Abstract: Prior to recording/reproducing information to/from an optical disk rotationally driven by a spindle motor, an optical pickup is moved to a plurality of measuring positions set beforehand in a radial direction of the optical disk. A relative tilt between the optical disk and the optical pickup is detected with the spindle motor being rotated so that a linear velocity at each of the measuring positions equals a linear velocity upon actually recording or reproducing the information thereat. The tilt detected at each of the measuring positions is stored as tilt detection data corresponding to each of the measuring positions.

Abstract: In a state in which an optical disk having a warping amount equal to or smaller than a predetermined amount is attached to a spindle motor, an output of tilt detection result is stored as a reference tilt value in a memory. At this time, a control signal corresponding to a driving inclining amount in which inclining the objective lens by the driving inclining amount minimizes the inclination of the objective lens from the attached optical disk is stored as a reference control value in the memory. An CPU a multiplies difference between a detection result of the tilt detection and the reference tilt value by a control constant, and adds the reference control value to the multiplied difference, and provides the thus-obtained control signal to a tilt driving circuit.

Abstract: A light-emitting element emits a light toward an optical disk. A plurality of light-receiving elements receives the light reflected from the optical disk. A light-shielding member is provided between the optical disk and at least one of the light-emitting element and the light-receiving elements so as to shield parts of the light at both sides in a radial direction of the optical disk. A tilt of the optical disk is detected according to an intensity distribution of the light on the light-receiving elements.

Abstract: In an objective lens actuating device, a magnetic field generating part generates a magnetic field with a focusing coil in a gap formed by an inner yoke and an outer yoke and an auxiliary magnetic field generating part generates an opposite magnetic field in respect to the magnetic field which is generated in the gap towards the focusing coil, at both ends of the inner yoke vertical to the focusing direction.

Abstract: In an objective lens actuating device, a magnetic field generating part generates a magnetic field with a focusing coil in a gap formed by an inner yoke and an outer yoke and an auxiliary magnetic field generating part generates an opposite magnetic field in respect to the magnetic field which is generated in the gap towards the focusing coil, at both ends of the inner yoke vertical to the focusing direction.

Abstract: A pickup drive unit is provided including at least a rack portion provided thereon with gear teeth to be engaged with grooves of a lead screw; a plate-shaped connecting portion made of a flexible material for connecting the rack portion to a fixing portion tightened to a pickup and for supporting the rack portion in a cantilever fashion to be deformable in a direction of either bringing close to, or removing from, the lead screw; and a compressed coil spring for applying a force pressing the rack portion against the lead screw; in which the distance on the plate-shaped connecting portion from an end on the side of the fixing portion to the contact portion between the gear teeth and the lead screw is made smaller than the distance from an end on the side of said fixing portion to another end on the side of the rack portion.

Abstract: In an objective lens actuating device, a magnetic field generating part generates a magnetic field with a focusing coil in a gap formed by an inner yoke and an outer yoke and an auxiliary magnetic field generating part generates an opposite magnetic field in respect to the magnetic field which is generated in the gap towards the focusing coil, at both ends of the inner yoke vertical to the focusing direction.

Abstract: In an objective lens actuating device, a magnetic field generating part generates a magnetic field with a focusing coil in a gap formed by an inner yoke and an outer yoke and an auxiliary magnetic field generating part generates an opposite magnetic field in respect to the magnetic field which is generated in the gap towards the focusing coil, at both ends of the inner yoke vertical to the focusing direction.

Abstract: An optical disk device includes an optical system having a beam converting unit and an objective lens. The beam converting unit converts a beam of laser light emitted by a laser light source into a main beam and at least one sub-beam. The objective lens places a main spot on the disk by the main beam and at least one sub-spot on the disk by the sub-beam, such that, when the main spot is on a center line of one of lands and grooves of an optical disk, the sub-spot is between the center line of one of the lands and the grooves and a center line of an adjacent one of the lands and the grooves. A first unit produces a first push-pull signal from a reflection beam from the main spot on the disk. A second unit produces a second push-pull signal from a reflection beam from the sub-spot on the disk. A tracking error signal generating unit produces a tracking error signal based upon the first push-pull signal.

Abstract: An optical head device supports an objective lens which faces an optical disc movable in a tracking direction. Light is caused to be emitted from a fixed optical system to be converged through the objective lens and to be incident on the optical disc. The light reflected by the optical disc is incident on the fixed optical system via the objective lens. The head also controls a position of the objective lens in the tracking direction using a tracking error detected by the fixed optical system. A movable deflection member deflects a bundle of rays incident thereon in the tracking direction from the fixed optical system in a direction perpendicular to a focusing direction and also to the tracking direction. A fixed deflection member deflects the bundle of rays incident thereon from the movable deflection member in the focusing direction and causes the bundle of rays to be incident on the optical disc via the objective lens.

Abstract: An apparatus for applying a bias magnetic field has a magnet rotatably supported around a rotational axis parallel to a face of a magnetooptic disk and magnetized in a direction perpendicular to the rotational axis; a coil section for controlling the rotation of the magnet by flowing a driving electric current therethrough; and a first coil constituting the coil section and having a first portion parallel to the rotational axis and located on a side opposite to the magnetooptic disk with respect to the magnet, the first coil further having a second portion parallel to the rotational axis and arranged on a side of the magnet in a position near the magnetooptic disk in comparison with the rotational axis. The first coil may have a third portion for connecting both ends of the first and second portions.

Abstract: In an objective lens drive unit, a magnetic circuit is constructed by two outer yokes, two inner yokes, a magnet and an upper yoke. The magnetic circuit applies a magnetic field to each of electromagnetic coils disposed in a bobbin having an objective lens. The outer yokes and the inner yokes are integrally formed with an actuator base. A through hole is formed in the upper yoke composed of one sheet metal such that a light beam transmitted through the objective lens passes through the through hole. Each of the inner yokes is inserted into the through hole and both end portions of the upper yoke are arranged and fixed to the two outer yokes such that an arranging state of the upper yoke is stabilized. Thus, the upper yoke is simply, reliably and precisely fixed to the inner and outer yokes.

Abstract: A separation type optical pickup device which comprises a fixed optical system and a movable optical system which is separated from the fixed system. The fixed optical system is unmovable with respect to an optical information recording medium. The fixed system includes an optical beam emission system and a deflection member which deflects a beam emitted from the emission system. The deflection member is disposed on an optical axis of the beam and rotatable about a rotary axis which is parallel to the optical axis of the beam. The movable optical system is movable with respect to the information recording medium and guides the beam transmitted from the fixed optical system to the recording medium.

Abstract: An apparatus for driving an optical system has an objective lens for converging a light beam for recording or reproducing information to a recording medium composed of a vertically magnetized thin film having magnetooptic characteristics, and a driving device for electromagnetically moving the objective lens in the direction of an optical axis thereof or in a direction perpendicular to the optical axis. The driving device has at least two magnetic circuits composed of yokes and permanent magnets and has coils passing through magnetic clearances of the magnetic circuits. The magnetic circuits are approximately arranged symmetrically with respect to the optical axis of the objective lens. Magnetizing directions of the permanent magnets constituting the magnetic circuits are asymmetrically set with respect to the optical axis of the objective lens.