SONY CORP. v. IANCU, decided May 22, 2019, Means-Plus-Function

U.S. Patent No. 6,097,676 is directed to recording and storing audio in multiple tracks (pages 2-3). The claim recites a “reproducing means,” which the board treated as a means-plus-function limitation with the function of reproducing the audio data of the channel designed by the default value stored in the storing means by the structure of a controller and synthesizer without requiring an algorithm (page 4). The prior art shows a computer-implemented structure (page 4). The specification teaches that the reproducing means comprises a synthesizer and controller, but further explains implementing by processing and discloses an algorithm (page 8). Since circuitry is not described but an algorithm is, the structure for this means limitation is a computer-implemented structure (page 9).

Hindsight: To broaden means-plus-function limitations, different structure should be provided. In this example, both computer-implemented (with an algorithm) and hardware (with a circuit) could have been described. This breadth would have created greater invalidity risk, so only describing the actual implemented system may be best for means plus function. Independent claims not using means-plus-function may be used for broader claiming. Different terminology may be used to keep narrow means limitations with alternatives for broader, non-means limitations.