Fujitsu Corporation

Kyoko Miyabe

Koichi Tezuka

Tohru Fujimaki

Satoshi Itami

Kazushi Uno

Mineo Moribe

Shingo Hamaguchi

Miyozo Maeda

Susumu Satoh

Haruhiko Izumi

An optical information recording/reproducing apparatus records information on and/or reproduces information from an optical recording medium based on a reflected light beam from the optical recording medium. The apparatus includes a light splitting part having a plurality of light splitting stages which split the reflected light beam from the optical recording medium into a plurality of light beams, and a photodetector unit including a plurality of photodetectors which receive the plurality of light beams from the light splitting part. The photodetector unit includes a plurality of photodetectors which receive light beams used to detect a focal error, at least one photodetector which receives a light beam used to detect a tracking error, and a plurality of photodetectors which receive light beams used to detect magneto-optic information recorded on the optical recording medium.

Optical information recording/reproducing apparatus

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.

Tracking and focus control system for optical disk apparatus

An optical disk is made up of a disk-shaped substrate having a surface, a first track and a second track provided on the surface of the substrate, where the first and second tracks are two mutually adjacent concentric tracks or two mutually adjacent track turns of a single spiral track, the first track extends along a first center line and the second track extends along a second center line, and an identification signal recording part extending along a third center line and prerecorded with an identification signal including at least a sector number and a track number for identifying a position on the optical disk. The third center line is arranged between the first and second center lines, and the identification signal prerecorded in the identification signal recording part is common to the first and second tracks on both sides of the identification signal recording part.

Optical disk having identification signal recorded between and used in

An optical information recording/reproducing apparatus records information on and/or reproduces information from an optical recording medium and detects a focal error based on a reflected light beam from the optical recording medium. The apparatus includes a composite prism which deflects a part of the reflected light beam to at least two positions excluding a central part of the reflected light beam, and a photodetector device having a plurality of photodetectors which respectively detect the deflected parts of the reflected light beam and output detection outputs. The focal error is detected based on the detection outputs of the photodetector device.

Optical information recording/reproducing apparatus having a composite

An optical information recording/reproducing apparatus records information on and/or reproduces information from an optical recording medium and detects a focal error based on a reflected light beam from the optical recording medium. The apparatus includes an optical element which deflects a part of the reflected light beam to at least two positions excluding a central part of the reflected light beam, and a photodetector device having a plurality of photodetectors which respectively detect the deflected parts of the reflected light beam and output detection outputs. The focal error is detected based on the detection outputs of the photodetector device.

Optical information recording/reproducing apparatus which detects focal

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.

Optical head unit for an optical disk using a diffraction grating

An optical head includes a lens system forming light reflected from an optical disk into parallel rays, a focal error and tracking error detection system detecting focal error and tracking error based on the parallel rays, an optical reproduced signal detection system detecting a reproduced signal reproduced from the optical disk based on the parallel rays, and a light blocking part for blocking, out of the parallel rays, at least a central portion in a light amplitude distribution of parallel rays supplied to the optical reproduced signal detection system.

Optical head having light blocking means positioned in front of a

An optical data recording/reproducing device, wherein the number of reflection in an optical path of coherent light formed between a coherent light source and an optical disk is twice or a larger even number of times, and the array direction of the coherent light source and photodetectors is substantially parallel to the face of the optical disk, resulting in a smaller size in the direction corresponding to the thickness of the optical disk.

Optical data recording/reproducing device and integrated head

An optical disk is adapted for use in an optical disk unit which irradiates a light beam spot on a target track on the optical disk and controls tracking of the light beam spot based on a tracking error signal which is generated based on a reflected light beam from the optical disk. The optical disk includes a disk shaped substrate, a spiral or concentric guide tracks provided on the substrate, a writable region provided on the substrate between two mutually adjacent track turns of the guide track, and a preformed track provided within the guide track and prerecorded with read-only information in a form of variations of a topological feature. The guide track and the topological feature have mutually different height positions so that a tracking error signal which is generated when the light beam spot scans the guide track has the same amplitude as a tracking error signal which is generated when the light beam spot scans the preformed track, and the height positions of the guide track and the topological feature are different from a height position which generates a maximum tracking error signal amplitude when scanned by the light beam spot.

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Kawasaki, Japan

Kyoko Miyabe