Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
1997-12-18
2001-05-15
Angebranndt, Martin (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S416000, C430S945000, C369S288000, C369S284000, C428S913000, C428S914000, C428S064800, C428S064400
Reexamination Certificate
active
06232036
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to an optical recording disk and, more particularly, to an optical recording disk for recording data thereon using a laser radiation.
(b) Description of the Related Art
Recently, there is a strong demand for an optical recording medium which is capable of recording/reproducing data thereon by using a laser radiation of a smaller wavelength, which is smaller than a current 780 nm or 830 nm wavelength, for a high-density recording. Among other optical recording media capable of smaller wavelength recording, an optical recording disk using an organic pigment has advantages of its low costs and easy processing thereto.
Cyanine or similar substance is recently proposed as an organic pigment for such a smaller wavelength recording in JP-A-6(1994)-3306086, JP-A-7(1995)-161068, JP-A-7(1995)-262604, JP-A-7(1995)-125441, JP-A-7(1995)-266705 etc. In the recording disk using such a substance, it is generally considered that changes in the optical constants and reduction of film thickness due to a thermal decomposition (or pyrolysis) of the organic pigment, as well as transformation or deformation of the substrate due to melting of the substrate, are generated in the recorded section of the disk, as in the case of 780 nm wavelength recording in a CD-R disk.
In such a recording disk, wherein the modulation factor during the recording is obtained by both or either of the decomposition of the pigment and the deformation of the substrate, cross-talk is a major problem since the transformation in the recorded section is large, and it is especially serious if a large bit extends toward the land area from the adjacent groove area in the case of groove recording.
In the case of a smaller track pitch to be applied to a digital audio disk (DVD), the cross-talk problem is more serious. In the above-mentioned patent publications and other publications such as JP-A-4(1982)-109441, JP-A-4(1992)-1182944, JP-A-6(1994)-282873 and JP-A-6(1994)-28287, although CD-R disk having a high reflectance and excellent characteristics are described, the problems and solutions thereof inherently involved in the organic pigment used in the high-density recording medium are not taught nor suggested.
To solve the above problems, the present inventors showed in Japanese Patent Application No. 7(1995)-213501 that small area of the chemical changes in the recorded section, sufficient modulation factor, high reflectance and large signal amplitude can be obtained by employment of the pigments having a characteristic of steep and large reduction in weight as a principal ingredient or an additive of the recording materials, together with the skeletons which have such a characteristic.
However, the present inventors found that the cross-talk problem arises again in the case of a smaller track pitch and a smaller groove width, such as in a recording disk having a high recording capacity of 5 giga-byte (Gbyte) or more recorded on a single surface.
SUMMARY OF THE INVENTION
It is therefore and object of the present invention to provide a high density recording disk having an organic pigment for a recording film.
The present invention provides an optical disk for use at a recording/reproducing wavelength of 500 nm to 700 nm, the optical disk comprising: a transparent substrate having a guide groove having groove depth between 100 nm and 200 nm, groove width between 0.2 &mgr;m and 0.4 &mgr;m and arranged with a pitch between 0.7 &mgr;m and 1.0 &mgr;m, for defining a groove area and a land area; and a recording film, a metallic reflective film and a protective film consecutively formed on the transparent substrate, the recording film containing an organic pigment, the disk having a property satisfying either one of the following requirements in each of the first through fourth aspect of the present invention.
(1) First Aspect:
A film thickness of the recording film at the groove area corresponds to a first interference mound of a disk reflectance, the recording film has a distinction coefficient between 0.03 and 0.09, and an absorbance A1 of the recording layer at a recording/reproducing wavelength and an absorbance A0 of a maximum absorbance or absorbance step most adjacent to the A1 are such that a ratio of A1/A0 resides between 0.07 and 0.18 and A0 resides in a range between 0.5 and 0.7.
(2) Second Aspect:
The recording film exhibits, in a thermogravimetric analysis, substantially no weight reduction at a temperature below a starting temperature of a main weight reduction, a reduction rate of 2% or more in the main weight reduction, and a total weight reduction of 30% or more, and exhibits, in a differential thermal analysis, an exothermic calorie peak between −10 &mgr;V/mg and +10 &mgr;V/mg and a peak width of 20° C. or less at exothermic calorie peak.
(3) Third Aspect:
The recording film exhibits, in a thermogravimetric analysis, substantially no weight reduction at a temperature below a starting temperature of a main weight reduction, a reduction rate of 2% or more in the main weight reduction, and a total weight reduction of 30% or more, and exhibits, in a differential thermal analysis, an exothermic calorie peak between 10 &mgr;V/mg and 30 &mgr;V/mg, the metallic film has an inverse of the specific electric resistance at a room temperature between 0.20/&mgr;&OHgr;·cm and 0.30/&mgr;&OHgr;·cm, a refractive index of 0.2 or less and an extinction coefficient between 3 and 5.
(4) Fourth Aspect:
The optical disk exhibits a distorted angle &thgr; of 15° or less in the reproduced signal reproduced at a linear speed of 4.9 m/s or above from a 10T or larger mark recorded at a linear speed of 4.9 m/s or above.
According to the present invention, a smaller cross-talk and a smaller mark length can be obtained for a smaller track pitch and a smaller groove width of a disk, wherein a high-density recording can be realized by a smaller wavelength and a high reflectance.
The above and other objects, features and advantages of the present invention will be more apparent from the following description, referring to the accompanying drawings.
REFERENCES:
patent: 5298608 (1994-03-01), Maruyama et al.
patent: 5389419 (1995-02-01), Maeda et al.
patent: 5415914 (1995-05-01), Arioka et al.
patent: 5492744 (1996-02-01), Koike et al.
patent: 5500301 (1996-03-01), Onishi et al.
patent: 5536548 (1996-07-01), Yasukawa et al.
patent: 5592464 (1997-01-01), Sugaya et al.
patent: 5633106 (1997-05-01), Aihara et al.
patent: 5652037 (1997-07-01), Ohkawa et al.
patent: 5753413 (1998-05-01), Nishida et al.
patent: 5853872 (1998-12-01), Shimamori et al.
patent: 5858613 (1999-01-01), Monden et al.
patent: 5862123 (1999-01-01), Horie et al.
patent: 5939163 (1999-08-01), Ueno et al.
patent: 0755052 (1997-01-01), None
patent: 4-361088 (1992-12-01), None
patent: 5-279580 (1993-10-01), None
patent: 9-058123 (1997-03-01), None
patent: 9-081966 (1997-03-01), None
Abstract of JP 09-274732, Oct. 1997.*
Abstract of JP 09-198714, Jul. 1997.*
Abstract of JP 09-081966, Mar. 1997.*
Abstract of JP 10-006644, Jan. 1998.*
Patent Abstracts of Japan, vol. 097, No. 004, Apr. 30, 1997, JP 08 332 772, Dec. 17, 1996.
Patent Abstracts of Japan, vol. 097, No. 004, Apr. 30, 1997, JP 08 339 573, Dec. 24, 1996.
Patent Abstracts of Japan, vol. 098, No. 002, Jan. 30, 1998, JP 09 274 732, Oct. 21, 1997.
Derwent Abstracts, AN 97-531 756, JP 09-254 543, Sep. 30, 1997.
Derwent Abstracts, AN 97-430 665, JP 09-193 545, Jul. 29, 1997.
Derwent Abstracts, AN 97-208 265, JP 09 058 123, Mar. 4, 1997.
Derwent Abstracts, AN 98-125 273, JP 10 006 644, Jan. 13, 1998.
Horie Michikazu
Kurose Yutaka
Maeda Shuuichi
Okamoto Yuko
Suzuki Yuki
Angebranndt Martin
Mitsubishi Chemical Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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