AN AUSTIN PATENT ATTORNEY’S OVERVIEW:
The technology in this case relates to electrical circuits, and specifically placement of components within circuits to measure time intervals of the circuits. In this case, GuideTech, appeals the district courts grant of summary judgment that Brilliant Instruments did not infringe on three of GuideTech’s Patents (U.S. Patent Number 6,226,231; U.S. Patent Number 6,091,671; and U.S. Patent Number 6,181,649).
A representative claim of the claim at issue is represented below (emphasis added).
- A time interval analyzer for measuring time intervals between signal events, said analyzer comprising:
a signal channel that receives an input signal;
a plurality of measurement circuits defined within said signal channel in parallel with each other, each said measurement circuit being configured to receive said input signal, measure an occurrence of a first event of said input signal with respect to a predetermined time reference and output a time signal corresponding to the measurement of said occurrence; and
a processor circuit in communication with said signal channel, wherein said processor circuit is configured to receive and compare said time signals from said measurement circuits to each other to determine a time interval between said first event measured by a first said measurement circuit and an event measured by a second said measurement circuit.
1. A time interval analyzer for measuring time intervals between events in an input signal, said analyzer comprising:
a trigger circuit that receives said input signal and that outputs a trigger signal at a triggering level upon occurrence of a first said event;
a first current circuit having a constant current source or a constant current sink;
a second current circuit having a current sink where said first current circuit has a constant current source; or
a current source where said first current circuit has a constant current sink;
a shunt, wherein said shunt and said capacitor are operatively disposed in parallel with respect to said first current circuit, wherein said shunt is disposed between said first current circuit and said second current circuit, and wherein said shunt receives said trigger signal and is selectable between conducting and non-conducting states between said first current circuit and said second current circuit, depending upon said trigger signal, so that said shunt is driven to said conducting state from said non-conducting state upon receiving said trigger signal at said triggering level.
The questions at hand in this case are associated with the above highlighted claim limitations. The first issue discussed by the court relates to infringement of the ‘231 patent. GuideTech challenged that district court’s grant of summary judgment of non-infringement of the ‘231 patent arguing that Brilliant’s datasheets show that the accused product operates on a single channel and uses two measurement circuits. In response, Brilliant argued that the accused products do not infringe because each signal channel contains only one measurement circuit, and simply borrows a second measurement circuit during a one-channel-two-edge mode.
The court of appeals agreed with GuideTech that the district court erred when granting summary judgment because a genuine issue of material fact exists as to whether the accused products have two measurement circuits contained within a signal channel. GuideTech’s expert witness stated that in the below schematic, a user may set the circuit to one-channel-two edge mode with Ch A as the input. The signal propagates through the red highlighted route, through a comparator, then into two multiplexers, where the outputs of the multiplexers are input into two measurement circuits.
The court of appeals reasoned that if this logic and schematics was viewed in GuideTech’s favor shows that only one signal channel operating contains two measurement circuits operating in parallel, which raises a genuine issue of material fact.
The second issue raised during this case relates to the infringement of the ‘671 and ‘649 patents. GuideTech challenged the district court’s grant of summary judgment that Brilliant’s accused products do not infringe the ‘671 and the ‘649 patents. GuideTech reasoned that nothing in the claims preclude the capacitor from being part of the first current circuit, and at the same time, operatively disposed in parallel with the shunt. GuideTech further argued that the operation of the accused products was equivalent to operatively disposing the shunt and the capacitor in parallel with respect to the first circuit.
Brilliant responded (and I agree) that accused products cannot literally infringe because the accused capacitor is part of the first current circuit, and therefore cant be in parallel with itself.
The court of appeals agreed with Brilliant that the district court properly granted summary judgment that Brilliant’s accused products do not literally infringe, but the court of appeals ruled that the district court erred when granting summary judgment that Brilliant does not infringe under the doctrine of equivalents.
The court of appeals reasoned that there is an issue of material fact under the doctrine of equivalents because the main different between the accused circuit and the claimed circuit is that the capacitor in the accused circuit aids in delivering power and is thus part of the first circuit. However, this feature in the accused design alters the function-way-result analysis, which creates a genuine issue of material fact under the doctrine of equivalents.
AN AUSTIN PATENT ATTORNEY’S TAKE-A-WAYS:
1) For several reasons, I am surprised by the court of appeals reasoning that because an added feature of the accused design may not alter the way the patent product that there may be infringement under the Doctrine of Equivalents. First, for the function-way-result test for the function of equivalents requires a limitation-by-limitation basis that the accused product performs substantially the same function, not the claim as a whole. My understanding of the function-way-result test is that whether the accused product performs substantially the same function in substnitally the same way with substantially the same result. Because there is the requirement for the limitation-by-limitation basis, it should be required to show that the an equivalent of the claimed limitation of “wherein said shunt and said capacitor are operatively disposed in parallel with respect to said first current circuit” is found in the accused product. Because, the shunt and capacitor in the accused product are within the same circuit they can’t operate in parallel and thus cannot function as an equivalent, even if the result is similar.
2) In this case, if GuideTechs products did not require the parallel feature why was this placed in the claims? I assume there are functional reasons for why the circuitry should/must have the measurement circuits operating in parallel, if not why is it worded as such in the claims? By including terms such as “ a plurality” and “in parallel” in the claims, the claims are limited by such wording. A broader term instead of in parallel, my just be “responsive to each other” or a similar limitation.