JPH0354743A - Optical disk - Google Patents

Abstract

PURPOSE:To obtain different recording layers on both surfaces and to facilitate production by sticking a transparent substrate which carries the recording layer of a DRAW type on the main surface and the other transparent substrate which carries the rewriting type recording layer on the main surface to each other in such a manner that the respective recording layers face each other. CONSTITUTION:The transparent substrate 2 which carries the recording layer 1 of the DRAW type consisting of a cyanine dye stuff, etc., on the main surface and the other transparent substrate 2a which carries the rewriting type recording layer 5 by a magneto-optical or phase change on the main surface are stuck to each other by an adhesive agent layer 4 via annular spacers 3 in such a manner that the respective recording layers 1, 5 face each other while an internal space is maintained. A magnetic hub 10 is adhered to both apertures of a central hole. The air sandwich type optical disk which has the different recording layers on both surfaces and allows easy production is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an optical information recording disk (hereinafter referred to as an optical disk), and particularly to a recordable and rewritable optical disk.

BACKGROUND ART Write-once optical discs as shown in FIG. 3 have been known. Such a write-once optical disk is prepared by preparing two perforated substrates 2 each carrying an organic cyanine dye recording layer 1 on its main surface, and maintaining an internal space with each cyanine dye recording layer 1 facing each other. They are attached with an adhesive layer 4 with an annular spacer 3 interposed therebetween. In recent years, there has been a growing desire to record information in a rewritten manner on such write-once optical discs.

Therefore, an optical disc that can be freely written to and rewritten was developed in Japanese Patent Application Publication No. 6
2-250532. Such an optical disc, as shown in FIG.
A write-once recording layer 1 made of a metal oxide is provided on the outer peripheral side,
GdTbF, which is a rewritable recording layer, is placed on a part of the inner circumferential side.
By providing a magneto-optical medium made of an e-based alloy or a phase change type recording layer 5 such as SnTeSe on the same substrate plane, both additional writing and rewriting can be performed.

However, in such a write-once and rewritable optical disk, after partially forming the magneto-optical recording layer or the phase change recording layer 5 and the write-once recording layer 1, each having a different laminated structure, on the main surface of one substrate 2. It is necessary to form a film to protect one recording layer and to form the other recording layer on the remaining portion of the substrate 2.

Therefore, the number of manufacturing steps increases, and the chances of defects occurring on the recording layer increase, resulting in a decrease in product yield.

SUMMARY OF THE INVENTION An object of the present invention is to provide an air sandwich type optical disk that has different types of recording layers on both sides and is easy to manufacture.

The optical disc of the present invention mainly consists of a transparent substrate carrying a write-once recording layer and another transparent substrate carrying a rewritable recording layer on its main surface, which are attached to each other with the respective recording layers facing each other. It is characterized by

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1(a) shows a perspective view cut away on the diameter of the optical disc of this embodiment, and this optical disc includes a transparent substrate 2 carrying a write-once recording layer 1 such as a cyanine dye on its main surface;
Another transparent substrate 2a carrying a rewritable recording layer 5 by magneto-optical or phase change on its main surface is placed on the adhesive layer via an annular spacer 3 while maintaining the internal space with each recording layer 1.5 facing the other transparent substrate 2a. 4, they are attached to each other. Further, magnetic hubs 10 are bonded to both openings of the center hole.

In the case of shaping the first disc of this embodiment, the second
Assembly is performed in the order of steps shown in Figures (a) to (d).

First, a circular transparent substrate 2 is formed from a plastic material such as PMMA. A recording layer of an organic cyanine dye thin film is formed on one main surface of the substrate 2 by spin coating or the like.

In this way, a transparent substrate carrying a write-once recording layer is produced.

Similarly, a multilayer magneto-optical recording layer 5 made of a rare earth metal alloy is formed on the main surface of another circular transparent substrate 2a by sputtering or the like. In this way, another transparent substrate carrying a rewritable recording layer is created.

First, as shown in Fig. 2(a), a pair of annular inner and outer peripheral spacers 3 are aligned and fixed to a positioning jig, and adhesive 4 is applied around the entire circumference of the spacers while supporting the substrate. Apply over the area.

Next, as shown in FIG. 2(b), the write-once type transparent substrate is placed so that its recording layer faces downward, and the center of the substrate is aligned at the center hole, and placed on the spacer 3. Gently press the spacer from above so that it is filled between the spacer and the substrate to adhere it.

Next, as shown in FIG. 2(C), the substrate with the spacer attached thereto is turned over and fixed to a jig, and adhesive 4 is applied onto the spacer in the same manner as in the step shown in FIG. 2(a).

Next, as shown in FIG. 2(d), the above-mentioned rewritable transparent substrate is placed on a spacer in the same manner as in the step shown in FIG. 2(b), and left at room temperature for a predetermined time, and then at 60°C for 2 hours. The adhesive is heated and then left at room temperature for a predetermined period of time to solidify the adhesive.

Finally, the magnetic hubs 10 are bonded to both openings of the center hole for finishing, and the optical disc 7 is obtained.

In this way, an air sandwich type optical disk is formed in which the substrate is an acrylic plate such as PMMA, and the recording films include, for example, a cyanine dye thin film and a magneto-optical recording thin film on both sides.

Alternatively, even if a thin film of Te-based metal oxide is used as the write-once recording layer, an air sandwich type optical disc can also be formed using a phase-change alloy recording thin film as the rewritable recording layer.

Furthermore, as shown in FIG. 1(b), the previous disk using the write-once recording layer of Te-based metal oxide has a write-once recording layer 1.
A transparent substrate 2 carrying a rewritable recording layer 5 by magneto-optical or phase change is placed between the transparent substrate 2a carrying a recording layer 5 which is rewritable by magneto-optical or phase change, with the recording layers 1 and 5 facing each other, and an inert adhesive layer 4 interposed therebetween. A structure in which it is directly attached is also possible.

Effects of the Invention As described above, according to the present invention, additional IF is added to the main surface.
Because the structure is made up of a substrate carrying a recording layer and another substrate ε carrying a rewritable recording layer on its main surface, each of which is attached to each other with the respective recording layers facing each other, each recording film is formed by a separate process. This reduces the number of manufacturing steps and improves product yield.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of an optical disk according to the present invention, FIG. 2 is a partially cutaway perspective view for explaining the assembly process of the optical disk, and FIGS. 3 and 4 are partially cutaway perspective views of a conventional optical disk. It is. Explanation of symbols of main parts 1... Write-once recording layer of cyanine dye, etc. 2...
... Substrate 3 ... Spacer 4 ... Adhesive layer

Claims (2)

[Claims] (1) A transparent substrate carrying a write-once recording layer on its main surface and another transparent substrate carrying a rewritable recording layer on its main surface are attached to each other with the respective recording layers facing each other. Optical information recording disc. (2) Claim 1, wherein the transparent substrates are attached to each other via a spacer while maintaining an internal space.
The optical information recording disc described.