JPS63124247A - Production of optical disk - Google Patents

Abstract

PURPOSE:To form the uniform outside circumferential wall and to obtain an optical disk having high accuracy by perpendicularly holding two sheets of disk substrates in such a manner that recording layers face each other at a specified spacing and injecting an adhesive agent into the spacing from the center of the substrates while rotating the substrates. CONSTITUTION:The optical disk substrates 1, 1' formed with the recording layers on the opposed surfaces are sucked under vacuum to optical disk substrate holders 2, 2'. Spacers 3, 3' for determining the center of the disk substrates 1, 1' are made of fluoroplastic so as to contact the adhesive agent 4. The adhesive agent 4 is injected into the spacing between two sheets of suck disk substrates 1, 1' from the enter thereof while the substrates are perpendicularly held and are kept rotated. The influence of gravity is then canceled and the adhesive agent is evenly spread toward the outside circumference. The liquid drops can no longer follow up the rotation of the disk substrate 1 when the viscosity of the adhesive agent 4 increases on progression of curing thereof. The balance is then maintained by slowing down the rotation of a motor 5. The liquid drops are thereby entirely annihilated in the final and the uniform outside circumferential wall is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing an optical disc that includes a recording layer on the surface of a disc substrate and optically records and reproduces information.

BACKGROUND OF THE INVENTION Optical disks are high-density recording media and have excellent features such as low cost relative to recording capacity, high access speed, and high transfer rate, and are extremely useful as next-generation memories.

Optical discs are usually used by bonding two disc substrates with their recording surfaces facing each other in order to ensure a sufficient recording capacity and to easily protect the recording medium.

Since recording media are formed on the surfaces of the two disk substrates, a photocurable adhesive cannot be used. Therefore, a thermosetting type such as epoxy type or polyester type is selected.

However, these adhesives have drawbacks such as relatively long curing time and poor workability.

For example, when applying adhesive to one side of a disk substrate and superimposing and bonding another disk substrate, the excess adhesive that protrudes from the outer edge will surround the surface of the disk substrate and adhere to the holder. There was a drawback.

Conventionally, in order to prevent this, a protective film was pasted on the surface of the disk substrate, and the protective film was peeled off after the adhesion was completed.

Problems to be Solved by the Invention However, in the above configuration, the amount of adhesive protruding is not uniform and its shape is unstable.

One of the characteristics required for optical discs is good dynamic balance, but factors that worsen this dynamic balance include variations in the thickness of the disc substrate, concentricity of the inner and outer diameters of the disc substrate, and adhesive layers. There are problems such as uneven thickness and uneven amount of adhesive protruding from the outer peripheral edge, etc. If there is variation in weight in the circumferential direction of the disk, the core will run out during high speed rotation and normal operation will be difficult. It had

In view of the above-mentioned problems, the present invention provides a method for manufacturing an optical disc in which the amount and shape of adhesive protrusion are made constant.

Means for Solving the Problems In order to achieve the above object, the method for manufacturing an original disk of the present invention is such that two disk substrates are arranged so that their recording layer surfaces face each other with a certain gap, and the two disk substrates are The adhesive is injected into the gap from the center of the disk substrate while simultaneously rotating the two disk substrates while holding the disk substrate vertically.

The present invention provides a method for manufacturing an optical disk in which the amount and shape of adhesive sticking out is constant by the above method, and the adhesive is applied from the center of two disk substrates while holding them vertically and rotating them. When injected, the effect of gravity is canceled and the material spreads evenly toward the outer circumference.

When the adhesive reaches the outer periphery and a small amount overflows, the injection is stopped, and the overflowing excess adhesive flows down the outer peripheral wall of the two disk substrates. By setting the setting, excess adhesive becomes droplets and stays at an apparent fixed position, wetting the entire circumference of the rotating disk substrate.Then, the adhesive hardens and its viscosity decreases. As it rises, the number of droplets gradually decreases, and eventually a uniform outer peripheral wall is formed over the entire circumference. At this time, there is no need for the adhesive to wrap around the surface of the disk substrate as in the conventional case, and a beautiful appearance can be easily formed.

EXAMPLE Hereinafter, a method for manufacturing an optical disc according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a method of manufacturing an optical disc in an embodiment of the present invention. In Figure 1, 1 and 1'
are original disk substrates, and original disk substrates 1 and 1, on which recording layers are formed on their inner sides, ie, opposing surfaces, are vacuum-adsorbed to optical disk substrate holders 2 and 2'. Spacers 3 and 3' are used to define the centers of the optical disk substrates 1 and 1', and are made of fluororesin because they come into direct contact with the adhesive. Further, the spacer 3 provided on the motor 6 side is connected to the shaft of the motor 6. Furthermore, an injection port 3a for injecting adhesive is provided at the center of the spacer 3' on the opposite side from the motor 6, from which the adhesive is injected into the gap between the optical disk substrates 3 and 3'. There is. 4 is the adhesive, in this case unsaturated polyester is used.0 Figure 2 shows the disc when the adhesive is injected from the injection port 3a of the Spaceago, and after the adhesive is overflowed, the injection is stopped, and the excess. This figure shows the condition of the adhesive. Although the optical disk substrate 1 and the optical disk substrate holder 2 are rotating counterclockwise, the adhesive droplet is still at the position where it moves around the outer periphery of the optical disk substrate 1. Wet it one by one. As the adhesive 4 continues to harden and its viscosity increases, the droplets become unable to follow the rotation of the optical disk substrate 1, but the rotation of the motor 6 is slowed down to maintain balance.

By doing the above, the droplets will finally disappear completely and a uniform outer peripheral wall can be formed.

FIG. 3 is a sectional view of an optical disk bonded by the manufacturing method in this example. Adhesive 4 is the original disk substrate 1
It can be seen that 1' and 1' are firmly adhered, and the outer peripheral cross section forms a uniform semicircular shape.

Effects of the Invention As described above, in the present invention, two disk substrates are held vertically so that the recording layers face each other with a certain gap between them, and the disk substrates are placed in the gap while rotating the substrates. By injecting the adhesive from the center, a uniform outer peripheral wall is formed, and an optical disc with good dynamic balance and high precision can be obtained.

Furthermore, there is no possibility that the adhesive will bleed into the disk surface.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a method of manufacturing an optical disk according to an embodiment of the present invention, FIG. 2 is a front view showing one step of the manufacturing method, and FIG. 3 is a cross-sectional view of an optical disk manufactured according to this embodiment. . 1.1'... Optical disk substrate, 2,2'...
...Optical disk board holder, 3, 3'...
・Spacer, 4...adhesive, 5...motor. Name of agent: Patent attorney Toshio Nakao and 1 other person1,
J''--One light V board 22'--One forked and reverse Akebono ψ material 3.3'-11 S゛

Claims (1)

[Claims] Two disk substrates each having a recording layer on one side are placed so that the recording layer surfaces face each other with a certain gap between them, the two disk substrates are held perpendicularly, and the two disk substrates are simultaneously rotated. A method for manufacturing an optical disc, characterized in that adhesive is injected into the gap from the center of the disc substrate.