| 摘要 |
PURPOSE:To position a magnetic head securely at a target position taking the maximum seek operating time by adjusting a output signal from a adding amplifier even when a velocity signal deviates from optimum value. CONSTITUTION:When change of control is made into positioning control, if velocity signal V changes and exceeds an usual level, the peak value to be held at peak hold circuit 20 becomes high. As a consequence, the voltage level Vg of the gain adjust signal G to be output from the peak hold circuit 20 becomes high, and the gain of an AGC amplifier 21 is set at value greater than usual value. Therefore, the level of a velocity signal V to be output from the AGC amplifier 21 becomes greater than the usual level. With this, if values of input resistances r1 and r2 and value of feedback resistance rf are kept constant, the output signal (or negative voltage signal) from the add amplifier 11 becomes great, and the voice coil motor speed is reduced more quickly than the usual. |
