| 摘要 |
PROBLEM TO BE SOLVED: To enlarge the angle detection range without requiring complicated processing. SOLUTION: In the encoder 1, the rotation ratio between slit plates 13A and 13B with a gear rotating in interlock with each other is 6:10, a PD 16 of each of scale plates 17A and 17B is assigned to attributes from A to J every phase angle 36°. In the encoder 1, based on the combination of the attributes of PD 16 corresponding to the true angle calculated from each one-dimensional profile of the scale plates 17A and 17B, the frequency of the slit plate 13A can be specified over three periods, and hence the angle detection range can be enlarged. In the encoder 1, it is not necessary to dispose a plurality of lattice windows of different diffraction patterns differently from the conventional art, and complicated processing is not required. COPYRIGHT: (C)2008,JPO&INPIT
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