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“Composed Of” Means “Consisting Essentially Of” in This Case

February 06, 2001

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Last Month at the Federal Circuit - March 2001

Judges: Michel (author), Lourie, and Bryson

In AFG Industries, Inc. v. Cardinal IG Co., No. 00-1285 (Fed. Cir. Feb. 6, 2001), the Federal Circuit vacated the district court’s grant of SJ of noninfringement and remanded the case for further proceedings.

AFG Industries, Inc. and Asahi Glass Co. (collectively “AFG”) sued Cardinal IG Co., Inc. (“Cardinal”) and Andersen Windows, Inc. (“Andersen”) in the Eastern District of Tennessee for infringement of claim 1 of U.S. Patent No. 4,859,532 (“the ‘532 patent”). The district court had severed and stayed the action against Andersen, leaving Cardinal as the sole Defendant. After a Markman hearing to con - strue the language of claim 1, the district court had entered SJ of noninfringement in favor of Cardinal.

The ‘532 patent is directed to low-emissivity coatings for windows. Coatings of this type generally consist of alternating thin layers of metal laminated onto a transparent substrate. The ‘532 patent describes a coating having multiple thin layers of silver, interspersed by thin layers of metal oxide, such as zinc oxide. By interspersing layers between the silver layers, the silver becomes increasingly reflective of radiant heat without sacrificing visible light transmission.

Claim 1 of the ‘532 patent defines a laminated product comprising a substrate and a five-layer coating “composed of” three layers of zinc oxide interspersed with thin layers of silver. The specification states that additionally, interlayers of other materials may be inserted in the coating between layers or at the interface between the coating and the air in order to improve the adhesion or durability of the coating layers. Claim 1, however, does not specifically refer to any such interlayers.

Cardinal’s accused product uses a coating containing layers of zinc oxide and silver, but with “barrier layers” of titanium dioxide either between layers or on top of the coating. If such barrier layers are not used, the silver layers oxidize upon contact with the air, rendering the silver black and unsuitable for use in the coatings.

To determine whether the district court’s grant of SJ had been proper, the Federal Circuit first turned to the language of claim 1, specifically the use of “composed of” as a transition phrase. Cardinal argued that “composed of” should be interpreted as a closed transition phrase similar to “consisting of,” thereby excluding interlayers. AFG countered that “composed of” was similar to open transition phrases such as “comprising.” The Federal Circuit noted that 1942 precedent from the Court of Customs and Patent Appeals defining this term was rather equivocal. It observed, however, that the MPEP, although owed no deference, states that the scope of “composed of” should be interpreted in light of the specification.

Based on the specification and testimony during the Markman hearing, the district court interpreted the phrase “composed of” to mean “consisting essentially of,” therefore excluding ingredients that materially affect basic characteristics of the composition. Therefore, the coatings of claim 1 could include interlayers as disclosed in the specification, as long as such interlayers did not materially affect the properties of the invention.

The Federal Circuit also overturned the district court’s construction of the term “interlayer” to mean “a layer placed between other layers.” Cautioning against the use of “non-scientific dictionaries for defining technical words,” the Court noted that the district court’s construction would eliminate the distinction between the terms “layer” and “interlayer.” Instead, the Court turned to expert testimony given during the Markman hearing to support its construction and commented that “[t]his case presents a good example of how extrinsic evidence can and should be used to inform a court’s claim construction, and how failure to take into account the testimony of persons of ordinary skill in the art may constitute reversible error.” AFG Indus., slip op. at 17.

Based on the foregoing, the Federal Circuit arrived at its own construction of the terms “layer” and “interlayer.” It construed “layer” as a “thickness of material of substantially uniform chemical composition,” and “interlayers” as having “a thickness not to substantially affect the optical properties” of the coating. When determining whether a layer is optically significant, the focus should be on whether the material itself has optical effects, rather than whether the absence of such a layer would affect the optical properties of other layers (i.e., by allowing oxidation to occur).

Having come to the above claim constructions, the Federal Circuit concluded that it could not determine whether the layers of titanium dioxide in the Cardinal products were optically significant, since the only evidence available was the thickness of the layers. Therefore, the Court reversed the district court’s grant of SJ of noninfringement, and remanded for further proceedings.