| 摘要 |
PURPOSE:To correctly detect the rotating speed of a rotary body by counting forward or backward rotation pulses from a rotary encoder arranged coaxially with a motor and correcting said pulses according to positive or negative variation in the sign of the incremental number of pulses. CONSTITUTION:The rotary encoder 12 is arranged on the rotary body 11 and an A-phase signal SA and a B-phase signal SB having a phase difference are outputted by the forward or backward rotation. Then a pulse generating circuit 13 outputs a positive pulse AP with the signal SA or backward pulse BP with the signal SB, and the forward and backward pulses are inputted to and counted by a forward-side counter 14 and a backward-side counter 15. A computer 18 finds the incremental number of pulses from the last read to a current read. Further, the incremental number of pulses is increased by one when the sign of the incremental number of pulses varies from positive to negative or decreased by one when the sign varies from negative to positive, thus making corrections. The speed of the rotary body is computed from the corrected incremental number of pulses and a pulse read time. Thus, corrections are made according to variation in the sign of the incremental pulse number, so the speed is accurately detected.
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