| 摘要 |
PROBLEM TO BE SOLVED: To enhance a real-time property in an absolute displacement measuring apparatus. SOLUTION: An ABS sensor 1 outputs signals which indicate the coarse position and the fine position of a moving element with reference to a fixed element. The signals are processed respectively by a demodulation circuit 2 and a demodulation circuit 3. The signal which indicates the coarse position is processed by an ABS data computing part 4, and high-order-digit data DH for absolute-position data is generated. The signal which indicates the fine position is introduced to a PLL counting-pulse generation part 7 via a selector 5. In the PLL counting-pulse generation part 7, a pulse signal PULSE which corresponds to the phase difference between a dense-scale phase signal CMP which is input and a reference signal CNT which is generated at the inside, and the phase of the reference signal CNT is controlled in such a way that the reference signal CNT at the inside follows the phase signal CMP, A counter 8 counts the phase signal PULSE so as to generate low-order-digit data indicating the fine position. The data DH and the data DL are synthesized by a microcomputer 9, and the absolute position data is found.
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