Claims Limited During Prosecution Cannot Be Construed to Broaden Their Scope, Despite the Presence of the Transitional Phrase "Comprising"

In Board of Regents v. BENQ America Corp. (No. 07-1388; July 24, 2008), the Federal Circuit affirms a district court's claim construction and decision granting summary judgment of non-infringement of a patent. Directed to character pattern recognition and a communications apparatus based on telephonic keypad entry, the patent describes a method in which the keypad entry is compared to a vocabulary of "syllabic elements," which can be combined to form a word.

The district court construed the term "syllabic element" to mean "a one-syllable letter group that either comprises a word or can be combined with other one-syllable letter groups to form a word." The Federal Circuit agrees, rejecting the patentee's argument that "syllabic element" need not be limited to a single syllable. Both the patent specification and the prosecution history readily differentiated between a "word" and a "syllabic element." Moreover, the prosecution history revealed that the patentee amended the claim to distinguish it from a prior art reference that disclosed the matching of entries with words. To broadly define "syllabic element" to words having any number of syllables would produce a "nonsensical result."

The Federal Circuit also concurs that the vocabulary of syllabic elements must be composed of only syllabic elements. Again, the prosecution history showed that the patentee submitted an amendment to distinguish the claim from the same prior art, which disclosed a vocabulary of complete words. Recognizing that the use of the transitional phrase "comprising" generally does not exclude from infringement additional, unrecited steps, the Federal Circuit holds that the phrase cannot be used to broaden the scope of a claim that was narrowly defined during prosecution to obtain the patent.