Functional Language Renders Claims Indefinite

Patent claims broadly reciting functions of a “controller” are indefinite under 35 U.S.C. § 112, second paragraph, according to the court in Markem-Imaje Corp. v. Zipher, Ltd., Civil No. 07-cv-00006-PB (D. N.H. Aug. 9, 2012).  The court therefore granted accused infringer Markem’s motion for summary judgment of invalidity.

A representative patent claim recited a tape drive having two motors and a controller, the court emphasizing language at issue describing functional capabilities of the controller as follows:

wherein the controller energizes both said motors to drive the spools in a tape transport direction, and said controller calculates a length of tape to be added to or subtracted from tape extending between said spools in order to maintain tension in said tape between predetermined limit values and controls said motors to drive the spools to add or subtract the calculated length of tape to or from the tape extending between said spools.

Markem argued that functional language was indefinite where it recited a claim’s point of novelty.  However, the court explained that U.S. Supreme Court precedent to that effect had been overruled by the 1952 Patent Act, and specifically by the means-plus-function provision of Section 112, sixth paragraph.  Further, the Federal Circuit has made clear that functional language is permissible even where, as here, the sixth paragraph of Section 112 is not invoked.  Instead, whether functional claim language is indefinite must be determined according to context.

The functional language at issue here was problematic because “the claimed function can be performed through various structural means and a person skilled in the art cannot determine the structures that are encompassed by the claim.”  The patent owner, Zipher, conceded that a controller could not perform the claimed functions without special programming. However, Zipher did “not argue that its functional claim terms connote specific structure.”  Rather, Zipher’s “position [was] that the functional terms encompass all means by which the functions can be performed.”

Further, the claims would have been indefinite even if construed to recite means-plus-function limitations.  The court found “instructive” a line of Federal Circuit cases that “made clear that a patent’s specification must disclose the algorithm that enables the computer to perform the claimed function because the algorithm serves as the ‘defining structure [that] render[s] the bounds of the claim understandable to one of ordinary skill in the art.’”  Where a patent fails to disclose such an algorithm and only discloses “the existence of software or a general-purpose computer,” claims are indefinite.  Here, the patents failed to disclose sufficient algorithmic structure.

Summary judgment having been granted in favor of Markem, this case is surely headed back to the Federal Circuit (it having been there once already to vacate a holding of non-infringement based on claim constructions that were found to be incorrect).