Sharp Kabushiki Kaisha Corporation

Sharp Kabushiki Kaisga

Akira Takahashi

Kenji Ohta

Junji Hirokane

Yoshiteru Murakami

Hiroyuki Katayama

Michinobu Mieda

Junichiro Nakayama

Naoyasu Iketani

Tetsuya Inui

Junsaku Nakajima

Toshihisa Deguchi

Kazuo Van

Go Mori

Tomoyuki Miyake

Hideyoshi Yamaoka

Hideharu Tajima

Shigeo Terashima

Nobuyuki Takamori

Ippei Suzuki

Yukinori Nishitani

Noboru Iwata

Tatsushi Yamamoto

Hideaki Sato

Junichi Washo

Toshio Ishikawa

Shohichi Katoh

Toshikazu Nagaura

Takao Hyuga

Shinji Yamagami

Masayasu Futagawa

Tetsurou Muramatsu

Hiroyuki Ikenaga

Junji Hirogane

Toshiyuki Tanaka

Hiroshi Fuji

Kunio Kojima

Takeshi Yamaguchi

Toshihiro Tamura

Mitsunobu Yoshida

Yoshikazu Fujii

Toshiharu Inui

Hirotaka Toki

Tomokazu Ise

Shinya Hirata

Nobuyuki Usui

Kouji Ohta

Junsaku Nakayima

Ichiro Hiramatsu

An optical information recording medium characterized by comprising a temperature-sensitive layer formed on a substrate, for reversibly changing in reflectance and/or transmittance with a temperature change. A temperature-sensitive layer having the property of changing in reflectance with a temperature change is used, as well as the property of changing in light interference effect with a temperature change, thereby providing an optical information recording medium capable of providing a higher, more stable reproduction signal power.

Optical information recording medium

A disc cartridge of the present invention is provided with a protrusion section on a shutter sliding surface so as to surround at least part of an opening. Moreover, a shutter for opening and closing the opening is provided with a shielding section for covering the opening and the protrusion section and a sliding surface for sliding on a shutter sliding surface during opening and closing operations of the shutter.

Disc cartridge

An information processing medium includes a substrate, a single layered or multilayered thin film layer formed on the substrate, and a thin protective film formed to cover at least one surface of the thin film layer. The thin protective film is mainly comprised of a synthetic resin. At least either one of a Young's modulus and a linear expansion coefficient of the thin protective film has a value compensating a radial skew variation of the substrate caused by a change in ambient conditions.

Information processing medium and information processing apparatus using the same

A disc cartridge of the present invention has an arrangement in which a disc cover is provided so as to cover one side of a disc in a disc shape having a recording layer for recording/reproducing information. This arrangement protects a surface for recording/reproducing from being damaged, being attached by dust, or being dirty. Meanwhile, this arrangement gives a significantly thinner thickness to the disc cartridge.

Disc cartridge and disc drive

A disk cartridge having a small size and a sufficient portability. The disk cartridge has a size of 58 mm (L)&#xd7;54 mm (L)&#xd7;4 mm (L), a thickness less than 5 mm and a small area less than a square of 65 mm. The disk cartridge has a notch 10 formed on the insertion side and having a width of 2 mm (L) and a length of 27.5 mm (i.e., a taper portion of 6 mm (L)+a straight portion of 21.5 mm (L)).

Disk cartridge

A magneto-optical storage medium includes an interference layer, a magnetic domain expansion layer, an intermediate layer, a magnetic masking layer, a recording layer, and a protection layer which are sequentially formed on a substrate. The magnetic domain expansion layer produces a smaller frictional force due to wall coercivity than do the other magnetic layers. The intermediate layer has the Curie temperature T which is lower than those of the other magnetic layers. The magnetic masking layer is in a perpendicular magnetization state at temperatures that are in a proximity of T , and changes into an in-plane magnetization state at temperatures that are higher than the proximity of T . The recording layer produces a higher coercive force than those produced by the magnetic domain expansion layer at room temperature.

Magneto-optical storage media

Featured is a recording and reproducing method of a magneto-optical recording medium including a recording layer for recording thereon information magneto-optically and a readout layer which has in-plane magnetization at room temperature and where a transition occurs from in-plane magnetization to perpendicular magnetization as temperature raises. The method includes projecting a light beam onto such a magneto-optical recording medium so as to form a perpendicularly magnetized area in the readout layer by duplication of the magnetization of said recording layer to the area. In further embodiments, the recording medium further includes an intermediate layer made of non-magnetic film formed between the readout and recording layers and the readout and recording layers are composed of rare-earth transition metal alloys such as TbFeCo (recoding layer) readout layer, made of GdFeCo (readout layer).

Magneto-optical recording medium and recording and reproducing method and optical head designed for the magneto-optical recording medium

In order to provide a magneto-optical recording medium which can select a single recording magnetic domain in the recording layer accurately and expand and transfer the same to the reproducing layer, the magneto-optical recording medium is arranged in the following manner. That is, the magnetization direction of the reproducing layer is in-plane at room temperature and shifts to perpendicular at or above a predetermined temperature T . The recording layer is a magnetic layer which is magneto-statically coupled to the reproducing layer and shows the perpendicular magnetization up to its Curie temperature. The magnetic mask layer is provided between the recording layer and reproducing layer, and the magnetization thereof is reduced to 0 (zero) at or above a predetermined temperature (T ) which is at or above T . The magnetization of the magnetic mask layer is larger than that of the recording layer at least in a range between room temperature and T .

Magneto-optical recording medium

A magneto-optical recording medium of the present invention has a recording layer made of a perpendicular magnetization film, and a readout layer which is in an in-plane magnetization state at room temperature and changes into a perpendicular magnetization state with a rise in temperature. When the magneto-optical recording medium is irradiated with a light beam, the readout layer separates into three regions: a region in an in-plane magnetization state, a region in a perpendicular magnetization state, and a region having a temperature not lower than the Curie temperature thereof. Only the region in the perpendicular magnetization state allows copying of the magnetization of the recording layer. Therefore, even when the diameter and intervals of recording bits on the recording layer are very small, it is possible to reproduce a target recording bit separately from a recording bit adjacent to the target recording bit.

Method of reproducing information on a magneto-optical recording medium for achieving super resolution reproduction of high resolution recorded information

A magneto-optical recording medium comprising a reproducing magnetic layer having a magnetic layer which is in an in-plane magnetization state at room temperature but shifts to a perpendicular magnetization state as temperature rises, a dielectric layer and a recording magnetic layer having a magnetic layer which exhibits a perpendicular magnetization, sequentially from a photo-receptive side, the recording medium being further comprising a metal layer between the reproducing magnetic layer and the dielectric layer.

Magneto-optical recording medium and process for producing the same

An optical disk including concentric or spiral grooves, a first series of pits formed in the interrupted portions, and a second series of pits formed in portions of lands. Both of the first and second series of pits represent address information. The portions of the lands and the interrupted portions of the grooves are located in different radial directions. With this arrangement, even when the optical disk has a reduced track pitch, accurate address information is obtained, achieving a high-density recording optical disk.

Method for manufacturing an optical disk

A reproduction layer, a magnetic domain extending layer, an intermediate layer, and a recording layer are formed in this order. The magnetic domain extending layer, the intermediate layer, and the recording layer are exchange-coupled. The intermediate layer has a Curie temperature lower than that of any other magnetic layer. A non-magnetic intermediate layer is formed between the reproduction layer and the magnetic domain extending layer. Upon reproduction, magnetization information in the recording layer is transferred to and extended in the magnetic domain extending layer, where an extended magnetic domain is formed. The reproduction layer is magnetostatically coupled with the magnetic domain extending layer, so that the extended magnetic domain is transferred to the reproduction layer. This makes it possible to provide a magneto-optical recording medium characterized in moving of magnetic domain walls and extension of magnetic domains in good conditions, and increased signal intensity with a simpler structure.

An optical disk is provided with a recording layer, and with an optical coupling layer on a light-incident side of the recording layer. An optical recording and reproducing device and method include an objective lens and a hemispherical lens, which converge a light beam from a light source and project the light beam onto the optical disk. The hemispherical lens is provided in close proximity to the optical coupling layer, in a position such that an interval therebetween is not more than the wavelength of the light produced by the light source. The light beam converged by the objective lens and the hemispherical lens is coupled with the optical coupling layer while substantially maintaining a direction of propagation in which it was propagating while inside the hemispherical lens.

Optical recording and reproducing method optical recording and reproducing device, and optical recording medium

An optical disk has address recording sections each of which has a wobbled part of one of side walls of a groove. Each address recording section is formed by providing convexes of a groove in an adjacent land so as to widen the groove. With the wobbles thus provided in a concavo-convex form, address information is recorded. Besides, the address recording sections thus provided in the grooves are linearly disposed in radial directions of the optical disk. By thus arranging the optical disk on whose grooves and/or lands information is recorded, mixing of wobble frequency components in reproduced information signals does not occur, the sector method is applicable to the optical disk, and information signals of high quality can be obtained.

Optical recording medium having tracks, each track having a plurality of wobble sections/one-side wobble regions

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Nara, Japan

Akira Takahashi