Patent ID: 7943897
Filing Date: 2011-05-17
Classification: G01D

Abstract:
1. An optical encoder comprising: a light emitting section; and a light receiving section having a plurality of light receiving elements placed so as to be aligned in one direction in an area where a light beam from the light emitting section may reach, for detecting movement of a moving object which is composed of a light-ON section for enabling the light beam to come incident into the light receiving element when the moving object passes through a predetermined position corresponding to the light receiving element, and a light-OFF section for disabling the light beam from coming incident into the light receiving element when the moving object passes through a predetermined position corresponding to the light receiving element, the light-ON section and the light-OFF section alternately passing through the predetermined position when the moving object moves in the one direction, the moving object also including an index pattern section placed in a predetermined reference position, the optical encoder further comprising an output section for receiving inputs of a first light receiving signal outputted by the light receiving element when the light-ON section and the light-OFF section of the moving object pass through the predetermined position corresponding to the light receiving element and a second light receiving signal outputted by the light receiving element when the index pattern section of the moving object passes through the predetermined position corresponding to the light receiving element, the output section outputting an incremental channel signal indicating movement information of the moving object based on at least the first light receiving signal out of the first and the second light receiving signals, while outputting an index channel signal indicating the reference position of the moving object based on at least the second light receiving signal out of the first and the second light receiving signals, wherein the incremental channel signal and the index channel signal are out of phase with each other, and the output section outputs a composite signal composed of the incremental channel signal and the index channel signal, in which the incremental channel signal is present in one voltage range out of a first voltage range higher than a reference voltage and a second voltage range lower than the reference voltage, while the index channel signal is present in the other voltage range out of the two voltage ranges.