United States: Claim Not Limited to The Singular Form Unless Patentee Manifests A Clear Intent to do so

The U.S. Court of Appeals for the Federal Circuit, in overturning a summary judgment ruling of non-judgment based on an erroneous claim construction, held that absent a clear indication by the patentee of its intent to limit a claim term to a single element, use of the indefinite articles "a" or "an" will be presumed to mean one or more elements, especially when combined with the transitional claim term "comprising." Scanner Technologies Corporation v. ICOS Vision Systems Corporation, 2004 U.S. App. LEXIS 8108 (Fed. Cir. Apr. 23, 2004) (Michel, J.).

This case involves an apparatus patent and related method patent relating to technology and processes for inspecting electronic components. The invention uses illumination to scan ball grid arrays (BGAs) to make sure they are in proper positioning within electronic devices. BGAs are used in most electronic devices to conduct electrical impulses in those devices.

In construing the claims for both patents, the district court construed the phrase an "illumination source," which did not appear in the claims of either patent, and found it to be limited to "only one illumination source." The claims of the apparatus patent recited "an illumination apparatus positioned for illuminating a ball grid array," and the claims of the method patent recited "illuminating a ball grid array." In a motion for reconsideration, Scanner challenged the court’s claim construction, pointing to the distinction between the term construed, "illuminating source" and the actual claim term, "illuminating apparatus." The district court recognized the distinction but found it to be not significant for the purpose of claim interpretation.

The district court, citing Instuform Technologies, Inc. v. Cat Contracting, Inc. and North American Vaccine, Inc. v. American Cyanamid Co., also interpreted the claim term "an" in the phrase "an illuminating apparatus" to be limited to a singular element. This was important since limitation of this term to a singular meaning meant that ICOS did not infringe since its device uses plural illuminating sources. Scanner appealed.

On the issue of whether it was proper for the district court to use the term "illumination source" as its basis for claim construction, the Federal Circuit found that it was improper to construe terms that did not appear in the patent claims. However, the Court found that since the district court also construed the terms "illuminating" and "illuminating apparatus," the error was harmless.

In rejecting the district court’s restrictive interpretation of the words "an" and "a," the Federal Circuit held that indefinite articles, such as "a" and "an," should be construed to mean one or more elements when used in open-ended claims such as those using the transitional phrase "comprising." The Court cautioned that limiting such language to the singular is only appropriate in rare circumstances where the patentee manifests a clear intention to so limit. The panel distinguished the Instuform and North American Vaccine cases, noting that in Instuform the term "a cup" was limited to a singular element because the claim and specification repeatedly described the term as "a single cup" and "the cup" meaning only one cup. In addition, the patent specification and drawings only disclosed use of one cup. In distinguishing North American Vaccine, the Court noted that the claim in issue did not use the term "comprising," which in itself indicates that the elements or steps to follow may be supplemented by additional terms. The Court instructed that when the open claim term "comprising" is combined with the article "a" or "an" it "creates the presumption that the article is construed to mean one or more elements or steps, unless there is evidence of a clear intent to limit the claims."