Claim construction and Infringement

Minebea filed suit against Think Outside for infringement of U.S. Patent 4,433,225. Minebea Co, LTD. v. Think Outside, Inc., et al.
The '225 patent discloses a mechanism for preventing an "oddly-shaped" key top, such as an L-shaped keytop, on a computer keyboard from tilting and binding when it is pressed down on an area of the keytop surface that is not directly above the keyswitch. The mechanism consists of a pair of lever arms that are joined by a central pivot. The comparable part of Think Outside is used to prevent studs from sliding.

CAFC agrees with the district court's decision that the written description limits the scope of the claim term "pivot" to a structure that is fixed in position relative to the level arms, and thus excludes sliding motion.

Having construded the scope of "pivot", CAFC affirmed the district court's decision that "Think Outside's pin and slot do not literally meet that limitation because its pin and slot structure allowed for sliding motion, and thus was not a fixed pivot."

CAFC also concluded that the Think Outside's pin and slot did not meet the "pivot" limitation under the doctrine of equivalents. The court stated that "if one were to only replace the central pin and slot structure with a fixed central pivot, SPK (the comparable product of Think Outside) would not function."