Puradigm LLC sued DBG Group Investments and related entities for infringing U.S. Patent No. 8,585,979, which covers a photo-catalytic air purification cell. The patent relies on reflective surfaces to direct UV energy to a catalyst coating. The district court granted summary judgment of noninfringement, ruling that the patent's scope was limited by prosecution history disclaimer. Puradigm argued that the disclaimer did not apply and that the district court misinterpreted the term 'specular UV reflector.' The Federal Circuit reviewed the case de novo to determine if the applicant clearly surrendered subject matter during the patent application process.
The court analyzed whether the applicant made a 'clear and unmistakable surrender of subject matter' during prosecution. The examiner had rejected claims based on prior art (Bigelow) that disclosed polished aluminum reflectors. The applicant argued that Bigelow did not disclose a 'specular reflector,' stating, 'Nowhere in Bigelow is anything regarding a specular reflector disclosed—either expressly or inherently.' The court held that this statement constituted a disclaimer because the patent's specification emphasized that 'specular reflection' means 'mirror-like reflection' distinct from 'diffuse reflection,' which diminishes performance. The court rejected Puradigm's argument that the disclaimer was invalid because the examiner initially rejected the applicant's distinction; the law allows an applicant's argument to disavow scope even if the examiner did not rely on it. Furthermore, the court found no acquiescence, as the applicant explicitly stated it 'neither agrees nor disagrees' with the examiner's position and reserved the right to challenge it. Finally, the court determined that the disclaimer of polished aluminum reflectors logically extended to unpolished aluminum reflectors. Since unpolished surfaces produce more diffuse reflection than polished ones, and the patent claimed only mirror-like specular reflection, the accused unpolished products were excluded from the claim scope.
The decision reinforces the strict application of prosecution history disclaimer in patent infringement cases. Patent owners cannot broaden the scope of their claims to cover materials that were explicitly distinguished from prior art during the application process. The ruling confirms that a disclaimer of a specific material finish (polished) extends to a less refined version (unpolished) if the distinction relies on the physical property of reflection (specular vs. diffuse). The case is affirmed, and the summary judgment of noninfringement stands.
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