Justia Federal District Court Opinions

DECISION

Harris Corporation (Harris) appeals the judgment of the United States District Court for the Eastern District of Pennsylvania, holding Harris liable for willfully infringing claims 1 and 14 of U.S. Patent No. 5,198,904 (the '904 patent) assigned to Comark Communications, Inc. (Comark). See Comark Communications, Inc. v. Harris Corp., 47 USPQ2d 1469 (E.D.Pa.1998) (awarding costs and attorneys' fees); Comark Communications, Inc. v. Harris Corp., No. 95-CV-2123, 1997 WL 431000 (E.D.Pa. July 17, 1997) (denying Harris's renewed motion for judgment as a matter of law (JMOL) and granting increased damages in light of the jury's finding of willfulness); Comark Communications, Inc. v. Harris Corp., No. 95-CV-2123, 1997 WL 87260 (E.D.Pa. Feb. 24, 1997) (claim construction). Because the district court did not err in construing claim 1 of the '904 patent, and because substantial evidence supports the jury's findings of infringement and willfulness, we affirm the decision of the district court.

BACKGROUND

Comark makes and sells ultra-high frequency (UHF) television transmission equipment. Conventional television signals contain two primary components: the video portion of the signal and the audio portion. In the early and mid-1980s, most high-power UHF television transmitters used separate hardware devices to amplify the video and audio signals for transmission. In the late 1980s, Comark developed an amplification system that operated in "common amplification" mode. Comark's common amplification mode allowed the video and audio signals to be combined before amplification and amplified together in the same amplification tube. By using the common amplification technique, the Comark system was able to reduce the amount of hardware required to perform the amplification, increase efficiency, and provide a built-in redundancy to those customers using a multi-tube system. The common amplification technique, however, suffered from cross-modulation problems that produced distortions known as H sync spurs that disrupted the audio portion of the signal.

The H sync spurs caused two problems. First, the primary H sync spur occurred at the frequency of 15.734 kHz that is used for transmission of the Broadcast Television System Committee stereo pilot, which indicates to television sets that the audio signal is being broadcast in stereo. As a result, this H sync spur sometimes caused false and intermittent triggering of the stereo processing circuitry in televisions tuned to the UHF signal. Second, the sum total of the H sync spurs could increase the overall modulation of the audio carrier to a level that exceeds regulatory limits.

Comark corrected the H sync spur problem with a circuit that uses a sample of the transmitter's video signal to "precorrect" the audio signal, thereby canceling the effects of cross-modulation. Comark filed a patent application for this invention on February 25, 1991 which issued as the '904 patent on March 30, 1993. The '904 patent is entitled "Aural Carrier Correction System and Method." In this appeal, only claims 1 and 14 are at issue. They read as follows:

1. An aural carrier correction system for a common amplification television transmitter which amplifies both an aural signal and a visual signal simultaneously, the transmitter including at least a IF vision modulator for receiving a video signal and for outputting the visual signal, the system comprising:

a video delay circuit for receiving and delaying the video signal to provide a delayed video signal;

a complimentary [sic] non-linear amplifier for receiving the delayed video signal and for separately and controllably generating a non-linear amplitude domain video signal and non-linear phase domain video signal; and

an amplitude and phase modulator for receiving the aural signal and for amplitude and phase modulating the aural signal using the non-linear amplitude domain video signal and the non-linear phase domain video signal, respectively, to generate a modified aural signal; and

an adder circuit for adding the modified aural signal to the visual signal outputted by the IF vision modulator to reduce unwanted noise appearing at specific frequencies in an output aural signal output from the transmitter.

14. A method for reducing unwanted aural carrier modulation caused by a video signal in a common amplification television transmitter which amplifies both an aural signal and a visual signal simultaneously, the method comprising the steps of:

mixing an aural carrier with an amplitude modulated video signal to generate a commonly amplified television transmission signal;

demodulating the commonly amplified television transmission signal to provide a demodulated aural signal;

performing a spectral analysis of the demodulated aural signal to determine the presence and frequency of unwanted aural signal noise resulting from unwanted aural carrier modulation;

generating a non-linear amplitude domain video signal and a non-linear phase domain video signal which respectively having amplitude and phase components that are directly opposite to unwanted amplitude and phase components added to the aural signal by the video signal;

amplitude and phase modulating the aural signal using the non-linear amplitude domain video signal and the non-linear phase domain video signal, respectively, to generate a modified aural signal; andadding the modified aural signal to the visual signal in the transmitter.

The claimed correction circuit, represented by figure 1 from the '904 patent, is reproduced below:

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