Abstract: An optical pickup device suitable for use as an optical system of; e.g., an optical disc reproducing apparatus, for carrying out reproduction of desired information on an optical disc; e.g., a magneto-optical disc, a compact disc (CD) or a video disc. The device uses diffraction and various optical rotation devices to direct the incident and reflected light rays to the optical disk and to photodetectors. More specifically, light emitted by a laser source is trisected into 0-th and .+-.1-th order light. The rays are then rotated by an optical rotation device. The rays are converged on the optical disk, reflected, and then rotated again. The rays are then deflected to a photodetector, which then produces light quantity detection signals; e.g., tracking error signal.

Abstract: An optical pickup device suitable for use as an optical system of, e.g., an optical disc recording and/or reproducing apparatus, for carrying out recording/reproduction of desired information onto an optical disc, e.g., a magneto-optical disc, a compact disc (CD) or a video disc. The device uses diffraction and various optical rotation devices to set the polarization ratio and to direct the incident and reflected light rays to the optical disk and to photodetectors. More specifically, a laser source, emitting light polarized in a single direction, is trisected into 0-th and +/-1-th order light. The rays are then rotated by an optical rotation device with +1-th order light rotating one way and -1-th order light rotating the other. The rays are converged on the optical disk, reflected, and then rotated again, providing a predetermined ratio of S and P polarized reflected light. The rays are then deflected by a hologram film to a photodetector, which then produces light quantity detection signals, e.g.

Abstract: A data storage disk drive includes an optical head positioned in spaced relationship to the data storage disk by a holder for an objective lens and a piezoelectric body and a resilient body which are mounted on a surface of the holder which faces the data storage disk. An AC power supply applies an AC voltage to the piezoelectric body to produce a flexural standing wave that keeps the resilient body in quasi contact with the data storage disk for making substantially constant a gap between the optical head and the data storage disk.

Abstract: Apparatus for generating a signal corresponding to a reference phase of a reference rotor of a motor relative to the stator, includes a field magnet having a plurality of north and south poles mounted on the rotor; a Hall-effect element associated with the field magnet and mounted on the stator for generating a position signal corresponding to the position of the rotor relative to the stator for use in changing-over energization of coils on the stator; a plurality of equally spaced cut-out portions along the periphery of the rotor forming a plurality of equally spaced toothed portions; an optical detector associated with the toothed portions and mounted on the stator for generating a speed signal corresponding to the rotational speed of the rotor relative to the stator; a differentiating circuit for differentiating the position signal to produce a differentiated signal; and an AND gate supplied with the differentiated signal and the speed signal for producing the phase signal corresponding to a reference phas

Abstract: Apparatus for detecting the direction of a magnetic field includes a magnetoresistive device comprising an insulating substrate, first and second ferromagnetic metal film strips on the substrate for providing first and second main current conducting paths respectively perpendicular to each other, the ends of the strips being connected together to form an output terminal and having current input terminals connected to the opposed ends of the strips. A stationary bias magnet is disposed adjacent the magnetoresistive device for supplying a bias flux at a predetermined angle relative to a main current conducting path.In one application of this apparatus, the magnetic field is supplied from, for example, a magnet, such as a rotary magnet, thereby to apply, with the bias flux, a composite flux to the magnetoresistive device. An output signal is derived from the output terminal that is a function of the direction in which the magnetic field is supplied.