| 摘要 |
PROBLEM TO BE SOLVED: To easily increase the reliability as an encoder in a detection unit for detecting the rotation amount of a motor shaft. SOLUTION: This detection unit 2 has a plurality of light receiving elements 25 and 26 for outputting output signals S1 and S2 corresponding to light quantity of incidence light to a signal processing circuit 7, the incidence lights coming into the light receiving elements 25 and 26 have different light quantities. The effective area of the plurality of light receiving elements 25 and 26 is set so that the output values of the output signals S1 and S2 where light quantities of incidence lights are small and that come from the light receiving elements 25 and 26 are equal to the output values of the output signals S1 and S2 where light quantities of incidence lights are large and that come from the light receiving elements 25 and 26. Thus, when there is difference between light quantities of the incidence lights to the light receiving elements 25 and 26 side, the output values of the output signals S1 and S2 on the light receiving elements 25 and 26 are corrected and the uniformity of the output signals S1 and S2 is improved, so that troublesome processing is not required on the signal processing circuit 7 side. COPYRIGHT: (C)2009,JPO&INPIT
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