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Federal Circuit Construes Claims in First Instance to Determine Issue of Infringement

July 29, 2009

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Last Month at the Federal Circuit - August 2009

Judges: Newman, Schall, Patel (author, District Judge sitting by designation)

[Appealed from: D. Utah, Senior Judge]

In Wavetronix v. EIS EIectronic Integrated Systems, Nos. 08-1129, -1160 (Fed. Cir. July 29, 2009), the Federal Circuit affirmed the district court’s finding of noninfringement. Wavetronix LLC (“Wavetronix”) sued EIS Electronic Integrated Systems (“EIS”) for infringing U.S. Patent No. 6,556,916 (“the ’916 patent”). Claim 1 of the ’916 patent, the only independent claim in dispute, is directed to a system for monitoring the flow of automobile traffic by “generating a probability density function estimation” from the positions of multiple vehicles and defining the traffic lanes from the “probability density function estimation.” Wavetronix accused the automatic setup of EIS’s Remote Traffic Microwave Sensor (“RTMS”) device of infringing the ’916 patent literally or under the DOE.

Wavetronix’s ’916 patent is directed to “teaching” a traffic monitoring device the location of the traffic lanes on a given thoroughfare using detection and observation of actual automobile traffic. Slip op. at 4. Multiple histograms display a two-dimensional grid with peaks and valleys representing the relative heaviness of vehicle traffic across a set of “range bins” representing spatial distances from the sensor. The specification teaches that these histograms exemplify the “probability density function estimation” recited in claim 1.

EIS’s RTMS device also counts vehicles in several lanes of thoroughfare. The initial determination of lane locations may occur manually or via the “Setup Wizard,” the feature of EIS’s device that Wavetronix accuses of infringement. The Setup Wizard informs the installer how many lanes to expect, and the RTMS monitors and detects the signals, while the Setup Wizard processes the data. As data are compiled, the Setup Wizard identifies “local maxima” for each increment of time. Id. at 8. A local maximum is identified when the value at a particular position in the increment of time is greater than the values at the positions to the immediate left or right. After dentifying all the local maxima present during a particular interval, the Setup Wizard ignores everything except the “first” local maximum, which is the local maximum nearest to the sensor. The next step involves an array called the “NAMP array,” which Wavetronix contends generates a probability density function estimation. The NAMP array adds up the number of first local maxima per position over the course of the setup period. The system records first local maxima, not discrete automobiles.

The district court granted SJ of noninfringement to EIS. The district court also granted SJ to Wavetronix on EIS’s best mode and inequitable conduct defenses. The district court did not enter an order on claim construction.

On appeal, the Federal Circuit reminded that an infringement analysis involves a two-step process: the court first determines the meaning of disputed claim terms and then compares the accused device to the claimsas construed. The Court noted that the district court did not construe claim 1’s “probability density function estimation” limitation. The Court noted that it generally refused to construe claims in the first instance but indicated that it would construe the claim term here for three reasons. First, the district court’s opinion referenced the question of claim construction without construing the term, and the Court determined that it was apparent that the district court’s views on the matter had been exhausted. Second, both parties agreed that the Court should construe the claim limitation. Third, the record contained considerable evidence and expert testimony to allow the Court to construe the claim without prejudicing either party.

The parties agreed on the definition of probability density function (“PDF”) but disputed the definition of probability density function estimation (“PDFE”). EIS focused on “probability” and argued that a PDFE must represent a probabilistic analysis. On the other hand, Wavetronix argued that an “estimate” of a PDF does not need all the characteristics of an actual PDF, including estimating the actual probability that a vehicle has driven in a given lane. Wavetronix’s argument provided that any histogram that allowed for an estimation of lane boundaries was a PDFE because any graph that allowed for lane detection must have some correlation with the number or probability of cars in each lane.

The ’916 patent does not explicitly define PDFE. The specification refers to a PDF “as estimated,” “PDF estimation,” a “PDF estimator,” and “estimated PDFs.” In certain places, the specification refers to PDF and PDFE interchangeably. The Court stated that the concept of “PDF” was defined with greater clarity in the specification than “PDFE.” The specification describes PDF in terms of a graph in which enough data are collected to observe peaks, which represent the centers of lanes, and valleys, which represent the lane boundaries or edges.

The Court held that the difference between the two concepts was that a PDF is a mathematical function, whereas a PDFE is an approximation of such a function using actual finite data. A PDFE is an estimate of a PDF because the PDFE is based on actual data points rather than a perfectly smooth mathematical model. But a PDFE also compares values across a range of positions like a PDF. Because the Court found that a PDFE must estimate a PDF with sufficient precision to indicate both where vehicles are located and where they are not, the Court construed PDFE to be “a finite data set large enough to approximate a function of a continuous variable whose integral over a region gives the probability that a random variable falls within the region.” Id. at 20.

Having construed PDFE, the Court turned to the issue of infringement. Regarding literal infringement, Wavetronix contended that the Setup Wizard used the NAMP array to define traffic lanes, as recited in claim 1. Wavetronix further argued that the accused device used detections of first local maxima to conclude “it [was] probable” that vehicles travelled in certain range slices. Id. at 21. EIS responded that the accused device performed no probability analysis and, indeed, no such probability analysis could be performed using the NAMP array. Instead, EIS asserted that the NAMP array collected data for a number of bins corresponding to spatial positions, but those data could not fairly be said to represent probabilities.

The Court held that the PDFE claim term required a representation of vehicle frequencies across a range of positions with sufficient detail to provide meaningful information about where traffic lanes began and ended. The Court noted that the parties were in agreement regarding how the accused system operated, and the processing of the sensor data in the NAMP array, which was used to select lanes, did not involve comparisons among values for the range slices. The Court stated that there was only one value per lane, and, therefore, the peak and the valley represented whole lanes rather than lane centers or boundaries. Thus, the Court found that the NAMP array was too coarse to be a PDFE in the sense required by the ’916 patent, and the RTMS device did not literally infringe the ’916 patent. Wavetronix next argued that the district court did not give adequate consideration to the possibility of DOE. EIS contended that Wavetronix waived the argument. The Court held that there was no infringement by equivalents, assuming, without deciding, that Wavetronix did not waive the argument. The Court held that the Setup Wizard did not define lanes in substantially the same way as the patented method because it simply confirmed whetherthe range slices of a uniform width were aligned with actual traffic lanes on a one-to-one basis. The Setup Wizard’s determination of where lanes were located was made in relation to a specific threshold rather than as a comparison between different range slices. The Court reasoned that the peaks and valleys that are critical to the method of the ’916 patent were irrelevant to the way the Setup Wizard used data to select lanes.

Accordingly, the Court affirmed the district court’s finding of noninfringement. The Court also affirmed that EIS could not prevail on its inequitable conduct and best mode counterclaims.

Summary authored by Jessica R. Underwood, Esq.