| 摘要 |
PURPOSE:To fix the loop gain of a servo system and to stabilize a servo operation by sampling an error signal with a signal synchronized with the information signal. CONSTITUTION:Input signals (a) and (b) are supplied to an input terminal 22 of a waveform shaping circuit 20 as well as to the negative and positive input terminals of operational amplifiers IC1 and IC2, respectively. Then these signals (a) and (b) are compared with reference voltages Vth(W) and Vth(R). If the input voltage is higher than Vth(W), the outputs of IC1 and IC2 are set at +15V and -15V respectively. The error signal supplied to the terminal 22 is delivered as it is from an output terminal 26 in the form of a sample holding error signal. In such a way, an error signal is sampled with a signal synchronized with an information signal. As a result, the loop gain of a servo system is fixed and the servo operation is more stabilized. In addition, the more accurate and more stable record and reproduction are possible to a recording medium. |
