| 摘要 |
An optical disk apparatus is provided with an actuator (4) that moves a beam spot that is formed by an optical head (2) on an optical disk (1) to recording surfaces (1a), (1b); position control portions (8, 9) that control a position of the beam spot based on the output signal of the optical head; a disturbance estimation observer (11) relating to the actuator; and a summing circuit (10) that takes a sum of the output of the position control portion and the output of the observer, so as to drive the actuator based on the output of the summing circuit. The optical disk apparatus further is provided with a system controller (7) that turns the observer on and off; a LPF (12) that attenuates the high-frequency components of the output of the observer and retains the final value of the observer when the observer is turned off, and a switching circuit (13) that switches between the output of the observer and the output of the LPF according to whether the observer is on or off. When the observer processing is off, the output of the LPF is supplied to the summing circuit. Thereby, instability in the control due to observer processing can be avoided even at the time of mode transition or addition of disturbance from outside. |
