JPH01109552A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain a recording medium which does not increase the crosstalks of signals even if a high-density optical recording material is used by forming said medium into the structure in which recording layers are formed only in the grooves formed on a base material having the grooves for tracking servo on the surface. CONSTITUTION:The grooves are spirally formed at, for example, 0.8mum width and 0.1mum depth at 1.6mum pitch on the surface of the substrate 1. The optical recording materials 2 are provided in the grooves for tracking servo. The coating of this optical recording material 2 is executed by coating the material 2 over the entire surface of the substrate 1, then pressing the blade of a cutter thereto to completely remove the material 2 on the outside of the grooves. Pits 3, 4 after recording have the shapes shown in the figure when 1MHz signals are recorded on the recording layers 2 by projecting a 780mum semiconductor laser on said layers while subjecting such optical recording medium to the tracking servo. The performance as excellent as <=20% crosstalk is thus obtd.

Description

[Detailed description of the invention] Industrial applications The present invention relates to optical recording media.

Conventional Technology The need for large-capacity external storage media has been increasing as a core technology supporting an advanced information society. Optical recording media using laser beams have appeared as one answer to this social demand. For this reason, optical recording media are always required to have higher storage densities and faster information transfer speeds. However, it is extremely difficult to satisfy these two requirements simultaneously. This is because in order to increase the recording density, the recording focus must be small, and on the other hand, in order to achieve a high transfer rate, it is necessary to increase the sensitivity of the recording material.

FIG. 3 shows a cross-sectional view of a conventional optical recording medium.

When recording on this medium, the radius of focus becomes large, and when they are adjacent to each other, the positions 6 and 7 come into contact, resulting in increased crosstalk.

Problems to be Solved by the Invention However, the higher the sensitivity of the material, the larger the recording pit diameter during recording, which has the drawback of increasing crosstalk between adjacent focal points. In addition, in general, highly sensitive materials often have poor reliability (and it has been difficult to find recording materials that are both highly sensitive and highly reliable.

Means for Solving the Problems The present invention attempts to solve these conventional problems and simultaneously satisfy high recording density and high reliability. The optical recording material is formed only in the grooves formed in the grooves.

Function: In the optical recording medium of the present invention, the optical recording material exists only in the groove for tracking servo, so even when irradiated with strong recording light, the size of the recording spot will not exceed the groove width. Therefore, crosstalk between adjacent recording focuses does not increase.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a cross-sectional view of the optical recording medium of the present invention cut at right angles to the direction of grooves for tracking servo. When recording on such a medium, two adjacent pits 3 and 4 can maintain a predetermined distance, as shown in FIG. 2, even if recording is performed with a slightly higher energy. Therefore, it is possible to use an optical recording material with very high sensitivity, or it is possible to record at high output using an optical recording material that is not so sensitive but has excellent stability.

Example 1 A dye +
11 was applied thickly to the entire surface.

Next, the dye (1) applied outside the grooves was completely removed by applying a cutter blade to the surface. 1. Irradiate the dye with a 780 nm semiconductor laser while applying tracking servo. The Mtlz signal was recorded. The recording conditions are output 5
At 10 mW and a linear velocity of 3 m/s, the Airy disk of the focused laser was 1.2 μm, and the frequency duty ratio was 50150. As a result of reproducing the signal on the recorded disc at a reproduction output Q of 3 mW, the fifth
As shown in the figure, the recording output is 5-5-1O and the C/N is 50dB.
In addition, excellent performance with crosstalk of 20% or less was obtained.

Comparative Example 1 Using the same glass disk as in Example 1, a dye fil was coated on the surface to a thickness of 0.16 μm, resulting in a recording medium having the cross-sectional structure shown in FIG. 3. On the other hand, while applying the tracking servo with a recording output of 5-5-1O,
FIG. 4 shows a cross section of the optical recording medium after recording with a semiconductor laser (780 nm).

Figure 6 shows the results when this was reproduced at 0.3 mW. As is clear from the figure, the crosstalk is already large even at low outputs, but it becomes even larger on the high output side, and accordingly, the C/N also decreases on the high output side.

Effects of the Invention As is clear from the examples, the optical recording medium of the present invention, which is characterized in that the recording material exists only in the tracking groove, does not cause large signal crosstalk even when a high-density optical recording material is used. Therefore, it is a very effective medium when recording at high speed using a high-power laser (ie, high transfer speed).

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an optical recording medium according to an embodiment of the present invention in an unrecorded state, Fig. 2 is a sectional view of an optical recording medium according to an embodiment of the present invention in a post-recorded state, and Fig. 3 is a comparison. 4 is a sectional view of the comparative example in an unrecorded state, FIG. 5 is a graph showing the electrical characteristics of the example of the present invention, and FIG. 6 is the electrical characteristics of the comparative example. This is a graph showing. 1...substrate, 2...optical recording material, 3,
4...Pit after recording. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1
1-1 obscene 2-° general drum key

Claims (1)

[Claims] An optical recording medium having a structure in which a recording layer is formed only in the grooves on a base material having grooves for tracking servo on the surface.