A Computer-Implemented Invention Claimed by Means-Plus-Function Must Disclose More Than A General Purpose Computer or Microprocessor

Aristocrat Technologies Australia PTY Limited v. Ingernational Game Technology, [2007-1419](March 28, 2008) [BRYSON, Lourie, Schall] The Federal Circuit affirmed the district court's determination that U.S. Patent No. 6,093,102 directed to an electronic slot machine that allows a player to select winning combinations of symbol positions was invalid for indefiniteness.
BRIEF: The key question in this case is the definiteness of the claim term "game control means" or "control means" that is used several times in claim 1. The parties agreed the term "control means" is a means-plus-function term that invokes 35 U.S.C. § 112 ¶ 6. As such, the scope of that claim limitation had to be defined by the structure disclosed in the specification plus any equivalents of that structure; in the absence of structure disclosed in the specification to perform those functions, the claim limitation would lack specificity, rendering the claim as a whole invalid for indefiniteness under 35 U.S.C. § 112 ¶ 2.
The trial court explained that in a means-plus-function claim “in which the disclosed structure is a computer or a microprocessor programmed to carry out an algorithm, a corresponding structure must be a specific algorithm disclosed in the specification, rather than merely ‘an algorithm executed by a computer.’” Because the specification of the ’102 patent lacked any specific algorithm or any step-by-step process for performing the claimed functions of controlling images on the slot machines' video screen, paying a prize when a predetermined combination of symbols comes up or defining the pay lines for games, the court held the asserted structure to be insufficient to satisfy section 112 paragraph 6.
The Federal Circuit said that in cases involving a computer-implemented invention in which the inventor has invoked means-plus-function claiming, it has consistently required that the structure disclosed in the specification be more than simply a general purpose computer or microprocessor. The point of the requirement that the patentee disclose particular structure in the specification and that the scope of the patent claims be limited to that structure and its equivalents is to avoid pure functional claiming. The Federal Circuit said that for a patentee to claim a means for performing a particular function and then to disclose only a general purpose computer as the structure designed to perform that function amounts to pure functional claiming. Because general purpose computers can be programmed to perform very different tasks in very different ways, simply disclosing a computer as the structure designated to perform a particular function does not limit the scope of the claim to "the corresponding structure, material, or acts" that perform the function, as required by section 112 paragraph 6. The Federal Circuit concluded the patent does not disclose the required algorithm or algorithms, and a person of ordinary skill in the art would not recognize the patent as disclosing any algorithm at all. Accordingly, the means-plus-function limitations of claim 1 lacked sufficient disclosure of structure under 35 U.S.C. § 112 ¶ 6 and were therefore indefinite under 35 U.S.C. § 112 ¶ 2.