Sony Corporation

Other

Fujitsu Corporation

Hiroyuki Takemoto

Atsushi Takeuchi

Hiroshi Nakayama

Yoshihito Fukushima

Mineo Moribe

Tadao Suzuki

Kenichi Itoh

Takehiko Numata

Mitsuo Arima

Katsuhiko Ohtomo

Sohmei Endoh

Masayoshi Nagata

Koichi Iida

Sumio Kuroda

Makoto Watanabe

Minoru Kikuchi

Masaki Kagawa

Jiro Fujiwara

Takahiro Igari

Minoru Matsuura

Hiroshi Nomura

Naohisa Manjome

Hiroki Tsuchiya

Yuko Asano

There is provided an optical recording medium substrate including a polycarbonate in which an average molecular weight is in a range from 15000 to 16000, and mass per unit volume at 25° C. is in a range from 1.1930 g/cmto 1.2000 g/cm.

Optical recording medium substrate, optical recording medium, and method of manufacturing optical recording medium substrate

There is provided a cartridge including a running portion which causes both end portions of a disc-shaped recording medium to run, and a pressing portion which presses one end portion of the disc-shaped recording medium to press the other end portion against the running portion. Static friction coefficients of a portion of the pressing portion coming in contact with the one end portion and a portion of the running portion coming in contact with the other end portion are different.

Cartridge for accomodating a disc-shaped recording medium

Binary information previously recorded in an innermost rim side area is enabled to be stably reproduced. A record medium is formed by sequentially laminating a first information layer, an intermediate layer, a second information layer, and a cover layeronto a substrate. First grooves are previously formed in the innermost rim area of the substrate. Second grooves are previously formed in an area where data is recorded. The first grooves are set to be shallower and narrower than the second grooves. Thus, such a situation that a BCA signal is modulated by diffraction due to the grooves can be reduced.

Record medium, its manufacturing method, mother disc for record medium, and its manufacturing method

An optical information recording medium, which includes both of a land surface and a groove surface as a recording track and presents high signal quality. The optical information recording medium includes both a land and a groove as the recording track on a substrate, in which a laser light is irradiated from a reverse side of the substrate to thereby carry out a recording and a reproduction, and an inclination angle of a groove side is 25&#xb0; or more and 40&#xb0; or less, and both of arithmetic average roughness (Ra) on the land surface and the groove surface are assumed to be 0.2 to 0.7 nm.

Optical information recording medium, original disc for optical information recording medium, and method of manufacturing the same

The present invention provides an optical disk comprising: at least a rewritable region and a read-only data region, wherein the rewritable region includes a plurality of groove tracks and a plurality of land tracks, the read-only data region includes a plurality of groove tracks and a plurality of land tracks, read-only data comprising control data are written as concavo-convex pits to the groove tracks and/or the land tracks in the read-only data region, and the width of each groove in the read-only data region is smaller than that of each groove in the rewritable region. According to the first optical disk of the present invention, the area of rewritable regions for users can be ensured as broadly as possible failing to deteriorate the high-speed performance of the system.

Optical disk

Optical information recording medium

An optical disc is disclosed, having tracks formed in a spiral shape or a concentric circle shape, each of the tracks being radially divided into a plurality of zones, data being recorded and/or reproduced at different angular velocities in the individual zones in such a manner that the angular velocity in the same zone is the same, wherein a buffer area is formed at a zone boundary, and wherein at least one pit portion is formed in the buffer area so that the pit portion is almost radially adjacent to a pit portion of a zone on the inner periphery side and a pit portion of a zone on the outer periphery side.

Optical disc and optical disc drive apparatus

A magneto-optical disk having recording tracks are formed along concentric grooves or a spiral groove. A non-groove region where no grooves are made is provided in a middle part of each recording track. In the non-groove region, there is formed a pit pattern representing information about the recording track. A track-counting U-groove is formed in the non-groove region, for detecting that the light spot of a reading laser beam has moved across the recording track. With the disk thus structured, it is possible to record information at high density and to access a desired recording track at high speed.

Optical recording medium

Using MSR (magnetically induced super-resolution) technology, a read-head field is applied to a magneto-optical recording medium when reading an information signal from a recording layer of a magneto-optical recording medium, in order to magnetize the read light-irradiated magnetic layer in one direction in a part of an area within the read light spot. The magneto-optical recording medium using MSR technology adopts the on-land recording method in which an information signal is written to the land, which enables read of an information signal by the MSR technology with a smaller read-head field.

Magneto-optical recording medium, and magneto-optical recording/reproducing apparatus

An optical disc has formed in an area inside the inner circumference of an information recording area formed thereon concentric or spiral continuous or discontinuous recesses at a lager pitch than the track pitch in the information recording area . The optical disc is manufactured by installing a hub substantially in the center of an optical disc substrate with reference to the recesses by positioning the hub with respect to the optical disc substrate. A stamper for manufacturing the optical disc substrates is produced by exposing a photoresist layer to a laser beam by turning on and off the laser beam while rotating a glass substrate having the photoresist layer applied thereon and scanning the laser beam radially of the glass substrate .

Optical disk with recesses inside an inner circumference of an information recording area and method of making same

On the assumption that a phase difference caused by a birefringence at the substrate is &phgr;,while a one caused by the magneto-optic Kerr effect of the recording layer is &phgr;,, the magneto-optical recording medium formatted to record information in the groove meets the conditions: &minus;20&deg;<&phgr;,<&plus;10&deg; and &minus;45&deg;<(&phgr;,&plus;&phgr;,)<&plus;15&deg;, the magneto-optical recording medium formatted to record information on the land meets the conditions: &minus;20&deg;<&phgr;,<&plus;10&deg; and &minus;15&deg;<(&phgr;,&plus;&phgr;,)<&plus;45&deg;, and the magneto-optical recording medium formatted to record information at both the land and groove meets the conditions: &minus;20&deg;<&phgr;,<&plus;10&deg; and &minus;15&deg;<(&phgr;,&plus;&phgr;,)<&plus;15&deg;.

Magneto-optical recording medium

An optical recording medium capable of being reproduced by a conventional drive device which meets an optical disk having grooves and no groove in an area in which pits are formed. In the optical recording medium having pits 1 showing information signals in the shape of protruding and recessed parts, it is assumed that the depth t1 of the above mentioned pits t2 of the pits 1 is located within a range of 0.3 to 0.6 .mu.m. Herein, n designates the refractive index of the base of the optical recording medium and designates the wavelength of the light used for reproduction.

Growing community of inventors

Miyagi, Japan

Hiroyuki Takemoto