| 摘要 |
PROBLEM TO BE SOLVED: To improve the accuracy of speed control and to ensure the seek operation by estimating the moving speed of a light spot and the external force from the interval of zero crosses of a positional error signal and a command value of the positional control, and controlling in accordance with these estimated values. SOLUTION: By a target speed producing circuit 43, the target speed 44 is produced from the remaining number of tracks. Also, the speed of the light spot against a track coordinate is measured by a speed measuring circuit 48. By an estimation circuit 50, the actual speed of the light spot and the external force are estimated in accordance with the actual speed 49 of the light spot and a seek control signal 54, then a speed estimated value 52 of the light spot and the estimated value 53 of the external force are outputted. The difference between the target speed 44 and the speed estimated value 52 of the light spot is obtained by a subtracter 45, and a speed loop gain is adjusted by a speed control gain circuit 46 and further corrected by a correction circuit 47 based on the estimated value 53 of the external force then outputted as a seek control signal 54. This output value is added to an actuator as the driving force, then the required control is executed.
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