| 摘要 |
PURPOSE:To obtain a tachogenerator using an encoder signal, by obtaining a speed signal with little change in ripple using the encoder signal. CONSTITUTION:With the rotation of a slit plate, advance signals A and -A and delay signals B and -B both comprising a proximate triangular wave signal obtained from first and second photodetectors are differentiated with a differentiation circuit 38 to make square wave signals 38a-38d, which are taken out selectively with switches 41a-41d of a switching means 41 by a time of + or -pi/4 specified by a selectively logic circuit 43. Then, a synthetic signal obtained by synthesization of the square wave signals 38a-38d differentiated correspondingly to the + or -pi/4 time, namely, a speed signal is outputted as required level value at an output terminal 42. Thus, a tachogenerator can be obtained using an encoder signal.
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