Au coeur du litige Silicon Graphics, Inc. (SGI) v. ATI Technologies, Inc. and Advanced Micro Devices (AMD) (Fed. Cir. 2010) se trouve l‘interpétation des revendications et plus spécifiquement celle du terme “a”.
Le brevet de SGI concerne une puce pour le calcul de graphique incluant des nombres avec virgule flottante (“floating point calculations”). La revendication en cause inclut l’expression “rasterization circuit . . . that rasterizes the primitive according to a rasterization process which operates on a floating point format.” La puce de ATI utilise à la fois les calcul avec virgules flottantes et la notation à virgule fixe.
Selon la cour de première instance, il n’y avait pas contrefaçon puisque le procédé d’ATI n’opère pas esclusivement en virgule flottante (“as a whole”).
La Federal Circuit a renversé le jugement:
The use of the indefinite article â€œà€ in the claim, when coupled with the list of processes provided in the specification, makes it clear that the claims’ references to “a rasterization process†means “one or more rasterization processes.â€
The limitation “a rasterization process which operates on a floating point format†therefore means that “one or more of the rasterization processes (e.g., scan conversion, color, texture, fog, shading) operate on a floating point format.†This construction is also in line with the rest of the specification. Nowhere does the specification teach that all rasterization processes must operate on a floating point format.