Patent ID: 7161586
Filing Date: 2007-01-09
Classification: G06F

Abstract:
1. A method of operating an optical motion sensing device comprising a light source and a photodetector device including an array of photosensitive elements exhibiting a determined pixel pitch, the method comprising the steps of: a) illuminating a surface portion with radiation by means of the light source; b) detecting radiation reflected from the illuminated surface portion by means of the photodetector device; c) detecting and measuring displacement with respect to the illuminated surface portion; and d) outputting motion reports that are each representative of a magnitude of the detected displacement which is a fraction of the pixel pitch, e) comparing the magnitude of the detected displacement with a determined displacement threshold selected to be within a range of 0.06 times the pixel pitch to 0.25 times the pixel pitch; and f) increasing or decreasing the flash rate if the magnitude of the detected displacement is respectively greater or lower than the displacement threshold so that the detected displacement is kept around the displacement threshold.