| 摘要 |
PROBLEM TO BE SOLVED: To provide an encoder for obtaining rectangular wave output signals having a 90 degree phase difference from each other. SOLUTION: This encoder is equipped with a cycle measuring means 15 for measuring the cycle of one of two digital signals having a 90 degree phase difference from each other on a cycle-by-cycle basis by a counter circuit working on a system clock, an A/B phase detection means 21 for latching information on whether the other is on an "H" level or on an "L" level, assuming that one of two digital signals having a 90 degree phase difference from each other is a latch signal, a cycle calculation means 23 for calculating a 1/2 time period and a 1/4 time period from an output of the measuring means 15, that is, from the cycle of one digital signal, and obtaining two digital signals rectangularly waveform-shaped into an "H" zone and an "L" zone only for a prescribed period of time, and an AO/BO output choice means 33 comprising a selector circuit using an output of the detection means 21 as a selection signal, and choosing which is outputted first of the two rectangular waveform-shaped digital signals. COPYRIGHT: (C)2004,JPO&NCIPI
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