Patent ID: 8102371

Claim:
A calibration method of projection effect between an object plane O upon which an optical navigation system is disposed, and an image plane M of a sensor of the optical navigation system comprising a light emitting module and the sensor, wherein an incident light is emitted by the light emitting module and reflected by the object plane O as an reflected light on the image plane M, an included angle θ i is an angle of non-zero value between the reflected light and O, a directional A 1 on the object plane is perpendicular to the reflected light, and a directional A 2 on the object plane is perpendicular to A 1 ; the calibration method of projection effect comprising steps: (a) moving the optical navigation system with a first and a second real displacement of X 0d , and Y 0d along A 1 and A 2 , respectively, along a predetermined trace relative to the object plane, and a ratio of Y 0d :X 0d being R; (b) sensing the predetermined trace by the sensor to obtain a projection trace; (c) calculating a projection effect value PF according to θ s : if R=1, PF=sin θ s ; and (d) calibrating the projection trace with the projection effect PF, to obtain a calibration trace in proportion to the predetermined trace.