Hitachi, Ltd.

Junji Nakajima

Motoyuki Suzuki

Koji Iijima

Masayuki Inoue

Yoshio Suzuki

Makoto Miyamoto

Kunikazu Ohnishi

Yukio Fukui

Masaaki Kurebayashi

Hisamitsu Tanaka

Koji Iljima

There are provided an optical disk device and tilt correction processing method for performing recording/reproduction by rapidly acquiring an optimal tilt correction value for an optical disk having a plurality of recording/reproducing layers. In an optical disk device capable of recording or reproducing information by irradiating a laser beam to each of a plurality of recording/reproducing layers of an optical disk, the tilt value is stepwise set within a predetermined range at a predetermined radius position of the recording/reproducing layer located at the farthest distance from the laser beam irradiation side so that an optimal tilt correction value can be obtained from the quadratic function by the method of least squares of the jitter or the like obtained from the disk. By applying the optimal tilt value obtained to the other recording/reproducing layer, it is possible to start recording or reproduction in a short time.

Optical disk device and tilt correction method thereof

A masking type light control layer for decreasing its reflection factor in a high-temperature region is formed on phase pits of an optical disc, and the phase pit depth is set to a predetermined value. A light spot for reproduction is shaped to an elliptical form and two sub-flux beams on the optical disc are spaced by 5/4 track pitch from a principal flux beam in the radial direction of the optical disc. The kind of optical disc is discriminated and reproduction laser power and characteristics of an equalizer circuit are switched in accordance with the type of an optical disc. Through this, a stable servo signal detection can be ensured and repetitive reproduction characteristics can be improved.

Optical disc with phase pits and a reproducing apparatus for data

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Yokohama, Japan

Junji Nakajima