| 摘要 |
PROBLEM TO BE SOLVED: To provide an encoder which can maintain accuracy of an origin position regardless of an installation error of a detection head.SOLUTION: In a scale 1, a pattern 12 for origin detection and a displacement detection pattern 11 are formed. A detection head 2 outputs an origin detection signal S1, a phase compensation signal S2, and a displacement detection signal Sm. A signal processing part 3 generates an origin signal by amplifying and adding up the phase compensation signal S2 and/or the origin detection signal S1, and detects a position of the detection head 2 with respect to the scale 1 on the basis of the origin signal and the displacement detection signal Sm. The detection head 2 has a light source 4, a composite light reception grid 5, and a composite light-receiving element 6. The composite light reception grid 5 has a light receiving grid 52 for origin detection and a light receiving grid 53 for phase compensation arranged shifted in a measurement direction with respect to a light receiving grid 51 for origin detection. The composite light-receiving element 6 has: a light-receiving element 62 for origin detection outputting the origin detection signal S1; and a light-receiving element 63 for phase compensation outputting the phase compensation signal S2.SELECTED DRAWING: Figure 2 |
