Oxygenator Water Technologies, Inc. v. Tennant Company

Background

Oxygenator owns U.S. Patent Nos. RE45,415, RE47,092, and RE47,665. The patents concern using electrolysis—an electrical process involving electrodes in water—to form very small oxygen bubbles that can remain suspended in the water. Tennant manufactures and sells commercial floor scrubbers that use electrolysis to oxygenate water. Oxygenator believes the scrubbers infringe its patents.

The parties asked the court to perform claim construction, which is the process of determining the legal meaning and scope of words and phrases in patent claims. The court’s definitions will guide later proceedings, including any determination of infringement. The court did not decide infringement, patent validity, or indefiniteness in this opinion.

Agreed terms

The parties agreed on constructions for seven terms, and the court adopted those constructions because they were consistent with the claims and the patents’ internal evidence. The adopted terms included “microbubble,” “critical distance,” “aquarium reservoir container,” “supersaturate,” “concave,” “radial direction relative to the longitudinal center axis,” and “a suspension comprising oxygen microbubbles and nanobubbles.”

Disputed terms and rulings

The court construed “water” to mean “any aqueous medium that can support the electrolysis of water.” It declined to add the patent specification’s references to resistance or to 2,000 parts per million of dissolved solids. The court found those references ambiguous or inconsistent with the record, and it noted that the prosecution history described ordinary sources such as municipal tap water, well water, lake water, and irrigation water.

The court construed “nanobubble” to mean “a bubble with a diameter less than that necessary to break the surface tension of water.” It declined to add a requirement that the water have an opalescent or milky appearance, treating that description as a consequence of the bubbles’ size rather than part of the definition. The court also declined to construe “conductivity produced by the presence of dissolved solids such that the water supports plant or animal life,” “aqueous medium,” and “oxygenated aqueous composition.” It concluded, however, that the disputed conductivity phrase did not include water that supports saltwater life, based on the patents’ specification and prosecution history.

For the water-flow terms, the court construed “flowing water . . . through an electrolysis emitter,” “deliver electrical current to the electrodes while water flows through the tubular housing,” and “passing water through the tubular housing” to require moving water through the electrolysis emitter by means other than electrolysis. It construed “a flow-through oxygenator” as “a device that oxygenates water as the water passes through it.” The court rejected Tennant’s broader interpretation that would have included placing an emitter in stationary water, explaining that the claims at issue described water moving through the device.

The court construed “tubular housing” as “an enclosure shaped like a cylinder, hose, or tube.” Although the wording of the construction is broad in ordinary language, the court explained that the term requires a circular cross-section in the context of the patents. It construed “a tubular flow axis from the inlet to the outlet” as “a main line of flow through the tubular housing from the inlet to the outlet,” rather than requiring a straight path.

The court construed “a power source” and “an electrical power source” as “electrical and mechanical equipment and their interconnections used to generate and/or convert power.” Thus, the term includes equipment that converts and delivers power, not only the device that initially generates it.

The court declined to construe “incapable of breaking the surface tension of the water.” It rejected Tennant’s proposed interpretation that the phrase necessarily meant “containing nanobubbles,” noting that microbubbles could also be substantially unable to break the water’s surface tension. The court also declined to construe “the microbubbles and nanobubbles remain in the water at least in part for a period up to several hours,” reasoning that “up to” has an ordinary meaning indicating a maximum rather than a minimum.

The court construed “the water temperature is a factor for formation of the suspension” to mean that “the method uses water temperature as a factor in forming the suspension.” It did not require temperature to be the deciding factor in whether a suspension could form. For the aquarium-container limitation, the court construed the term to mean that “the water with microbubbles and nanobubbles is contained in a two and one half gallon aquarium reservoir container to determine the period for which the microbubbles and nanobubbles at least in part remain in the water.”

Finally, the court declined to construe “a first anode electrode portion that is nonparallel to a second anode electrode portion.” It rejected Tennant’s proposal that the claim require two physically separate anodes, finding that the claim’s reference to portions could describe parts of one anode.

Other issues and disposition

Oxygenator argued that Tennant should be prevented from taking certain claim-construction positions because they differed from positions Tennant had taken in petitions for review of the patents before the Patent Trial and Appeal Board. The court declined to apply that bar, noting that the record did not show Tennant had prevailed on those earlier positions or gained an unfair advantage.

The court ordered that the terms in the three patents be construed as set forth in the opinion. Judge Eric C. Tostrud did not decide whether any claim was infringed or invalid, and Tennant remained free to pursue invalidity arguments later in the litigation.