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Don't Be Left Flat: Words Matter When Drafting Patent Claims - IP Blog

In Wasica Finance GmbH v. Continental Automotive Systems, Inc., No. 15-2078 (Fed. Cir. 2017), the patentee Wasica Finance discovered, among other things, the importance of using consistent terminology in the patent specification and claims.

The patent-in-suit, now expired U.S. Patent No. 5,602,524, is directed to a system for monitoring tire pressure in vehicles. In an appeal from two inter partes review decisions from the Patent Trial and Appeal Board, the United States Court of Appeals for the Federal Circuit affirmed in part that certain claims of the ‘524 patent are unpatentable as anticipated or obvious.

The ‘524 patent describes that conventional tire pressure monitors communicate pressure readings through electromagnetic signals, which are susceptible to interference that causes inaccurate pressure readings. The ‘524 patent attempts to address this deficiency by providing a pressure measuring device and a transmitter in each tire, and a corresponding receiver for each transmitter. The transmitters are configured to send a unique identification signal that enables the receivers to distinguish signals from different transmitters and process pressure data only from the designated transmitter.

A first issue on appeal involved the proper constructions of the terms “electrical pressure signal” and “pressure transmitting signal.” The patentee argued that these claimed signals must include numerical values of the pressure inside the tire. This proffered construction aimed to distinguish the claims from conventional switch-based sensors that are configured to send a binary signal to trigger an alarm when the pressure dropped below a threshold.

To the dismay of the patentee, the Court rejected its interpretation in light of the claim language and the ordinary and customary meaning of the claim terms. Because the claim recited a display device that “displays data as numbers or symbols which have been taken from the pressure transmitting signal received from the receiver,” the Court held that the term “pressure transmitting signal” must be broad enough to encompass exclusively non-numerical symbols. Similarly, the claim recites that the electrical pressure signal is “representative of the air pressure,” and the Court held that non-numeric symbols can be representative of air pressure, in much the same way that a gas indicator light is representative of a low fuel level without indicating a specific numeric value indicating the volume of remaining fuel.

A second issue on appeal was the construction of the term “emittance of a predetermined switching signal,” which the patentee contended must be limited to wireless transmissions. The Court rejected this interpretation in light of the plain and ordinary meaning of “emit,” which is to “to send out,” and the presence of embodiments in the specification in which the switching signal propagated in both wireless and wired form.

The Court further noted that the ‘524 patent used the terms “emit” and “transmit” interchangeably throughout the specification and the claims. For instance, one of the claims recited that the transmitter emits a pressure transmitting signal to a receiver, but transmits an identification signal to the same receiver. The Court held that conflating these two terms effectively amounted to a definition equating these terms. Accordingly, although different terms are generally presumed to have different meanings, the patentee’s conflation of these two terms undercut the its proffered construction of the term “emittance of a predetermined switching signal.”

In light of these constructions, the Court affirmed the Board’s decision that certain claims of the ‘524 patent are unpatentable as anticipated or obvious.

The Court’s resolution of the issues demonstrates the importance of carefully and consistently crafting language in the specification and claims to support the intended meanings of important claim terms.  Further, when the disjunctive “or” is used to describe a series of alternatives, drafters should consider adding dependent claims to cover each of these alternatives affirmatively. This strategy could help avoid prior art references that disclose some but not all of the elements in a claimed disjunctive list from invalidating all of the claims of the patent.

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