Kabushiki Kaisha Toshiba

Katsutarou Ichihara

Nobuaki Yasuda

Yoshiaki Terashima

Akira Kikitsu

Sumio Ashida

Takashi Fujita

Takashi Ishigami

Akio Hori

Sumio Ikegawa

Yasuhisa Shiraishi

Shuichi Komatsu

Hideki Ohkawa

Norio Ozawa

Hiromichi Kobori

Senji Shimanuki

Shinji Arai

Masahiko Hirose

Yoshiharu Ochi

A magneto-optical information storage medium includes a substrate, a recording layer formed on the substrate and having an axis of easy magnetization extending in the direction perpendicular to its surface, a nonmagnetic layer formed on the recording layer, and a bias layer, formed on the nonmagnetic layer, for generating bias magnetic field H.sub.B (T) in accordance with a temperature. The magnetization of the recording layer is reversed by bias magnetic field H.sub.B (T) in first and second magnetization reversal temperature regions T.sub.W and T.sub.E (T.sub.W &gt;T.sub.E). Information is recorded on such a magneto-optical information storage medium by radiating a first laser beam having a first power level for heating an irradiated portion to a temperature in region T.sub.W. In addition, information erasing is performed by radiating a second laser beam having a second power level which is lower than the first power level and heats an irradiated portion to a temperature in region T.sub.E. Overwrite is performed by power-modulating between the first and second power levels and radiating the modulated laser beam onto a previously recorded area of the medium.

Magneto-optical recording medium comprising recording layer and thermal

A magneto-optical recording medium including a recording layer and a bias layer being stacked one upon the other to apply coupling interaction which is mainly magnetostatic interaction to each other, the bias layer having a magnetization-reversing temperature higher than that of the recording layer. The medium is irradiated with laser beam pulses having a recording level and an erasing level lower than the recording level, thereby recording and erasing the information. When the medium is irradiated with the laser beam pulse having the recording level and the irradiated region is cooled to the magnetization reversing temperature T.sub.rR, the magnetization of the beam-irradiated region of the recording layer is aligned with a direction of the leakage magnetic field leaking from the recording layer. When the medium is irradiated with the laser beam pulse having the erase level and the irradiated region is cooled to T.sub.rR, direction of magnetization of the beam-irradiated region of the recording layer is aligned with a direction of the leakage magnetic field applied from the bias layer to the recording layer.

Method of magneto-optically recording/erasing information and

A method of magneto-optically recording and erasing information which comprises irradiating pulse-like laser beam onto a magneto-optical information storage medium including recording and bias layers which has perpendicular magnetic anisotropy and which are stacked one upon the other to apply coupling interaction which is mainly magnetostatic interaction to each other, and magnetization-reversing temperature of the bias layer being higher than that of the recording layer. When the recording laser beam is irradiated onto the medium, the beam-irradiated portion of the medium is heated to form a reversed magnetic domain in the bias layer, magnetization of the recording layer is reversed by first leakage magnetic field applied to the recording layer when beam-irradiated portion is then cooled, and magnetization of the bias layer is directed in same direction as that under initial state by second leakage magnetic field, applied to the bias layer. When the erasing layer beam is irradiated onto the medium, the beam-irradiated portion of the medium is heated to the magnetization-reversing temperature of the recording layer, and due to third leakage magnetic field applied to the recording layer at this time, the direction of magnetization of the recording layer is re-reversed.

Method of magneto-optically recording and erasing information onto a

An optical recording medium and methods of manufacturing the same are disclosed. The optical recording medium is provided with a transparent adhesive layer containing organic compounds such as hydrocarbon or the like that constitute resin materials, and metallic compounds whose thermal expansion coefficients are nearly equal to those of inorganic transparent materials that constitute a transparent protective layer, whereby peel-off phenomena to be caused by secular variation can be avoided.

Optical recording medium and method of manufacturing the same

In a reversible memory system, a pulsed laser beam generated from a laser unit is directed to a recording layer formed on a substrate 1. The recording layer essentially consists of a recording medium, for example, an iron-nickel alloy containing iron as a major component and 27 to 30 atomic % of nickel, which undergoes martensite transformation from a low-temperature phase to a high-temperature phase at a predetermined temperature Af and which undergoes a stress-induced transformation at a characteristic temperature Md. When a region of the recording layer is irradiated with the laser beam having a predetermined intensity, the region undergoes a stress-induced transformation so that the region is changed from the high temperature phase to the low temperature phase.

Reversible memory structure for optical reading and writing and which is

According to a disk-shaped magneto-optical recording medium of the invention, a transparent thin film serving as an interference layer is formed on a transparent substrate. The thin film is subjected to a plasma surface treatment, thereby decreasing the fused oxygen content in at least a surface portion thereof. A recording layer of a rare-earth-transition metal amorphous ferrimagnetic alloy thin film is formed on the plasma surface-treated film. Since the content of active, fused oxygen contained in at least the surface portion of the film decreases, rare-earth element oxide can hardly be formed in a boundary region between the recording layer and the transparent thin film. The content of the rare-earth element in this region is smaller than the average content in the overall recording layer.

Magneto-optical recording medium and manufacturing thereof

A magneto-optical recording disk has a transparent resinous substrate with a pre-groove, and a metallic recording layer formed above the substrate. A transparent adhesive layer is provided between the substrate and the recording layer, for allowing a laser beam to pass therethrough, and for causing the recording layer to be tightly adhered to the substrate to thereby prevent the recording layer from being peeled off from the substrate. The adhesive layer is comprised of a fluorine resin material.

Optical recording medium with fluorine resin adhesive

An optical information recording/reproducing system comprises (A) a recording medium including a recording-bit producing layer, which is comprised of a fluorescent substance, and a photoconductive layer, both layers being interposed between conductive layers, at least one of which is transparent; (B) means for selectively applying a voltage to both sides of the recording medium; (C) means for radiating an optical recording beam to a site on the recording medium while applying a voltage to the recording medium and, then, applying a high electric field to the recording-bit producing layer by way of the photoconductive layer, the resistance of the recording-bit producing layer being lowered at the site, thereby developing a dielectric breakdown and, hence, causing the fluorescent substance to lose the fluorescence, so that information is recorded; and (D) means for radiating an optical reproducing beam on the recording medium without applying any voltage to the recording medium and, then, reproducing information depending on whether fluorescence has been produced. The system is characterized by an improved S/N ratio upon reproduction and an increment to the storage capacity.

Optical system for recording/reproducing information by means of a

A data recording medium comprising, as a recording layer, a thin magnetic alloy film having an axis of easy magnetization along a direction perpendicular to the surface thereof, and an anticorrosion protective layer formed on the recording layer. This recording medium is featured in that the anticorrosion protective layer is formed of a thin oxide film which is obtained by subjecting the surface portion of the recording layer to an anodic oxidization. This protective layer may be further covered with a dielectric film as a second protective covering.

Data recording medium

An ornament coated with silicon carbide having black luster which has been formed by chemical vapor deposition aided by D.C. glow discharge using hydrogen, a silicon compound and a hydrocarbon. The black ornament according to the present invention is very suitable for a case of a watch, a frame of eyeglasses and so on.

Growing community of inventors

Tokyo, Japan

Katsutarou Ichihara