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Optical data recording medium and method for reproducing recorded data

a technology of optical data and recording medium, which is applied in the direction of optical recording/reproducing/erasing methods, instruments, digital recording, etc., can solve the problems of insufficient resolution limit, difficult to achieve a thin thickness of resin layer, and limit in how thick the reproducing layer is

Inactive Publication Date: 2010-04-29
SHARP KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an optical data recording medium that can reproduce signals from marks with shorter mark lengths and can record data at high densities. This is achieved by using a reproducing layer that can face the light-incident surface of the substrate and has a smaller beam spot size. The thickness of the reproducing layer can be designed without limitation, and the resolution limit can be improved by irradiating the light beam from above the reproducing layer. Overall, this invention allows for better data storage and reproduction in optical data recording media.

Problems solved by technology

However, in the conventional optical data recording media, resolution limit is not enough.
In the example, a resin layer is used as the reproducing layer, and the resin is so adhesive that it is very difficult to attain a thin thickness of the resin layer.
Therefore, there is a limit in how thick the reproducing layer can be.
The arrangement in which the thickness of the reproducing layer is thin in view of the above limitation faces the following problem: for example, in the case that the reproducing layer has a greater transmittance with a thicker thickness, the thin thickness limits how much the laser spot can be reduced, thereby prohibiting the optical data recording medium from having a better resolution limit.
Also, it is considered that the resolution limit of the optical data recording medium is limited by various factors apart from the limitation of the thickness of the reproducing layer.

Method used

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  • Optical data recording medium and method for reproducing recorded data

Examples

Experimental program
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example 1

[0104]As an Example 1, an optical data recording medium having the following arrangement was produced (hereinafter, referred as “Example 1 disc”). As shown in the FIG. 1, pits creating a non-flat surface are provided on polyolefin-based resin substrate 5 having a 0.5 mm thickness. The pits corresponded to recorded data. On that surface of the polyolefin-based resin substrate 5 on which the pits are formed, an Al layer 4 (30 nm in thickness) used as a reflective layer, as Si layer 4 (50 nm in thickness) used as an light absorption layer, and a ZnO film 2 (225 nm in thickness) used as a reproducing layer were formed in this order. On a top surface of the reproducing layer 2, glass 1 (0.5 mm in thickness) as a cover layer was placed.

[0105]Also, as a Comparative Example, an optical data recording medium with following arrangement was produced (hereinafter referred as “conventional disc”). As shown in FIG. 4, pits creating a non-flat surface were provided on a polyolefin-based resin subs...

example 2

[0112]In Example 2, a material of the reproducing layer was examined.

[0113]An optical data recording medium (hereinafter Example 2 disc) used in Example 2 was identical with the Example 1 disc in the Example 1, except that the reproducing layer of the Example 2 disc was made of, instead of ZnO, SnO2. Correlation between mark lengths for signals, and qualities of the signals was measured for the Example 1 disc and Example 2 disc. The measurement was carried out as in Example 1. That is, the measurement of a C / N (appraisal standard of signal quality) of pits having 0.1 μm through 0.5 μm mark length (pit length) was carried out.

[0114]The results of the measurements of the Example 1 disc and the Example 2 disc are graphed in FIG. 6. In FIG. 6, the solid line is the result of the Example 1 disc, whereas the broken line is the result of the Example 2 disc. In FIG. 6, the horizontal axis shows the pit length, and the vertical axis is OTF (optical transfer function) showing C / N (appraisal s...

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Abstract

An optical data recording medium, in which irradiation of a light beam is used for recording and / or reproducing data includes (i) a substrate having an a rise and / or a recess which are a light-incident surface, (ii) a reflective layer, provided on the light-incident surface of the substrate, for reflecting the light beam, (iii) a light absorption layer for converting, to heat, a light of the light beam to heat on the surface of the reflective layer, (iv) a reproducing layer, provided on the surface of the heat-light converting layer, having a transmittance that changes in accordance with a light intensity distribution of the light beam. The optical data recording medium is excellent in super-resolution property, and enables reproduction of a shorter mark length.

Description

[0001]This Nonprovisional application is a Divisional application of prior copending U.S. patent application Ser. No. 10 / 824,926, filed on Apr. 14, 2004, entitled OPTICAL DATA RECORDING MEDIUM AND METHOD FOR REPRODUCING RECORDED DATA by Hideharu Tajima, Nobuyuki Takamori, Go Mori and Masaki Yamamoto (the same inventors as the inventors of this divisional application).[0002]This Nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2003 / 155668 filed in Japan on May 30, 2003, the entire contents of which are hereby incorporated by reference.FIELD OF THE INVENTION[0003]The present invention relates to (i) an optical data recording medium for recording or reproduction of data, and (ii) a method for reproducing data from the optical data recording medium.BACKGROUND OF THE INVENTION[0004]In order to obtain an optical data recording medium having bigger storage capacity, there has been a demand for a technique to record and reproduce a signal in accor...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G11B7/24G11B5/09G11B7/0045G11B7/005G11B7/007G11B7/013
CPCG11B7/24G11B7/243G11B7/257G11B2007/2571G11B2007/24304G11B2007/2432G11B7/258
Inventor TAJIMA, HIDEHARUTAKAMORI, NOBUYUKIMORI, GOYAMAMOTO, MASAKI
Owner SHARP KK
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