Abstract: An aberration correcting apparatus and an optical pickup apparatus using this apparatus, in which a spherical aberration based on a thickness error of an optical disc substrate can be preferably eliminated and a thickness error permission range of the optical disc substrate can be widened even if an objective lens of a high numerical aperture is used.

Abstract: A tracking servo apparatus in which reflection light obtained when a laser beam is irradiated onto a recording surface of an optical disc is photoelectrically converted, thereby obtaining a photoelectric conversion signal, a tracking error signal showing a deviation amount of an irradiating position of said laser beam for a track in a disc radial direction on the recording surface is generated by the photoelectric conversion signal, a spherical aberration occurring in an optical system is detected, a level of the tracking error signal is corrected on the basis of the detection result, and the irradiating position of the laser beam is moved in the disc radial direction in accordance with the level-corrected tracking error signal.

Abstract: A variable optical unit is provided with at least two phase-shift regions for providing light with phase differences. Phase-shift amount of the phase-shift region is adjusted by the applied voltage in accordance with birefringence of an information medium. A light beam emitted from a light source is incident on the variable optical unit through a collimator lens and a beam splitter. The light beam is polarized in accordance with the aforementioned phase-shift amount of the variable optical unit and converged by an objective lens to radiate the information medium. The reflected light polarized due to the effect of the birefringence of the information medium is polarized again according to the phase-shift amount of the variable optical unit. The reflected light is thereby polarized in the direction in which the beam splitter can reflect the reflected light and then the reflected light reflected by the beam splitter is detected by the condenser lens and an optical detector.

Abstract: A phase device for providing a phase difference between an inner radius portion and an outer radius portion of a light beam which is emitted from a light source is provided in an optical path between the light source of an optical pickup apparatus and an objective lens. The light beam to which the phase difference has been provided is converged by the objective lens and irradiated to an optical disc. An interference of an inner radius portion and an outer radius portion of the returning light beam caused when the light beam is diffracted by the optical disc with ±1 primary diffracted light caused by the diffraction is suppressed. Therefore, an intensity fluctuation of the returning light beam caused by the interference is suppressed. A spherical aberration error showing a thickness error of the optical disc and a focusing error having a high linearity can be detected with high precision on the basis of the returning light.

Abstract: An optical pickup reads or records information on a recording surface of a first optical record medium or a second optical record medium, each of which has a protection film different in thickness from each other. The optical pickup includes: a light beam source for emitting a light beam; a dividing unit for dividing the light beam into a non-diffracted light, which is a portion of the light beam other than diffracted lights, and a first order diffracted light; and a converging unit for converging the non-diffracted light and the first order diffracted light. Further, an optical path length between the light beam source and the converging unit is determined so that the non-diffracted light is converged onto the recording surface of the first optical record medium and a spherical aberration of the non-diffracted light converged onto the recording surface of the first optical record medium is minimized.

Abstract: A magnetic optical disk player comprises a turn table for turning a magnetic optical disk, a recording head and an erasing head movable along two different radial directions of the turn table respectively, and bias magnets for generating bias magnetic fields distributed along moving areas of the recording and erasing heads and having the directions opposite to each other, wherein the recording head and the erasing head each includes an objective, movable coils coupled with the objective, and drive magnet for generating a drive magnetic field interlinking the movable coils in the same direction as that of the bias magnetic fields. The directions of the bias magnetic fields for erasing and recording heads are opposite to each other. The magnetic fields for generating electromagnetic forces to drive the objective in the erasing head and the recording head are also opposite to each other.

Abstract: A magnetic optical disk player comprises a turn table for turning a magnetic optical disk, guides for guiding a recording head carriage and an erasing head carriage along two different radial directions of the turn table, drivers for individually driving the recording head carriage and the erasing head carriage, and bias magnets for generating bias magnetic fields distributed along moving areas of the recording and erasing head carriages and having the directions opposite to each other, wherein the drivers include movable coils coupled with the recording head carriage and the erasing head carriage, drive magnets for generating drive magnetic fields interlinking the recording head coil and the erasing head coil, and a leaking flux from the drive magnets passes through the plane in the same direction of the bias magnetic field. The directions of the bias magnetic fields for erasing and recording heads are opposite to each other.

Abstract: An opto-magnetic disk unit is constructed so that predetermined areas existing in the front of the unit recording areas can be detected. In addition, at least one of first and second saturation magnetizations are recorded on each of the detected predetermined areas. At the time of reproduction, signal processing on the output of the pickup is performed after a part of the output of the pickup corresponding to the one section of the predetermined area is clamped to a predetermined level. Also at the time of reproduction, gain controlling of a circuit for signal processing the output of the pickup may be performed based on the level difference between the signal read from a first saturation magnetization section and the signal read from a second saturation magnetization section. An opto-magnetic disk is also provided having recording areas including at least one of first and second magnetization saturation levels arranged in the front of the unit recording areas.

Abstract: An optical pickup for an optical recording disk in which a holder supports at least some of the optical member and has fixed thereto electrical coils for driving the holder perpendicularly to the disk and parallel to the disk. The holder is supported by four cantilevered supports having fixed ends fixed to a magnetic yoke forming part of the magnetic circuits in conjunction with the electrical coils. Preferably, the cantilevered supports are insulated from the yoke so as to provide power supply paths for the coils.

Abstract: In an optical pick-up unit, there is provided with a structure for supporting a holder holding at least an objective lens through a spring support assembly so that said holder is movable in both of a focusing direction and a tracking direction, carried on a carriage capable of traveling at a high speed in the tracking direction, a spring constant of the spring support assembly is so set as to be larger in the tracking direction than in the focusing direction, whereby an amount of a positioning error of the objective lens produced in the tracking direction when the carriage is driven at a high speed is reduced. As a result, by the thus reduced amount of the positioning error of the objective lens, the optical pick-up unit is improved in access time in comparison with the conventional optical pick-up unit.

Abstract: A photo-electro-magnetic disc device has a photo-electro-magnetic disc accommodated in a disc cartridge load as a unit into cartridge holder loaded in the disc device. The cartridge holder with the end of a loading mechanism moves the disc onto a turn table. An optical head and a magnetic field applying part for recording data are loaded facing opposite sides of the disc. Magnetic members are provided on the same side of the disc as is the optical head and are connected to the cartridge holder which is made of magnetic material as to confront magnetic field applying part through the disc. A magnetic circuit which includes the disc is thus formed whereby the magnetic flux from the magnetic field applying part passes through the disc thereby providing a high magnetic field strength throughout the entire region of the disc to be irradiated by a light spot from the optical head.

Abstract: An improved optical system support and positioning device for use in an optical reading apparatus, for instance, an optical or audio disc reading apparatus, in which the tracking function of the optical system is improved. An electromagnetic positioning structure moves the optical system parallel and perpendicular to the direction of the optical axis of the optical system while the optical system is supported by a support element. The support element includes a pair of cantilevered flexible members, a pair of substantially parallel support members, and an intermediate section joining ends of the flexible members and support members. In accordance with the invention, the distance between fixed ends of the support members is greater than the distance between the free ends thereof.