Pioneer Corporation

Pioneer Electronic Corporation

Fujitsu Corporation

Citizen Holdings Company, Ltd.

Masayuki Iwasaki

Akihiro Mochizuki

Masakazu Ogasawara

Sakashi Ootaki

Yasuo Yamagishi

Takanori Maeda

Toshiaki Yoshihara

Fumiyo Onda

Yoshitsugu Araki

Makoto Sato

Hisashi Yamaguchi

Takuma Yanagisawa

Ikuya Kikuchi

Shunsuke Kobayashi

Naoki Fujii

Hideki Hatano

Tetsuya Iida

Seiichi Ohsawa

Takashi Yamaji

Mitsuru Sato

Osamu Kasono

Akira Sugimoto

Seiichi Osawa

Kasumi Ikegami

Shinya Sato

Mitsuaki Hirose

Akira Yokoi

Hiroyuki Gondo

Takeshi Toyoda

Kimiaki Sato

In an optical disk drive mounting a drive unithaving a control use circuit, and a pickuphaving an aberration correction liquid crystal elementand a drive use circuitwhich drives the aberration correction liquid crystal element, wherein the drive use circuitstores astigmatic data for correcting a static astigmatism peculiarly provided in an optical system in the pickupin an astigmatic data storage, and drives the aberration correction liquid crystal elementbased on the astigmatic data. By storing the static astigmatic data peculiar to the pickup, inside the pickup, it is possible to transfer the stored astigmatic data to the optical disk drive side easily, and to correct the astigmatism by driving the aberration correction liquid crystal element based on the astigmatic data.

Optical disk drive and optical pickup having aberration correction means

A first electrode of a liquid crystal cell () is composed of a plurality of concentric electrodes (to) of a concentrically circular shape, the plurality of concentric electrodes are divided into a first group of concentric electrodes () near the center and a second group of concentric electrodes () near the periphery, and a concentric electrode between the two groups is an independent single electrode (). A first correction unit that corrects spherical aberration of a high density DVD is composed of the two groups and a second correction unit that corrects aberration of a conventional DVD is composed of the first group of concentric electrodes (). In the case of correcting the aberration of the conventional DVD, the independent concentric electrode () is supplied with a voltage between the voltages respectively supplied to adjacent concentric electrodes (), (). In the case of correcting the aberration of the high density DVD, the independent concentric electrode () is supplied with a voltage equal to the voltage supplied to the concentric electrode immediately lateral thereto ().

Liquid crystal optical element having grouped concentric electrodes

In an optical pickup apparatus which includes at least a laser light source and an object lens and can apply a laser beam to different types of optical discs, an aberration correction liquid crystal device is placed on the optical axis of the laser beam emitted from the laser light source. The aberration correction liquid crystal device includes a first electrode section being placed on the side of the laser light source and having a first electrode pattern for correcting aberration concerning a first optical disc, a second electrode section being placed on the side of the optical disc and having a second electrode pattern for correcting aberration concerning a second optical disc different from the first optical disc in type, and liquid crystal being sandwiched between the first and second electrode sections.

Aberration correction liquid crystal device and optical pickup apparatus

An aberration correcting unit is provided for correcting an aberration of a light beam radiated onto an object to be detected and then reflected from the object. This unit comprises an aberration correcting device comprising a first corrector configured to correct the aberration of the light beam radiated onto the object; and a second corrector configured to correct the aberration of the light beam reflected from the object and to divide the reflected light beam into a plurality of light beams. The aberration correcting unit further comprises a first driver configured to drive the first corrector and a second driver configured to drive the second corrector.

Device and unit for correcting aberration of light beam

An aberration correcting optical unit includes an optical element for causing a phase change to light passing therethrough by the application of voltage and electrode layers for applying voltages to the optical element. The optical element is sandwiched between the electrode layers. At least one of the electrode layers includes a plurality of electrodes which are electrically isolated from one another. The plurality of electrodes are disposed such that an electric field generated in a portion of the optical element corresponding to a portion between the plurality of electrodes is larger than a predetermined intensity when a predetermined voltage is applied to the optical element.

Aberration correcting optical unit, optical pickup apparatus and information recording/reproducing apparatus with single and multi-layer electrodes

An optical pickup apparatus includes a photodetector for receiving a diffracted light reflected from the recording medium; and a tilt detector for detecting a tilt amount of the recording medium on the basis of a light intensity within an interference region of a 0th-order diffraction light and at least one diffraction light other than the 0th-order diffraction light of the reflected light received by the photodetector.

Optical pickup apparatus and tilt amount detecting method

An aberration correcting unit includes: a first element having a liquid crystal sandwiched between first electrode layers, the first element having a first predetermined orientation direction and providing a light with a phase change by applying a voltage; a second element having a liquid crystal sandwiched between the second electrode layers, the second element having a second predetermined orientation direction that is substantially perpendicular to the first orientation direction and providing a light with a phase change by applying a voltage; and a polarization-direction changing element which is arranged between a light source of the light beam and the first and second elements to change a polarization direction of the light beam.

Aberration correcting unit, optical pickup apparatus, and recording/reproducing apparatus

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.

Optical pickup and information recording and/or reproducing apparatus including the same

An information recording medium includes a substrate, and one or a plurality of layers formed on the substrate, wherein at least one of the layers is formed by mixing a base material and a hard material which has a predetermined thickness and determines a predetermined thickness of the layer.

Information recording medium including layer of uniform thickness and reproducing device thereof

An aberration correction device for correcting aberration produced in a light beam, which includes: a first electrode layer and a second electrode layer being opposed to each other; and a liquid crystal disposed between the first electrode layer and the second electrode layer for producing a change in phase in a light beam passing therethrough in accordance with voltages applied to the first electrode layer and the second electrode layer. The first electrode layer is divided into a plurality of phase adjustment portions which are electrically isolated each other. Each of the plurality of phase adjustment portions includes a pair of electrodes arranged in such a form that produces an electric field distribution for correcting the aberration by applying predetermined voltages thereto.

Aberration correction apparatus and method

A liquid-crystal panel is placed in an optical path of an optical beam from a light source to a recording surface of a recording medium for compensating wavefront aberration of the optical beam by giving a phase difference to the optical beam. The liquid-crystal panel comprises a layer of a liquid crystal material having an index of birefringence, wherein the product of the index of birefringence and thickness of the layer of the liquid crystal material is 0.4 &mgr;m or more.

Liquid-crystal panel, optical pickup, and information reproducing system

An apparatus and a method are provided for compensating an aberration occurring in a reflected light beam from a recording medium. The apparatus includes a liquid crystal unit including a first electrode layer having divisional electrodes and a second electrode layer, and a liquid crystal element which provides a light beam with a phase change when an electric field is applied; a detector for receiving the reflected light beam through the liquid crystal unit to generate a detection signal; a voltage generator for generating voltages to be applied to the divisional electrodes; and a controller for performing aberration compensation control by changing the applied voltages to each of the divisional electrodes with reference to an applied reference voltage to a predetermined divisional electrode. The controller determines the applied reference voltage based on an amplitude change of the detection signal when the applied voltages to the divisional electrodes are changed.

Optical reproducing aberration compensation system having appropriate correction signals applied to a liquid crystal detector

An optical pickup is provided with: a light emitting device for emitting a light beam onto a record medium comprising a transparent layer, which is transparent for the light beam and through which the light beam is transmitted; a light receiving device for receiving a reflection light of the light beam from the record medium; a liquid crystal compensating device for compensating birefringence, which is generated in the light beam when the light beam is transmitted through the transparent layer, by controlling an orientation direction of liquid crystal molecules in a liquid crystal layer so as to give a canceling phase difference to the light beam transmitted through the liquid crystal layer; a generating device for generating an indication signal indicative of the birefringence; and a controlling device for controlling the orientation direction on the basis of the indication signal so that a first angle between a standard line, which is perpendicular to an optical axis of the light beam and is set in advance, and the orientation direction in a plane perpendicular to the optical axis is kept to be constant and that a second angle between the optical axis and the orientation direction in a plane including the optical axis is changed, to thereby generate the canceling phase difference in the light beam transmitted through the liquid crystal compensating device.

Optical pickup, information recording apparatus and information reproducing apparatus

An LCD panel will rotate based on an external control signal by a prescribed angle such portion of light flux, that enters an objective lens, corresponding to a predetermined incident point and, at the same time, will change by a prescribed length an optical path of this portion of optical flux whose aberrations are in excess of a prescribed standard value. It is thus possible to compensate the wave-front aberrations due to the differences in the effective optical-path length and also to control the effective numerical aperture of the objective lens by utilizing linearly polarized light as the light to be emitted from the laser beam source. It is also possible to compensate the aberrations due the differences in the substrate thickness of the optical recording medium and those due to a tilt of the optical recording medium.

Growing community of inventors

Tsurugashima, Japan

Masayuki Iwasaki