| 摘要 |
PROBLEM TO BE SOLVED: To synchronize a zero-point signal, outputted from the peak detection part of the zero-point signal with an A/B phase pulse signal for interpolating the travel amount (length) of a scale as a reference signal. SOLUTION: A- and B-phase signals are supplied to an interpolation pulse generating section 11 for forming the digitized A- and B-phase signals for interpolation within a single pitch of the scale; the phase relation between the phase region of the A-phase signal (B-phase signal) and a reference signal ZD outputted from a peak detection section 14 is detected by a pattern detection section 18; and a reference zero-point signal is outputted from a coincidence detection section 20. In this case, the reference zero-point signal is synchronized with the A- and B-phase signals that are digitized at a phase-shift region, for example, at two regions which are ahead of the phase region of the reference signal ZD.
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