| 摘要 |
PURPOSE:To control the read part highly accurately and stably by directly detecting the moving speed of the read part, and signal-processing the same by a digital system then converting the same to an analog signal and using the same as a feedback signal to a read part drive motor. CONSTITUTION:The pulse signal of the frequencies corresponding to the moving speeds of a read part R is outputted from a noncontact detector 1. This pulse train signal is inputted via a waveform rectifying circuit to the 1st counter 4, by which it is pulse-counted. On the other hand, a reference clock signal is outputted from a reference frequency signal generator 2, and is pulse-counted by the 2nd counter 5. The count values of the 1st counter 4 and the 2nd counter 5 are subtrated in a subtractor 6, and the subtraction result output thereof is converted to an analog signal by a D/A converter 7. The converted output VOUT is inputted as a feedback signal to a drive motor to a control circuit and is corrected by the portion of an error value. In this way, the scanning speed of the read part is controlled highly accurately and stably. |
