| 摘要 |
PURPOSE:To smooth the speed control of a linear actuator by causing a counter circuit to count a clock pulse from a reference clock pulse generator, outputting a digital signal having a reverse size from a memory circuit and permitting a digitalanalog converter to output a speed detecting signal. CONSTITUTION:At the time of accessing a track, track crossing optical information of an optical disk 1 is given to a photodetector 72 through an objective lens, etc., held by a tracking actuator 4. An addition amplifier 74 adds the output of the photodetector 72 to obtain the sum signal of the output of the photodetector 72, that is, an RF signal S1. When said signal S1 is inputted to a speed detecting circuit 54, the speed detecting signal S6 can be obtained and inputted to a speed curve generating circuit 55. Then the current of the coil 6 of the linear actuator 5 is controlled through a power amplifier 53, and accordingly the linear actuator 5 controls the optical head 3, that is, the moving speed of the light spot. Thus the linear actuator can be smoothly controlled.
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