Abstract: A magnetic head position detecting method is provided in which a first and a second position detection signal representative of a particular position of a magnetic head with respect to a magnetic disk is obtained. The first and the second position detection signal preferably is obtained by utilizing a burst pattern formed on the magnetic disk. Subsequently, a third position detection signal is generated by multiplying the first and the second position detection signals by a predetermined gain so that the third position detection signal changes linearly. The particular position of the magnetic head is detected by using the third position detection signal. In addition, a magnetic disk apparatus implementing the magnetic head position detecting method is provided.

Abstract: The present invention ensures successful focus acquisition in an optical disk drive independent of a travelling speed of an objective lens at the time when a focus servo circuit loop is closed. The present invention provides sending a signal to a focus actuator for bringing an objective lens close to an in-focus position while a focus servo circuit loop is opened; closing the loop by shutting off the signal sent to the focus actuator; adding an offset of a predetermined level to the focus error signal; detecting that the focus error signal to which the offset is added reaches a predetermined level; and closing the loop when it is detected that the predetermined level is reached, and gradually decreasing the value of the offset to be added to the focus error signal.

Abstract: The present invention is intended to provide a method for putting an optical head in a stationary state, and an optical disk drive apparatus for doing so without the need of a dedicated sensor for detecting an absolute position of the optical head in the radial direction of the optical disk or a device for fixing the head.

Abstract: An optical disk drive apparatus operable under track following mode and seek mode wherein, upon the detection of a track following operation error, a seek operation is initiated for seeking a new target track at a predetermined number of tracks distant from the current track. The seek operation is controlled to follow a velocity profile thus regaining control over an optical head that may have been jolted into an out of control velocity when the track following error occurred. The velocity profile provides for a reduced velocity as the target track is approached. The new target track is selected at a relatively large number of tracks distant from the current track if the head velocity is high and at a relatively small number of current tracks if the head velocity is low. If the current track is sensed to be an outer track, the new target track is selected toward the inner track and if the current track is sensed to be an inner track, the new target track is selected to be an outer track.

Abstract: An optical disk drive includes a gain control for controlling the gain of a focus servo loop in response to the seek velocity of an optical head. At a low seek velocity, the focus servo gain is reduced to minimize the influence of beam scattering on the groove of an optical disk onto a focusing error signal (FES) and a tracking error signal (TES).

Abstract: The present invention provides an optical disk drive apparatus, and a method for driving the same, which makes the most of the ability of acceleration and deceleration in an actuator in a simple system configuration to realize fast seek operation of high reliability. An optical disk drive apparatus according to the present invention provides the means for determining whether the number of tracks from a current track to a target track is smaller than the predetermined number and the means for driving the fine actuator in the tracking direction under the velocity control based on a tracking error signal if the number of tracks from the current track to the target track is smaller than the predetermined number.

Abstract: In this invention, a driving circuit for moving a head in the radial direction on the recording surface of a disk is coupled to a velocity detecting circuit for detecting the velocity at which the head moves. A velocity profile is provided for storing information on the target velocity of the head. A driving signal generating circuit is coupled to the velocity profile and the velocity detecting circuit for comparing a signal from the velocity detecting circuit with a signal from the velocity profile. The driving signal generating circuit outputs a driving signal to the driving circuit based on the result of the comparison. A controller is coupled to the driving circuit for measuring a time required for moving the head a predetermined distance at a predetermined reference value, and modifying the driving signal based on the result of the comparison. Scatter in feedback quantities or fluctuation in the driving signal during velocity control is thereby corrected.

Abstract: A method and apparatus for initializing disk drive apparatus wherein a pickup head is positioned near the mid-range of tracks on a disk by moving the head at power-on to an innermost track and thereafter moving the head outwardly. As outward movement begins, a tracking error signal is sensed to indicate a track crossing, and the number of tracks crossed are counted until the head is at the mid-range of tracks. A velocity profile is used to speed movement of the head to its destination.

Abstract: The invention is a positive peak level comparator for generating a positive peak pulse when a TES (Tracking Error Signal) is higher than a predetermined positive level, a negative peak level comparator for generating a negative peak pulse when the TES is lower than a predetermined negative level, and a logic circuit for generating an output pulse when said positive peak pulse and said negative peak pulse have been alternately input thereto. The arrangement prevents the TES from being miscounted even if the TES is distrubed due to the occurrence of, for example, a noise at a level close to either said predetermined positive level or said predetermined negative level and either said peak pulse or said negative pulse is successively generated.

Abstract: The invention is a positive peak level comparator for generating a positive peak pulse when a TES (Tracking Error Signal) is higher than a predetermined positive level, a negative peak level comparator for generating a negative peak pulse when the TES is lower than a predetermined negative level, and a logic circuit for generating an output pulse when said positive peak pulse and said negative peak pulse have been alternately input thereto. The arrangement prevents the TES from being miscounted even if the TES is distrubed due to the occurrence of, for example, a noise at a level close to either said predetermined positive level or said predetermined negative level and either said peak pulse or said negative pulse is successively generated.