JPS58166546A - Recording member and recording and reproducing method - Google Patents

Abstract

PURPOSE:To perform the multilevel recording of information, by adjusting the intensity of a recording beam, and forming a different parts which have greater surface reflectance and less surface reflectance than an unrecorded part. CONSTITUTION:On a substrate 1, the 1st layer 2 having greater surface reflectance R2 is formed and then the 2nd layer 3 having less reflectance R1 is also formed thereupon. When incident light having relatively small intensity is irradiated to the substrate, only the 12nd layer 3 having a low melting point is melted and removed to expose the 1st layer 2 having the greater reflectance. When incident light having greater intensity is irradiated to the substrate, the 1st and 2nd layers are both melted and removed. The material of the substrate and the reflectance of the 1st, the 2nd layer materials, and film thickness are selected so that R3<R1<R2, realizing ternary recording of 0, 1, and -1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording member and a recording/reproducing method. In particular, the present invention relates to a recording member and a recording/reproducing method that utilizes evaporation, deformation, etc. due to heat generated directly or indirectly by irradiating a recording thin film formed on a substrate with a recording beam such as a laser beam.

Various recording members have been proposed so far for recording and reproducing information by irradiating them with a focused beam. But all these
When irradiated with light, the surface reflectance of the recorded area is either larger or smaller than that of the unrecorded area, and this difference in reflectance is made to correspond to two values, for example 0 and 1, for recording and playback. I am doing it.

By adjusting the intensity of the recording beam, the present invention achieves
The object of the present invention is to form portions with higher and lower surface reflectances than unrecorded portions, thereby performing multi-level recording of information.

FIG. 1 shows a recording film having a two-layer structure as an example of a recording film used in the present invention. A first layer 2 having a high refractive index, that is, surface reflectance, is formed on a substrate l, and A second layer 3 formed thereon/having a lower reflectance than this
This makes the recording film have an antireflection structure. Let the reflectance of this part be R1.

FIG. 6B shows the case where the recording pattern is irradiated with incident light of relatively low intensity. In this case, the second layer 3 with a lower melting point
The first layer 2 having a high reflectance appears on the surface. Let the reflectance of this part be R1.

FIG. 6(c) shows the case where incident light with a higher intensity than this is irradiated. In this case, the first layer 2 having a higher melting point can be used together with the second layer. This results in 0
．． 1. It becomes possible to perform three-value recording representing -1.

According to the present invention, for example, predetermined information is recorded in a portion with a surface reflectance R3, and an address or the like of the information is recorded in a portion with a surface reflectance R3. In this case, the substrate for recording the address is stronger than the recording of the predetermined information, as long as it has high mechanical strength and a low refractive index. Glass is a typical example, but various types of plastics can be used. Materials can also be used. In the case of plastic, part of the substrate surface may melt when the first layer is melted and removed.
This has no effect on the recording and reproduction of the present invention. As the material for the first layer, it is preferable to use a material with low thermal conductivity, such as BI or Te. Also %Kasho 55-126480K
As mentioned above, this portion may have a compositional change in the thickness direction.

The second layer consists primarily of organic material. It is desirable that the material forming the second layer has absorption for light of a predetermined wavelength, but even if it does not have absorption, the second layer will absorb heat generated in the first layer. It is melted away.

Furthermore, an intermediate layer may be provided between the first layer and the second layer in order to improve the reliability of the second layer.For this intermediate layer, for example, the material described in Japanese Patent Application No. 55-113510 may be used. I can do that.

For recording members with a multilayer structure of three or more layers, information corresponding to the surface reflectance of each layer can be recorded by sequentially melting and removing the upper layer, which has a lower melting point, in the same way as with a two-layer structure. .

It is preferable that the difference in melting point between the first layer) and the second layer is 501T or more. It is preferable that the difference in reflectance between the two is 5% or more.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 Te (m point 450C) was vacuum-deposited to a thickness of 40 nm on a glass substrate, and 5bzSs (melting point 5so
r) was vacuum-deposited to a thickness of 30 nm to form a first layer. A second layer was formed by coating polyα-methylstyrene (melting point: xzoC) on top of this to a thickness of 50 nm to complete a recording member. Semiconductor laser wavelength (8
The reflectance for light of 30 nm) is 60%, and the reflectance of the polyα-methylstyrene 1 surface is 30%. Further, the reflectance of the glass substrate is 5%. Writing was performed using a semiconductor laser while rotating the recording member at 24 rpm. When the laser output is below 7mW, polyα-
Only the methylstyrene layer was melted away.

When the laser output was increased to 7.5 mW or more, Sb Goose S
Even the @/Te layer was melted and removed.

Example 2 - A first layer was formed by vacuum-depositing Bj (melting point: 270 tl') to a thickness of 50 nm on a glass substrate. On top of this
A recording member was completed by vacuum depositing HHyi (melting point 76C) to a thickness of 7Qnm to form a second layer. The Bi coating surface reflectance is 65%, and the n-C36Hta surface reflectance Fi is 52%. Writing was performed on the recording member in the same manner as in Example 1.

n-Cs8H when the laser output is less than 8mW? Only the fourth layer is melted and removed, and at asmw or higher, up to the Bj layer is melted and removed.

[Brief explanation of the drawing]

FIG. 1 (-i-(b) and (c) are partial sectional views of the recording member of the present invention. 1... Substrate, 2... First layer, 3... Second layer. Layer. Figure 1 (θ-n (1)
)(C)

Claims (1)

[Scope of Claims] 1. In a recording member having at least two thin films on a substrate, the substrate and the thin films are made of materials with different reflectances, and the thin film of the two thin films is closer to the substrate. A recording member characterized in that it is made of a material whose melting point is higher than that of the other material. 2. A first layer formed on a substrate and having a reflectance for light of a predetermined wavelength that is larger than the reflectance of the substrate, and a first layer formed on this layer that has a lower melting point than the first layer and has a predetermined wavelength. a step of preparing a recording member comprising a second layer having a reflectance for light that is smaller than the reflectance of the first layer; A recording/reproducing method characterized by comprising a step of irradiating the irradiation light by changing the energy of the irradiation light so that both the first and second layers are melted.