JPS61943A - Light memory disk - Google Patents

Abstract

PURPOSE:To obtain a light memory disk excellent in weatherproof by interposing a thin Cr film layer excellent in adhesion between a substrate and a recording film or between the recording film and a protective layer. CONSTITUTION:A thin Cr layer 37 is provided on a substrate 31, and a thin TeOx film 33 is formed as a recording film on it. Further, a protective substrate 34 is stuck fast through bonding resin 36 to complete a disk. In such constitution, peeling off is not caused for a long time between the substrate and recording film under surroundings of 90% humidity, and weatherproofness is improved remarkably. The reason is that Cr has high adhesion to material to be bonded and enhances adhesion between the substrate 31 and recording film 32. Proper thickness of the thin Cr film between the substrate and recording film is from 0.5nm to 5nm. By interposing this thin Cr film layer 68 between the recording film 63 and protective layer 64, adhesion of the two can be enhanced effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the structure of an optical memory disk in which information is recorded in a recording film by means of light irradiation.

Conventional configurations and their problems In recent years, optical memory disks capable of recording and reproducing in real time have been highly anticipated as large-capacity memories. For example, this uses light to irradiate a high-speed rotating disk to record bits on its recording film, and then read the data using the light. Recording and playback are performed without contacting the disk, so there is no need to damage the pickup or the disk, and there is no need to damage the information. It has advantages such as fast access.

FIG. 1 shows a part of a cross section of an optical memory disk and an example of a light irradiation state. A concave or convex groove trunk 12 that enables light tracking is formed on a substrate 11 made of a transparent material, and a recording film 13 is formed on this. During recording and reproduction, tracking control is performed so that the light spot 15 runs along this groove track 12.

Recording that enables real-time recording and playback [13 is Te
There is an Ox (0<x<2) thin film. This TeO work is T e
It is a mixture of O2 and Te, and undergoes phase transformation due to heat caused by light irradiation, increasing reflectance and decreasing transmittance, thereby forming recording bits.

Since the volume change of the recording film itself is not utilized, the protective layer 14 made of resin or the like can be directly formed on the recording film 13. Therefore, it is possible to obtain a disk structure that has excellent strength and is easy to handle.

One of the important factors required for optical discs is weather resistance, and it is necessary to guarantee the quality of the disc over a long period of time. However, under harsh conditions of high temperature and humidity, the deterioration of disc quality is accelerated and the warranty period is shortened.

For example, in the case of a disk in which a TeO□ thin film 23 is formed on an acrylic substrate 21 having groove tracks 22 as shown in FIG. %, no change in disc quality is observed even after several decades in an environment of normal temperature and humidity.However, under a harsh environment of 70°C and 90% humidity, the substrate 21 and T e Ox Thin film 2
Peeling can be seen between 3 and 3. This is considered to be because moisture infiltrates through the substrate and this moisture breaks down the bonding force between the substrate 11 and the TeO thin film 13. Optical memory disks play the role of storing data over long periods of time, and it is desirable that the disk quality remains intact even under harsh environments. In this sense as well, it can be said that the optical memory disk with the above-mentioned configuration has a problem with weather resistance, and it is desirable to guarantee quality for a longer period of time. A similar effect can be obtained by providing a Ni layer for Or.

OBJECT OF THE INVENTION The present invention solves the above-mentioned problems, and provides an optical memory disk with excellent weather resistance and no peeling between the substrate and the recording film even under harsh conditions of high temperature and high humidity. With the goal.

Structure of the Invention The present invention improves the adhesion between the substrate or the protective layer and the recording film by interposing a Cr thin film layer between the substrate and the recording film or between the recording film and the protective layer, and improves the adhesion between the substrate or the protective layer and the recording film under high temperature and high humidity conditions. This prevents the recording film from peeling off even if it is located underneath.

DESCRIPTION OF THE EMBODIMENTS FIG. 3 is a sectional view of an optical memory disk showing an embodiment of the present invention. On an acrylic substrate 31 having concentric or serpentine groove tracks 32, an Or thin film layer 37 with a thickness of, for example, 2 nm is provided by, for example, a vacuum evaporation method, and a Teoz thin film 33 as a recording film is further applied thereon. was formed to a thickness of about 120 nm by vacuum evaporation.Furthermore, in order to protect the recording film 33, an acrylic retentive substrate 34 was adhered via an adhesive resin 36 to complete the disk. In the case without the Or thin film layer 37, as mentioned above, peeling occurred between the substrate and the recording film after about 1000 hours in an environment with a temperature of 70'C and a humidity of 90%, but in the case of the present invention shown in FIG. In this case, no peeling occurred for up to 7,000 hours, and the weather resistance was greatly improved. This is because Cr has very good adhesion to the other material and acts as a bridge between the acrylic substrate 31 and the recording film 32, increasing the adhesion between them. Figure 4 shows the time until peeling occurs between the substrate and the recording film and the Cr thin film layer under an environment of temperature 70°C and humidity 90% when discs were made with various thicknesses of the Cr thin film layer in Figure 3. The relationship between the thickness of By adding a Cr thin film layer, it takes a long time to reach peeling, and it is effective when the thickness is 0.5 nm or more.

FIG. 5 shows whether the presence of a Cr thin film layer between the substrate and the recording film affects the recording and reproducing characteristics. This rotates the disk at 180°upm, and
The C/N was determined when recording a single frequency s MHz gold, and when there is no Cr thin film layer, it shows eodB [7], but when there is an OOrCr thin film layer, there is almost no change in C, /H. However, when the thickness exceeds 6 nm, the C/N starts to decrease. This is because the Cr thin film layer is located on the front side of the silver film when viewed from the light irradiation side, so as the Cr thin film layer becomes thicker, the reflectance change of the recorded bit becomes smaller, but there is no problem if the thickness is 6 nm or less.

From the above, the thickness of the Cr thin film layer between the substrate and the recording film is 0.
．． A range of 5 nm to 6 nm is suitable. It is also effective to interpose this Cr thin film layer between the recording film 63 and the protective layer 64, as shown in FIG. 6, to improve the adhesion between the two. However, in this case, the Cr thin film 68 is not in a positional relationship that affects recording and reproduction, so 0. Snm
If the film thickness is above, there is no problem with adhesion.

Although the recording film is described as Teox, other components,
For example, the effect is the same even if Teox is added with Ge, Sn, etc. Furthermore, it is effective for recording films having a multilayer structure as well as for recording films having a perforated recording mechanism.

In this embodiment, the substrate is made of acrylic, but the same effect can be obtained by using a polycarbonate substrate.

Effects of the Invention As described above, according to the present invention, by interposing a Cr thin film layer with excellent adhesion between the substrate and the recording film, or between the recording film and the protective layer, the substrate or the protective layer and the recording layer are interposed. It is possible to obtain an optical memory disk with improved adhesion to the film and excellent weather resistance, which has great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an optical memory disk showing an overview of the optical memory disk, FIG. 2 is a cross-sectional view of a conventional optical memory disk, FIG. 3 is a cross-sectional view of an optical memory disk according to an embodiment of the present invention, and FIG. Same optical memory disk Cr
A characteristic diagram showing the relationship between the thickness of the thin film layer and the time until separation occurs between the substrate and the recording film. Figure 5 shows the relationship between the thickness of the Cr thin film layer and C.
FIG. 6 is a cross-sectional view of an optical memory disk according to a second embodiment of the present invention. 11.21. 31... Board, 12, 22.32
... Groove truck, 13.23.33.63...
...Recording film (Tea, thin film), 14, e
4----Protective layer, 26°36...adhesive resin, 37.68...Cr thin film layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 (Me/111161 Figure 5 C, Ark tank IF + thickness (First J

Claims (3)

[Claims] (1) An optical memory disk comprising at least a substrate and a recording film formed on the substrate, and having a Cr thin film layer on at least one side of the recording film. (2) The optical memory disk according to claim 1, wherein the thickness of the Cr thin film layer is in the range of 0.5 nm to 5 nm. (3) The optical memory disk according to claim 1, wherein the recording film has TeO_x (0<x<2) as a main component.