| 摘要 |
PROBLEM TO BE SOLVED: To provide a scale signal division circuit enabling accurate position data output by detecting abnormality of phase modulation signals when response rate of detector has been exceeded. SOLUTION: This scale signal division circuit is provided with a generation means generating a digital sine wave as a modulation signal, D/A converters 3-4 multiplying each scale signal of different phase on the above digital sine wave, respectively, an addition means 8 adding multiplication results from these D/A converters to output phase modulation signals, a counter means 11 counting a specified counter value based on the phase modulation signals output from the addition means and an output means 12 outputting a signal indicating phase shift between the level variation in the above phase modulation signals and the end time of counting by the above counter means, as well as an error detection means 14 detecting error generation in the phase modulation signals from both level shift in the phase modulation signals and signals in counting completion by the counter means.
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