Optical recording medium

Abstract

An optical recording medium with a high productivity is provided which can certainly record/reproduce data even when a blue or blue-violet laser beam is used as an irradiation light. An optical recording medium has a substrate and a recording layer. The recording layer includes a recording portion and a coating portion. The recording portion and the coating portion are all made substantially from Bi and O. The ratio of the number of O atoms to the total number of Bi atoms and O atoms of the coating portion is less than that of the recording portion. The ratio of the number of O atoms of the recording portion is in the range of from 62% to 77%. The ratio of the number of O atoms to the total number of Bi atoms and O atoms of the coating portion is in the range of from 60% to 70%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional side view schematically showing the structure of an optical recording medium according to a first exemplary embodiment of the present invention;

FIG. 2 is a flow chart showing an outline of manufacturing steps of the optical recording medium;

FIG. 3 is a cross sectional side view schematically showing the structure of an optical recording medium according to a second exemplary embodiment of the present invention;

FIG. 4 is a cross sectional side view schematically showing the structure of an optical recording medium according to a third exemplary embodiment of the present invention;

FIG. 5 is a graph showing a relationship between the reflectivity, 8T C/N values and the ratio of the number of O atoms to the total number of Bi atoms and O atoms of the coating portion of the recording layer for some samples in Working Example 1 of the present invention and Comparative Example 2;

FIG. 6 is a graph showing a relationship between the reflectivity, 8T C/N values and the ratio of the number of O atoms to the total number of Bi atoms and O atoms of the coating portion of the recording layer for some samples in Working Example 3 of the present invention and Comparative Example 2; and

FIG. 7 is a graph showing a relationship between the reflectivity, 8T C/N values and the ratio of the number of O atoms to the total number of Bi atoms and O atoms of the recording layer for the sample in Comparative Example 1.

Claims

1. An optical recording medium comprising: a substrate; anda recording layer formed over the substrate, wherein:the recording layer includes a recording portion, and a coating portion which coats at least one side of the recording portion in a direction of thickness;the recording portion and the coating portion are both made substantially from Bi and O;a ratio of number of O atoms to a total number of Bi atoms and o atoms of the coating portion is less than that of the recording portion;a ratio of number of O atoms to a total number of Bi atoms and o atoms of the recording portion is in a range of from 62% to 77%; andthe ratio of the number of O atoms to the total number of Bi atoms and O atoms of the coating portion is in a range of from 60% to 70%.

2. The optical recording medium according to claim 1, wherein the ratio of the number of O atoms to the total number of Bi atoms and O atoms of the coating portion is in a range of from 62% to 68%.

3. The optical recording medium according to claim 1, wherein the recording layer is configured such that the coating portion is provided on both sides of the recording portion in the direction of thickness.

4. The optical recording medium according to claim 2, wherein the recording layer is configured such that the coating portion is provided on both sides of the recording portion in the direction of thickness.

5. The optical recording medium according to claim 1, wherein a laser beam of a wavelength in a range of from 380 nm to 450 nm is irradiated for recording/reproducing data.

6. The optical recording medium according to claim 2, wherein a laser beam of a wavelength in a range of from 380 nm to 450 nm is irradiated for recording/reproducing data.

7. The optical recording medium according to claim 3, wherein a laser beam of a wavelength in a range of from 380 nm to 450 nm is irradiated for recording/reproducing data.

8. The optical recording medium according to claim 4, wherein a laser beam of a wavelength in a range of from 380 nm to 450 nm is irradiated for recording/reproducing data.