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“Commercially Available” Vacuum Sensor Satisfies Structural Disclosure Requirements for Means-Plus-Function Limitations

May 24, 2001

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Last Month at the Federal Circuit - June 2001

Judges: Linn (author), Bryson, and Dyk

In Budde v. Harley-Davidson, Inc., No. 99-1533 (Fed. Cir. May 24, 2001), the Federal Circuit affirmed-in-part, vacated-in-part, and remanded a decision by the District Court for the Northern District of California. The two issues on appeal involved the construction of means-plus-function claim limitations and, more particularly, whether the patent specification disclosed structure corresponding to those limitations.

William Budde sued Harley-Davidson, Inc. and Harley-Davidson Motor Company (collectively “Harley-Davidson”) for infringement of U.S. Patent No. 4,955,348 (“the ‘348 patent”) in June 1997. The ‘348 patent relates to a fuel-injectionconversion system for two-cylinder motorcycle engines. For proper operation, fuel-injection systems typically receive timing information indicating which cylinder needs to be charged with fuel. Unlike most fuel-injection systems, which receive timing information from the engine’sspark distributor, the patented system derives timing information electronically. Specifically, the patent discloses deriving timing information by (1) measuring the camshaft position, (2) firing a timing pulse in response thereto, and (3) measuring the time between successive timing pulses so as to determine which of the two cylinders needs to be next charged with fuel. Steps (1) and (2) are performed by the engine’s standard ignition system, which already employs camshaft position sensors (e.g., points, solid-state devices, or Hall effect devices) and delivers pulses to fire the spark plugs in response to the camshaft position. The sensors track the camshaft position using a metallic timing cup having a pair of windows cut into the cup’s sides. The patent discloses feeding the output of the ignition system to an electronic control unit that measures the time span between successive pulses and, from that measurement, determines which cylinder should be injected with fuel.

Claim 1 of the ‘348 patent requires a “fuel injection conversion system” comprising, among other things, “an electronic sensing means for determining when the ignition system of the engine delivers an electronic pulse to fire each spark plug of the cylinders and producing an electronic signal in response thereto.” The district court had held that the structure corresponding to the claimed function had to actually sense the firing of each spark plug and could not be structure that simply sensed the position of the camshaft. The district court then concluded that the patent specification failed to disclose structure corresponding to this means-plus-function element, but did not hold the claim invalid for indefiniteness under 35 U.S.C. § 112.

Claim 1 also requires a status-sensing means for measuring a combination of air intake and engine temperature and vacuum in the intake manifold and producing electronic signals therefrom. Despite Harley-Davidson’s argument to the contrary, the district court had held that the patent specification did disclose structure corresponding to this means-plus-function element.

After concluding that he could not prove infringement based on the district court’s claim construction, Budde moved the district court to enter a final judgment of noninfringement and appealed. Harley-Davidson filed a conditional cross appeal, asking that the Court review the district court’s construction of “status sensing means” only if it reversed the district court’s construction of “electronic sensing means.”

Initially, the Federal Circuit ruled that a challenge to a claim containing a means-plus-function limitation as lacking structural support requires a finding by clear and convincing evidence because such a finding necessarily means that the claim is indefinite and is, therefore, invalid; and invalidity must be shown by clear and convincing evidence.

Turning to the plain language of the claims, the Court held that, contrary to the district court’s construction, the function of “determining when the ignition system of the engine delivers an electronic pulse to fire each spark plug” does not require direct detection of electronic pulses. Rather, the determination can be indirect. Turning to the specification, the Court noted that the sensor that determines the position of the camshaft, in response to which another structure delivers a pulse to fire each spark plug, at least indirectly determines when the ignition system delivers an electronic pulse to each spark plug. The Court thus rejected the district court’s construction, holding that the patent specification discloses structure (i.e., the camshaft position sensor) corresponding to the
“electronic sensing means.”

Having reversed the district court’s construction of “electronic sensing means,” the Federal Circuit turned to Harley-Davidson’s conditional cross appeal of the construction of “status sensing means.” As claimed, the “status sensing means” must measure vacuum in the intake manifold. According to the district court, the specification disclosed corresponding structure in the form of a “commercially available” vacuum sensor that produces an analog output. But, on appeal, Harley- Davidson asserted that such a generic reference would (1) improperly allow Budde to incorporate by reference every commercially available vacuum sensor; and (2) prevent one of ordinary skill in the art from understanding the scope of claim 1. The Federal Circuit rejected both arguments, concluding that the only question was whether the characterization in the patent specification of the vacuum sensor would be understood by one skilled in the art as structure capable of performing the function recited in the claim limitation. Relying on the district court’s finding that vacuum sensors were well known in the art, the Court answered this question affirmatively and affirmed the district court’s construction of “status sensing means.”