Patent ID: 7839387

Claim:
A method for operating an optical motion sensing device comprising a light source and a photodetector device, said method comprising the steps of: a) illuminating a surface portion with radiation by means of the light source; b) detecting radiation patterns reflected from the illuminated surface portion by means of the photodetector device; c) extracting motion features from the detected radiation patterns by comparing intensity between pixels of said photodetector device by means of comparators with a determined hysteresis threshold; d) detecting and measuring displacement with respect to the illuminated surface portion based on said extracted motion features; e) determining whether the optical motion sensing device is moving or at rest; f) adjusting said determined hysteresis threshold of the comparators between at least a low hysteresis threshold value and a high hysteresis threshold value, by selecting a higher hysteresis threshold value, when the optical motion sensing device is at rest,than the hysteresis threshold value selected when the optical motion sensing device is moving.