Patent Law

Wavetronix v. EIS Electronic Integrated Systems (Fed. Cir. 2009)

Wavetronix's patent covers a big brother sensor to monitor vehicle trafic and to ensure that drivers are properly using the carpool (high-occupancy vehicle) lane. EIS was accused of infringement but convinced the Utah-based district court to grant summary judgment of non-infringement.

On appeal, the Federal Circuit has affirmed – largely based on claim construction of the claim term 'probability density function estimate' or PDFE used to define the traffic lanes. 

The excerpted claim reads as follows: 1. … a method for defining traffic lanes, comprising … b. generating a probability density function estimation … of said selectable plurality of vehicles; and c. defining said traffic lanes … from said probability density function estimation.

Writing for the court, Judge Patel (sitting by designation from the N.D. of Cal.) construed PDFE to as '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.'

[Updated] That definition - requiring an approximation of a continuous variable – helps EIS.  The EIS system can also automatically define the traffic lanes based on traffic data, but the company claims that its device does not do so with 'probability analysis' but rather uses large binary bins.  Based on this distinction Judge Patel held that the EIS system data is 'too coarse' to be a PDFE.

Even in a close case such as this, the court held that the DOE cannot rescue the patentee because of the tight requirements of element-by-element application of the DOE and the doctrine of vitiation.