JPS59203257A - Production of information recording medium - Google Patents

Abstract

PURPOSE:To pevent attracting of scobs of plastic to recording layers and deformation of substrates at a punching time by punching a center hole for revolving shaft after a pair of substrates having recording layers are joined with recording layers inside. CONSTITUTION:A pair of disc-shaped transparent plastic substrates 1 having recording layers 2 are joined with recording layers 2 inside into an air sandwich through spacers 4 and 5. At this time, it is unnecessary to remove projections 3 formed by the injection molding. The center part of this recording medium is cut by a cutting tool 6 to form the center hole, and projections 3 are removed as spools 7. Thus, attracting of scobs of plastic to recording layers 2 and deformation of substrates 1 are prevented at a time of center hole forming.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing an information recording medium.

Recently, an information recording medium called "optical disc", which uses a high energy density beam such as a laser beam, has been developed and is being put into practical use.

Such a recording medium is generally a disk-shaped transparent plastic substrate on which metals such as Bi, Sn, In, and Te, semimetals, or semiconductors are deposited in the form of a thin film by vapor deposition or the like.

This type of recording medium does not require darkroom operation, provides high-density, high-contrast recording, allows add-on information (additional recording), and scans recorded information with laser light. It has the advantage that it can be continued by doing so. However, during handling and storage of the recording medium, problems such as scratches on the surface of the recording layer, adhesion of dust, etc., and oxidation deterioration due to contact with air occur, which adversely affects recording and reading. will give.

As one means for eliminating such defects, a so-called "T-Sand German 4. An information recording medium in which two disc-shaped substrates are directly bonded together has been proposed.

To record and read information on this type of disc-shaped information recording medium, a center hole provided at the center of the medium is inserted into the rotation axis of a rotating body, and the medium is rotated while recording is performed with a laser beam. This is done by scanning the layers.

Conventionally, when assembling such information recording media, one disk-shaped plastic substrate is formed by injection molding, etc., a center hole is punched out during molding, a recording layer is provided on one side by vapor deposition, and two sheets are assembled. The two substrates are bonded together via a spacer or directly. When such operations are performed.

Plastic chips are generated during punching, which adhere to the substrate and increase the BER (pit error rate) when a recording layer is provided, adversely affecting writing and reading.
Therefore, cleaning of the substrate is required.

Furthermore, since a punching mechanism is provided in the mold of the injection molding machine to punch out the center hole, stress is instantaneously applied to the molded plastic substrate, which may cause the substrate to deform.

An object of the present invention is to provide a method for manufacturing a disk-shaped information recording medium that eliminates the drawbacks of the prior art.

That is, the invention is to provide a recording layer on which information can be written and/or read using a laser beam on a transparent disc-shaped plastic substrate, and to arrange at least two substrates each having a recording layer on one side with the recording layer inside. In a method for manufacturing an information recording medium, which comprises bonding the medium to the substrate through a step or directly.

This method of manufacturing an information recording medium is characterized in that after bonding both substrates, a central hole for one rotation axis is punched out.

The present invention will be explained in detail below.

The transparent plastic substrate used in the present invention is acrylic resin (polymethyl methacrylate).

polycarbonate), yg-lyethylene terephthalate.

Polyvinyl chloride 81 or the like is used, and the thickness of the substrate is 0. 1.0 to 1.51 nm is preferable for 1% or more of Sn.

It is molded into a disc-shaped substrate by means such as injection molding.

There are no particular restrictions on the material used for the recording layer, and materials used in the technical field, such as Te, can be used.

Zn, In, Sn, Zr, AA! ,
Metals such as Cu and Ga.

Half metal % of Bi, As, Sb, etc.-Ge, Si
Semiconductors such as, alloys or combinations thereof are used.

To provide a recording layer of these materials on the substrate, vapor N-sputtering, ion blating, etc. are used, and the appropriate thickness of the recording layer is 6008 to 1.5 OA. Further, if necessary, a protective layer such as a polymer may be provided on the recording layer by, for example, spin coating.

1 to 6 are explanatory diagrams showing one embodiment of the method of the present invention.

FIG. 1 is a sectional view of a recording medium element, in which a recording layer 2 made of Te is provided by vapor deposition on a disc-shaped transparent plastic substrate 1 obtained by injection molding. Note that a protrusion 6 is formed at the center, which is unique when this type of molded product is made by injection molding, but in the present invention, such a protrusion does not need to be removed.

Figure 2 is a sectional view showing a state in which two substrates (recording medium elements) as described above are bonded with the recording layer 2 inside using an adhesive or the like via spacers 4 and 5. It is possible to form a so-called Ersandermanch structure and protect a recording layer.

Further, if necessary, this space may be maintained at a reduced pressure, or an inert gas such as nitrogen or argon may be injected.

FIG. 6 shows a state in which a center hole is punched out in the center of the air sand 9-inch type recording medium assembled as shown in FIG.

According to the present invention, as described above, the center hole is punched out after the substrate is assembled into an air sandwich type structure, so that plastic chips do not adhere to the recording layer during punching.

The conventional step of cleaning the surface of the substrate to be deposited can be omitted. Also, since the center hole is punched out by cutting, the stress applied to the substrate is small.

Deformation of the substrate can be prevented. Furthermore, since there is no need to provide a punching mechanism for punching the center hole in the mold for molding the substrate, the mold can be simplified and the center hole of the two substrates can be slightly misaligned, vibrations during rotation, etc. can be avoided. No such troubles will occur at all.

[Brief explanation of drawings]

1 to 6 are process diagrams showing one embodiment of the method of the present invention. 1...Substrate 2...Recording layer 4, 5...S-S 6-...Cutting tool (and 3 other people) Fig. 1 Fig. 2 @ Fig. 3

Claims (2)

[Claims] (1) In a method for manufacturing an information recording medium in which two disk-shaped substrates each having a recording layer on at least one plastic substrate are bonded with the recording layer inside, one rotation is made after bonding both substrates. A method for manufacturing an information recording medium, which comprises punching out a center hole for a shaft. (2) A method for manufacturing an information recording medium according to claim (1), wherein the center hole is punched out by cutting.