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Sunbeam Products, Inc v. Homedics

December 15, 2010


Appeal from the United States District Court for the Western District of Wisconsin in case No. 08-CV-0376, Magistrate Judge Stephen L. Crocker.

The opinion of the court was delivered by: Bryson, Circuit Judge.

NOTE: This disposition is nonprecedential.

Before BRYSON, PLAGER, and CLEVENGER, Circuit Judges.

This case concerns a patent on the force-transmitting bearings for a platform scale that Sunbeam Products, Inc., asserted against its competitor HoMedics, Inc. Sunbeam moved for summary judgment of infringement; HoMedics moved for summary judgment on its invalidity counterclaim. The trial court granted summary judgment of noninfringement in favor of defendant HoMedics, although HoMedics never specifically moved for that order. Because the ground on which the court granted summary judgment was well developed in this case, we hold that Sunbeam was not unfairly surprised or prejudiced by the termination of this case in favor of HoMedics. And because the patent in suit clearly excluded the structure found in the accused devices from the scope of its claims, we affirm.


The patent in suit, U.S. Patent No. 5,133,420 ("the '420 patent"), is entitled "Bearing Support for a Scale Platform." The patent has nine claims. The two independent claims, claim 1 and claim 8, are at issue in this appeal. Claim 1 recites a platform scale including bearings that are mounted on the underside of said platform to support said platform with respect to said base with said bearing members engaging said levers intermediate their ends to apply a rotating force to said levers in response to a load on said platform, said bearing members being loosely coupled to said platform permitting horizontal displacement, said bearing members each having stand portions and depending column portions each, said depending column portions having a lower end, assembly means on said stand portions and on said platform retaining said stand portions in face-to-face engagement with the underside of said platform and permitting limited displacement of said bearing members in a horizontal direction . . . . '420 patent, col. 5, ll. 4-18. Claim 8 is similar, although it claims a bearing that is in "sliding engagement" rather than in "face-to-face engagement" with the underside of the platform. Id., col. 6, ll. 23-32. The district court treated the two claims identically.

The bearings transmit the force applied against the upper platform of the scale to the force-sensing levers on the scale's base. The bearings, located at each corner of the scale, are designed to ensure that a vertical force is applied against the force-collection levers even if weight is unevenly distributed on the platform, or if a non-vertical force is applied against the platform, or if the upper and lower platforms of the scale are out of alignment. Figure 3 of the '420 patent illustrates a bearing attached to one corner of the scale and engaging with a force-collecting lever. Figure 10 illustrates a single, unattached bearing. In an assembled scale, the bearing depicted in figure 10 is attached to the underside of the platform.

The bearing described in the '420 patent has a base portion consisting of coplanar flanges 42b, 42c, and 42d. Two of the flanges, 42b and 42c, contain a slot 42e. During assembly, a corresponding tab on the underside of the platform is inserted into each of the slots and is bent against the underside of the platform, thus connecting the bearing to the scale. Because the slot is larger than the tab, the connection is loose and the bearing is free to move horizontally, to a limited degree, with respect to the platform. '420 patent, col. 3, ll. 50-56. The columnar section 42f of the bearing is perpendicular to the flanges. It includes a slot 42g into which fits the force-sensing lever 18c. The lever in turn transfers the force from the bearing to the weight-sensing mechanics of the scale. Id., col. 3, ll. 63-68; col. 4, ll. 1-3. Allowing for horizontal movement between the bearing and the underside of the platform ensures that the slot 42g will align with the force-sensing lever at lever notch 44 while remaining vertical vis-A-vis the platform. The bearing must remain vertical, according to the '420 specification, so as to cause "rotational movement of the force collecting levers" but prohibit the application of any "twisting or lengthwise moment of force on the force levers or additional friction," which would produce inaccuracies and inconsistent weight measurement." Id., col. 4, ll. 6-11.

The '420 patent includes a detailed discussion of the prior art bearings, including those disclosed in U.S. Patent No. 4,452,326 ("the '326 patent"). The specification of the '420 patent characterizes the '326 patent as teaching "the concept of having a one-piece bearing member which is loosely connected to the platform so that it may pivot or rock to adjust itself to the proper engagement with the bearing portion on the force collection lever." '420 patent, col. 1, ll. 42-46. The scale disclosed in the '326 patent has a dimpled indentation on the under-side of the base at each of its four corners. Each bearing has a rounded nose that fits into the dimple. '326 patent, col. 1, ll. 44-53. That construction allows the bearing to rock and pivot in the dimple. The resulting tilting motion of the bearing ensures that the columnar portion of the bearing properly engages the force-collection lever even if an uneven or skew force is applied against the platform or if the upper and lower portions of the scale are not in precise alignment.

The '420 patent specification criticizes the prior art pivoting bearing on the ground that it "prevents the application of pure vertical force to the force collecting lever and increases the possibility that an undesired binding or force moment will be applied to the force collection lever." '420 patent col. 1, ll. 46-51. The bearing design claimed in the '420 patent, by contrast, is intended to ensure that the forces transmitted by the bearing "are applied vertically with no binding or twisting between the force collection levers and their mounting means" and that, as a result, the bearing will "apply only vertical forces to the [force collection] levers." Id., col. 2, ll. 9-12, 16-17.

HoMedics's accused scales all include bearings similar to the bearing disclosed in the '326 patent. Each of the HoMedics bearings is machined with a nose-like protrusion that fits into a corresponding dimple on the under-side of the platform. The trial court noted that the accused bearings all rock and pivot within their corresponding dimples in the underside of the platform. Sunbeam does not dispute that the HoMedics bearings rock and pivot in that manner. Sunbeam's position is that in addition to rocking and pivoting, the HoMedics bearings are capable of some horizontal movement and therefore infringe the '420 patent.

The parties focus their dispute on the limitation in claim 1 (and the corresponding limitation in claim 8) that describes the relationship between the underside of the platform and the bearing: "retaining said stand portions in face-to-face engagement with the underside of said platform and permitting limited displacement of said bearing members in a horizontal direction." Id., col. 6, ll. 14-16. In a claim construction order issued on April 29, 2009, the district court ruled that in both claims 1 and 8, "the bearing member and the platform are parallel to each other, they are not on a 'pivot.'" The claimed assembly means, according to the court, "allows the bearing member and the platform to stay in face-to-face (claim 1), sliding engagement (claim 8) with limited horizontal movement." That structure, the court explained, "insures the desired 'pure downward force.'" By contrast, the court noted, in the prior art design the bearing member "pivots about a point on the platform [thus] prevent[ing] the application of a pure vertical force."

During the claim construction proceedings, HoMedics argued that the "horizontal direction" limitation prohibits any vertical movement at all between the underside of the platform and the face of the bearing. The district court rejected that argument and held that in the claimed structure, there must be "sufficient clearance so that the bearings may move horizontally with respect to the platform" and that "for the claimed horizontal movement to occur, there has to be some vertical movement, however minuscule; the scale would not work at all if it completely disclaimed vertical movement."

Subsequently, on October 14, 2009, the court entered an order granting summary judgment for HoMedics. Again focusing on the disputed "face-to-face" and "sliding engagement" limitations, the court noted that the '420 patent criticized the prior art bearing that rocks and pivots on the ground that "a bearing member that can pivot or rock is undesirable because it could lead to binding or torque on the force collection lever, which would decrease the accuracy of the scale." The '420 patent bearing, according to the court, purports to improve on the prior art "by exerting 'a pure downward force between the scale platform and the force-collection lever.'" The court therefore ruled that the claims required the base of the bearing to be "oriented parallel to the platform and remain parallel to the platform at all times." The court stated that in so ruling it was not altering or amending its April 2009 claim construction order, in which the court had stated that the claims allowed vertical movement to the extent required to facilitate the desired horizontal movement. Instead, the court explained that its ...

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