JPS60197956A - Optical disk - Google Patents

Abstract

PURPOSE:To obtain a titled optical disk which has a high weather resistance and a structure by sticking a protective plate to the surface of a recording layer through an organic material layer which has a high heat resisting property and can absorb a deformation of the surface of the recording layer. CONSTITUTION:An organic material layer 5 which has a high heat resisting property and absorbs a variation of the surface of a recording layer caused by a variation of a pit shape at the time of recording is applied to the surface of a recording layer 2. As for this organic material layer, a silicon compound resin, etc. are applied thinly and uniformly by a spin coating method, etc., and thereafter, after hardening it to some extent by heating, etc., a protective plate 7 made of glass, etc. is stuck to the upper face of the organic material layer 5 by using an adhesive agent 6 such as an ultraviolet hardened resin, etc. and formed as one body. As for an optical disk A constituted in such a way, the protective plate 7 obstructs completely a fact that moisture in the air invades the recording layer 2, therefore, that which has an extremely high weather resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The BJ4 of the present invention relates to optical discs, and particularly relates to improving the weather resistance and mass productivity of optical discs by making them thin and close-contact.

BACKGROUND TECHNOLOGY Original disk line is a disk-shaped transparent substrate with an optical recording layer provided on the surface, and a laser beam used to record image information on this optical recording layer.High-density recording. Since it is possible to record a large amount of information, it has recently attracted particular attention as a recording medium for one document file.

Figure 1 shows an optical disc (Direcl Bead After Write) with a protective layer that has been commonly used in the past.
te) is a cross-sectional view of a main part showing an example of irradiation with a laser beam. A recording layer 2 in which pits are formed by being irradiated with is deposited. A protective layer 3 is provided on the surface of the recording layer 20 from the viewpoint of improving the weather resistance of the recording layer 2 and handling it.

However, in the optical disc with the above configuration,
The protective layer 3 must have a thickness of 100 μm or more in order to obtain a protective effect, which makes it extremely difficult to manufacture, and it also has the problem of not being able to completely block out moisture in the atmosphere.

As a solution to this problem, an air sandwich type optical disc shown in FIG. 2 has been proposed. This air sandwich type optical disc has a recording layer 2' attached to the lower surface of a transparent substrate 1', which is disposed opposite to the upper surface of the recording layer 2 with an air gap 4 interposed therebetween. The optical disc has upper and lower transparent substrates 1
．． 1' can completely protect the recording layers 2 and 2', but if the air gap 4 is made completely airtight, moisture resistance will improve, but the internal gas will expand with changes in temperature and external pressure. This causes deformation. On the other hand, if the air cup is communicated with the outside air through a small hole, L≧ due to temperature change is prevented, but the recording layer 2.2' is attacked by moisture in the atmosphere. Furthermore, in the above-mentioned air sand inch type optical disc, the dimensions of the air gap 4 must be made uniform with accuracy and high precision, which causes various problems such as making it unsuitable for mass production. ing. Here, it is possible to adhere a protective plate to the surface of the recording layer 20 using an adhesive, but if the adhesive comes into contact with the recording layer 2, the recording layer 2 will be instantly eroded. become unable to fulfill its role as

DISCLOSURE OF THE INVENTION An object of the present invention is to provide an optical disc that is excellent in weather resistance and mass-producibility, and can have high recording sensitivity.

In order to achieve such an object, the optical disc according to the present invention has an organic material layer on a recording layer provided on a transparent substrate, which has high heat resistance and absorbs changes in the surface of the recording layer during recording. , a protective plate is adhered to the surface of this organic material layer.

Therefore, since the optical disc according to the present invention is of the contact type, it can be made much thinner than the air gap type, and is also structurally strong and suitable for mass production.

Furthermore, since the protective plate is bonded to the surface of the recording layer via the organic material layer, weather resistance is greatly improved. It was,
Since the weather resistance is improved and the heat conduction to the recording layer is improved, it becomes possible to use a recording layer made of a material that has low weather resistance, a low melting point, and a low thermal conductivity, but has high sensitivity.

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 3 is a cross-sectional view of essential parts showing an embodiment of an optical disc according to the present invention, and the same parts as those in FIGS. 1 and 2 are indicated by the same symbols. be. In the figure, reference numeral 5 denotes an organic material layer coated on the surface of the recording layer 2, which has high heat resistance and absorbs changes in the surface of the recording layer due to changes in pit shape during recording. As this organic material layer 5, (R, 58
10) A silicone resin or tsum consisting of n is used. However, R is an organic substance. Further, when forming the organic material layer 5, Cta, spin code, dipping, spraying, etc. can be used, but spin code is most suitable for thin and uniform coating. After the organic material layer 5 is applied, it is cured to some extent by heating or the like, and then glass is applied to the upper surface of the organic material layer 5 using an adhesive 6 such as an ultraviolet curing resin.

They are integrated by gluing a protective plate 7 made by Zorasnax or the like.

In the optical disc constructed in this way, the protection plate 7 completely prevents moisture in the air from penetrating the recording layer 2, so that the optical disc has extremely high weather resistance. In this case, the protective plate 7 is bonded using the adhesive 6, but since the adhesive 6 is prevented from directly contacting the recording layer 2 by the organic material layer 5, Erosion of the recording layer 2 by the adhesive 6 is completely prevented. In addition, when the protective plate 7 is bonded to the surface of the recording layer 2, there is a problem that the surface deformation of the recording layer 2 due to bit deformation during recording is prevented, and heat dissipation of the recording layer 2 due to the adhesive is reduced. )
This will result in deterioration of recording properties, but if an organic material layer 5 is provided on the surface of the recording layer 2 that has high heat resistance and can absorb surface deformation of the recording layer 2, , these problems will be solved all at once. Furthermore,
When the organic material R5 is provided, the heat dissipation for recording/fit 2 is increased, so it is possible to use a recording layer 2 with a low melting point and low thermal conductivity but with high sensitivity.As explained above, In the original disc according to the present invention, since the protective plate is bonded to the surface of the recording layer through an organic material layer that has high heat resistance and can absorb surface deformation of the recording layer, It has the excellent effect of increasing weather resistance without adversely affecting the structure, and having a strong, thin structure suitable for mass production.

[Brief explanation of drawings]

FIGS. 1 and 2 are sectional views of main parts showing a conventional example of an original disc, and FIG. 3 is a sectional view of main parts showing one embodiment of an optical disc based on the BAK of the present invention. DESCRIPTION OF SYMBOLS 1... Transparent substrate, 2... Recording layer%5... Organic material layer, 6... Adhesive, 7... Protective plate. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] (11) A transparent substrate that is light-transmitting and heat-resistant, and by being attached to the surface of this transparent substrate, P-pit deformation is caused by a laser beam supplied through the transparent substrate, and information is recorded. a heat-resistant organic material layer that absorbs surface deformation of the recording layer during recording; and a protective layer that is adhered to the surface of the organic material layer. An optical disk club characterized by having a plate.