Patent ID: 7227464
Filing Date: 2007-06-05
Classification: G06F,Y02D

Abstract:
1. A method for automatically waking up an optical motion sensing device from a sleep mode to a motion detection mode, said optical motion sensing device comprising a light source, a photodetector device, a motion sensing unit and a control unit, said motion detection mode being defined as a mode during which motion is detected between said optical motion sensing device and a portion of a surface illuminated by said light source at a defined flash rate being set between minimum and maximum flash rate values, said motion sensing unit sending motion reports to said control unit, said sleep mode being defined as a mode during which said flash rate is set to a low flash rate value being lower than said minimum flash rate value and no motion report being reported from said sensing unit to said control unit, wherein the method comprises during the sleep mode the steps of: a) illuminating said surface portion with radiation by means of the light source at said low flash rate value; b) detecting a radiation pattern reflected from the illuminated surface portion by means of the photodetector device; c) detecting occurrence of a loss-of-tracking event between two successive reflected radiation patterns detected by the photodetector device indicating the user has returned; d) increasing the flash rate at least to said minimum flash rate value if an occurrence of the loss-of-tracking event is detected; e) entering into said motion detection mode.