In Mettler-Toledo, Inc. v. B-Tek Scales, LLC, the Court of Appeals for the Federal Circuit affirmed a verdict of non-infringement and invalidity. Specifically, the Federal Circuit held that one of the patents at issue was not infringed based on a claim construction of means-plus-function limitations that were limited to a single disclosed embodiment.  

The patents at issue in Mettler-Toledo relate to scale technology for weighing trucks or other large objects. U.S. Patent No. 4,815,547 (the ‘547 patent) describes an individual load cell and U.S. Patent No. 4,804,052 (the ‘052 patent) describes a system and method for correcting weight measurements based on the location of objects on a scale. Following a jury verdict that both patents were not infringed and that the ‘052 patent was invalid as obvious, the district court denied Mettler-Toledo’s JMOL. Mettler-Toledo appealed.  

On appeal, Mettler-Toledo disputed the claim construction of the ‘547 patent. The district court found that the scope of several of the means-plus-function terms is limited to a multiple slope integrating analog to digital (A/D) converter, and equivalents thereof. Slip Op. at 6. The accused products included a different A/D converter, namely, a deltasigma A/D converter. Mettler-Toledo argued that the district court erred by limiting the claims to the preferred embodiment, rather than to a generic A/D converter. Id. In response, B-Tek argued that the claimed functions were never linked to a generic A/D converter.  

The Federal Circuit rejected Mettler-Toledo’s argument, noting that a means-plusfunction claim limitation is limited to the structures disclosed in the specification and equivalents. Slip Op. at 7. Reviewing claim construction de novo, the Federal Circuit found that a label in a figure or a reference to “an A/D converter” in the abstract did not support a broader structural disclosure because those descriptions were not specifically linked to any claimed function. As such, the Federal Circuit agreed with the district court that the patent disclosed only a single embodiment and the claimed function was necessarily limited to that embodiment. The court further stated that although generic A/D converters were known in the art, by invoking means-plus-function language, the claim terms were limited to the specifically disclosed A/D converter and its equivalents. The court suggests that the claim terms could have supported a broader construction if means-plus-function terminology was not used.

In view of the Mettler-Toledo decision, patent practitioners should be cautioned that means-plus-function terms may be construed more narrowly than intended. If meansplus- function claim terms are desired, patent applicants should consider specifically linking or associating the claimed function with all structures that support that function, including any generic structures.