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Applicants May Have Disclaimed Scope of Protection During Prosecution History

August 07, 2001

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Last Month at the Federal Circuit - September 2001

Judges: Dyk (author), Schall, and Friedman

The Federal Circuit, in Pall Corp. v. PTI Technologies, Inc., No. 00-1203 (Fed. Cir. Aug. 7, 2001), affirmed SJ of noninfringement of PTI Technologies, Inc.’s (“PTI”) U.S. Patent No. 4,663,041(“the ‘041 patent”). The Federal Circuit also vacated and remanded SJ of noninfringement of Pall Corporation’s (“Pall”) U.S. Patent No. 4,609,465 (“the ‘465 patent”).

Both patents relate to filter technology for filtering high-temperature corrosive chemicals such as hot acids used in the etching process of semiconductor chips.

The ‘041 patent, assigned to PTI, relates to a filter element made wholly of fluorocarbon resin. In prior art filter elements, only the filter membrane was made of fluorocarbon resin. Filter elements include a filter material and net supporters. During prosecution of the ‘041 patent, PTI originally claimed net supporters made of “thermoplastic fluorocarbon resin.” In light of a prior art rejection, PTI narrowed the claims to particular thermoplastic resins (PFA, FEP, and EPE).

Pall moved for SJ of noninfringement of the ‘041 patent. According to the district court’s construction, the claims of the ‘041 patent require that the net supporters be made entirely of one of PFA, FEP, or EPE. Because Pall’s net supporters did not possess the claimed net supporters made entirely of PFA, FEP, or EPE, the district court found no infringement by Pall.

The ‘465 patent, assigned to Pall, is directed toward a filter cartridge for removing particulates from a destructive fluid such as hot acid or solvent. A filter cartridge contains a cylindrical filter arrangement with top and bottom caps. The filter cartridges described in the ‘465 patent are fabricated from fluoropolymers, which are highly resistant to destructive fluids such as hot acid or solvent. The claimed filter cartridge of the claims at issue in the appeal comprised “first and second impervious fluoropolymeric end caps.”

PTI moved for SJ that its filter cartridges did not infringe the ‘465 patent. In construing the claims of the ‘465 patent, the district court had held that the first and second end caps means that each end cap is a unitary structure and cannot comprise two separate components. Because the end caps of PTI’s cartridges required two components, the district court had held that PTI did not infringe.

On appeal, Pall argued that the district court had improperly construed the claims. PTI conceded that the district court’s construction was erroneous, but asserted that the patent prosecution history foreclosed any interpretation of the claims that would include the subject matter of the accused devices.

The Federal Circuit agreed that the district court had improperly construed the claims. Contrary to the district court’s interpretation, the language of the claims did not indicate that the first end cap must be a unitary structure that cannot comprise two elements welded together. Looking at the specification, the Federal Circuit found that the drafter did not intend to use the claim language in a manner different than its ordinary meaning.

In addition, during prosecution of the ‘465 patent, Pall had submitted an Information Disclosure Statement (“IDS”) that listed a one-page brochure of a filter cartridge by HR Textron and PTI. The IDS and references were filed simultaneously with an amendment after final rejection. Because of the information disclosure rules in effect at the time of the amendment, Pall’s amendment included a concise statement of relevance for each reference disclosed. In characterizing the HR Textron and PTI brochure, Pall stated that none of the materials included in the brochure disclose a filter cartridge or assembly as claimed.

PTI asserted that Pall’s statement forecloses any interpretation of the claims that would include the PTI filter cartridges because these cartridges were described in the brochure. The Federal Circuit vacated the district court’s SJ decision and remanded for a determination of what a person of ordinary skill in the art would have believed to have been excluded after reviewing the prosecution history as a whole, including the brochure and the statements made by the applicant.