| 摘要 |
PURPOSE:To shorten the access time by adding a speed signal and a speed reference signal in proportion to the speed of a magnetic head so as to generate a speed error signal and then adding the speed error signal and a feed forward signal to drive a voice coil motor. CONSTITUTION:An output of a binary output circuit 10 in accordance with the number of tracks between a present position and a marker track of a magnetic head 21 is added to a read only memory 11 and a speed reference signal generating circuit 15. The circuit 15 receives a logical signal which shifts in the positive direction and a logical signal 2 which shifts in the reverse direction, outputs it to an addition amplifier 16 and the amplifier 16 further receives an output of a speed signal generating circuit 20 and inputs it to an addition amplifier 17. the amplifier 17 further receives a singal 4 outputted from an analog switch 14, adds it and drives a voice coil motor 19 through a power amplifier 18. A polarity change-over circuit 13 receives signals 1 and 2, supplys a polarity of an output signal of a D/A converter 12 to a change-over switch 14 and the switch 14 receives a logical signal 3 of decelerating motion and outputs the signal 4. Thus, the access time can be shortened. |
