Patent ID: 7907120

Claim:
A method of tracking movement of an optical mouse, comprising: providing a source of non-coherent light in a movable housing for illuminating a work surface at a low angle of incidence; providing a two dimensional array of photo detectors in the housing for producing arrays of data elements responsive to light reflected from surface irregularities on the illuminated work surface; and providing circuitry in the movable housing for capturing a first array of data elements from the two dimensional array of photo detectors at a first time, for examining the first array of data elements to determine whether or not a characteristic condition exists in the first array of data elements; for capturing a second array of data elements from the two dimensional array of photo detectors at a second time, and for tracking movement of the housing relative to the work surface by comparing at least some of the data elements of the first array with at least some of the data elements of the second array if it is determined, from the examination of the first array of data elements, that the characteristic condition does not exist in the first array of data elements, wherein the characteristic condition is related to the uniformity of at least a majority of the data elements of the first array.