Court Opinion

ID: 9494437
Source: CourtListenerOpinion
Date Created: 2023-08-05 15:38:00.555105+00
Date Added: 2024-06-11T17:56:24.982465
License: Public Domain

CLEVENGER, Circuit Judge,
concurring.
As the court correctly holds, whether Xerox can succeed at trial in this patent infringement suit depends upon whether the stroke symbols employed by the defendants are “unistroke symbols.”
I agree with the court that the definition of unistroke symbols requires that the symbols achieve “definitive recognition” and employ “spatial independence.” I further agree that the district court erred in its explanation of why the accused symbols fail to meet those parts of the definition of unistroke symbols. I also agree with the court that “unistroke symbols” require graphic separation. The question to be resolved on remand is whether the accused symbols have sufficient graphic separation to meet the limitations of the claims in suit.
I agree with the court that unistroke symbols, as claimed in the ’656 patent, must have sufficient graphic separation to permit a computer to definitively and correctly recognize a symbol immediately upon delimitation or pen lift. And I agree that a group of accused symbols need not form any particular alphabet, whether it be a 26 letter alphabet or another of greater or fewer characters. Presumably, any accused system will have enough characters to permit cogent information in some language to be recorded by the use of the *1370unistrokes employed in the particular system. Thus no particular alphabet is required, even by claims 10 and 11, which only specify “an alphabet of mutually independent unistroke symbols.”
I am writing separately to emphasize a point that seems to be implicit in the court’s holding. This point has to do with whether, in order to infringe, all of the accused symbols, as opposed to only some of them, must be proven to be unistroke symbols. The file history of the ’656 patent makes it perfectly clear that every symbol made by a single stroke that is used by the defendants must be a “unis-troke symbol,” as defined by the court.
During the course of prosecution of the ’656 patent, the applicant was required to distinguish his invention over the Whitaker ’645 patent. In doing so, the applicant asserted that “Whitaker “is not wholly composed of ‘Unistroke’ symbols.... ” This assertion can only be taken to mean that the ’656 patent only reads on a system of symbols all of which are unistroke.
In a file memorandum, the examiner noted comments made by the applicant’s representatives, who “clarified that the claimed invention does require all handwritten unistroke symbols to be a single stroke.” The applicant’s written understanding of the same comments made to the examiner, contained in “Patent Owner’s (Xerox’) Summary of May 24, 1999 Personal Interview with Examiners,” is the same: although the patent does not require any particular alphabet of letter symbols, the patent requires that “all claim requirements are met for the unistroke symbols that are used.” This means, clearly, that every unistroke symbol (meaning a symbol that is composed with a single unbroken stroke) must meet the complete definition of “unistroke symbol.” This, in turn, means that for Xerox to prevail, it must prove that each unistroke symbol in the accused symbols (i.e., all symbols except for “x” which is composed with two strokes) has (a) graphic separation, (b) definitive recognition, and (c) spatial independence.
That every accused symbol made by a single stroke must itself be a “unistroke symbol” as claimed and defined in the prosecution history is confirmed in the reexamination proceedings. There, the examiner distinguished the claimed unistroke symbols over the Sklarew reference because it “does not disclose an alphabet consisting entirely of unistroke symbols” (emphasis supplied by the examiner).
Consequently, on remand, unless the infringement issue is susceptible to resolution by summary judgment, the jury will have to decide if every one of the accused symbols that is composed by a single stroke meets all of the tests of a “unis-troke symbol.” This is so, because in order to escape the reach of potentially invalidating prior art, the patentee insisted that his invention requires that every symbol composed by a single stroke must be a complete “unistroke symbol.”