| 摘要 |
PURPOSE:To prevent a fact that an amplification degree is different by a direction of the right rotation or the left rotation of an encoder, by constituting so that the amplification degree of an amplifier is controlled by a control signal from a peak detecting circuit. CONSTITUTION:When a counting value of a pulse signal outputted from a pulse- converting circuit 3 reaches a prescribed value decided in advance, the counting operation is stopped. In this case, a counting circuit 4 receives a setting signal V5, simultaneously outputs a signal for closing switches 25, 26 to a peak detecting circuit 2, and also outputs a signal for opening the switches 25, 26 as soon as the counting operation ends. As a result, the peak detecting circuit 2 starts the operation simultaneously with generation of a prescribed burst waveform signal of an encoder, executes an AGC operation of an amplifier 1, and stops the operation at the point of time when the center part of the burst waveform signal becomes the highest frequency. Thereafter, a control signal V4 is applied to the amplifier 1, and it is held continuously until the setting signal V5 is applied to the counter 4 in the next time. |
