Abstract: A circuit (40) and method for applying drive voltages to a voice coil motor (VCM) (22) of a mass data storage device (10) has two driver sets, each having a high side driver (HSD) (42,46) and a low side driver (LSD) (44,48) connected to the VCM (22). Each driver set has two SENSEFETs (50,52), each having a power FET and a sense FET. A circuit (106,104) is provided for sensing a sense current in the sense FET of the LSD, and a circuit (60,76,74) is provided for increasing the bias on the gates of the SENSEFET (52) in the LSD when the sense current falls below a predetermined level (VREF). Also, a circuit (113,114,110) is provided for driving a predetermined current in the SENSEFET of the HSD when the sense current falls below the predetermined level. Thus, a current at the predetermined level always flows in the SENSEFETs (50,52).

Abstract: The present invention implements a servo system which can support changes of the higher resonance frequencies of the actuator with a simple configuration at low cost.

Abstract: A tile actuator of an object lens in an optical disk device is controlled by a tilt controller that includes a filter for stopping a signal with first resonance frequency of the tilt actuator, a filter for amplifying a signal with a frequency less than the rotational frequency of the disk, and a filter for restricting current for driving the tilt actuator.

Abstract: Disclosed is a servo gain compensating method for compensating a servo gain when in a seek operation and in a positioning process in an information storage device. The servo gain compensating method and a device thereof make compensation to a precise servo gain even when a temperature changes abruptly. The information storage device includes a head for reading information from a storage medium, an actuator for moving the head, a control circuit for calculating a drive quantity compensated by the servo gain value from positional information read by the head, and a driving circuit for driving the actuator on the basis of the drive quantity.

Abstract: A servo control apparatus of an optical pickup is provided for reading recorded information from a recording medium and generates a read signal. The apparatus includes an error signal extracting part for extracting an error signal which indicates a deviation amount of a reading position from a target reading position of the optical pickup; a drive part for driving the optical pickup to change the reading position; an equalizer for equalizing the error signal and supplying a drive signal which indicates a driving amount of the drive part; a detecting part for detecting a dropout portion in the read signal; an identifying part for identifying a form of the dropout portion detected in the detecting part; and a controller. The controller performs control to change a gain of the equalizer in accordance with the identified form of the dropout portion.

Abstract: In recording on an optical disk, tracking control is performed using tracking error signals detected during an OFF period and a rear time segment within an ON period of a recording pulse signal. The time segment for detecting the tracking error signal within the recording pulse ON period is variably controlled in accordance with recording conditions such as a disk type and recording speed. This control can effectively prevent a tendency of pits being formed off the center line of a track toward the inner circumference of the optical disk due to the influence of residual heat from an adjoining inner track, thereby allowing pits to be formed accurately on and along the track center line.

Abstract: A method and arrangement for automatically setting a gain in a control loop using a tuning signal provides in a one method step, measurement of existing gain while a tuning signal is input, and then calculating consequent gain changes, which is to be carried out in the control loop, from a measured value for the gain. The reciprocal of the measured gain is calculated and the reciprocal of measured gain is used to calculate a gain change to automatically re-establish the gain.