Hitachi, Ltd.

Yoshimi Kato

Isao Ikuta

Hisashi Andoh

Yoshihito Maeda

Masaichi Nagai

Hiroyuki Minemura

Tatsuya Sugita

Yoshio Sato

Yutaka Sugita

Nobuyoshi Tsuboi

Tetsuya Fushimi

Nobuo Tsukamoto

Atsuko Naruse

An optical information handling device in which reflectivity of the conventional reproduction-only type optical disk is lowered to 60% or less and is made equal to the reflectivity of write-once type and rewritable type optical disks, whereby interchangeability in these of these disks is possible.

ROM type optical recording medium with a high reflectivity and an

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

The information processor uses a portable memory formed on a transparent substrate which is able to be overwritten by laser power modulation system. The memory includes a disk type recording medium rotatably incorporated within a thin case, and carries out write/read/erase by means of a first magnetic field application device, a second magnetic field application device, and an optical head radiating light through the case which has at least a transparent light-incident portion. The case includes therein a rotation means for rotating the recording medium within the case, thereby enabling even further reduction in size of the information processor.

Optical disk memory and information processing apparatus

High density optical information recording even at room temperature is achieved by control of the diameter of crystalline portions exhibiting quantum size effects of fine semiconductor particles distributed in a dielectric matrix, using the non-crystalline to crystalline phase transition of the fine particles. The quantum size effects mean that the optical properties of the medium depend on the diameter of the crystalline portions. Various methods of recording, reproducing and erasing information using this optical recording medium are possible. The invention is applicable to other optical devices.

Methods of varying optical properties, optical devices, information

The information processor uses a portable memory which is able to be overwritten by laser power modulation system. The memory includes a disk type recording medium incorporated rotatably in a thin case, and carries out write/read/erase by means of a first magnetic field application device, a second magnetic field application device, and an optical head radiating light through this case.

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Takahagi, Japan

Yoshimi Kato