Hitachi, Ltd.

Hisashi Andoh

Isao Ikuta

Masaichi Nagai

Yoshihito Maeda

Hiroyuki Minemura

Yoshio Sato

Tatsuya Sugita

Nobuyoshi Tsuboi

Yutaka Sugita

Yoshimi Kato

Yoshimi Katou

Toshiki Kaneko

Ryuji Watanabe

Yoshiaki Kita

Tetsuya Fushimi

Nobuo Tsukamoto

Tetsuro Minemura

Kiyoji Iwashita

Kiyoshi Konno

Atsuko Naruse

Yoshimi Katoh

Kinko Shimizu

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 present invention provides an optical recording medium using an amorphous-crystalline phase-change for recording and erasing, wherein reflectivity of an optical recording medium-constituting recording film in an amorphous state is larger than that of the optical recording medium-constituting recording film in a crystalline state, or wherein absorptivity of an optical recording medium-constituting recording film in an amorphous state is smaller than that of the optical recording medium-constituting recording film in a crystalline state.

Optical recording media and information recording and reproducing units

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 invention relates to an optical memory in which an optical recording medium is built in a case, and also to a memory apparatus. Recording, reproducing and erasing operations are performed by irradiating light via a transparent portion of the case onto the built-in optical recording medium. The optical recording medium built in the case has face vibrations with respect to the case, because it is moved within the case. The present invention is characterized by employing such a construction for optically mitigating irregular fluctuation in reflectivity caused by this face vibration. In the optical memory of the present invention, the reflectivity fluctuation caused by an interference effect made between reflection light from the case and air, and also reflection light from the optical recording medium and air due to the relative deviation in the face vibrations, may be reduced by antireflection films provided in the case and the optical recording medium. In a memory apparatus of the present invention, the abovedescribed memory is mounted, the fluctuation in the reflectivity is monitored and laser power is varied in order to further mitigate the reflection vibrations.

Optical memory and information processing apparatus

There is provided a compact and thin optical disk unit as a memory unit suitable for a portable computer such as a book type computer and a portable recording/reproducing apparatus. In the optical disk unit, the diameter of an objective lens is limited and a beam shaping prism, a beam splitter, a mirror and a 1/4 wavelength plate are formed into a unitary structure to make easy the optical axis adjustment of an optical head and ensure highly accurate assembling.

Information processing apparatus and optical head incorporated therein

An overwritable optical disk apparatus in which a finite conjugate optical system is employed. The apparatus comprises an optical head for converging diffused light from a light source onto an optical disk for performing data write/read operation, a driving unit for rotating the disk and a beam splitter for guiding the light reflected from the optical disk to a photodetector for detecting light reflected from the optical disk. Influence of disk displacement occurring in accompanying the rotation of the disk and disk eccentricity are suppressed to a minimum by encasing rotatably the optical disk within a credit card size casing which is adapted to be loaded and held stationarily in the optical disk apparatus. Thin structure of the optical head and miniaturization of the optical disk apparatus are realized with light utilization efficiency for data write/read operation being increased.

Optical disk apparatus and optical head

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.

Information processor and disk memory used in the same

An optical recording medium, which comprises a recording layer capable of reversibly undergoing a phase change between a crystalline state and an amorphous state by irradiation of an electromagnetic energy, the crystalline state of the recording layer being composed of a single phase of substantially a three-component compound or a higher multi-component compound can attain high speed recording and high speed erasing that cannot be obtained with the conventional optical recording medium.

Optical recording medium

A thermal printing head in accordance with the present invention has a substrate formed of an electrical insulator, heating elements formed on the substrate, and conductive layers formed on the part of the heating elements that is adjacent to and on either side of heat generating portions of the heating elements. The resistivity of heating elements is set at a value of not less than 1000 .mu..OMEGA..cm and, simultaneously, the thickness of conductive layers is set at a value of not more than 300 nm. By virtue of this arrangement, it is possible to reduce the distance between the heat generating portions of the head and the printing paper or ink sheet, and the thin conductive layers contribute to minimizing diffusion of the heat. The thermal printing head is therefore capable of efficiently and accurately transferring heat generated by the heat generating portions to the printing paper or ink sheet. The head is suitable for producing half-tone prints and is capable of producing highly gradated prints such as fully-colored prints.

Thermal printing head

A production method of a vacuum circuit breaker electrode comprises the steps of mixing conductive metal powder, and refractory material powder with a higher melting point than said conductive metal powder, compacting the resultant mixture to form a compact, presintering the compact in a atmosphere of high purity hydrogen, sealing a presintered body in a capsule while exhausting, heating and degassing, and subjecting the sealed capsule to hot isostatic pressing treatment. The conductive metal powder is one or both of Cu and Ag. The hot isostatic pressing treatment is effected at a temperature higher than a melting point of the conductive metal so that the presintered body is sintered under liquid phase, and a part of molten conductive metal component is seeped out on a sintered body surface.

Method for making vacuum circuit breaker electrodes

An information recording and reproducing apparatus is disclosed, which makes use a recording medium made of a metal or alloy having phases different in their crystalline structures at at least two temperature regions in the solid state and capable of causing phase transformation by heating and quenching. Information such as signals, letters, patterns and symbols are recorded in a distinctive manner and erased by making use of a change in the spectral reflectance owing to the phase transformation. Rewriting can be made easily by making use of the energy of a light beam such as a laser beam.

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Hitachi, Japan

Hisashi Andoh