Patent ID: 6252584
Filing Date: 2001-06-26
Classification: G06F

Abstract:
A detecting device of an encoder used in an optomechanical encoder of a related pointing device, comprising:a photodetector having a first, a second and a third active area, each of the active areas receiving light signals from a working light beam through optical through holes of predetermined width of a code wheel and outputting electric signals responsive thereto, the first, second and third active areas being spaced one from an adjacent other by a distance approximating one half the predetermined width of the optical through holes; anda detection circuit including a first and a second comparator unit, wherein a first input of the first comparator unit is connected with an output of the first active area, a second input thereof is connected with an output of the second active area, and is further connected with a first input of the second comparator unit, a second input of second comparator unit is connected with an output of the third active area, whereby the detection circuit compares each two of the electric signals outputted from the three active areas for delivering a predetermined phase greater than 0 degrees and less than 180 degrees, and a predetermined duty cycle.