JP2743866B2 - Optical disk medium and optical disk recording / reproducing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high recording density optical disk medium capable of recording / reproducing information and an optical disk recording / reproducing method, and more particularly to an optical disk medium having a land area and a groove area as recording areas, and an optical disk recording / reproduction. About the method.

[0002]

2. Description of the Related Art A conventional optical disk medium and its recording / reproducing method will be described with reference to the drawings. FIG. 5 is a perspective sectional view of a conventional optical disk medium substrate having only a land portion as a recording / reproducing area, and FIG. 6 is a perspective sectional view of a conventional optical disk medium substrate having only a groove portion as a recording / reproducing area. FIG. The interval between the land portion 11 and the adjacent land portion in FIG. 5 or the interval between the groove portion 12 and the adjacent groove portion (track pitch) in FIG.
6 μm. When only the lands are used as the recording / reproducing areas, the lands are formed sufficiently wide. When only the grooves are used as the recording / reproducing areas, the grooves are formed sufficiently wide. In such a method, to increase the recording density, the track pitch must be narrowed.
Due to the limitations of the substrate manufacturing technology, there is a limit to high density.

In order to increase the recording density per optical disc, both the land and the groove are used as recording areas, and the ratio d of the width d of the groove to the width D of the land is set.
An optical disk medium with a / D of 1.0 is disclosed in
No. 7027 (see FIG. 7). Also,
In order to further improve the recording density, it is necessary to reduce the interval (groove pitch) between the groove portions. This is difficult in manufacturing due to the limitations of the substrate manufacturing technology.

[0004]

When an optical disk medium is manufactured using a substrate having such a structure, as shown in FIG. 8, the recording / reproducing performance at the land portion and the recording / reproducing performance at the groove portion are reduced. A big difference occurs. In addition, record
There is no study as to whether the polarization plane of the laser beam used for reproduction is perpendicular or parallel to the guide groove. Furthermore, while reducing the group pitch, d / D
It is very difficult in production to make 1.0.

An object of the present invention is to provide an optical disk medium and an optical disk having the same recording / reproducing performance of a land portion and a groove portion while maintaining a high ratio of a recording area to a disk area, that is, uniform characteristics over the entire disk surface. It is to provide a recording / reproducing method.

[0006]

SUMMARY OF THE INVENTION According to the present invention, land portions and groove portions having different heights are alternately arranged spirally or concentrically with respect to the center of rotation to form guide grooves. In a recordable / reproducible optical disk medium in which a recording film capable of recording, erasing or reading is formed and a land portion and a groove portion are used as recording areas, the width D of the land portion is different from the width d of the groove portion. The ratio d / D of the width d of the groove portion to the width D of the land portion is:
In the optical disc recording / reproducing method using this optical disc medium, the laser beam used for recording / reproducing is linearly polarized, and the polarization plane of the laser beam is Is preferably perpendicular to the guide groove.

Further, according to the present invention, land portions and groove portions having different heights are alternately arranged spirally or concentrically with respect to the center of rotation to form guide grooves, and recording, erasing or recording is performed by irradiating a laser beam. In a recordable / reproducible optical disk medium in which a readable recording film is formed and a land and a groove are used as recording areas, the width D of the land is used.
And the width d of the groove portion is different, and the ratio d / D of the width d of the groove portion to the width D of the land portion is in the range of 0.85 to 0.98. In an optical disk recording / reproducing method using an optical disk medium,
It is desirable that the laser light used for recording / reproducing be linearly polarized light and that the plane of polarization of the laser light be parallel to the guide groove.

[0008]

According to the present invention, the width d of the groove and the width D of the land are determined.
By changing the polarization direction of the laser beam used for recording / reproducing according to the magnitude of the ratio d / D, uniform and good recording / reproducing characteristics can be obtained over the entire surface of the optical disk medium. In addition, when the group pitch is narrowed to increase the recording density, a margin at the time of manufacturing a substrate can be obtained at the same time.

[0009]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view of a substrate showing a first embodiment of the optical disk medium of the present invention, and FIG. 2 is a diagram showing the relationship between the groove width d and the land width D of the optical disk medium of FIG. It is a figure which shows the change of carrier level difference (DELTA) C and noise level difference (DELTA) N with respect to ratio d / D. In FIG. 1, the ratio d / D of the groove width d to the land width D is 0.9 to 1.2.
5, a SiN first dielectric film (80 nm) and a TbFeCo magnetic film (25 n
m), a SiN second dielectric film (18 nm) and an AlTi reflection film (40 nm) were sequentially laminated by a sputtering method, and a UV protective film was further formed thereon to obtain a magneto-optical disk medium.

The magneto-optical disk medium was evaluated by using the optical disk recording / reproducing method of the present invention in which the laser beam used for recording / reproducing was linearly polarized light and the plane of polarization was perpendicular to the guide groove. The difference between the carrier level C1 and the noise level N1 of the land part, the carrier level C2 and the noise level N2 of the group part is represented by ΔC = C1.
−C2, ΔN = N1−N2. D / D of ΔC and ΔN
2 is shown in FIG. When d / D is smaller than 1.0, that is, when the width of the land portion 1 is larger than the width of the groove portion 2, the carrier level of the land portion 1 becomes larger than the carrier level of the groove portion 2, and ΔC becomes smaller. It grows positive. However, if d / D is greater than 1.0, ΔC monotonically decreases. On the other hand, ΔN increases almost monotonously. Therefore, in an optical disk medium having a land portion and a groove portion as a recording / reproducing area, in order to make the performance of the land portion and the performance of the groove portion the same, the ratio d / d of the width d of the groove portion to the width D of the land portion. D is about 1.05
To 1.15.

FIG. 3 is a schematic sectional view of a substrate showing a second embodiment of the optical disk medium of the present invention. FIG. 4 is a diagram showing the relationship between the width d of the groove portion and the width D of the land portion of the optical disk medium of FIG. It is a figure which shows the change of carrier level difference (DELTA) C and noise level difference (DELTA) N with respect to ratio (d / D). In FIG. 3, S is formed on a disk substrate manufactured by changing the ratio d / D of the width d of the groove portion to the width D of the land portion from 0.75 to 1.05.
iN first dielectric film (61 nm), GdFeCo magnetic film (30 nm), TbFeCo magnetic film (30 nm), Si
N second dielectric film (124 nm), AlTi reflection film (40
nm) were sequentially laminated by a sputtering method, and a UV protective film was formed thereon to obtain a magneto-optical disk medium. Where G
The dFeCo magnetic film and the TbFeCo magnetic film are exchange-coupled so that the transfer of magnetization from the TbFeCo magnetic film to the GdFeCo magnetic film occurs.

The magneto-optical disk medium was evaluated using the optical disk recording / reproducing method of the present invention in which the laser beam used for recording / reproducing is linearly polarized light and the plane of polarization is parallel to the guide groove. The difference between the carrier level C1 and the noise level N1 of the land part, the carrier level C2 and the noise level N2 of the group part is represented by ΔC = C1.
−C2, ΔN = N1−N2. D / D of ΔC and ΔN
4 is shown in FIG. When d / D is larger than 1.0, that is, when the width of the land portion 1 is smaller than the width of the groove portion 2, the carrier level of the land portion 1 becomes larger than the carrier level of the groove portion 2, and ΔC becomes smaller. It grows positive. However, if d / D is smaller than 1.0, ΔC monotonously decreases. On the other hand, ΔN increases almost monotonously. Therefore, in an optical disk medium having a land portion and a groove portion as a recording / reproducing area, in order to make the performance of the land portion and the performance of the groove portion the same, the ratio d / d of the width d of the groove portion to the width D of the land portion. D about 0.85
And between 0.98 and 0.98.

[0014]

According to the present invention as described above,
A high-density optical disk medium having uniform characteristics over the entire surface of the disk while maintaining a high ratio of the recording area to the disk area, and a recording / reproducing apparatus for the medium can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic perspective sectional view of an optical disk medium substrate showing a first embodiment of the present invention.

FIG. 2 is a diagram showing changes in carrier level difference ΔC and noise level difference ΔN with respect to d / D.

FIG. 3 is a schematic perspective sectional view of an optical disk medium substrate according to a second embodiment of the present invention.

FIG. 4 is a diagram showing changes in carrier level difference ΔC and noise level difference ΔN with respect to d / D.

FIG. 5 is a perspective sectional view of a conventional optical disk medium substrate having only a land portion as a recording area.

FIG. 6 is a perspective sectional view of a conventional optical disk medium substrate having only a groove portion as a recording area.

FIG. 7 is a perspective sectional view of a conventional optical disk medium substrate having a land portion and a groove portion as recording areas.

FIG. 8 is a diagram showing a comparison between C / N ratios of a land portion and a groove portion when a substrate having a d / D of 1.0 is used.

[Explanation of symbols]

 11 Land 12 Groove 13 Slope

Claims (6)

(57) [Claims] 1. A recording groove which is formed by alternately arranging land portions and groove portions having different heights spirally or concentrically with respect to a center of rotation to form a guide groove, and capable of recording, erasing or reading out by irradiating a laser beam. In a recordable / reproducible optical disk medium in which a film is formed and a land portion and a groove portion are used as recording areas, the width D of the land portion is different from the width d of the groove portion, and the width d of the groove portion is different from the width d of the groove portion. An optical disc medium, wherein a ratio d / D to a width D of the land is in a range of 1.05 to 1.15. 2. The optical disk medium according to claim 1, wherein a magnetic film is used as said recording film. 3. An optical disk recording / reproducing method using an optical disk medium according to claim 2, wherein the laser light used for recording / reproducing is linearly polarized light, and the polarization plane of the laser light is perpendicular to the guide groove. An optical disk recording / reproducing method characterized by the following. 4. A recording groove which is formed by alternately arranging land portions and groove portions having different heights spirally or concentrically with respect to the center of rotation to form a guide groove, and capable of recording, erasing or reading out by irradiating a laser beam. In a recordable / reproducible optical disk medium in which a film is formed and a land portion and a groove portion are used as recording areas, the width D of the land portion is different from the width d of the groove portion, and the width d of the groove portion is different from the width d of the groove portion. An optical disc medium, wherein a ratio d / D to a width D of the land is in a range of 0.85 to 0.98. 5. The optical disk medium according to claim 4, wherein a magnetic film is used as said recording film. 6. An optical disk recording / reproducing method using an optical disk medium according to claim 5, wherein the laser beam used for recording / reproducing is linearly polarized light, and the polarization plane of the laser beam is parallel to the guide groove. An optical disk recording / reproducing method characterized by the following.