Abstract: A thermally assisted magnetic recording method is implemented for a storage disk with a magnetic recording layer which includes recording areas and non-recording areas. In this method, a heating laser is moved relative to the disk in facing relation to the magnetic recording layer for locally heating the recording areas. As the laser spot transitions from a recording area to the subsequent non-recording area, the heating is stopped. In cooperation with the heating laser, a magnetic field applier locally magnetizes the recording areas of the magnetic recording layer for recording signals. As the magnetic field applier transitions from a recording area to the subsequent non-recording area, the application of the magnetic field is stopped after the heating by the heating laser is stopped.

Abstract: A magnetic recording method is provided for a magnetic recording medium including a magnetic recording layer. In accordance with the method, a recording magnetic field is applied to a local region in the recording layer to form a recording mark in the recording layer. Then, another recording magnetic field is applied to another local region in the recording layer to form another recording mark in the recording layer. Each of the recording magnetic fields is adjusted in strength in accordance with the length of the recording mark to be formed in the recording layer. The adjusted recording magnetic field is applied locally to the recording layer.

Abstract: The present invention is intended, as an object thereof, to improve stability against both temperature changes and light source output changes, and includes an achromatic lens having a composite structure of glass or a plastic lens having a diffraction grating counteracting a focal length change due to a wavelength change of light, where a lens holder is adhered to an opposite side to a light source of an overhang of the achromatic lens made of glass while the lens holder is adhered to a light source side of the overhang of the plastic lens with the diffraction grating.

Abstract: The present invention is intended, as an object thereof, to improve stability against both temperature changes and light source output changes, and includes an achromatic lens having a composite structure of glass or a plastic lens having a diffraction grating counteracting a focal length change due to a wavelength change of light, where a lens holder is adhered to an opposite side to a light source of an overhang of the achromatic lens made of glass while the lens holder is adhered to a light source side of the overhang of the plastic lens with the diffraction grating.

Abstract: The present invention is intended, as an object thereof, to improve stability against both temperature changes and light source output changes, and includes an achromatic lens having a composite structure of glass or a plastic lens having a diffraction grating counteracting a focal length change due to a wavelength change of light, where a lens holder is adhered to an opposite side to a light source of an overhang of the achromatic lens made of glass while the lens holder is adhered to a light source side of the overhang of the plastic lens with the diffraction grating.

Abstract: A disk cartridge includes a data storage disk and a casing for accommodating the disk. The disk includes a recoding portion and a non-recording portion. The casing has an inner surface facing the disk. An anti-static layer is provided on the inner surface of the casing for eliminating the static electricity generated on the disk. An elastic member or cushion is provided on the inner surface of the casing. The recording portion of the disk is brought into contact with the anti-static layer only when the disk is not rotating.

Abstract: A master medium for magnetic transfer includes a substrate having a concave portion formed in its surface corresponding to a pattern of recorded information to be transferred; a first perpendicular ferromagnetic layer deposited in the concave portion; and a second perpendicular ferromagnetic layer layered on the substrate surface and the first perpendicular ferromagnetic layer surface. The substrate surface and the first perpendicular ferromagnetic layer surface are flattened to form a single flat surface. In the master medium for magnetic transfer, a magnetic field change in a direction parallel to the substrate surface at a magnetization boundary of the first perpendicular ferromagnetic layer is steep. Since the influence of the change of an external magnetic field is reduced, it is possible to perform accurate transfer from the master medium for magnetic transfer to a slave medium for magnetic recording.

Abstract: An optical head includes a lens carrier movable at least radially of a magneto-optical disk in facing relation thereto. An object lens is mounted on the lens carrier to converge a laser beam for forming a laser spot on the disk. The object lens has an optical axis and includes a lens surface directed toward the disk. A patterned coil is formed on the lens surface at least in one layer and has a light-passing opening corresponding to the optical axis of the object lens. A light-pervious layer is formed on the lens surface for closing the light-passing opening of the coil.

Abstract: An initialization magnetic field Hi as an external magnetic field is applied in a direction crossing (perpendicularly) the surface of the substrate 10 to initialize the medium 1, so that the first magnetic film 11 and the second magnetic film 12 can be initialized simultaneously. In this method for initializing a medium, the magnetization direction of the initialization magnetization H1i at the first magnetic film 11 and the magnetization direction of the initialization magnetization H2i at the second magnetic film 12 accord with each other with regard to a direction crossing the substrate 10.

Abstract: A master medium for magnetic transfer includes a substrate having a concave portion formed in its surface corresponding to a pattern of recorded information to be transferred; a first perpendicular ferromagnetic layer deposited in the concave portion; and a second perpendicular ferromagnetic layer layered on the substrate surface and the first perpendicular ferromagnetic layer surface. The substrate surface and the first perpendicular ferromagnetic layer surface are flattened to form a single flat surface. In the master medium for magnetic transfer, a magnetic field change in a direction parallel to the substrate surface at a magnetization boundary of the first perpendicular ferromagnetic layer is steep. Since the influence of the change of an external magnetic field is reduced, it is possible to perform accurate transfer from the master medium for magnetic transfer to a slave medium for magnetic recording.

Abstract: A disk cartridge includes a data storage disk and a casing for accommodating the disk. The disk includes a recoding portion and a non-recording portion. The casing has an inner surface facing the disk. An anti-static layer is provided on the inner surface of the casing for eliminating the static electricity generated on the disk. An elastic member or cushion is provided on the inner surface of the casing. The recording portion of the disk is brought into contact with the anti-static layer only when the disk is not rotating.

Abstract: An optical head unit used for an optical disk apparatus is provided. The optical head unit includes an object glass assembly for focusing a laser beam from a light source on an optical disk, an actuator movable at least in a focus control direction, a carriage for supporting the actuator and moving the actuator in a track control direction, and a slider which is attached to the carriage and capable of adjusting its posture in relation to a surface of the optical disk. The object glass assembly is provided with a plurality of lens units. Each lens unit includes at least one lens. One of the plural lens units is supported by the slider.

Abstract: An optical disk apparatus comprising an optical element for dividing the reflected light into a plurality of light beams for generating a tracking error signal and a focus error signal, and deflecting these light beams into different directions from each other, a first calculating means for calculating the focus error signal on the basis of outputs from said photodetecting means, and a second calculating means for calculating the tracking error signal on the basis of the outputs from said photodetecting means in accordance with a structure of a track. The second calculating means outputs a tracking error signal by a push-pull method when a track has a successive groove. The second calculating means outputs a tracking error signal by a heterodyne method when a track has only a row of pits.

Abstract: An optical disk device in which a moving state of a beam irradiating position is detected during the operation of an optical head in response to a jump signal, and in which an acceleration signal and a deceleration signal for said optical head are corrected based on a detection result for the subsequent jump operation, resulting in canceling an individual difference or the variation of the characteristic of the optical head.

Abstract: An optical information recording-and-reproducing unit includes a diffraction section provided with a reflected optical beam reflected on a storage medium. The diffraction section has at least first and second areas, and from each of the first and second areas, a +1-order diffraction light and a -1-order diffraction light are produced. The unit further includes first and second optical detection sections respectively provided with one of a pair of +1-order diffraction lights and a pair of -1-order diffraction lights produced from the first and second areas of the diffraction section. The unit still further includes a first circuit section for generating a tracking error signal based on output signals of the first and second optical detection sections. In the unit, the light provided to the first optical detection section forms a first spot in a far-field state before convergence, and the light provided to the second optical detection section forms a second spot in a far-field state after convergence.

Abstract: A track retrieval system retrieves a track of an optical disk based on track cross pulses which correspond to a number of tracks scanned by a scan beam. The track retrieval system includes a pulse shaping circuit for generating a pulse at a zero-crossing of a track error signal which is dependent on a tracking error of the scan beam relative to the track, a masking circuit for outputting track cross pulses by masking an output of the pulse shaping circuit for a predetermined time after the pulse is output from the pulse shaping circuit, so that pulses generated by the pulse shaping circuit within the predetermined time due to chattering are eliminated, a counter for counting the track cross pulses output from the masking circuit and for outputting a counted value, and a control unit for setting the predetermined time in the masking circuit based on a moving speed of the scan beam which is calculated from the counted value output from the counter.

Abstract: An access control circuit for use in an optical disk unit including a linear drive mechanism for linearly sliding an optical head to thereby shift a beam spot to a target track on an optical disk. The slider of the linear drive mechanism and the optical head are integrally structured. The sliding speed of the linear drive mechanism is detected by a speed detection unit and the target speed of the linear drive mechanism is calculated by a target speed calculation unit. The difference between the sliding speed and the target speed is detected by a speed difference detection unit and thereby a speed difference signal is obtained. Then, the speed difference signal and a high-frequency signal from an oscillation unit are added together and the sum signal is output to a current supply unit, and thereby a drive current in accordance with the sum signal is supplied from the current supply unit to the linear drive mechanism to drive the same.