Sharp Kabushiki Kaisha Corporation

Yasuo Nakata

Nobuo Ogata

Yukio Kurata

Yoshio Yoshida

Takahiro Miyake

Hideaki Sato

Yoshihiro Sekimoto

Tomoyuki Miyake

Kunio Kojima

Tetsuo Ueyama

Toshiharu Inui

Hiroshi Fuji

Keiji Sakai

Kohji Minami

Shigemi Maeda

Toshiyuki Tanaka

Hiroyuki Yamamoto

Yukio Watanabe

Jun Akiyama

Mitsuo Ishii

Toshio Ishikawa

Osamu Miyazaki

Toshiya Nagahama

Atsushi Asada

Katsuhiro Kubo

Makoto Horiyama

Etsuji Minami

Chiaki Kiyooka

Tomio Mashiyama

Teruaki Inoue, Deceased

Kazuko Inoue

Takayuki Inoue

Teruaki Inoue

Hideaki Satou

An optical pickup device has a semiconductor laser emitting light which is in turn branched via a diffraction grating into at least three beams of light including a main beam and two sub beams which are in turn condensed via an objective lens on an optical disk at a guide groove and reflected by the optical disk to provide three reflections of light which are in turn received by detectors, each divided into two regions, respectively, to generate a tracking error signal. The diffraction grating is divided into three regions including a first region, a second region and a third region located intermediate therebetween, each having a periodical structure out of phase, the periodical structure having grating grooves in a direction determined depending on the phase of the second region to incline relative to a direction perpendicular to the guide groove of the optical disk.

Optical pickup device recording and/or reproducing information on and/or from a plurality of kinds of recording media

A pickup for a magneto-optical recording medium is provided, which improves quality of reproduced signals by eliminating a phase difference between the polarizations and is capable of coping with magneto-optical recording media of different recording/reproducing systems. A return light beam of light reflected by a magneto-optical recording medium is polarized and separated into &#xb1; first-order diffracted lights through a light-branching diffraction element provided between a light source and an objective lens. The &#xb1; first-order diffracted lights are compensated for their phases through first and second phase compensation elements so that there is no phase difference between the polarizations, and are, further, polarized and separated through the first and second polarization/separation elements, and are received by first and second light detectors. Use of the first and second phase compensation elements having different phase compensation amounts makes it possible to cope with the magneto-optical recording media of different recording/reproducing systems.

Pickup for magneto-optical recording medium

Beam shaping means may have a shaping ratio set to allow a light beam emitted from a semiconductor laser and having an elliptic intensity distribution to have an ellipticity of no more than two to obtain a spot achieving high light availability and reduced in size. Furthermore, the shaping ratio can be set to no more than 2.5 to allow a polalized-beam splitter (light separation means) and other components to be arranged in a converged flux passing between the semiconductor laser and a collimator lens.

Optical pickup device

A light spot detects a focus offset amount based on an amount of variation of a focus error signal when a light spot passes a boundary between a land section and a groove section adjacent to the land section on an optical disk. Specifically, an amount of variations in the focus error signal at a center of a land section at a time the light spot passes the boundary between the land and the groove adjacent to the land is detected as a focus offset amount, and an amount of variation in the focus error signal at a center of the groove section is detected as a focus offset amount for the groove sections, thereby providing an optical information recording/reproducing device which permits recording/reproducing information on and from a tracking area of an optical disk under just-in-focus conditions without increasing a cost of the device nor being affected by an error due to changes over time or variations in optical disks.

Optical information recording/reproducing apparatus having focus error signal compensation

A reproducing light quantity control method for an optical memory device includes the steps of (1) recording test data on an optical recording medium; (2) reproducing the test data recorded on the optical recording medium by changing a reproducing light quantity in a plurality of light quantity values; (3) measuring a quality value and a signal quantity of each of a plurality of reproducing signals from the test data; (4) selecting an optimum reproducing signal quantity from a plurality of reproducing signal quantities in accordance with quality values of the plurality of reproducing signals so as to decide a target value of reproducing signal quantity; and (5) recording the target value on a target value recording region of the optical recording medium. This method reduces the time required to obtain a target value of a reproducing signal quantity and speeds up an operation from installing of the optical recording medium to finishing of preparation for recording and reproducing.

Reproducing light quantity control method for optical memory device, and reproducing light quantity control device, and optical recording medium

A hologram laser unit to be used for performing recording and reproducing operations of information for an optical disk, includes a light source, a photodetector, and a hologram element which are formed integrally with each other. The hologram element includes: a first hologram for detecting information signals from the optical disk, the first hologram being provided in an area having an effective diameter corresponding to a numerical aperture suitable for the optical disk; and a second hologram for compensating for only a transmitted light amount of light traveling toward the optical disk from the light source, the second hologram being provided contiguously outside the first hologram.

Hologram laser unit and optical pickup device including the same

In an optical information recording-reproduction apparatus, a focus servo control circuit generates a focus error signal and a light beam is accurately converged on a surface of an optical disk according to a focus servo control signal based upon the focus error signal. In accordance with the present invention, the focus error signal is compensated by selecting a land section focus offset amount by a switch when land sections are tracked, and it is compensated by selecting a groove section focus offset amount when groove sections are tracked. As a result, since the land sections and the groove sections are controlled by different focus servo control signals, recording and reproducing operations are carried out at the most optimal focusing positions respectively obtainable, thereby making it possible to significantly improve the quality of a reproduced signal.

Optical information recording/reproducing apparatus having focus servo

An optical disk having thereon intermittent spiral guiding grooves composed of a pit array, wherein each guiding groove has a wobbling side wall at either side, so that the pit array is used as a data reproduce-only area and spaces between adjacent guiding grooves are used as a data recordable area, thereby realizing a high-density optical disk having both the data reproduce-only area and data recordable area.

Optical disk including wobbled guiding groove composed of pits, optical

A light sensor is divided into two light receiving sections which receive light reflected by an optical disk. A first intermediate address signal is generated from a difference signal of outputs of the light receiving sections. A second intermediate address signal is generated from a sum signal of outputs of the light receiving sections. An address generating circuit generates an address signal by using the first and second intermediate address signals. An optical disk device stably generating an address signal regardless of a displacement of an objective lens and a change in reflectance of the optical disk is thus provided.

Optical disk device for reproducing address information from wobbled

An optical pickup for irradiating a first recording medium and a second recording medium with light, at least one of the substrate thickness and the refractive index of the first recording medium being different from that of the second recording medium, where the optical pickup includes: a light source for emitting the light; a polarized beam splitter for receiving the light and for transmitting at least a portion of the light while reflecting the remaining portion of the light depending on the polarization direction of the light; a first objective lens for focusing the portion of the light reflected by the polarized beam splitter onto the first recording medium; and a second objective lens for focusing the portion of the light transmitted through the polarized beam splitter onto the second recording medium.

Optical pickup having two objective lenses

An information recording-reproduction method wherein: upon reproducing, recorded information corresponding to a predetermined number of sectors from the leading sector of each of a plurality of information tracks on an optical disk is preliminarily stored on a buffer memory, and during a period in which the optical pickup is shifted to another information track, the recording information, stored in the buffer memory, is reproduced; and upon recording, during a period in which the optical pickup is shifted to another information track, recording information is temporarily stored in the buffer memory, and after completion of the recording, the recording information is recorded on the optical disk. In this method, information tracks, which are formed on the optical disk discontinuously with one .another, are regarded as if they were continuous tracks, and the apparent recording and reproducing operation is carried out continuously.

Information recording-reproduction method

A polarization detector includes a polarization diffraction element having a substrate with two facing surfaces which are placed in parallel with each other, a first diffraction grating formed on one surface of the substrate, and a second diffraction grating formed on the other surface of the substrate, with light being incident upon the first diffraction grating. Further, each grating pitch of the first diffraction grating and the second diffraction grating are nearly equal to a wavelength of the incident light. A limiting member is also included for limiting an incident region of the incident light with respect to the polarization diffraction element. The limiting member is formed on a light incident side of the first diffraction grating. Further, a converging lens is included for respectively converging light transmitted through the first diffraction grating and the second diffraction grating and light diffracted by the first diffraction grating and the second diffraction grating into different beam spots. Finally, a pair of photodetectors are included for detecting each optical intensity of the two beam spots converged by the converging lens.

Polarization detector

A display apparatus of the invention includes: a plurality of display devices arranged in one direction, each of the plurality of display devices having a display area; and a plurality of image transmission means corresponding to the respective display devices, one end face of each of the image transmission means being coupled to a display area of the corresponding one of the display devices, other end faces of the image transmission means corresponding to the adjacent ones of the display devices being in contact with each other, the plurality of image transmission means being bent toward the one direction in which the display devices are arranged. Alternatively, a display apparatus of the invention includes: a plurality of display devices disposed in two directions, each of the plurality of display devices having a display area; a plurality of image transmission means corresponding to the respective display devices, one end face of each of the image transmission means being coupled to a display area of the corresponding one of the display devices, other end faces of the image transmission means corresponding to the adjacent ones of the display devices being in contact with each other, some of the plurality of image transmission means each having inward facing slopes and outward facing slopes on two pairs of opposing faces, the outward facing slopes of the image transmission means being directed to a direction in which the corresponding display device has no adjacent display devices.

Display apparatus having a plurality of display devices

In an objective lens driving apparatus used in an optical information recording and reproducing apparatus or the like, a vibration is suppressed and a resonance peak on transfer function is suppressed when movable portions are moved in focusing and tracking directions and when these portions are turned around focusing and tracking directions. An elastic body which supports the movable portions movably in two directions, i.e., focusing direction and tracking direction to a fixed portion includes a bent portion in an intermediate portion between the side of movable portion and the side of fixed portion. A damper member is adhered to bridge a gap between a branched arm portion branching from a linear portion extending from the side of movable portion, and a fixed portion. The bent portion couples two linear portions and which are not on the same line.

Objective lens drive device with support system

A polarization diffraction element comprising two diffraction gratings formed on both faces of a substrate respectively. Both the diffraction gratings have grating lines which are arranged at the same grating pitch, and whose directions mutually form a predetermined minute angle. The grating lines may also be arranged parallel to each other. In this case, the relationship between grating pitches D.sub.1, D.sub.2 of the respective diffraction gratings and the wavelength .lambda. of an incident light is expressed as:

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Takaichi-gun, Japan

Yasuo Nakata