摘要 |
PURPOSE:To obtain a speed detector comprising only one half period detector by sequentially detecting half periods of a rotational speed proportional signal, transferring the detection output with half period timing and then adding the detection output to the transferring output. CONSTITUTION:A frequency generator signal 3 is subjected to frequency conversion as the rotational speed of a motor 1 varies with time. Consequently, the time interval between adjacent leading edge and trailing edge of a shaped speed proportional signal, i.e. the time interval of half period, varies. A half period detector 7c outputs a detection output 8d corresponding to the time interval of half period. A transfer unit 12 transfers the detection output 8d immediately after elapse of half period thus producing a transfer output 8e. An adder 13 adds the detection output 8d and the transfer output 8e to produce a control output, i.e. a speed detection output 8f. |