Claim 1 reads as follows:
A gaming machine
having display means arranged to display a plurality of symbols in a display format having an array of n rows and m columns of symbol positions,
game control means arranged to control images displayed on the display means,
the game control means being arranged to pay a prize when a predetermined combination of symbols is displayed in a predetermined arrangement of symbol positions selected by a player, playing a game, including one and only one symbol position in each column of the array,
the gaming machine being characterised in that selection means are provided to enable the player to control a definition of one or more predetermined arrangements by selecting one or more of the symbol positions and
the control means defining a set of predetermined arrangements for a current game comprising each possible combination of the symbol positions selected by the player which have one and only one symbol position in each column of the display means,
wherein the number of said predetermined arrangements for any one game is a value which is the product k1 . . . x . . . ki . . . x . . . km where ki is a number of symbol positions which have been selected by the player in an ith column of the n rows by m columns of symbol positions on the display (0 < i ≤ m and ki ≤ n).

I
The district court observed that 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 court explained that the claim describes the “game control means” as performing three functions: (1) to control images displayed on the display means; (2) to pay a prize when a predetermined combination of symbols matches the symbol
positions selected by the player; and (3) to define the pay lines for the game according to each possible combination of the selected symbol positions.

The district court noted that 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. See In re Donaldson, 16 F.3d 1189, 1195 (Fed. Cir. 1994) (en banc).

The court noted that there were slight linguistic differences in the parties’ characterizations of the functions performed by the “control means,” but that the differences were unimportant, because there was no adequate disclosure of structure in the specification to perform those functions, regardless of how they were defined. Although Aristocrat argued that the structure corresponding to the recited functions was a standard microprocessor-based gaming machine with “appropriate programming,” the court noted that the specification contained no “guidance to determine the meaning of ‘standard microprocessor’ or ‘appropriate programming.’” The court ruled that “[m]erely stating that a standard microprocessor is the structure without more is not sufficient.” In particular, the court noted that the specification did not create any specific structure or new machine because “it does not set forth any specific algorithm” for performing the recited function.
Citing decisions of this court, 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 lacks “any specific algorithm” or any “step-by-step process for performing the claimed functions of controlling images on the slot machines [sic] 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. In addition, the district court held that the specification did not link the asserted structure to any of the claimed functions. The court held claim 1 invalid for that reason as well.

II
On appeal, Aristocrat first argues that the district court erred by failing to construe the disputed term “game control means” or “control means” in claim 1. Aristocrat argues that because the district court did not construe the functions of the “control means” term under 35 U.S.C. §112 ¶ 6, it could not have properly determined whether the specification recited adequate structure corresponding to those functions.
The district court stated that “[t]he determination as to which function description is the accurate construction is not pertinent to the summary judgment motion because the structure is lacking in description and is not found in the specification.” Aristocrat argues that our decision in Oakley, Inc. v. Sunglass Hut Int’l, 316 F.3d 1331, 1340 (Fed. Cir. 2003), requires that a “determination [of definiteness] requires a construction of the claims according to the familiar canons of claim construction.”

The district court committed no error in its analysis of the means-plus-function limitation in this case. The court described the two competing claim constructions proposed by the parties, and the court’s description made clear that there was virtually no difference between them. Moreover, the district court, later in its opinion, effectively gave a construction of the functions of the “control means” limitation when it stated that the specification contained no algorithm that described or recited the claimed functions. Describing the claimed functions, the court wrote: “The specification contains no step-by-step process for performing the claimed functions of controlling images on the slot machine’s video screen, paying a prize when a predetermined combination of symbols comes up or defining the pay lines for games.” That characterization of the claimed functions of the “game control means” is not materially different from the characterization that Aristocrat argues the district court should have adopted in analyzing the means-plus-function limitation. To the extent the court’s characterization differs from Aristocrat’s, it is only because the court’s characterization omits some of the detail found in Aristocrat’s characterization. The omission of that detail, however, has no effect on the question whether the specification discloses sufficient structure to perform the claimed functions. In fact, Aristocrat’s description of the claimed function would appear to require more by way of specificity in the disclosed structure than would the court’s characterization. The district court therefore committed no reversible error with respect to this issue. Next Page ->