| 摘要 |
PROBLEM TO BE SOLVED: To enable both a constant angular velocity(CAV) mode or constant linear velocity(CLV) mode with a simple speed servo circuit by calculating a frequency signal representing a disk rotating speed and adjusting the set rotating speed value with a frequency signal. SOLUTION: In CAV mode, a frequency generating device 2 generates the frequency signal representing the rotating speed and a speed servo means 3 controls a disk driving means according to the result of a comparison with a set target rotating speed to adjusts the rotating speed to the target rotating speed. In CLV mode, on the other hand, a speed processing means 8 receives a data frequency signal determined by the linear velocity at the position where a disk passes by a pickup 9, and calculates and sends a determined rotating speed value to the speed servo means 3. The servo means 3 adjusts a driving means 1 so that the disk rotates at the determined rotating speed.
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