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Means-Plus-Function Element Limited to Single Disclosed Structure and Equivalents Thereof

February 08, 2012

Decision icon Decision

Last Month at the Federal Circuit - March 2012

Judges: Bryson, Moore (author), Reyna

[Appealed from: E.D. Tex., Magistrate Judge Giblin]

In Mettler-Toledo, Inc. v. B-Tek Scales, LLC, Nos. 11-1173, -1200 (Fed. Cir. Feb. 8, 2012), the Federal Circuit affirmed the district court’s denial of JMOL after jury verdicts that one of the two patents-in-suit was not infringed and that the other patent-in-suit was not infringed and was invalid. The Court also affirmed the district court’s denial of sanctions against Mettler-Toledo, Inc. (“Mettler”) for allegedly withholding and destroying relevant documents.

Mettler owns U.S. Patent Nos. 4,815,547 (“the ’547 patent”) and 4,804,052 (“the ’052 patent”), which are directed to technology used to weigh objects such as large commercial trucks. The ’547 patent describes an individual load cell that is one of several cells used in a scale. The cell produces an electrical signal when deformed, for example, by an object to be weighed. The ’052 patent is directed to a system and method for weighing objects on a scale, which includes a correction based on the location of the object on the scale. That system of the ’052 patent ensures that the measured weight is the same regardless of where on the scale the object is placed.

After Mettler sued B-Tek Scales, LLC (“B-Tek”) for infringing certain claims of the ’547 and ’052 patents, a jury found that B-Tek did not infringe any of the asserted claims. The jury also determined that the asserted claims of the ’052 patent would have been obvious. Mettler moved for JMOL on both the infringement and invalidity issues, which the district court denied. B-Tek moved for sanctions after trial, alleging that Mettler had concealed certain documents, and the district court denied B-Tek’s motion. Mettler appealed the district court’s denial of its motion for JMOL for both patents. B-Tek cross-appealed the denial of sanctions.

On appeal, the Federal Circuit applied Fifth Circuit law in reviewing the denials of JMOL. In the Fifth Circuit, JMOL is appropriate if the facts and inferences point so strongly and overwhelmingly in favor of one party that a reasonable jury could not have concluded otherwise. First considering denial of Mettler’s motion for JMOL with regard to the ’547 patent, the Court found claim 1 of the ’547 patent illustrative of the asserted claims. Claim 1 is directed to a weighing apparatus comprising a counterforce and various means-plus-function elements associated with an electronic circuit. The circuit, as described in the ’547 patent, includes an analog-to-digital (“A/D”) converter to convert an analog signal related to the object’s weight into a digital signal used by a microprocessor. The preferred embodiment in the ’547 patent identifies a “multiple slope integrating A/D converter” as the A/D converter. In the accused products, which the jury determined did not infringe either literally or under the DOE, the A/D converter was a delta-sigma A/D converter.

Mettler limited its arguments regarding the ’547 patent to a single claim construction issue: whether the district court properly construed three means-plus-function terms to require a “multiple slope integrating A/D converter” for each of them rather than any generic A/D converter. The means-plus-function terms in dispute were “circuit means associated with said counterforce,” “means for producing digital representations of loads applied to said counterforce,” and “means for transmitting said digital representations.” The district court ruled that the appropriate structure for the disputed means-plus-function claim elements is the multiple slope integrating A/D converter and equivalents thereof. Mettler argued that a generic A/D converter was the proper structure for the terms in dispute because (1) generic A/D converters were well known in the art and the district court erred by importing features of the preferred embodiment or best mode into the claims; (2) Figure 5 of the ’547 patent illustrates an “Analog to Digital Converter 100,” showing that the specification discloses generic A/D converters in addition to the preferred multiple slope integrating A/D converter; (3) the Abstract mentions generic A/D converters; and (4) the ’547 and ’052 patents have similar specifications, yet the district court applied a different claim construction to the ’052 patent, ruling that a generic A/D converter was indeed included in the claim terms of the ’052 patent.

The Federal Circuit rejected Mettler’s arguments and agreed with the district court’s construction. According to the Federal Circuit, a means-plus-function claim limitation is limited to the structures disclosed in the specification and equivalents thereof, and “[s]tructure disclosed in the specification is ‘corresponding’ structure [for a means-plus-function term] only if the specification or prosecution history clearly links or associates that structure to the function recited in the claim.” Slip op. at 7 (quoting B. Braun Med. Inc. v. Abbott Labs., 124 F.3d 1419, 1424 (Fed. Cir. 1997)). The Federal Circuit cautioned that “[i]f a patentee chooses to disclose a single embodiment, then any means-plus-function claim limitation will be limited to the single disclosed structure and equivalents thereof.” Id. (citing Nomos Corp. v. Brainlab U.S.A., Inc., 357 F.3d 1364, 1368 (Fed. Cir. 2004)).

The Court found that, in every instance where the specification of the ’547 patent referred to an “A/D converter,” it was referring to the preferred embodiment, which included only the multiple slope integrating A/D converter. Although the Court recognized that generic A/D converters were known in the art, it noted that the patentee chose to use means-plus-function language, which limited the terms to the disclosed embodiments and their equivalents. The Court further found that the single statement in the Abstract did not link that disclosure to any claimed function, as required by B. Braun Medical. Finally, the Court explained that the ’052 patent mentions a generic A/D converter and links it to the claimed function, but that, in contrast, the ’547 patent does not include that language and is therefore limited to the only A/D converter it discloses—the multiple slope integrating A/D converter. For these reasons, the Federal Circuit affirmed the district court’s denial of JMOL of infringement with regard to the ’547 patent.

Concerning the ’052 patent, Mettler argued that JMOL should have been granted because the cited prior art reference, GB 1,462,808 (“Avery”), did not teach correcting for load position, which was a limitation of each asserted claim. The Federal Circuit disagreed, finding substantial evidence to support the jury determination that Avery taught correcting for load position. According to the Federal Circuit, Avery disclosed a system that corrected for an “unevenly loaded” scale, which was sufficient for a jury to find that Avery disclosed correcting for a load position. Further, B-Tek’s expert testified that Avery disclosed that feature, providing more evidence on which the jury could have relied. The Federal Circuit also disagreed with Mettler that Avery taught away from correcting for an unevenly loaded scale. According to Mettler, Avery discloses that “because the transducer signals are corrected or adjusted individually . . . the combined output need not be corrected to compensate for uneven loading.” Slip op. at 10 (citation omitted). Finally, Mettler argued that Avery failed to teach moving a weight around the scale to calibrate the system. The Federal Circuit dismissed that argument, noting that the claims did not require moving a weight around the scale. Accordingly, the Federal Circuit affirmed the district court’s denial of JMOL on the nonobviousness of the ’052 patent.

The Federal Circuit next considered the denial of B-Tek’s motion for sanctions. The Court found that, in order to develop its case rebutting lost profits damages, B-Tek requested documents related to Mettler’s manufacturing capacity and Mettler stated that it had no such documents. During trial, however, a Mettler employee admitted that a production schedule and a plant diagram existed, and that some of those documents had been destroyed.

Applying the Fifth Circuit’s standard for the denial of sanctions—abuse of discretion—the Federal Circuit concluded that the district court had correctly considered the relevance of the documents and any harm to B-Tek due to the withholding. The district court, for example, found that Mettler did not hide the documents because Mettler’s representative, in a deposition, spoke about manufacturing capability and mentioned the production schedule. The district court also found that the documents were not particularly relevant to manufacturing capacity. Additionally, the district court noted that B-Tek could not show harm or prejudice because B-Tek ultimately prevailed on the issue of infringement and did not have to rely on its damages case. Accordingly, the Federal Circuit found no abuse of discretion and affirmed the denial of sanctions.

Summary authored by Carlos M. Tellez, Ph.D., Esq.