JPH0391128A - Optical recording member - Google Patents

Abstract

PURPOSE:To increase an initial reflectivity and an increase in the change of the reflectivity before and after recording by forming a high-refractive index dielectric layer at the odd number layer and a low-refractive index dielectric layer at the even number layer, and laminating these layers to >=2 layers, then forming a recording layer by using a material which is changed in double refractive index by irradiation with a laser beam. CONSTITUTION:The high-refractive index dielectric layer 2 consisting of any of ZnS, ZnSe, TiO2, CeO2 or HfO2 is formed at the odd number layer and the low-refractive index dielectric layer 3 consisting of any of MgF2, CaF3 or NaAlF4 is formed at the even number layer. These layers are laminated in 2 to 7 layers. Th recording layer 1 is formed by using the material which is formed with recesses or holes or is changed in double refractive index by the irradiation with the laser beam. The initial reflectivity and the change in the reflectivity of a boring type optical disk or phase change type optical disk etc., are increased in this way.

Description

[Detailed description of the invention] [Industrial application field] The present invention records information by irradiating laser light.

The present invention relates to an optical recording ff1 body to be reproduced, and particularly to an optical recording carrier having an improved film structure of an optical recording film.

[Prior art and problems to be solved by the invention] In recent years, efforts have been made to develop rewritable information recording carriers (also referred to as "optical recording media" or "optical discs") that record and reproduce information using laser light. is being advanced. These optical record carriers include "punching type optical recording media" in which bits are formed by partially melting or sublimating the recording film using the heat of laser light, and "punching type optical recording media" in which bits are formed by partially melting or sublimating the recording film by the heat of laser light, and in which bits are formed by changing the complex refractive index of the recording film by heat. "Phase-change optical recording media" that record information, or "alloy-forming optical recording media" that record information by forming an alloy at the interface of two types of recording layers using heat, have been used. The initial reflectance of the medium is at most 50%. Therefore, compared to playback-only optical discs, greater playback power (laser light irradiation) is required.
The load between drives is increasing. Further, since the reflectance change between the recorded portion and the unrecorded portion is as low as about 20%, a large reproduction output cannot be obtained.

In order to increase the initial reflectance of the recording medium, A g and A u are added to the main component of the recording film or to the additive reflective layer.

It is possible to use high reflectivity metals such as AJI, Cu, Rh, etc., but these metals also have high thermal conductivity, so
It is not possible to form good bits because the sensitivity to laser is low and heat spreads easily.Also, it is possible to use interference as a means to increase the initial reflectance of the disk without using metals with high thermal conductivity. However, no significant improvement can be expected with a single-layer interference film.Therefore, we developed a method that maintains the thermal conductivity of conventional recording media without using high-reflectance metals, while reducing the initial reflectance and changes in reflectance before and after recording. It is desired to develop a medium that can increase the amount of energy.

[Means to solve the problem]

In the present invention, a high refractive index dielectric layer is formed in the odd-numbered layers of an optical record carrier in which a plurality of layers are formed on a disk substrate, and a low-refractive index dielectric layer is formed in the even-numbered layers. After laminating more than one layer, a recording layer is formed using a substance whose complex refractive index changes by laser irradiation, or a low refractive index dielectric and a high refractive index dielectric are alternately laminated on top of the recording layer. !
The above-mentioned problems have been solved by providing an optical record carrier with a 411-speed transmission.

〔Example〕

Below, specific examples of the optical record carrier of the present invention are shown in FIG.
This will be explained with reference to FIG. 6 and the like.

<Example 1> While rotating a PC disk substrate in a vacuum chamber evacuated to about 10-'Pa, vacuum evaporation was performed.
A film of ZnS100n11 is formed in the first layer and the fifth layer,
M g F 2170nn in the second and fourth layers.

A 5-layer interference layer made of 200 nm of ZnS was provided as the third layer, and on top of that was a Te-based phase change recording Jl1100.
A film of n1m was formed.

The film structure of this disk is shown in FIG. 2, and the spectral reflectance of this recording layer before and after the phase change is shown in FIG. The Te-based phase change medium has a through hole, an initial reflectance of 30%, and a recording area of 5.
However, in a disk provided with such a five-layer interference layer, when observed at a wavelength of 830 nll, the initial reflectance is 61% and becomes 78% after recording. In this way, the change in reflectance of the phase change medium could be shifted between the high reflectance layers by the five-layer interference layer. When this disc was recorded with a single frequency of 450 kHz at a linear velocity of 1.3 m/s and reproduced with a reproduction power of 0.3 + 1 W,
A C/N of 47 dB was obtained.

<Example 2> After forming the five-layer interference layer shown in Example 1 on a PC board,
20nll of Te-based drilling medium was applied to the sixth layer. FIG. 4 shows the relationship between the film thickness and the reflectance when the third layer ZnS film thickness of such a disk is changed. When the thickness of the third layer is 80 nn, it functions as a low-to-hiah type drilling medium with a reflectance of 50% in the unrecorded part and 82% in the recorded part, but when the thickness of the third layer is about 165 nn. The unrecorded portion is 35% and the recorded portion is close to 0%, and functions as a high-to-low type drilling medium. In this way, by adjusting the thickness of the multilayer interference layer, the behavior of the reflectance change of the medium can be changed significantly in appearance.

<Example 3> On a PC board, as shown in FIG. 5, ZnS was formed in the first layer as a high refractive index dielectric layer, and M g F 2170 nll was formed as the second layer as a low refractive index dielectric layer. After the membrane,
A phase change medium recording layer of 100n11 was provided, and the fourth layer was made of M g F and the fifth layer was made of Z n S.
A film of 100 nfl was deposited.

The initial reflectance of the disc was 37%, and after recording it was 2.
This will increase by 6% to 63% (see Figure 6).

However, in a disk with a single layer of phase change medium that does not use an interference layer, the initial reflectance is 12%, and after recording it is 27%, which is 15%.
The reflectance increases only.

In this way, by using a multilayer interference layer, it is possible to increase the initial reflectance of the recording medium and also increase the change in reflectance.

〔effect〕

The optical record carrier of the present invention has the excellent feature of increasing initial reflectance and change in reflectance in hole-punched optical discs, phase change optical discs, and the like.

[Brief explanation of drawings]

1, 2, and 5 are enlarged partial sectional views of the optical record carrier of the present invention, FIG. 3 is a spectral reflectance characteristic diagram of the optical record carrier of the first embodiment, and FIGS. 4 and 6. 2A and 2B are characteristic diagrams showing the relationship between the film thickness of the recording film and the reflectance in the media of the second example and the third example, respectively. DESCRIPTION OF SYMBOLS 1... Recording layer, 2... High refractive index material, 3... Low refractive index material, 4... Substrate.

Claims (2)

[Claims] (1) An optical recording carrier in which multiple layers are formed on a disk substrate made of resin or glass, in which the odd-numbered layers are made of ZnS.
, ZnSe, TiO_2, CeO_2 or HfO_2, and the even numbered layers are MgF_2, CaF_3 or NaAlF_6.
Form any one of the low refractive index dielectric layers and laminate 2 to 7 layers of these, and further use a material in which recesses or holes are formed by laser irradiation, or a material whose complex refractive index changes. An optical record carrier comprising a recording layer. (2) An optical record carrier in which multiple layers are formed on a disk substrate, in which a high refractive index dielectric layer is formed in the odd-numbered layers and a low-refractive index dielectric layer is formed in the even-numbered layers. After laminating two or more layers, a recording layer was formed using a substance whose complex refractive index was changed by laser irradiation, and then a low refractive index dielectric and a high refractive index dielectric were alternately laminated on top of the recording layer. An optical recording carrier characterized by having a film structure.