This a good example of an application where the patentee did not recite more in the claims than he had to. While possibly the only way he could have imagined doing the programming back at the time of the invention was to use a large, external computer, the nature of the programming was not important. The patentee therefore correctly claimed it generically, and was rewarded with infringement under the doctrine of equivalents for after-arising technology, even if a literal construction of the claim terms based on the specification may not have been sufficient.
Background / Facts: The patents at issue relate to technology for reducing acoustic feedback in a programmable digital hearing aid. The asserted claims recite “a filter … programmed to equalize and reduce the effect of … acoustic feedback both in amplitude and phase,” or a “filter … programmed to effect substantial reduction of acoustic feedback.” The lone embodiment described in the specification utilized an external computer connected to the hearing aid to calculate and program coefficients for the filter, which reflected the size and complexity of computers at the time of the patent application in 1986. However, advances in computer technology occurring after the patents issued allowed changes in the nature and location of claimed calculations.
Issue(s): Whether the “programmable” aspect and all equivalents should be limited to external or fixed programming of the type described in the specification.
Holding(s): No. The ordinary meaning of “programmable,” as it would have been understood by one of skill in the art at the time of the invention, does not limit where the provided values originate. The claims do not specify where the programming occurs, how frequently it occurs, or what structure provides the programming. While the improvement in technology allows the accused devices to constantly recalculate filter coefficients using electronics located on the hearing aid, the accused devices nonetheless perform the same function in substantially the same way, with substantially the same result claimed.