Patent No. 4,750,118 (the ' 118 Patent) and the reissue patent, U.S. Patent No. Re. 35,364 (‘364 patent) which claim improvements for a remote control garage door operating system. Under the ‘364 patent, the opener functions when the transmitter sends a pre-programmed factory code to the receiver. The receiver recognizes an activation signal as one of multiple codes previously stored in the microprocessor memory. The system initially functions in "program" mode to select a code, then a mechanical "switch" shifts the system into "operate" mode, where the microprocessor verifies that the transmitted signal matches one of the stored codes. Overhead Door Corp. ("Overhead"), Chamberlain's competitor, markets another garage door opener system, the Intellicode system, that uses a software program rather than a mechanical switch to determine memory location during the code selection process.
Overhead filed a declaratory judgment action, asking the district court for Northern Texas to rule that the Intellicode system does not infringe the ‘364 patent. Chamberlain filed a counterclaim asserting willful infringement by Overhead. Both parties filed motions for summary judgment, and the court referred the matter to a special master. After a Markman hearing, the special master ruled as a matter of law that the Intellicode system does not infringe the ‘364 patent, either literally or under the doctrine of equivalents. The district court adopted the entire report from the special master and consequently granted Overhead’s motion for summary judgment. Chamberlain appealed this decision.
On appeal, the Federal Circuit reviewed de novo both the district court’s claim construction and its ruling on the issue of summary judgment. First, the Federal Circuit agreed with the district court that the term "memory selection switch" in claim 1 described a mechanical device distinct from the microprocessor rather than software programmed into the microprocessor. In reaching this decision, the Federal Circuit rejected Chamberlain’s argument that the written description encompassed a software embodiment of the switch. Therefore, the Court affirmed the district court’s finding that the software program in the Intellicode system did not literally infringe the "memory selection switch" claimed in Chamberlain’s patent. The Federal Circuit, however, believing that the Intellicode system might infringe under the doctrine of equivalents, disagreed with the district court and ruled that a genuine issue of material fact did exist. The Federal Circuit found considerable evidence that one of ordinary skill in the art would find that the systems were not substantially different. The decision to use hardware or software to accomplish a given function is simply a matter of design choice. Thus, the Federal Circuit vacated the district court’s ruling of summary judgment for Overhead.
Additionally, the Federal Circuit reviewed the district court’s construction of claim 5. The Federal Circuit looked to both the claim language and patent prosecution history and ruled that the district court’s construction of the claim as describing only a mechanical embodiment of the invention was too narrow. Relying on prior decisions in which it held that proper application of the doctrine of equivalents may allow a patent claim to encompass a later developed technology, the Federal Circuit found that the correct construction of claim 5 would also include a software embodiment of the invention. Thus, the Federal Circuit remanded the case to the district court for reconsideration of infringement under the doctrine of equivalents in light of the corrected claim construction.
Prepared by the liibulletin-patent Editorial Board.