JPS61198445A - Optical disc - Google Patents

Abstract

PURPOSE:To restore a damaged protecting coating film into the original state by coating a protection coating film formed by a transparent thin film material to the surface of optical beam incidence side of a disc base in an exfoliatable way so as to coat a new protecting coating film. CONSTITUTION:The protection coating film 6 is adhered into a recessed part 7 formed on a disc base 1 normally in a very stable state, but since the adhesive force between the film 6 and the base 1 is due to electrostatic combining force or resin scattering, the protection coating film 6 is exfoliated easily. The possibility of deformed or damaged surface 1b of the disc base 1 in exfoliation is precluded. In forming a new protecting coating film 6 onto the disc base 1 after exfoliation of the damaged protection coating film 6, a protection coating film 6 applied in advance with an electric charge is inserted into the recess 7 and the film is depressed upward.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to disks such as video disks, compact disks, write-once optical disks, and magneto-optical disks.

[Conventional technology]

Optical discs can reproduce signals formed on a transparent disc by making a beam of light incident on a recording film attached to one side of the disc substrate and reflecting it on the recording film. There is. Since the disc substrate transmits the light beam, it must be made of a transparent material.For this reason, the disc substrate is usually made of glass, acrylic resin, or epoxy resin.

Synthetic resins such as polycarbonate are used, but in recent years synthetic resin materials have come into wide use because they have advantages such as being easy to mold and can be manufactured at low cost.

However, if the disk substrate is made of synthetic resin, the surface of the disk substrate on the light beam incident side may be damaged or deformed during use, or the light transmittance may decrease, causing noise during signal reproduction. or cause
In severe cases, inconveniences such as a state where reproduction is impossible may occur.

[Problem that the invention seeks to solve]

The present invention has been made in view of the problem of soft soil, and provides an optical disc in which even if the surface of a disc substrate on the light beam incident side is damaged, it can be recycled and restored to good reproduction accuracy. The purpose is to

[Means for solving problems]

In order to achieve the above object, the optical disc according to the present invention includes at least one transparent thin film-like protective coating on the other light beam incident side surface of a synthetic resin disc substrate having a recording film on the negative side. If a scratch or the like occurs on this protective coating, the protective coating can be peeled off from the disk substrate and replaced with the removed state or with a new protective coating attached. By doing so, it is possible to restore the condition to a state where the above-mentioned scratches and the like have not occurred.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

First, as shown in FIG. 1, an optical disk has a disk substrate 1 made of a transparent synthetic resin such as acrylic resin, epoxy resin, polycarbonate resin, etc. in the shape of a disk. A recording layer 2 is formed on the side surface 1a.

This recording layer 2 can be formed by, for example, forming an uneven portion corresponding to a signal to be recorded on the side surface 1a of the disk substrate 1 by an injection method, and vacuum-depositing aluminum as a reflective coating on this surface. However, the recording layer 2 may be formed by a photosensitive resin method (2P method) other than the above-mentioned injection method.
An optical disk is constructed by joining the two discs facing each other with a spacer 4.4 interposed between them, and a hub 5 integrally provided with the spacer 4 on the inner peripheral side attached to the center part.

As shown in FIG. 2, a transparent protective coating 6 is coated on the incident side surface 1b of the disk substrate 1 on which the light beam is incident from the optical head. If the surface is damaged due to carelessness during handling, it can be peeled off and removed, or replaced with a new one.

Here, the protective coating 6 is preferably formed of a material having substantially the same refractive index as that of the disk substrate 1, particularly preferably the same material. An annular recess 7 is formed on the light beam incident side surface 1b of the disk substrate 1, and a protective coating 6 is installed in the recess 7. Moreover, between the protective coating 6 and the disk substrate 1, By electrostatically bonding the abutting surfaces or by sprinkling a transparent resin between them and interposing the resin therebetween, the protective coating 6 is bonded to the disk substrate 1 during normal use of the optical disk. I try to keep it in the same state as I put it on.

In this case, if sufficient bonding force can be obtained between the protective coating 6 and the disk substrate 1 through the above-mentioned electrostatic bonding or resin dispersion, it is not necessary to form the recess 7 into which the protective coating 6 is attached. There isn't.

This embodiment has the above-mentioned configuration, and under normal conditions, the optical disc is used with the protective coating 6 coated on the disc substrate 1.

If the protective coating 6 is damaged or deformed during use of this optical disc, the refraction state of the light beam incident through the protective coating 6 will change, causing malfunctions in signal reproduction. Not only does it generate noise, but in severe cases, playback becomes impossible.

Therefore, the protective coating 6 damaged in this way is removed by peeling it off from the disk substrate 1, and the protective coating 6 is left in a state where it remains removed or a new protective coating 6 is applied. As a result, the light beam incident surface is restored to a scratch-free state, allowing proper signal reproduction.

Here, the protective coating 6 is normally bonded within the recess 7 formed in the disk substrate 1 in an extremely stable state;
Since the binding force between them is due to electrostatic bonding or resin dispersion, the protective coating 6 can be easily peeled off without deforming or damaging the surface 1b of the disk substrate 1. There is no risk of it happening. In addition, in order to attach a new protective coating 6 to the disk substrate 1 after peeling off the damaged protective coating 6, the protective coating 6 that has been charged in advance is inserted into the recess 7 and is pressed from above. This can be done by doing. Furthermore, an electrostatic bonding force can be generated by attaching the protective coating 6 that does not apply an electric charge to the disk substrate 1 after it is attached to the concave part 7, and furthermore, by applying a transparent liquid resin to the concave part 7. By attaching the protective coating 6 with or without a charge applied after spinner coating, the protective coating 6 can be firmly bonded to the disk substrate 1 via this liquid resin.

It is preferable to form the protective coating 6 as thin as possible from the viewpoint of preventing the focal point of the light beam from shifting. However, if it is made too thin, scratches penetrating the protective coating 6 may damage the disc during use. Since there is a risk of damaging the substrate 1 itself, the thickness of the disk substrate 1, which is formed to a thickness of about 11 to 1.3+++w, is
It is preferable to use a protective coating 6 having a thickness of about 300 μm.

According to the inventor's experiments, when a 100 μ-thick protective film was applied to a disk substrate of 1111 thickness using acrylic resin, most of the scratches that could occur during normal handling were The damage does not reach the surface of the disk substrate, and by peeling off and removing the damaged protective coating, it has become possible to reproduce signals in extremely good condition.

〔Effect of the invention〕

As explained in detail above, the optical disc according to the present invention has a structure in which a protective coating formed of a transparent thin film member is removably adhered to the surface of the disc substrate on the light beam incident side, so that the optical disc can be used. Occasionally, if the protective coating is damaged or deformed, or its translucency decreases, it can be re-corrected by peeling off the protective coating or by applying a new protective coating in its place. It is possible to restore a state in which signals can be reproduced, and the life of the optical disc as a whole can be extended.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
It is an enlarged view of the main part of the figure. DESCRIPTION OF SYMBOLS 1... Disc substrate, 2... Recording layer, 3... Disc, 6... Protective film.

Claims (1)

[Claims] 1. An optical disc comprising a synthetic resin disc substrate having a recording film on one side, and at least one transparent thin film-like protective coating removably adhered to the other surface of the optical beam incident side.