Patent ID: 7435942
Filing Date: 2008-10-14
Classification: G06F

Abstract:
1. A method for detecting motion of an optical sensor relative to a surface along a plurality of directions, the method comprising steps of: generating sets of signals responsive to motion along each of at least a first, second, and third direction, said directions not necessarily all different, each of said sets of signals consisting of a plurality of signals, said plurality including a main signal and one or more secondary signals, said main and secondary signals representing at least partially independent components of a complex signal whose complex phase changes in response to motion along one of said directions, wherein the sets of signals are generated from an array including a plurality of groups of photosensitive elements, which serve as a filter on spatial frequencies of light received on the array, and wherein at least one set of the sets of signals is generated using a spatial frequency different from that of the remaining sets of signals; combining said sets of signals to generate a first complex signal for each of said directions at a first time; combining said sets of signals to generate a second complex signal for each of said directions at a second time subsequent to said first time; computing a third complex signal for each of said directions wherein each of said third complex signals is a predicted value for each of said second complex signals, said predicted signal depending on a number of values representing distance moved; and determining the optimum values of said values representing distance moved by the step of minimizing the differences between said second and third complex signals.