| 摘要 |
PROBLEM TO BE SOLVED: To prevent the voltage level of a detection signal from decreasing, by changing the amplification rate of a multiplication section from the difference obtained by comparing a voltage signal obtained via a track that does not have slit patterns with a reference voltage. SOLUTION: The encoder device obtains a second voltage signal (13a), by receiving transmitted light passing through a second track (3) by a second photoreceptor (13), at the same time, amplifies the difference by comparing the second voltage signal (13a) with a reference voltage (Vref) for feeding back to a first amplifying section (20), and makes the amplification rate variable for setting the difference to zero.
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