Patent ID: 7884801

Claim:
A method for sensing displacement of an optical sensor relative to a surface, the optical sensor having at least a first and a second array, each array having a plurality of photosensitive elements, the method comprising: generating for each array a first set of quasi-sinusoidal signals at a first time and a second set of quasi-sinusoidal signals at a second time in response to motion of light received thereon in at least a first direction (x); computing from said first and second sets of quasi-sinusoidal signals from each of said arrays a phase angle change (ΔØ x1 , ΔØ x2 ) for said first and second sets of quasi-sinusoidal signals received from each of said arrays; computing from said first and second sets of quasi-sinusoidal signals from each of said arrays radius values (R x1 , R x2 ) for said first and second sets of quasi-sinusoidal signals received from each of said arrays; and combining said phase angle changes (ΔØ x1 , ΔØ x2 ) for each of said arrays using radius-weighted-averaging to provide a single weighted average phase angle change ΔØ x resulting from said motion in the first direction.