| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce the number of times of trigonometric function arithmetic in an encoder. <P>SOLUTION: An encoder comprises a scale 10, a sensor 20, an A/D converter 30, a phase detector 60, a corrector 70 and a position detector 80. The scale 10 is provided with a periodic pattern 11. The sensor 20 is capable of moving relatively to the scale, reads the periodic pattern and outputs a plurality of analog signals each having a change cycle corresponding to the periodic pattern and the phases of which are different from each other. The A/D converter 30 generates a plurality of digital signals by performing analog/digital conversion in a time dividing manner on the plurality of analog signals outputted from the sensor. The phase detector 60 detects a phase from the plurality of digital signals. The corrector 70 calculates a correction value by using a relative moving speed of the scale and the sensor and the phase detected by the phase detector and calculates a correction phase from the correction value and the phase detected by the phase detector. The position detector 80 determines positions of the scale and the sensor in a relative moving direction by using the correction phase. <P>COPYRIGHT: (C)2013,JPO&INPIT |
