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March 4, 1999


The opinion of the court was delivered by: Kocoras, District Judge.

                             MEMORANDUM OPINION
                                 AND ORDER

This matter is before the Court on cross motions for summary judgment. For the following reasons, the plaintiffs' motions are denied and the defendants' motions are granted.


Plaintiff Brita Wasser—Filter—Systeme ("Brita") owns the rights to United States Patent Number 4,969,996 ("the `996 patent"). Brita brought a patent infringement suit against Recovery Engineering, Inc. ("Recovery"), Signature Brands, Inc. ("Signature"), and Culligan International Company ("Culligan"). The `996 patent is entitled "Water Purification Device with an Intake Funnel" and contains nine claims. The abstract for the patent describes a water purification device having an intake funnel, a sleeve which is sealingly connected to the funnel, a filter cover, and a filter bottom in which a granulate-type filter agent can be introduced.

According to the `996 patent, prior art devices of this type allegedly encountered interruption of water flow through the filter cartridge because of air or gas bubbles being entrained at the bottom of the cartridge. To address this water flow problem, the `996 patent provides a filter cartridge having an "air collecting space" for collecting accumulated gas from the filter outlets and diverting this gas away from the bottom of the cartridge. The gas is then directed up a chimney-like half-tube and vented out a hole in the sleeve.

In the present lawsuit, Brita asserts claims of patent infringement against Defendants Recovery Engineering, Inc. ("Recovery"), Signature Brands, Inc. ("Signature"), and Culligan International Company ("Culligan"). Each of the Defendants produces their own water filtration system device. Brita alleges that all three of these filtration devices infringe the `996 patent.

Claim 1 is the `996 patent's only independent claim. Each of the parties' disputes involves Claim 1 of the patent, or language in a dependent claim that matches language in Claim 1. This claim reads as follows:

  A water purification device comprising an intake
  funnel, a sleeve wherein said sleeve is sealingly
  connected to said funnel at an upper end of said
  sleeve, said sleeve further having an opening formed
  therein, an insert having approximately cylindrical
  side walls, a filter cover and a filter bottom for
  accommodating a granulate filter agent therein with
  means defining an air collecting space, located in at
  least a portion of the filter bottom, said means
  defining the air collecting space extending upwardly
  at least partially towards the side wall and to the
  opening in said sleeve, with said filter bottom having
  opening means to allow the passage of filtrate
  therethrough, and with said filter cover having
  opening means whereby fluid can be passed into the

`996 patent, Claim 1.

The Court conducted a Markman hearing on July 8, 1998, and Issued a written opinion interpreting that claim on August 7, 1998. See Brita Wasser—Filter—Systeme GmbH v. Recovery Engineering, Inc., 1998 WL 473467 (N.D.Ill. Aug. 7, 1998). The Court agreed with the parties that no extrinsic evidence was necessary to construe the disputed terms in the `996 patent. In that opinion, the Court made several interpretations.

1. "Means defining an air collecting space"

The Court determined that the claim term "means defining an air collecting space" is a means-plus-function element and thus must be construed under 35 U.S.C. § 112, ¶ 6. The function disclosed for this element is a space which gathers and then removes air bubbles from the filter bottom. The corresponding structure for this element requires a space with both a vertical and horizontal component, though these components are not restricted by the precise structures disclosed by the preferred embodiment.

2. "Sleeve" and "an opening formed therein"

The Court found that the word "sleeve" in Claim 1 means "a single continuous structure with two open ends that fits over something else." The "opening formed therein" is limited to a single opening which is a permanent part of the sleeve.

3. "to the opening in said sleeve"

Finally, after examining the claim language and the file history, this Court determined that the chimney portion of the air collecting space must reach the elevation of the sleeve opening, and not merely extend in a direction toward the opening.


The purpose of summary judgment is to avoid an unnecessary trial. See Matsushita Elec. Indus. Co. v. Zenith Radio Corp., 475 U.S. 574, 587, 106 S.Ct. 1348, 89 L.Ed.2d 538 (1986). Summary judgment is appropriate where there is no genuine issue of material fact and the moving party is entitled to judgment as a matter of law. Fed.R.Civ.P. 56. Summary judgment is as appropriate in a patent case as in any other case. See Barmag Barmer Maschinenfabrik AG v. Murata Machinery, Ltd., 731 F.2d 831, 835 (Fed.Cir. 1984).

The burden is initially on the movant to identify the portions of the pleadings, depositions, and other evidence that the movant believes demonstrate the absence of a genuine issue of material fact. See Celotex Corp. v. Catrett, 477 U.S. 317, 323, 106 S.Ct. 2548, 91 L.Ed.2d 265 (1986). Where the non-movant bears the burden of proof at trial, the movant can discharge his burden by pointing out to the district court that there is "an absence of evidence to support the non-moving party's case." Celotex, 477 U.S. at 325, 106 S.Ct. 2548. Once the movant meets its burden, the non-movant must go beyond the pleadings and introduce affidavits or identify portions of the evidence of record showing that there is a genuine issue of disputed fact requiring trial. See id. at 324, 106 S.Ct. 2548.

The plaintiff in a patent infringement case bears the burden of proving that every limitation of one or more claims is met by the accused device, either literally or by the doctrine of equivalents. See Perkin—Elmer Corp. v. Westinghouse Elec. Corp., 822 F.2d 1528, 1532-33 (Fed.Cir. 1987). The standard of proof is a preponderance of the evidence. See SmithKline Diagnostics, Inc. v. Helena Laboratories Corp., 859 F.2d 878, 889 (Fed.Cir. 1988). To avoid summary judgment of non-infringement, the plaintiff must show that "the evidence is such that a reasonable jury could return a verdict for the [plaintiff]." See Anderson v. Liberty Lobby, Inc., 477 U.S. 242, 248, 106 S.Ct. 2505, 91 L.Ed.2d 202 (1986). Even under the doctrine of equivalents, "[w]here the evidence is such that no reasonable jury could determine two elements to be equivalent, district courts are obliged to grant partial or complete summary judgement." See Warner—Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17, n. 8, 117 S.Ct. 1040, 137 L.Ed.2d 146 (1997). It is with these principles in mind that we turn to the issues in this case.


Determining infringement involves two steps. First, the Court must construe the asserted claims as a matter of law to ascertain their meaning and scope. See Bai v. L & L Wings, Inc., 160 F.3d 1350, 1354 (Fed.Cir. 1998). Second, the claims as construed are compared to the allegedly infringing device. See id. In order for a device to infringe a claim, each claim limitation must be present in the accused device either literally or equivalently. See Dawn Equipment Co. v. Kentucky Farms, Inc., 140 F.3d 1009, 1014 (Fed.Cir. 1998) (citing Sofamor Danek Group, Inc. v. De-Puy-Moteck, Inc., 74 F.3d 1216, 1220 (Fed.Cir. 1996)). "The essential inquiry is whether `the accused product or process contains elements identical or equivalent to each claimed element of the patented invention.'" Litton Systems Inc. v. Honeywell Inc., 140 F.3d 1449, 1454 (Fed.Cir. 1998) (citing Warner—Jenkinson, 117 S.Ct. at 1054).

A patent may be infringed either literally or under the doctrine of equivalents. A device literally infringes a patent claim only if every limitation of the claim is present in the device. See Perkin—Elmer, 822 F.2d at 1532. "[A]ny deviation from the claim precludes a finding of literal infringement." Litton Systems Inc. v. Honeywell Inc., 140 F.3d 1449, 1454 (Fed. Cir. 1998).

The purpose of the doctrine of equivalents is to prevent competitors from pirating the essence of an invention while narrowly avoiding the literal language of the claims. See Laitram, 863 F.2d at 856-57. It is intended to prevent a competitor from making merely insubstantial changes, but is not intended to punish legitimate "designing around" the patent claims. See London v. Carson Pirie Scott & Co., 946 F.2d 1534, 1538 (Fed.Cir. 1991). Designing around the patent claims is encouraged, because it stimulates invention and benefits society with new and useful products. See id.

In determining whether a product infringes under the doctrine of equivalents, courts are to apply an "element-by-element analytical framework for infringement." Litton Systems, 140 F.3d at 1454. Under this framework, "the doctrine of equivalents must be applied to individuals elements of the claim, not to the invention as a whole." Id. (quoting Warner—Jenkinson, 117 S.Ct. at 1049). The Supreme Court cautioned against allowing a range of equivalents with "such broad play as to effectively eliminate that element in its entirety." Id. (quoting Warner—Jenkinson at. 1054).

The United States Supreme Court announced the function-way-result test for infringement under the doctrine of equivalents in Graver Tank & Manufacturing Co. v. Linde Air Products Co., 339 U.S. 605, 70 S.Ct. 854, 94 L.Ed. 1097 (1950). To prove infringement under the doctrine of equivalents, the patentee must show that the accused device performs substantially the same function, in substantially the same way, to produce substantially the same result as the claimed invention. See Graver Tank, 339 U.S. at 608, 70 S.Ct. 854. The functional equivalent of every limitation must be found in the accused device or there is no infringement. Pennwalt Corp. v. Durand—Wayland Inc., 833 F.2d 931, 937 (Fed.Cir.1987).

I. Culligan's Motion for Summary Judgment

Culligan seeks summary judgment that its glass pitcher filter system (the "Culligan System") does not infringe patent `996 either literally or under the doctrine of equivalents. According to Culligan, at least two crucial claim limitations are missing from the Culligan System. First, the Culligan System lacks an air collecting space that "reaches to the opening" in the sleeve. Culligan asserts that prosecution history estoppel prevents Brita from asserting that the scope of equivalents ensnares the notch in the side of Culligan's filter which fails to reach "to the opening." Second, Culligan argues that the Culligan System does not have a "means defining an air collecting space."

The Culligan System consists of a glass pitcher, in which sits a reservoir (a "hopper") for water which has not yet passed through the filter. A filter cartridge is inserted in a sleeve in the hopper, through which water passes to be purified. Inlet holes on the top of the cartridge receive water and outlet holes on the bottom emit filtered water. On the side of the Culligan filter cartridge is a notch, which cuts a triangle shape out of the side of the cylindrical cartridge. The base of the notch is on the bottom of the filter cartridge, with the triangle extending up to a point towards the middle of the cartridge. A small hole is formed in the sleeve near the top where it attaches to the hopper. The upper point of the triangular notch is a substantial distance below the hole in the side of the sleeve. The bottom of the cylindrical filter cartridge is flat, and the notch, located a distance from the outlet holes, cuts a triangle shape out of the circular filter bottom.

Water when placed in, the hopper moves downward through the filter cartridge and out the holes in the bottom of the cartridge, where it falls into the pitcher. According to Culligan, the triangular notch in the filter cartridge serves only to allow "the cartridge to be used as a replacement filter in Brita hoppers which have a rib extending along an interior surface of the hopper." The small hole in the side of the sleeve "allow[s] air within the pitcher to escape when it is displaced by the water coming through the filter cartridge." Unlike in Brita's sleeve, the Culligan System ...

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