Victor Company of Japan, Limited

Kenichi Shimomai

Hiroshi Tabata

Ikuo Matsumoto

Kazuo Yonehara

Kenji Tokui

Toyohito Asanuma

Masanori Takahashi

Tsutomu Matsumoto

Koji Tsujita

Katsunori Ohshima

Takayuki Deno

Fumitaka Tsuji

Hideo Machida

An optical disc has a first transparent substrate, a second substrate, and at least a first and a second recording layer formed between the substrates. The first substrate has a first surface and an opposing second surface, the first surface is a beam incidence surface for a laser beam, the second surface having a first concave section and a first convex section formed adjacent to each other thereon, the first concave section being farther than the first convex section from the incidence surface, first pre-pits being formed on the first concave section. The second substrate has a second concave section and a second convex section formed adjacent to each other thereon, the second concave section being farther than the second convex section from the incidence surface, second pre-pits being formed on the second concave section, a top surface of each second pre-pit being closer than a top surface of the second convex section to the beam surface. The second recording layer is farther than the first recording layer from the incidence surface. The second recording layer is formed with a dye mixture of cyanine dye and imonium dye having relations Wa&#x3e;Wb and na&#x3e;nb, in which Wa and Wb are a mass of the cyanine dye and the imonium dye, respectively, and 'na' and 'nb' are refractive indices of the cyanine dye and the imonium dye, respectively, to the laser beam having a specific wavelength, and having a relation na&#x2212;nc&#x3e;0.1 in which &#x201c;nc&#x201d; is a refractive index of the dye mixture.

Optical storage medium

A phase-change optical storage medium has a substrate and a recording layer having a plurality of tracks for storing information. A material of which the recording layer is made has been initialized in a crystalline state in which an amplitude of a tracking-detection signal is smaller than a saturation value of the amplitude, the tracking-detection signal being obtained by receiving a reflected beam from the recording layer when the recording layer is irradiated with a laser beam in an off-track state while the optical storage medium is being rotated.

Phase-change optical recording medium having tracking signal smaller than saturation value

A phase-change optical storage medium has a substrate, and a recording layer, to be recorded on which is at least one recorded mark representing information to be recorded by irradiating a recording light beam onto the recording layer in accordance with a recording pulse pattern of recording pulses rising from an erasing power and formed between a recording power larger than the erasing power and a bottom power smaller than the erasing power and of erasing pulses rising from the bottom power to the erasing power. The expressions (1) and (2): 1.00&#x3c;(R/R)&#x3c;1.15 . . . (1), 1.05&#x3c;(R/R)&#x3c;1.20 . . . (2) are satisfied for the recording layer, in which Ris a reflectivity exhibited by an un-recorded section of the recording layer, on which no data has ever been recorded, when irradiated with a reproducing light beam, Ris a reflectivity exhibited by the un-recorded section when irradiated with the reproducing light beam, after irradiated once with the recording light beam in accordance with the recording pulse pattern, and Ris a reflectivity exhibited by the un-recorded section when irradiated with the reproducing light beam, after irradiated nine times with the recording light beam in accordance with the recording pulse pattern.

Phase-change recording medium having the relation between pulse patterns and reflectivity of un-recorded section

Information to be recorded is recorded in a recording layer of a phase-change optical storage medium. The information to be recorded is modulated to generate modulated data. Desired mark-length data is generated based on the modulated data. Generated further based on the mark-length data is a recording pulse pattern of recording pulses rising from an erasing power and formed between a recording power larger than the erasing power and a bottom power smaller than the erasing power and of erasing pulses rising from the bottom power to the erasing power. A recording light beam is then irradiated onto the recording layer in accordance with the recording pulse pattern to record at least one recorded mark representing the information to be recorded. Used in recording is an optimum erasing power, as the erasing power, the optimum erasing power satisfying an expression (1): 1.000&#x3c;(R/R)&#x3c;1.030 . . . (1) in which Ris a reflectivity exhibited by an un-recorded section of the recording layer, on which no data has ever been recorded, when irradiated with a reproducing light beam, and Ris a reflectivity exhibited by the un-recorded section when irradiated with the reproducing light beam after irradiated once with a beam having the erasing power.

Optical recording method, optical recording apparatus and optical storage medium

An optical disk consists of a first laminated layer structure and a second laminated layer structure. The first structure has a first transparent substrate having a first surface and a second surface on both sides thereof, provided on the first surface being a light-incident plane via which a light beam is to be incident in recording or reproduction, formed alternately on the second surface being a plurality of first lands and first grooves, and a first organic-dye recording layer formed on the second surface to cover the first lands and grooves. The second structure has a second substrate, alternately formed on which are a plurality of second lands and second grooves, a reflective film formed on the second transparent substrate to cover the second lands and grooves, and a second organic-dye recording layer formed on the reflective film to face the second transparent substrate. The first and the second structures are bonded to each other via a bonding layer so that the first and second recording layers are provided between the first and second substrates. A formula &#x3b1;&#x2267;cos(20/Tb) is satisfied in which Tb is a thickness of the reflective film formed on a bottom of each second groove and &#x3b1;is an angle between a plane passing through an upper surface of each second land and a side wall of each second groove.

When an LPP (land pre-pit) is formed between shallow grooves or shallow pits, the LPP is formed on a land existing between the shallow grooves or the shallow pits. Further, the LPP is formed in a position displaced from a centerline of the land in the radial direction by a predetermined amount. Furthermore, a laser beam power utilized for forming a shallow groove or a shallow pit adjacent to the LPP is reduced so as to be lower than a regular laser beam power.

Optical disc having land pre-pits and variable groove depths

A method for manufacturing a disk substrate for mass production of a phase change optical disk, wherein an original disk substrate is having a resist layer ( ) applied on a glass substrate ( ), composed of the steps of forming a depression (pit &ldquo;p &rdquo; and groove &ldquo;g &rdquo;) having a first and a second depth by cutting laser to be exposed on the surface of the resist layer ( ), etching the depression having the first depth and the second depth from the surface of the resist layer ( ) of the disk substrate in atmosphere mixed with Argon and Oxygen in ratio of 10 to 90% under gas pressure of 0.1 to 1.5 Pa, wherein the first and the second depth of the depression (pit &ldquo;p &rdquo; and groove &ldquo;g &rdquo;) become predetermined value respectively, and ashing the resist layer ( ) from the glass substrate ( ).

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Mito, Japan

Kenichi Shimomai