Hitachi Maxell, Limited

Other

Sanyo Electric Co., Ltd.

Hiroshi Shirai

Atsushi Yamaguchi

Norio Ohta

Hiroyuki Awano

Satoshi Sumi

Reiji Tamura

Hitoshi Watanabe

Naoyuki Takagi

Yoshiharu Uchihara

Katsusuke Shimazaki

Masafumi Yoshihiro

Makoto Iimura

Akira Kashiwakura

Kazuyoshi Adachi

Satoru Oonuki

Kazuyo Umezawa

Nobuyuki Nagai

An optical disk includes a first area on which user information is recorded, and a second area in which a plurality of marks radially extending are arranged in a track direction in the optical disk. Information about the reflectance of the optical disk is recorded in the second area. It is intended to optimize the amplification factor of the reproduced signal on the basis of the information about the reflectance of the optical disk in the second area. Control data and user data can be reproduced quickly and highly reliably without depending on the relationship between the reflectances of a recording area and a non-recorded area of the optical disk.

Optical recording and reproducing apparatus capable of identifying the type of optical disc based on reflectance, and reproducing method for optical disc

Optical disk with a plurality of radially extending marks for recording reflectance data of the optical disk

A write-once optical information recording medium is provided that is capable of realizing a high transfer rate and a method of recording and reproducing information on and from the optical information recording medium. The optical information recording medium is constructed by stacking a reflective layer, a first dielectric layer, a recording layer, a write-protect layer, a second dielectric layerand a transparent cover layeron a polycarbonate substrate. The recording layeris made of a phase-change material, and the cover layeris made of UV curing resin. The recording layeris irradiated with a laser beam with a wavelength of 500 nm or less to change from a crystalline phase to an amorphous phase. The write-protect layerprevents the recording layerfrom changing back to the crystalline phase from the amorphous phase, formed by the phase change.

Optical information recording medium and method of recording and reproducing information on and from optical information recording medium

A magneto-optical recording medium which includes a reproducing layer. When a laser beam is irradiated to the magneto-optical recording medium, a magnetic domain in a recording layer is transferred, through enlargement, to a reproducing layer increased in temperature. The magneto-optical recording medium further includes a calibration area that has a calibration magnetic domain recorded in a predetermined pattern in the recording layer. In a reproducing apparatus, a laser beam of an optical head is adjusted in output depending upon a reproduced signal obtained by reproducing the calibration magnetic domain.

Magneto-optical recording medium including a calibration magnetic domain recorded in a predetermined pattern in a recording layer

A magneto-optical recording medium has, in order from the laser irradiation side, a second auxiliary magnetic film first auxiliary magnetic film and magneto-optical recording film First and second auxiliary magnetic films and change from in-plane magnetization to perpendicular magnetization when their respective critical temperatures T and T are exceeded. The Curie temperatures T , T and T of the magneto-optical recording film and the first and the second auxiliary magnetic films and their critical temperatures T and T satisfy the relationship: room temperature<T <T <T , T ,T . The first auxiliary magnetic layer has a film thickness greater than the thickness of the magnetic wall. In response to irradiation by the reproducing light beam, recording magnetic domain of magneto-optical recording film is transferred, with size reduction, to first auxiliary magnetic film and is then transferred, with magnification, to second auxiliary magnetic film This is ideal for reproduction of a high-density recording medium since an amplified reproduction signal is obtained from magnified magnetic domains

Magneto-optical recording media having an auxiliary magnetic layer

Magneto-optical recording medium and recording/reproducing apparatus therefor in which recorded magnetic domains are transferred from the recording layer to the reproducing layer

Growing community of inventors

Moriya, Japan

Hiroshi Shirai