In Grace Instrument Industries, LLC v. Chandler Instruments Company, LLC, [2021-2370] (January 12, 2023), the Federal Circuit vacated the district court’s finding that the claims of U.S. Patent No. 7,412,877 were indefinite.
The ‘877 patent relates to a viscometer for measuring the viscosity of drilling fluid. The discometer uses a “enlarged” chamber located between a lower chamber, housing the sample fluid, and a pressurization fluid inlet, located in the top section of the viscometer’s
pressure vessel. This enlarged chamber is large enough such that the level of the sample fluid, which before pressurization initially fills both the lower chamber and the enlarged chamber, never falls below the transition point between the lower chamber and enlarged chamber when the application of the pressurization fluid compresses the sample fluid.
1. A pressurized device comprising:
(a) a pressure vessel within which is vertically disposed at least one top section filled
with a pressurization fluid of a first density and at least one lower section filled with a test sample of a second density,
(b) an enlarged chamber with reduced openings positioned between the at least one top section and the at least one bottom section for communicating pressure with said top section and said lower section within said pressure vessel,
(c) whereby said pressurization fluid would not mix with said test sample because of the nature of their density difference.
The district court determined that the term “enlarged chamber” as used in the claims was indefinite, making the asserted claims of the ‘877 patent invalid. The district court explained that “enlarged” is a “term of degree” that “necessarily calls for some comparison against
some baseline.” Finding that the ’877 patent “does not provide the requisite objective boundaries” for a skilled artisan, the district court held that “enlarged chamber” is indefinite.
The Federal Circuit said that a patent is invalid for indefiniteness if its claims, read in light of the specification delineating the patent, and the prosecution history, fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention.” The ultimate conclusion that a claim is indefinite under 35 U.S.C. § 112, ¶ 2 is a legal conclusion, which we review de novo.
Grace argued before the district court that the term “enlarged chamber” should be construed as “the area between reduced openings that is large enough to hold excess test sample (i.e., the type of fluid normally used in these machines) to prevent mixing of pressurization fluid and test sample below the bottom fin during elevated pressurization.” The district court declined to adopt that construction, concluding that the ’877 patent fails to disclose objective
boundaries for a skilled artisan to know what the claimed “enlarged chamber” must be larger than. The Federal Circuit said that this was error.
The Federal Circuit said that the intrinsic record informs a skilled artisan that the ’877 patent and its claims are directed to a viscometer with an “enlarged chamber” that is large enough to prevent pressurization fluid from entering the lower section of the pressure vessel—where the viscosity of the test sample is being measured—during elevated pressurization. In other words, the enlarged chamber has to be able to contain enough sample fluid at the pre-pressurization stage such that, during pressurization, the sample fluid level does not fall below the bottom of the enlarged chamber and into the viscometer’s lower, testing section. Although “enlarged chamber” is not a term of art, the intrinsic record sufficiently guides a skilled artisan to the meaning of that term as used in the ’877 patent. Where the specification instructs as to the meaning of a claim term, “the inventor’s lexicography governs.”
The Federal Circuit concluded that the term “enlarged chamber” in the ’877 patent meant “a chamber that is large enough to contain excess test sample prior to pressurization to prevent mixing of the test sample and pressurization fluid in the lower measurement zone when the test sample is pressurized to maximum rated pressure.” The Court thus vacated the district court’s determination that “enlarged chamber” is indefinite, vacatef the district court’s invalidity determinations based thereon, and remanded for further proceedings
consistent with this opinion.