| 摘要 |
PURPOSE: To surely position a light beam to a target track by providing a count control signal generation means generating three count control signals having binarized phases different from each other. CONSTITUTION: A count pulse generation circuit 8 outputs either of an UP pulse signal 19 or a DOWN pulse signal 20 as a pulse signal according to the traverse direction whenever the light beam traverses a track by using TE1ϕ16, TE2ϕ17, RD18. The UP pulse signal 19, the DOWN pulse signal 20 are inputted to an up/down counter 9, and increases/decreases a count value 55. A CPU 10 obtains the present position of the light beam by the count value 55, and obtains a present moving speed also by measuring the change time of the position. Then, the CPU 10 controls an output to a D/A converter 11 based on the moving position and the moving speed of the light beam, and moves the light beam to the target track.
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