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Examination of Other Claims in Patent Is Not Wrong When Interpreting Means-Plus-Function Limitations

February 06, 2001
Swan, Jennifer S.

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Last Month at the Federal Circuit - March 2001

Judges: Lourie (author), Newman, and Gajarsa]

In Wenger Manufacturing, Inc. v. Coating Machinery Systems, Inc., No. 00-1121 (Fed. Cir. Feb. 6, 2001), the Federal Circuit reversed the district court’s grant of SJ of noninfringement to Coating Machinery Systems, Inc. (“CMS”), ordered judgment of infringement, and remanded the case for further proceedings.

Wenger Manufacturing, Inc. (“Wenger”) is the assignee of U.S. Patent No. 5,100,683 (“the ‘683 patent”) that relates to an apparatus and method for coating and drying food products, such as cereals. The claimed apparatus includes “a combined dryer and spray unit which includes an axially rotatable reel provided with a perforate sidewall.” Inside this reel, “at least one spray nozzle deposits the coating in slurry form onto the product.” The reel is surrounded by a housing that “includes a heat exchanger for heating the air and a circulating fan for forcing air through the perforations in the sidewall of the reel.” As the product passes through the rotating wheel, air is circulated through the reel to dry the product. As a result, the product is coated and dried.

Wenger filed suit against CMS, alleging that several of CMS’s coating and drying machines literally infringed the two claims of the ‘683 patent. CMS moved for SJ of noninfringement, and Wenger cross-moved for partial SJ of literal infringement. After construing the claims, the district court denied CMS’s motion and granted Wenger’s corresponding cross motion. On reconsideration, however, the district court changed its decision and granted CMS’s motion for SJ of noninfringement.

The issue turned on the claim construction of the phase “air circulating means associated with said dryer housing for circulating through said reel.” The Federal Circuit argued that this limitation met the parameters of 35 U.S.C. § 112, ¶ 6, but disagreed with the district court’s conclusions about the recited function and the corresponding structure. In particular, the Federal Circuit determined that while the district court had correctly identified “circulating air” as the recited function, it had incorrectly required the corresponding structure to have the ability to recirculate the air.

The Federal Circuit noted that the ordinary meaning of the term “circulate” denoted that the “air circulating means” is capable of moving air in a circuit through the reel and dryer housing. Therefore, the term “circulate” neither connoted nor required that the air had to also recirculate. Moreover, a dependent claim expressly recites the additional limitation of recirculating the air. The Federal Circuit ruled that although the statutory claim construction of § 112, ¶ 6, will usually trump the claim differentiation doctrine, the examination of other claims in a patent may provide guidance and context for interpreting a disputed means-plusfunction limitation. In this instance, the recited functions of “recirculation” in the dependent claim strengthened the presumption that the independent claim recited only a “circulation” function. In addition, the Federal Circuit noted that nothing in the prosecution history required a recirculation function in the claim.

Having construed this limitation, the Federal Circuit addressed the infringement issue and determined that the district court had erred in granting CMS’s motion for SJ of noninfringement based on its construction of the “air circulating means” limitation because the accused machines circulate air. Moreover, there was no evidence that Wenger had surrendered coverage of machines that do not recirculate air.

Accordingly, the Court reversed the SJ of noninfringement, ordered entry of judgment of infringement, and remanded.