Another Means-Plus-Function Patent: Invalid as Indefinite

The patent statute allows for patent claims to be written as a "means for" accomplishing a particular function. 35 U.S.C. § 112(f). When written in claim form, a "means for" claim appears extremely broad because it suggests coverage of all possible means or mechanisms for accomplishing the stated goal. However, the statute says otherwise. Rather than covering all possible mechanisms, Section 112(f) requires that the limitation be construed to only cover the "corresponding structure … described in the specification and equivalents thereof."

Here, the patent claims at issue all include a "computational means" that figure out whether or not someone is sleepy. And, on summary judgment, the district court found the claims indefinite because the claimed computational means were not supported by structure in the specification. That decision has been affirmed in a unanimous opinion written by Judge Taranto.