The United States District Court for the Central District of California denied a motion for partial summary judgment finding that certain means-plus-function limitations were sufficiently definite to survive a challenge to the patent's validity. The plaintiff filed a patent infringement action against the defendant over a patent that relates to a computer mouse with a roller element for scrolling in computer application programs. The defendant argued that the patent was invalid because the patent includes means-plus-function limitations that do not identify corresponding structure in the specification.

In analyzing the definiteness of the means-plus-function limitations, the district court noted that construction of such a limitation is a two step process involving first determining the function of the term and second connecting that function to sufficient structure. The district court also stated that "[w]hen a function is implemented in software, identification of a general purpose computer, microchip, or software program will not suffice as description of its structure."

The district court then turned toward construing one of the means-plus-function limitations, i.e., the limitation "means for scrolling" set forth in the independent claims of the patent. Although the parties agreed that "means for scrolling" is a means-plus-function limitation, they disagreed over the breadth of the function with the defendant claiming that nearly the entire independent claim comprised the function and the plaintiff arguing that only the initial portion lays out the function, with the language, "scrolling a portion of the bitmapped memory on the video monitor about a predetermined first axis." The district court agreed with the plaintiff.  

The district court concluded that the plaintiff's position was correct because "[t]he additional language included qualifies terms used in the function described and characterizes the result of the function." The remaining language relied upon by the defendant pertained to other limitations and not the "means for scrolling" function.

The district court then examined whether there was corresponding structure for the identified "means for scrolling" function. Noting that the parties disagreed once again, with the plaintiff contending that the structure is "Microsoft Windows 3.1 and newer versions," and with the defendant claiming that there is no corresponding structure and therefore the claim is indefinite, the district court again agreed with the plaintiff. The district court found that the specification disclosed sufficient structure, including an algorithm describing how Windows accepts and processes scrolling messages and sends corresponding commands for scrolling to an application running on the operating system. "In sum, the Court finds that the [patent-in-suit] identifying Microsoft Windows 3.1 and later versions and relating the associated algorithm, recites sufficient structure for one with ordinary skill in the art to associate it with the function claimed by the means for scrolling limitations ..."

The district court then went through a similar analysis for "program means" and concluded that it also contained sufficient structure.

Accordingly, the district court denied the motion for partial summary judgment on the grounds that the means-plus-function limitation were sufficiently definite. Kye Systems America Corp. v. Primax Electronics Ltd., Case No. 10-04481-RGK (FFMx) (C.D. Cal. July 15, 2011)