| 摘要 |
PROBLEM TO BE SOLVED: To digitally detect the moire fringes of an optical linear scale and to simplify a signal processing circuit. SOLUTION: A first timing circuit part 11 and a second timing circuit part 12 by which a signal to be outputted from a measuring part 10 composed of a CCD imaging element is formed to be step wave-shaped are installed. In addition, a data conversion part 15 which specifies the position of a scale on the basis of the step wave-shaped signal is installed. Regarding position data which is generated, old data is compared with new data at a prescribed sampling cycle in a movement-amount detection part 18. A pulse signal which corresponds to their difference is preset in a deviation counter 19. Until the counted value of the deviatio counter 19 becomes zero, pulses are outputted. As a result, an A/B-phase pulse signal in which the relative movement amount of the scale is interpolated is outputted.
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