Abstract: A fuzzy controller controls a track seeking operation and a track following operation for an actuator in accordance with a position error between a present position value and a reference value. When the actuator is in track seeking operation, the actuator is accelerated or decelerated based on a velocity error value between an actual velocity value of the actuator and a target velocity value determined from a velocity profile according to the position error. In a deceleration control of the actuator, a fuzzy inference value generated based on the velocity error value and its differentiated velocity error value is used for a control of the actuator, thereby reducing an occurrence of overshooting at a target track.

Abstract: Disclosed is a focus servo circuit for an optical pickup actuator capable of performing a normal focusing operation accurately and fast with detecting predetermined regions of a focus error signal and focus servo drive signal. The circuit has a focus zero detection unit for generating a focus zero detection signal with a detection of a predetermined region including a zero crossing from the focus error signal, a drive signal zero detection unit for generating a focus servo drive zero detection signal with a detection of a predetermined region including a zero crossing from the focus error signal and a unit for controlling the focus start enable signal thereby to start a focus servo of the optical pickup actuator with reference to both of the focus zero detection signal and the focus servo drive zero detection signal.