Tdk Corporation

Mitsubishi Rayon Company, Limited

Tomoki Ushida

Takashi Kikukawa

Mamoru Usami

Atsuko Kosuda

Motohiro Inoue

Hideki Hirata

Tsuyoshi Komaki

Kenji Yamaga

Takashi Yamada

Hiroyuki Arioka

Kazuki Suzawa

Junichi Ide

Atsushi Koyama

Yoshimi Sakai

Juichi Fujimoto

Haruhiko Yamaguchi

Kouji Hayama

Kentaro Iida

Teppei Osawa

Hideki Hijikata

An optical recording medium includes a recording and reading layer that is previously staked or formed afterword and has no concavo-convex pattern for tracking control, and a servo layer in which a concavo-convex pattern or a groove for tracking control is formed. Information can be recorded in the recording and reading layer while tracking is performed using the servo layer.

Optical recording and reading method, optical recording and reading apparatus, optical recording medium, and method for producing an optical recording medium

An optical recording medium includes a recording and reading layer that is previously staked or formed afterward and has no concavo-convex pattern for tracking control, and a servo layer in which a concavo-convex pattern or a groove for tracking control is formed. Information can be recorded in the recording and reading layer while tracking is performed using the servo layer.

An object of the present invention is to increase the number of stacked layers in a multilayer optical recording medium while simplifying the design of the multilayer optical recording medium is provided a multilayer optical recording medium including at least four recording and reading layers from which information can be reproduced by light irradiation, the layers stacked through intermediate layers. The multilayer optical recording medium includes a plurality of recording and reading layers that are continuous in order of stacking and includes at least one recording and reading layer group in which reflectance in a stacked state decreases from a near side of a light incident surface to a far side. A single-layer reflectance of the nearest recording and reading layer is set to 0.2% or more and less than 2.0%, and a light transmittance improvement process is applied to the light incident surface.

Multilayer optical recording medium

Simple design of a multilayer optical recording medium is achieved while suppressing interlayer crosstalk and confocal crosstalk in the multilayer optical recording medium. Simple recording and reading control by a recording and reading unit is also achieved. The multilayer optical recording medium includes at least three or more recording and reading layers deposited one above the other with intermediate layers interposed therebetween, and information can be read by light irradiation from the layers. The intermediate layers have film thicknesses of two types or less, and all the recording and reading layers except the recording and reading layer farthest from a light incident surface have substantially the same optical constant.

The multilayer optical recording medium with six or more recording and reading layers disposed one above the other has at least two or more recording and reading layer groups. The recording and reading layer groups each include a plurality of recording and reading layers successively disposed one above the other. The reflectance of each of the recording and reading layers in a stacked state decreases in the order from a front side near a light incident surface toward a back side far from the light incident surface. A recording and reading layer nearest the front side among the recording and reading layers in the recording and reading layer group nearer the back side has a reflectance in a stacked state higher than that of a recording and reading layer nearest the back side among the recording and reading layers in the recording and reading layer group nearer the front side.

The multilayer optical recording medium with at least four or more recording and reading layers disposed one above the other has at least two or more recording and reading layer groups each including the recording and reading layers successively disposed one above the other. In adjacent recording and reading layer groups with an intermediate layer interposed therebetween, a recording and reading layer nearest a front side in the recording and reading layer group nearer a back side is higher than the higher value of the reflectances in a stacked state of two recording and reading layers nearest the back side in the recording and reading layer group nearer the front side.

An information medium substrate is formed as a flat plate and includes a first convex part formed on one surface of the information medium substrate in a region between a rim part of a center hole and an inner circumferential edge of an information region and a second convex part formed on another surface of the information medium substrate at a position that overlaps a protruding end part of the first convex part in a thickness direction of the information medium substrate.

Information medium substrate and information medium

An optical recording mediumincludes a support substrate, an information layerformed on one of the surfaces of the support substrate, a first resin layerformed on the information layerand having a thickness of 30 to 200 &#x3bc;m, a moisture-proof layerformed on the other surface of the support substrate, a second resin layerformed on the moisture-proof layerand having a thickness of 30 to 200 &#x3bc;m, and a label layerformed on the second resin layer, and has such a structure that a laser beam is irradiated through the first resin layer. The second resin layercontains 0.5 to 2.8 mass part of a silicon antifoaming agent with respect to 100 mass part of an ultraviolet curing resin, and is formed by a screen printing method.

Optical recording medium

An optical recording medium including a light transmitting layer having a uniform thickness formed on a substrate, in which a burr or stripping hardly occurs at the inner periphery of the light transmitting layer, and a manufacturing method and a manufacturing device of the optical recording medium are provided. An optical recording mediumis manufactured by a manufacturing method including: molding a disc-like shaped substrateincluding an information recording faceA on one side; forming a light transmitting layerthinner than the substrateon the information recording faceA; forming a circular cutin the light transmitting layer; and punching out an area inside the cutby a punching toolto form a center holeA in the light transmitting layerand a center holein the substrate

Optical recording medium, and manufacturing method and manufacturing device thereof

When manufacturing an optical recording medium by forming a resin layer on a surface of a substrate and then forming a center hole that passes through the substrate and the resin layer, a method of manufacturing an optical recording medium according to the present invention forms the center hole by forming, in the resin layer, a circular cut with a larger diameter than the center hole so as to surround a formation position of the center hole and then pressing in a punching blade for forming the center hole from a rear surface side of the substrate. By doing so, detachment of the resin layer and the production of burrs at or near the center hole can be avoided while reducing the manufacturing cost.

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

An intermediate for an optical recording medium, according to the present invention, is an intermediate produced beforehand for manufacturing an optical recording medium that has a central mounting hole formed in a central portion thereof and one or more kinds of functional layers formed on a surface thereof, for enabling at least one of information recording and information reproduction. The intermediate has a provisional central hole, which is smaller in diameter than the central mounting hole, formed in a central portion thereof. This makes it possible to drop resin in the vicinity of the center of the intermediate without using a disk-shaped member, in performing spin coating on the intermediate, whereby it is possible to make the layer of applied resin substantially uniform in thickness.

Intermediate for optical recording medium and method of manufacturing the optical recording medium

An optical information medium having a light transmission layer obtained by curing a composition containing a urethane di(meth)acrylate (A) of the formula (I) and the other urethane di(meth)acrylate (B), and having a tensile elastic modulus of 600 to 1300 MPa at 25&#xb0; C. and a light transmittance of 80% or more at wavelength of 400 nm (in the formula, R=an alicyclic diisocyanate residue, R=an alkylene group or an organic group containing a cycloalkyl group or ester bond, R=H or methyl group.): 

Optical information medium

A disc-shaped optical recording medium formed by carrying out a film formation process on a disc-shaped substrate material and completed by forming a center hole at the last step is manufactured in a manner such that no eccentricity will occur when the recording medium is loaded onto a drive. At the last step of an optical disc manufacturing process, i.e., at the time of opening a hole in the center partof the disc-shaped substrate materialformed with at least a resin layer on one side thereof, the center partis removed in a manner such that the diameter of the chucking center holeis larger on the disc-shaped substrate materialside than on the light transmitting resin layerside of the disc-shaped optical recording medium, thereby manufacturing the disc-shaped optical recording medium

Method for manufacturing discoid optical record medium and discoid optical record medium

An optical recording medium includes a support substrate, a first resin layer and a second resin layer formed on opposite surface sides of the support substrate, an information recording layer formed between the first resin layer and the support substrate and containing a recording film, and a moisture-proof layer formed between the second resin layer and the support substrate and the moisture-proof layer contains at least one element among elements contained in the recording film. According to the present invention, since the first resin layer is formed on the moisture-proof layer containing at least one element among elements contained in the recording film, on the information recording layer and the second resin layer is formed on the moisture-proof layer, it is possible to form the first resin layer and the second resin layer having substantially the same physical properties on the opposite sides of the support substrate and it is therefore possible to suppress the warpage of the optical recording medium due to heat and moisture to the minimum.

The invention provides an optical recording medium having excellent weatherability and a process for producing the same. The optical recording medium is provided with an organic dye layer, a reflecting layer and a protective layer in this order on a light-transmittable substrate. The organic dye layer contains an organic solvent in an amount of 2% to 15% by weight based on the organic dye. A solution, prepared by dissolving an organic dye in an organic solvent, is applied onto the light-transmittable substrate by a spin coating method to form an organic dye layer. A reflecting layer is formed on the organic dye layer without performing a drying treatment of the organic solvent in the organic dye layer, followed by forming the protective layer on the reflecting layer. The result is an optical recording medium containing an organic solvent in an organic dye layer in an amount of 2% to 15% by weight based on an organic dye.

Growing community of inventors

Tokyo, Japan

Tomoki Ushida