OPTICAL ENCODER

PROBLEM TO BE SOLVED: To provide an optical encoder capable of detecting main signals and subsignals and enlarging the range of operating temperatures. SOLUTION: A first light-receiving element 3 is fixed to a casing 4 via a substrate 5. The substrate 5 is supported by the casing 4 movably in a prescribed direction, so that the amount of movement of the first light-receiving element 3 in the prescribed direction to changes in operating temperatures is based on a linear expansion coefficient of the substrate 5. A second light-receiving element 2 is directly fixed to the casing 4, so that its amount of movement in a prescribed direction to changes in operating temperatures is based on a linear expansion coefficient of the casing 4. By making a ratio of the distance A between a fixed part 53 of the substrate 5 fixed to the casing 4 and the first light-receiving element 3 along the prescribed direction to the distance B between the fixed part 53 and the second light-receiving element 2 along the prescribed direction equal to a ratio of the linear expansion coefficient of the casing 4 to the linear expansion coefficient of the substrate 5, it is therefore possible to reduce changes in the positional relation between the first and second light-receiving elements 3 and 2 due to changes in operating temperatures and improve measurement accuracy. Thereby, it becomes possible to enlarge the range of operating temperatures. COPYRIGHT: (C)2011,JPO&INPIT