U.S. Patent No. 6,249,876, directed to EMI reduction by jittering switch frequency.
The claims recite a digital-to-analog converter “coupled” to a counter for the counter to cause the converter to adjust (pages 2-3). A court, in a previous decision, indicated that prior art with an EPROM in between the converter and the counter did not render the claim obvious (pages 3-4). In another previous court decision, the Federal Circuit noted that since the ROM takes the output of the counter as input and outputs a different, stored value to the digital-to-analog converter, no voltage, current, or control signals pass from the counter to the converter (page 5). In a later reexamination, the board affirmed a rejection over the same ROM prior art relying on “coupled” being joined into a single circuit (page 6). The Federal Circuit, in yet another previous decision, remanded the reexamination to the board for failure to evaluate the claim construction with more than a dictionary definition (page 7). On remand, the board indicated court interpretations are typically narrower than the broadest reasonable construction, indicating that the specification or claim itself does not further guide interpretation in this case (pages 7-8). In the current decision, the Federal Circuit holds that the claim requires some form of functional relationship and the board interpretation of being in the same circuit does not define any functional relationship (pages 10-11). The claim language includes the counter and converter as part of a circuit, so “coupled” must be more than just being part of a same circuit (pages 11-12). The specification teaches eliminating components as a goal, and every embodiment has the counter passing voltage, current or control signals to the converter (pages 12-13). Accordingly, “coupled” requires passing a control signal (pages 12-14).
Hindsight: The goal of the invention is used to help narrow the claims. Indicating goals is more common to avoid 101 rejections, so be careful to avoid narrowing claims through statements of benefit. The lack of alternatives to the connection between the converter and counter helped narrow. Alternatives help broaden, but this may be disadvantageous in avoiding invalidity. There is a collusion of various generalized approaches to drafting the specification and claims here. Using a more explicit term than “coupled” may be better, such as reciting passing of a control signal. “Coupled” may have a very broad meaning for a situation where the claim is trying to communicate a functional interaction.