JPS63142549A - Information carrier disk - Google Patents

Abstract

PURPOSE:To prevent deformation and failure of a disk substrate when recording and erasing are repeated by forming a recording medium layer on the disk substrate having heat resistance of >=200 deg.C thermal deformation temp. and forming a polyfluorocarbon layer and reflection layer thereon. CONSTITUTION:Track grooves 10 for guiding laser light are formed on one face of the disk substrate 9 consisting of a heat resistant resin material having >=200 deg.C thermal deformation temp. and the recording medium layer 11 is directly formed atop the same. The polyfluorocarbon layer 12 is further formed thereon by a sputtering method and after the reflection layer consisting of a thin metallic film is formed, a protective plate 14 is stuck by an adhesive agent 15 thereto. Recording and erasing are executed by projecting laser light 16 from the direction of the disk substrate 9. Since a heat insulating layer consisting of an inorg. material is not needed, the generation of the deformation, microcracks, etc., of the disk substrate by the heat of the laser light when the recording and erasing are repeated is prevented. The reliable disk is thus obtd.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an information carrier disk (hereinafter simply referred to as a disk) in which a recording medium layer is provided on a disc-shaped transparent substrate, and information is optically recorded, reproduced, or erased. It is related to the structure of

Conventional technology Conventionally, a recording medium layer is formed on one side of a disc substrate made of a disc-shaped transparent substrate, and minute holes are formed in the recording medium layer by irradiating laser light from the disc substrate side, or optically. Change the concentration 2 z4-.

Discs that perform recording and playback by converting the information into digital data have been put into practical use. Furthermore, erasing disks that allow repeated recording and erasing by reversibly changing the optical density of the recording medium layer are being put into practical use. In the case of this erasing disk, recording and erasing are performed by heating the recording medium layer with a laser beam above its melting point and then cooling it rapidly or gradually. When a resin material with low heat resistance, such as acrylic or polycarbonate, is used for the disk substrate, the disk substrate is deformed by the heat, making it impossible to repeat recording and erasing. Therefore, it is necessary to form a heat insulating layer between the disk substrate and the recording medium layer or on the recording medium layer to prevent thermal deformation.

Conventionally, various proposals have been made regarding the material of this heat insulating layer, but all of them are 5i02, A/N, 5i5N.
It was made of an inorganic material such as No. 4, and had a structure as shown in Figure 2. In FIG. 2, numeral 1 indicates a disk substrate made of a transparent resin material, and numeral 2 indicates a disk 37.

A track groove for guiding laser light is formed on one surface of the substrate 1; 3 is a first heat insulating layer made of an inorganic material formed on the track groove 2; 4 is a recording medium layer; A second heat insulating layer 5 made of an inorganic material is formed, and a protective plate 7 is attached via an adhesive 6 to protect this layer. In the configuration shown in FIG. 2, recording, reproduction, and erasing are performed by irradiating laser light from the direction of arrow 8 (for example, Japanese Patent Laid-Open No. 110052/1983).

Problems to be Solved by the Invention However, since the heat insulating layer is made of an inorganic material, there is a large difference in the coefficient of thermal expansion between the heat insulating layer and the disk substrate made of a resin material.・There was a problem in that the heat of the laser beam during repeated erasing caused the insulation layer to peel off between the disk substrate and cause minute cracks.

The present invention aims to provide a disk that prevents peeling and minute cracks between the heat insulating layer and the disk substrate, has excellent repeatability of recording and erasing, and has excellent productivity.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a disk substrate with integrally formed track grooves for use in the laser original image using a resin having heat resistance with a heat deformation temperature of 200°C or higher. formed of material,
After forming the recording medium layer directly on the track groove surface, a polyfluorocarbon film is formed on the recording medium layer by a sputtering method, and a reflective layer is formed thereon.

By protecting the recording medium layer formed on a heat-resistant disk substrate with a polyfluorocarbon layer, it is possible to prevent the disk substrate from deforming due to the heat of the laser beam during repeated recording and erasing. , it is possible to obtain a reliable disk that does not require a heat insulating layer made of an inorganic material.

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

In Fig. 1, 9 is 5, whose heat deformation temperature is 2o○°C or higher.

A disk substrate made of a heat-resistant resin material is provided with a trunk groove 10 for guiding laser light on one surface thereof.

11 is To 0x-Ge formed on the surface of the track groove 10.
The phase change recording medium layer has a composition of -8n and can be formed by sputtering, vapor deposition, or the like. Reference numeral 12 denotes a polyfluorocarbon layer formed by sputtering on the recording medium layer 11, and polytetrafluoroethylene, polytrifluoroethylene, etc. can be used as the polyfluorocarbon here. 13 is the layer 1 formed on the polyfluorocarbon layer 12. Cr
14 is a protective plate with adhesive 1.
5 is filled over the entire surface to form a laminated disk.

In the configuration shown in FIG. 1, recording and erasing are performed by irradiating a laser beam 16 in the direction of the disk substrate 9. That is, during recording, the recording medium layer 11 is heated and rapidly cooled to an amorphous state with low reflectance by irradiating it with a high power density laser beam focused to a spot diameter of about 1 μm, thereby forming information bits. During erasing, the recording medium layer 11 is heated and slowly cooled by irradiating it with a laser beam shaped like an ellipse (6/, -7) with low power density, becoming a crystalline state with high reflectance, and the information bits are erased. be done. Playback is recorded/
The recorded information bits are read using a laser beam of sufficiently lower power than during erasing. In addition, the reflective layer 13 improves the recording/erasing sensitivity by reflecting the laser beam that has passed through the recording medium layer 11. In this case, the accuracy of the film thickness of the polyfluorocarbon layer 12 is important; For example, λ/2n (where λ is the wavelength of the laser beam, n
is the refractive index of the polyfluorocarbon layer), so that it is possible to form a so-called optical gap with high precision.

In addition, regarding the heat resistance of the disk substrate 9, the following checks were conducted regarding the thermal deformation temperature and the repeated recording/erasing characteristics.

Example 1 Polycarbonate with a heat deformation temperature of about 130° C. was used as a disk substrate, a recording medium layer was formed directly on the disk substrate, and a polyfluorocarbon layer and a reflective layer were formed thereon. As a result of repeated recording and erasing with recording power smw and erasing power 16 mw (power at the recording medium layer), thermal deformation occurred in the disk substrate after about 100 repetitions, and noise increased significantly.

Example 2 An alicyclic methacrylate with a heat deformation temperature of 230°C was used as the disk substrate, and the same evaluation as in Example 1 was conducted. As a result, there was no increase in noise due to heat deformation after 10 repetitions. Good repeatability was obtained.

Example 3 Based on the results of Example 1.2 above, the composition ratio of the alicyclic methacrylate was changed to increase the heat distortion temperature to 150°C and 170°C.
i[::, 200° C. and the same evaluation was performed. As a result, by setting the thermal deformation temperature of the disk substrate to 200° C. or higher, there was no increase in noise due to thermal deformation, and good repeatability was obtained.

Based on the above results, the thermal deformation temperature of the disk substrate material was set to 200.
It was confirmed that thermal shock caused by laser light due to repeated recording and erasing can be prevented by heating the film to a temperature above ℃ without using a highly heat-resistant heat insulating layer made of an inorganic material.

In the embodiment shown in FIG. 1, an example of a phase change type optical disk has been described, but the present invention can also be applied to a magneto-optical disk in which recording and erasing are performed using the heat of a laser beam and a magnetic field. It is also possible to make a double-sided disc by using a disc substrate on which a recording medium layer, a polyfluorocarbon layer, and a reflective layer are formed as a protective plate.

Effects of the Invention The present invention forms a recording medium layer on a disk substrate having a heat distortion temperature of 200°C or more, and forms a polyfluorocarbon layer and a reflective layer, thereby replacing the conventional heat insulating layer made of an inorganic material. It can be removed, prevent peeling and minute cracks due to the difference in thermal expansion coefficient between the inorganic material heat insulating layer and the resin material disk substrate, and prevent deterioration of characteristics due to repeated recording and erasing. In addition, by forming a polyfluorocarbon layer by sputtering, 9/,
- It becomes possible to control the film thickness with high precision, and by selecting the film thickness of the layer, it is possible to improve the recording/erasing sensitivity by utilizing the interference effect. Furthermore, by making the recording medium layer sandwiched between resin materials that have a lower thermal conductivity than inorganic materials, it becomes difficult for the heat of the laser beam to escape, and the heat of the laser beam effectively acts on the recording medium layer. This allows recording and erasing with lower laser power than when using inorganic materials.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an information carrier disk according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional information carrier disk. 9... Disc substrate, 10... Track groove, 11... Recording medium layer, 12...
Polyfluorocarbon layer, 13... Reflective layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] Has a track groove on one side, heat deformation temperature is 200℃
An information carrier disk in which a recording medium layer, a protective layer, and a reflective layer are sequentially formed on a disk-shaped transparent substrate made of a resin material having heat resistance as described above, and the protective layer is made of a polyfluorocarbon sputtered film.