skilled in the art would find substantial ambiguity in this phrase as plaintiff has insisted it is used in the key disputed elements of claims one and two.
A close examination of the phraseology in some of the elements of claims one and two yields additional support for this conclusion. After announcing in its first lines that claim one involves a "converter for converting a video signal from a first to a second scan rate," the language of an important sub-element speaks of using a "frame buffer . . . for storing the video signal at a second scan rate differing from the first scan rate. " (Emphasis added.) Similarly, elements of claim two speak of "storing a portion of the video signal which is at a first scan rate" and "providing the stored portion of the video signal to a frame buffer at a second scan rate . . . ." (Emphasis added.) As plaintiff concedes (see Plaintiff's Closing Statement, filed under seal August 15, 1994, at 7), no one skilled in the art would argue that video signals are "stored" at any rate at all. As defendant has argued for some time, a video signal that is being stored in a frame buffer simply has no scan rate - it is static - so it is nonsensical to talk about "storing" such a signal at "different" "rates." Thus plaintiff has conceded, as it apparently must, that the language of the claims quoted in this paragraph, if taken literally, makes no sense. The fact that the language taken literally makes no sense would not be fatal, of course, if it were clear that persons skilled in the art would understand that the words do not mean what they say and that these elements of the claims have a non-literal meaning that would be both clear to persons skilled in the art and technologically significant. The court has concluded, however, that plaintiff's showings on these matters are not sufficiently persuasive.
While it seems likely that careful readers, skilled in the art, would understand that the subject language does not mean what it literally says, the court cannot conclude, on the record thus far developed, that such readers would construe these elements of the claims in the manner plaintiff construes them, or, if so construed, would find them technologically significant. Plaintiff, through Mr. Maietta and others, insists that what is meant to be claimed in the subject parts of these elements is a device or process in which data flows into the pixel buffer at one rate, is stored in the pixel buffer, then is released from the pixel buffer to flow to the frame buffer - and that the rate or speed at which the data flows from the pixel buffer to the frame buffer is different from the rate at which the data entered the pixel buffer.
While this interpretation does less violence to the language of the claims as written than some alternative interpretations, plaintiff's contention that persons skilled in the art would adopt this interpretation is undercut by what the court perceives, at this juncture, as a serious shortfall in plaintiff's evidence: plaintiff presented no persuasive evidence that anyone skilled in the art would care about these relative rates. In other words, plaintiff failed to explain, meaningfully, why it might be significant technologically that the data flow rate into the pixel buffer be different from the data flow rate into the frame buffer.
Plaintiff did offer testimony that could be used to support a finding that, under certain conditions and over very short (but not necessarily di minimis) intervals, data could in fact be expected to move out of the pixel buffer at a different rate than data moving into the pixel buffer. But plaintiff's evidence was not sufficient to establish how often or what percentage of the time this data flow rate differential could be expected. More importantly, plaintiff's evidence was not sufficient to establish that persons skilled in the art would care whether there was a difference in these two data flow rates. The court finds itself, after considering all the evidence and argument, unable to answer with any substantial confidence the following questions: "What difference does any such data flow rate differential make?" "Was this alleged differential important to the PTO?" "Would persons skilled in the art understand this differential as making any significant contribution to the invention?" "Is it material to the invention?" "Does it in any technologically significant way help define what is inventive about the claimed invention?"
Plaintiff might attempt to respond to these questions by pointing out that under the system contemplated in the patent there would be short periods during which data would back up in the pixel buffer while the frame buffer was fully occupied by other tasks and thus shut off to incoming video data from the pixel buffer. The difficulty with any such response is that while the "Detailed Description of the Invention" clearly discloses that data could back up for short periods in the pixel buffer, that Description never even intimates that the invention responds to this foreseeable development by causing the data to leave the pixel buffer at a rate that is faster than the rate at which the data entered the pixel buffer. Instead, in at least two separate passages, the "Description" insists that back up of data in the pixel buffer
is not a problem because during conventional blanking at the end of each incoming video scan line, pixel buffer 4 will have ample time to unload its data to frame buffer 8. If pixel buffer 4 is backed up to the point where it is not empty at the start of a new video scan line, control sequencer 14 clears the contents of pixel buffer 4 by providing a command on a reset (not shown) line (one of the Buf R/W lines 15).
Detailed Description, col. 4 (emphasis added). In another place the Description similarly asserts that "during the actual transaction period, pixel buffer 4 begins to back up with data. This is not a problem because during video blanking pixel buffer 4 has ample time to empty." Id. (emphasis added). If the inventor really contemplated using a faster flow of data out of the pixel buffer to deal with the problem of data backing up in that buffer, these are the obvious passages where that solution would have been described. But these passages mention nothing about a faster data flow rate out of the pixel buffer. They mention nothing about different "scan rates" or about data flow rate differentials. Instead, they suggest that the potential problems caused by data backing up in the pixel buffer are solved by the availability of "ample time to empty" "during conventional blanking at the end of each incoming video scan line."
The doubts created by the Description's failure to mention data flow rate differentials are intensified by testimony from defendant's expert, Dr. Stephen Carr, to the effect that the rates of data flow into and out of the pixel buffer would in fact be essentially the same over any period of time that was significant in this context. Decl. of Dr. C. Stephen Carr, filed July 5, 1994, at P.20.B; Tr. at II:126-27. While plaintiff attempted to attack this testimony on cross-examination (Tr. at II:150-56), the court is not aware of any evidence that plaintiff offered that directly contradicted it, i.e., that purported to explain why any data flow rate differentials that might arise during very short periods were material to the invention.
In sum, plaintiff has not adduced substantial evidence that would support a finding that a person skilled in the art would ascribe significance to the fact that data might flow out of the pixel buffer at a faster rate than the data flowed into the pixel buffer. That failure is important - in part because it makes less persuasive plaintiff's contention that persons skilled in the art would understand the ambiguous language in the claims to mean what plaintiff now insists that language means.
Another consideration that undermines the persuasiveness of plaintiff's interpretation of these key elements of the claims is that there is an alternative interpretation of them that, while doing more violence to the inartful language as written, appears to be appreciably more consistent with the claimed invention as a whole. That alternative interpretation builds from the notion (driven by common sense and the failure of the patent to state otherwise) that the phrase "scan rate" is in fact used consistently throughout the patent - i.e., that each time it is used, it means the same thing. That single, uniform definition is the definition that plaintiff concedes is the most common - and the definition that is used in the Abstract, the Background of Invention section, and in the first two lines of claims one and two: namely, the rate or speed at which the raster beam traverses or fills a screen or monitor.
Moreover, there is evidentiary support for the view that the inventor in fact intended the phrase "scan rate" to have this most common meaning even when it appeared in the disputed elements of claims one and two. This evidentiary support comes from the history of the prosecution of the patent as reflected in the file wrapper. The inventor's initial application was rejected by the PTO, in part because the examiner believed that claims one and two had been anticipated by a patent referred to as "Fernandez '257." Responding to this basis for the examiner's initial rejection, the inventor argued that what fundamentally distinguished the claimed invention from Fernandez was that "Fernandez's system, in contrast, does not convert the scan rate of the incoming video before sending the video data to the display. " RS002737 (emphasis added). And it appears that a principal purpose of the amendments that the inventor added in response to the initial rejection of the claims was to reinforce the message that that scan rate conversion was central to the claimed invention and to refuting the notion that Fernandez '257 had anticipated Mr. Maietta's claimed invention. In the quoted material that follows, the portions that are underlined were added to the claims in response to the examiner's initial rejection:
1. (Amended) A converter for converting a video signal from a first to a second scan rate comprising:
a pixel buffer for storing a portion of the video signal having a first interlaced raster video scan rate;