Nec Corporation

Kabushiki Kaisha Toshiba

Takeharu Shibatoko

Masaki Nakano

Chosaku Noda

Masatsugu Ogawa

Ryuichi Katayama

Yutaka Yamanaka

Kazuhiko Aoki

Toshiaki Iwanaga

Mitsuya Okada

Masashi Kubota

Hiroharu Satoh

Hideaki Ohsawa

Hideki Tanabe

Daisuke Eto

[PROBLEMS] To provide an optical information reproducing device capable of performing excellent super resolution reproduction at all times without complicating the hardware structure. [MEANS FOR SOLVING PROBLEMS] An optical information reproducing device () irradiates a laser beam to an optical information recording medium () in which effective spot size of the irradiated laser beam changes in accordance with intensity of the laser beam and reproduces information. The optical information reproducing device () includes: an asymmetry detection unit () as asymmetry detection device for obtaining asymmetry from a reproduction signal obtained by reproducing the information; and a laser power adjusting unit () as laser power adjusting device for controlling the laser beam intensity according to the asymmetry obtained by the asymmetry detection unit ().

Optical information reproducing method, optical information reproducing device, and optical information recording medium for performing reproduction of information by using laser beams

Optical information recording and reproducing mediumhas two recording layers of first and second recording layersand, from a laser beam incident surface side. In each control area, recording layer management information containing at least information indicating recording states of a plurality of areas into which the inside of data recording areaof each recording layer is divided is recorded. When recording or reproducing is performed on the second recording layer, the recording layer management information is checked, and a laser beam output is changed based on a recording state of an area corresponding to the first recording layer

Optical information recording and reproducing medium

In an optical disk medium, land recording tracks () are coupled by first and second coupling portions (and) at a particular radial position to form a tilt detecting mark SM.

Optical disk medium and optical disk recording/reproducing apparatus utilizing tilt detection areas having special marks

Growing community of inventors

Tokyo, Japan

Takeharu Shibatoko