Information recording medium and method of manufacturing resinous substrate for use in the recording medium

a technology of information recording medium and resinous substrate, which is applied in the manufacture of optical record carriers, record information storage, nuclear engineering, etc., can solve the problems of substrate warping, mechanical property deterioration, and difficulty in actual application practice, and achieve sufficient mechanical strength, sufficient tilt margin, and the effect of increasing the recording density

USRE43970E1Inactive Publication Date: 2013-02-05KK TOSHIBA
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Patent Information

Authority / Receiving Office
US · United States
Current Assignee / Owner
Publication Date
2013-02-05
Estimated Expiration
Not applicable · inactive patent

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Abstract

An information recording medium comprising a substrate having a recording surface provided with emboss pits or guiding grooves, a reflective film formed on the recording surface of the substrate, and a first protective film formed on the reflective film. This information recording medium is featured in that both sides of the information recording medium are constituted by a first surface provided with the protective film and by a second surface formed opposite to the first surface, and that an irradiated light beam is irradiated through the first surface, a recorded information being reproduced based on changes in light intensity of the reflected light beam. The distance between the recording surface of the substrate and the light incident surface is smaller than a thickness of the substrate, and a surface roughness “R” of the light incident surface meets a relationship represented by the following formula (1):R≦λ / (8n)  (1)wherein λ is a wavelength of the light beam, and n is a refractive index of the first protective film to a light having the wavelength λ.
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Description

[0001]This is a division of Application Ser. No. 09 / 283,161, filed Apr. 1, 1999. Allowed as U.S. Pat. No. 6,159,572.This application is a divisional reissue application of U.S. application Ser. No. 12 / 028,491, filed Feb. 8, 2008. U.S. application Ser. No. 12 / 028,491 is a reissue application of U.S. application Ser. No. 09 / 657,566, filed Sep. 8, 2000, now U.S. Pat. No. 6,465,069. U.S. Pat. No. 6,465,069 is a divisional of U.S. application Ser. No. 09 / 283,161, filed Apr. 1, 1999, now U.S. Pat. No. 6,159,572 and for which priority is claimed under 35 U.S.C. §121 and 35 U.S.C. §251. This application is based upon and claims the benefit of priority under 35 U.S.C. §119 from the prior Japanese Patent Application No. 10-091422, filed Apr. 3, 1998. Notice: More than one reissue application has been filed for the reissue of U.S. Pat. No. 6,465,069. The reissue applications are application Ser. Nos. 12 / 476,449, 12 / 476,441, 12 / 476,434, 12 / 476,428, 12 / 476,375, 12 / 476,456, 12 / 476,607, 12 / 476,627...

Examples

example 1

[0068]FIG. 1 is a cross-sectional view schematically showing one example of an optical disk according to this example. In the optical disk shown in FIG. 1, one of the surfaces of a disk substrate 1 having a thickness of 1.2 mm is formed into a recording surface on which emboss pits 2 are formed in conformity with a recorded data. The thickness of the substrate 1 may be suitably selected as long as the thickness in the range of from 0.6 mm to 1.2 mm. The surface of this recording surface provided with the emboss pits 2 is covered with a reflective film 3 and then with an over-coating consisting of a protective film (first protective film) 4. In the case of the optical disk shown in FIG. 1, The surface of the protective film 4 is the light incident surface.

[0069]The readout of the recorded data stored in the disk can be performed as follows. Namely, as shown in FIG. 1, a light beam 5 is converged by an objective lens 6 and then enters through the protective film 4. The light beam is t...

example 2

[0089]FIG. 4 is a cross-sectional view schematically showing one example of an optical disk according to this example. In the optical disk shown in FIG. 4, one of the surfaces of a disk substrate 1 having a thickness of 1.2 mm is formed into a recording surface on which emboss pits 2 are formed in conformity with a recorded data. The surface of this recording surface provided with the emboss pits 2 is covered by a reflective film 3, and then cover-coated with a first protective film 4 and a second protective film 18 in the mentioned order. In the case of the optical disk shown in FIG. 4, the surface of the second protective film 18 is the light incident surface.

[0090]The readout of the recorded data stored in the disk can be performed as follows. Namely, as shown in FIG. 4, a light beam 5 is converged by an objective lens 6 and then enters through the second protective film 18. The light beam is then reflected by the reflective film 3, thus producing a light reflection accompanying ...

example 3

[0098]FIG. 5 is a cross-sectional view schematically showing one example of an optical disk according to this example. In the optical disk shown in FIG. 4, one of the surfaces of a disk substrate 25 having a thickness of 1.2 mn is provided with guiding grooves 26 to be used for the tracking of light beam 5. On this guiding grooves 26 are further formed a reflective film 27, a first protective film 28 constituting a lower protective film, a recording film 29, and a second protective film 30 constituting a upper protective film in the mentioned order. The surface of this second protective film 30 is further over-coated by a third protective film 31. In the case of the optical disk shown in FIG. 5, the surface of the third protective film 31 is the light incident surface.

[0099]The readout of the recorded data stored in the disk can be performed as follows. Namely, as shown in FIG. 5, a light beam 5 is converged by an objective lens 6 and then enters through the third protective film 31...