A means-plus-function limitation is a functional limitation that claims function without structure. The claimed element presented for prosecution is pure function and not structure. This type of claiming is used often with software patents, which recite function via a series of computer implemented steps to carry out a means.
In Nevro v. Boston Scientific, decided in April 2020, Nevro appealed from a district court ruling that the following claim for a spinal cord modulation system was indefinite:
means for generating a paresthesia-free therapy signal with a signal frequency in a range from, etc. etc.;
Nevro argued that its specification disclosed sufficient structure – a signal generator that accomplished the claimed function of generating a paresthesia-free therapy signal. The district court found Nevro’s argument unconvincing, finding that since “signal generators” are already known in the prior art, the signal generator in the disclosure wasn’t sufficient structure here. The Federal Circuit reversed. To the Federal Circuit, the specification clearly recited a “signal or a pulse generator” not just a general-purpose computer to accomplish the claimed function. The Federal Circuit, unlike the district court, did not assess whether a signal generator is known or routine. Rather, they looked at the term from a specificity standpoint, asking whether the patentee disclosed a specific computer that is programmed for the function that is in the claim, not just a general-purpose computer.
The test for definiteness under a means-plus-function context is whether there is sufficient corresponding structure in the specification that links the structure in the specification to the function in the claim.
In SPEX Technologies v. Western Digital Corp., decided in May 28, 2021, the district court found the following claim term indefinite:
means for providing to a host computing device, in response to a request from the host computing for information regarding the type of peripheral device, information regarding the function of the target means.
The claimed function is providing specific information to a host computing device in response to a request from that host computing device. The issue came down to a “memory section 612a” which the patentee cited as being the structure for this claimed function. The district court found that the specification just did not support how the memory section 612a performed this claimed function. The Federal Circuit ended up reversing this case as well, finding that the specification clearly linked how the memory 612a stored data and provided that data to the host computing device when the host computing device requested the information. In this case, the structure was the memory 612a device that could store data and provide that data to the host computing device when the host computing device requested it (i.e., the function of the claim).
So, what’s good patent practice? Make sure every one of your claims is in the specification! Start with the claims; have them be the groundwork for your application. And have an algorithm! Drawings are a good thing.
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