Paradox Security Systems v. ADT Security Services et al (CAFC 2010-1012) non-precedential

The paradox for Paradox was pointing out signal sources in the accused devices.

Paradox argues that it is "axiomatic" that any signal must have a source and that, accordingly, a DC bias source must be coupled to the input of the transmit opto-coupler. Although the initial premise of this statement is correct, the conclusion hardly follows from it. Indeed, Dr. Williams' statements were entirely conclusory; he pointed to no structure in the DSC schematic shown above, or in any of the other schematics of DSC accused circuitry that were admitted into evidence, that identified a "DC bias source coupled to the transmit opto-coupler input" as construed by the court.

Paradox points to no structure in the schematics of the DSC accused devices that is the "source of [the] AC signal" and that is connected via wires to the transmit opto-coupler. Nor can it point to any capacitor or comparator through which the AC signal is passed.

Because Paradox can point to no structure introduced into evidence that unequivocally identifies a "DC bias source coupled to the transmit opto coupler input," or any "source of [an] AC signal," the accused DC circuitry fails to meet every limitation of asserted claims 1 and 2. Consequently, we affirm the district court's order granting JMOL of noninfringement with respect to claims 1 and 2.

The claim 5 claim construction dispute washed out for either non-infringement or failure to meet the written description requirement.

There are two reasons why we need not resolve this claim construction issue, however. First, assuming that the district court did err in construing claim 5 to mean that the circuitry combining both the AC transmit signal and the DC bias signal must be on the line side, that error was harmless. The reason is that Paradox produced no evidence that either the '406 patent's preferred embodiment or DSC's accused devices conform to either the construction adopted by the court or to Paradox's proposed construction. Second, the final limitation of claim 5 requires "a DC bias voltage generator responsive to a control signal to provide a low level DC signal as said DC bias signal." As discussed in Part II above, Paradox failed to identify this structure in the accused device. We therefore affirm the judgment of noninfringement of claim 5.

Affirmed.