Auto wake-up method from sleep mode of an optical motion sensing device

• Main Author: Afriat, Gil
• Format: Patent
• Language: English
• Published: 05.06.2007

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