Hitachi, Ltd.

Atsuko Naruse

Hiroyuki Minemura

Tatsuya Sugita

Tetsuya Fushimi

Yoshio Sato

Isao Ikuta

Hisashi Andoh

Yoshihito Maeda

Masaichi Nagai

Yoshimi Kato

An optical disk apparatus includes a recording method in which at least one of the scanning position, the irradiation time, the irradiation start point and the irradiation power of a light beam is arbitrarily changed, and a method and apparatus in which information is represented by a plurality of recording marks without being limited to two kinds of recording and erasion. In order to prevent overlapping recording/erasion, a recording clock generating unit delays a reference clock signal to generate a recording clock signal and a recording control unit transfers user data to an optical head in synchronism with the recording clock signal so that it is recorded on an optical disk. Also, the amount of delay is recorded to enable sure reading or reproduction. At the time of reading, a servo mark detection signal is divided to generate a clock signal having a variable frequency, thereby realizing an optical disk for which high-precision recording/reproduction is possible.

Optical disk apparatus

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Hitachi, Japan

Atsuko Naruse