Sanyo Electric Co., Ltd.

Other

Masahiro Irie

Kobe Natural Products & Chemicals Co., Ltd.

Kobe Natural Products

Toshio Harada

Fumio Tatezono

Yoichi Tsuchiya

Shuichi Ichiura

Seiji Kajiyama

Yasuyuki Kanou

Koutaro Matsuura

Koichi Tada

Masami Shimizu

Meguru Ohara

Kazuhiko Kuroki

Tsuyoshi Tsujioka

Toshio Tanuma

Yasuyuki Matsushita

Hitotoshi Kimura

Irie Masahiro

An optical disk recording/reproduction apparatus includes a semiconductor laser, an objective lens provided opposite an optical disk, an optical system for supplying a laser beam from the semiconductor laser to the objective lens, an aperture for not intercepting the laser beam in reproducing from a digital video disk and intercepting an outermost portion of the laser beam in reproducing from a compact disk, and a tracking servo mechanism for moving the objective lens in a tracking direction orthogonal to the running direction of a track of the optical disk. The aperture has an oblong opening that is longer in the tracking direction than in the track running direction.

Optical disk recording/reproduction apparatus for recording/reproducing information to/from optical disk of different standards

An apparatus for discriminating optical disks has an optical pickup provided with an objective lens having an effective numerical aperture of 0.55 to 0.65, which can compatibly reproduce information from a CD and an SD. The apparatus discriminates presence/absence of waveforms of two focus error signals detected when the effective numerical aperture of the objective lens is set at 0.55 to 0.65 and 0.20 to 0.45 respectively in a process of performing focus servo control, thereby discriminating various types of optical disks from each other. Thus, optical disks having different substrate thicknesses, different track pitches, different minimum pit lengths and different reflectivity can be quickly and simply discriminated from each other.

Apparatus for discriminating optical recording media of different thicknesses from each other and reproducing information therefrom

Apparatus for discriminating optical recording media of different

An optical material contains a photochromic compound which is expressed in the following general formula (I): ##STR1## where A represents an oxygen atom, a nitrogen atom, or a substituted nitrogen atom, B represents a thiophene ring, benzothiophene ring, pyrrole ring or indole ring, R.sub.1 represents a methyl group, an alkoxy group or a perfluoroalkyl group, R.sub.2 to R.sub.7 represent a hydrogen atom, a halogen atom, a hydroxy group, an alkyl group and the like respectively. This photochromic compound may be bonded with a polymer as a side chain in the position of A.

Optical material

An optical recording medium includes a recording layer, and a masking layer which is converted to a state having small absorption at the wavelength of a reproducing beam due to progress of decoloration caused by a thermal reaction upon irradiation with the reproducing beam, or due to facilitation of decoloration caused by a photon mode photochromic reaction through temperature rise upon irradiation with the reproducing beam.

Optical recording medium and reproducing method therefor

Disclosed herein is an optical recording material containing a photochromic compound which is expressed in the following general formula (I): ##STR1## where A represents an oxygen atom or a substituted or unsubstituted nitrogen atom, R.sub.1 represents an alkoxy group, R.sub.2 to R.sub.5 represent substituents such as a hydrogen atom, a halogen atom, a hydroxy group, a substituted or unsubstituted alkyl group and the like respectively, and B represents a substituted or unsubstituted thiophene ring, benzothiophene ring, pyrrole ring or indole ring.

Optical recording material and optical recording medium employing the

Disclosed herein is an optical recording medium comprising a recording layer containing a photochromic material and a polymer which are so combined with each other that a photostationary state attained upon irradiation with light of a specific wavelength is varied with temperatures, a reflective layer for reflecting light which is passed through the recording layer, and a substrate for supporting a laminate of the recording layer and the reflective layer.

Optical recording medium

Disclosed herein is a recording/reproducing method for an optical recording medium comprising a step of heating a recording layer containing a photochromic material and a polymer which are so combined with each other that a photostationary state attained upon irradiation with light of a specific wavelength is varied with temperatures, and a step of applying the light of a specific wavelength to the heated recording layer for bringing the same into a photostationary state and recording information. In order to reproduce the information, a portion of the recording layer which is in a photostationary state is selectively heated, and reproducing light is applied to reproduce recorded and unrecorded states.

Method of recording and reproducing for optical recording medium

Growing community of inventors

Ota, Japan

Toshio Harada