Patent ID: 6872934
Filing Date: 2005-03-29
Classification: G01D,G06F

Abstract:
1. A detector apparatus comprising: a movable member having light-transmitting regions disposed with a predetermined pitch and light-blocking regions between adjacent light-transmitting regions; a pair of photoelectric elements to detect light signals passing through said light-transmitting regions of said movable member and thereby generate corresponding voltage signals in different phases A and B when the movable member is moved; and a pair of wave-shaping circuits to generate binary signals in accordance with said voltage signals, said binary signals to allow recognition of a direction of movement of the movable member, each wave-shaping circuit including a smoothing circuit to smooth the respective voltage signal and obtain a threshold voltage and a comparator to compare the respective voltage signal and the respective threshold voltage and thereby generate one of the binary signals, wherein said pair of wave-shaping circuits is provided with an offset setting unit that provides an offset to the voltages obtained by smoothing said voltage signals, and generates said binary signals using threshold voltages obtained by using said offset.