Patent ID: 6806458
Filing Date: 2004-10-19
Classification: G06F

Abstract:
In an optical pointing device, a method for comparing a light intensity between pixels of a photodetector array, each of said pixels comprising a photosensitive element generating a sensed output signal in response to radiation, this method comprising the steps of:integrating said sensed output signals over time to provide an integrated signal for each of said photosensitive elements; integrating a first sensed output signal of a first pixel until the end of a first time period and storing the resulting first integrated signal; continuing the integration of a second sensed output signal of a second pixel until the end of a second time period to provide a second integrated signal; and comparing said first and second integrated signals to provide an output signal representative of an edge condition between said first and second pixels, wherein integration of said first sensed output signal is stored when a first one of said integrated signals generated by the photosensitive elements crosses a first level, said first time period being defined by the time taken by the first one of said integrated signals to reach said first level, and wherein integration of said second sensed output signal is continued until the first one of said integrated signals generated by the photosensitive elements reaches a second level, said second time period being defined by the time taken by the first one of said integrated signals to reach said second level.