| 摘要 |
PURPOSE:To contrive the improvement of the stability of a speed control system by estimating a track crossing speed of a light spot by a state observing device, and executing a track crossing speed control of the light spot based on a result of this estimation. CONSTITUTION:A state observing device 3 estimates a track crossing speed by receiving an output from a track crossing distance detecting circuit 2A for receiving an output of a track crossing detecting circuit 20 and an output from a direction detecting circuit 1, and an output from a driving current detecting circuit 121 of a head actuator 116, at the time of track access. Subsequently, based on this estimated speed, a speed control of an optical head is executed. In such a way, the stability of a speed control system is improved, and also, an access time to an optical disk device can be shortened.
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