| 摘要 |
PURPOSE:To attain highly accurate setting over a wide range and to change the range easily by correcting a counting value of a reversible counter for counting pulse signals outputted from a detecting means by using the weight factor of a setter selected by a selection control means. CONSTITUTION:When bright-dark optical gratings having 4mum squares formed on a main scale 10 and an index scale 15C, sine wave signals of 8mum per period are generated from the outputs of detecting circuits 16A-16C. When reference voltage is 0V, one pulse is generated every 2mum in a period. The selection control circuit 20 connects the detecting circuit 16A, 16B or 16C corresponding to a setter 12A, 12B or 12C selected by any one of selecting switches 22A-22C to the reversible counter 18. The counter 18 counts up pulse signals outputted from the connected detecting circuit. A correcting circuit 24 multiplies the counted value by any one of weight factors K2u, K1 and K2d of the selected setter and then corrects the multiplied value by an adjusting factor K set up by a setter 28. A D/A converter 26 converts the corrected counted value outputted from the circuit 24 into a voltage signal and outputs the signal as an analog electrical signal.
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