Sony Corporation

Etsufumi Yamamoto

Hidehiro Kume

Yoshiyuki Matsumoto

Koji Mitsumori

Hiroshi Oinoue

You Yoshitoshi

Yoshihiro Kobayashi

Kenji Nagashima

A tracking error signal calculation circuit has peak detection multiplication circuits which detect the peaks of the detection signals of left and right regions of a photodiode and multiply a coefficient for detecting the deviation of the beam light with respect to the track of the disc recording medium, subtraction circuits for removing an offset by subtracting these multiplication results from the detection signals, and a subtraction circuit which calculates a difference of the signal obtained by removing the offset (performs push-pull operation) and outputs a tracking error signal. The value of the coefficient can be changed by adding an alignment signal to the detection signal. In order to impart the frequency dependency to this coefficient, the alignment signal is added to the signal through a filter.

Optical disc apparatus and tracking error signal calculation circuit

In a disc drive for use in a disc recording/reproduction apparatus in which information is recorded to and/or reproduced from a disc, the rotational speed of the disc when a pause operation is performed is smaller than the rotational speed of the disc when information is recorded to or reproduced from the disc.

Apparatus and method for controlling rotational speed during a pause

Method of adjusting optics of an optical pickup using a light-emitting-and-receiving device comprising a semiconductor substrate on which a light-emitting portion and a light-receiving portion are integrally formed. The light-receiving portion consists of a first array and a second array of light-emitting elements. These two arrays are in line in the tracking direction of an optical disk. The light-emitting elements of each array are arrayed in the radial direction of the disk. The output signals from the light-emitting elements of these two arrays are summed up to produce a control signal. The position of the light-emitting-and-receiving device is adjusted in response to the control signal.

Method of adjusting optics of optical pickup using error negating signal

An optical pickup device for a recording and/or reproducing apparatus in which a light beam from a semiconductor laser element is converged by an object lens and irradiated on recording tracks of an optical disk and the light reflected by the disk is sensed to read and/or record data signals. The device includes photosensors each having an insensitive central zone and adapted to receive the reflected light to generate tracking error signals. The semiconductor laser element is so arranged that the light beam is projected on the optical disk so that the meridional plane of the light beam orthogonal to the junction plane of semiconductor layers of the semiconductor laser element is at such an angle with respect to a tangential line drawn to one of the recording tracks of the optical disk that non-symmetricities on both sides of said tangential line as a function of the de-focusing direction of the beam spot may be compensated.

Optical pickup device for a recording and/or reproducing apparatus

A tracking error signal generator for producing a tracking error signal by first detecting a light beam, which is irradiated from an optical pickup to an optical disc, by an optical detector so divided as to have two optical detecting portions in a direction of a recording track on the optical disc, and then controlling the light beam to follow the recording track on the optical disc in accordance with the detection outputs from the divided optical detector. The tracking error signal generator comprises first and second peak detecting means for detecting the respective peak values of detection output signals from the first and second optical detecting portions of the optical detector divided along the recording track on the optical disc, and arithmetic means for forming a difference signal between signals obtained by applying a coefficient smaller than 1 to multiply respectively the output signal of the first peak detecting means and the detection output of the first optical detecting portion, and signals obtained by applying a coefficient smaller than 1 to multiply respectively the output signal of the second peak detecting means and the detecting output of the second optical detecting portion.

Tracking error signal generator with DC offset cancellation

An optical pickup device is disclosed in which a light beam from a laser light source is converged by an object lens on a signal recording surface of an optical disk to follow recording tracks formed on the signal recording surface to read out or write data on or from the signal recording surface. A semiconductor laser unit is used as a laser light source and is so arranged that the meridional plane of the light beam emanating from the semiconductor laser unit is inclined 30.degree. to 60.degree. with respect to the tangential direction of the recording track.

Optical pickup device

A focusing error detecting apparatus having a first photo-detector of which the light receiving portion is halved to provide first and second light receiving portions asymmetrical with respect to the center of a beam spot of a bundle of incident laser beams, the first photo-detector being located in the optical path ahead of the focusing point of the bundle of the incident laser beams, a second photo-detector of which the light receiving portion is halved to provide first and second light receiving portions asymmetrical with respect to the center of a beam spot of a bundle of incident laser beams, the second photo-detector being located in the optical path behind a focussing point of the bundle of the incident laser beams and a calculating circuit for calculating a difference between a difference of detected outputs from the first and second light receiving portions of the first photo-detector and a difference of detected outputs from the first and second light receiving portions of the second photo-detector, thereby to derive a focusing error signal from the output of the calculating circuit.

An optical pickup device having a semiconductor laser element mounted on a substrate, a photo detector formed on the substrate to receive a laser beam emitted from the semiconductor laser element and an optical element mounted on the substrate to cover the photo detector to branch the direction of optical path of the laser beam, the optical element having its face opposing the semiconductor laser element formed as an inclined face on which a semitransparent reflection film is deposited. The optical path branching optical element is provided with preventing means by which, of laser beams incident on the optical element, a laser beam reflected and/or scattered within the optical element is prevented from irradiating the photo detector.

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Kanagawa, Japan

Etsufumi Yamamoto