Patent ID: 7629961

Claim:
A computer input device, comprising: an electronic imager positioned to create images of portions of a surface moving relative to the imager; an illumination source positioned to illuminate the portions of the surface imaged by the imager; and at least one controller coupled to the imager and the illumination source and configured to: selectively activate the illumination source, receive the images from the imager, and repeatedly adjust an activation rate for the illumination source according to a cyclical procedure comprising: determining, based on at least some of the images, a current imager velocity relative to the surface, activating the illumination source at one of at least three activation rates when the imager is moving relative to the surface and the current imager velocity is being determined, calculating a predicted imager velocity based on the current imager velocity and the imager velocity determined during a prior activation rate adjustment cycle, and selecting one of the at least three activation rates as the adjusted activation rate based on the predicted imager velocity.