JPH02116037A - Optical disk - Google Patents

Abstract

PURPOSE:To improve the appearance and yield of the optical disk by forming the optical disk into the structure in which a recording film or the recording film and a protective film are not formed on the side inner than the recessed part of the 2nd gate by an inner peripheral ring. CONSTITUTION:The both-face type optical disk formed by adhering an injection molded substrate 11 having the recessed part 12 called as the 2nd gate by the inner peripheral ring holding a stamper on the periphery inner than the recording part and two sheets of the optical recording media which are formed thereon and have the recording film 13 or the recording film and the protective film at need by epoxy 14 is formed into the structure in which the recording film 13 or the recording film and the protective film are not formed to the side inner than the recessed part 12. Bleeding of the adhesive agent is prevented in this way and the appearance and the yield are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc used in an optical memory that is promising as an external memory for computers.

[Prior Art] Conventional adhesion methods for double-sided optical discs are described in Japanese Patent Laid-Open No. 60-101737, Japanese Patent Laid-Open No. 60-113344, Japanese Utility Model Laid-Open No. 60-85726, and Japanese Patent Laid-open No. 61-80535. It has a sandwich structure, and
7-5033, JP-A-60-182053, JP-A-61
-5450 and JP-A-60-5452, etc., a close bonding structure was used.

Further, as the adhesive layer, an epoxy adhesive was used as in Japanese Patent Application Laid-Open No. 60-185235. Further, as a bonding method, attempts have been made to apply an adhesive using roll coating or spin cord, and then to cure it by applying heat and pressure, or pressure.

[Problem to be solved by the invention] In the air sandwich structure, the mechanical strength is weak due to the air layer sandwiched between them, and the eccentricity and surface runout increase due to substrate deformation due to changes in temperature and humidity, making the servo unstable. . Further, the recording layer needs to have strong oxidation resistance or a protective film for oxidation resistance.

A ceramic layer can be considered as a protective layer to prevent oxidation of the recording layer, but the air sandwich structure has a problem in that the ceramic layer is prone to cracking due to its weak mechanical strength.

In the close bonding structure, if a hot melt type adhesive is used, it has no heat resistance, so there is a problem that the recording film or protective film will crack when used for a long time or when exposed to high temperatures.

When cracks occur in the recording film or protective film, the pit error rate of the optical disc increases, making it unusable.

On the other hand, epoxy adhesives have good heat resistance and long-term reliability, so they are expected to be used as adhesives for optical discs.
However, when the substrate is made of plastic, there is a problem that there is no adhesive strength with the substrate.

FIGS. 3 to 5 show schematic cross-sectional views of conventional double-sided optical discs using epoxy adhesive.

Figure 3 shows the most common structure example, with 11 being an injection molded substrate;
Reference numeral 12 indicates a concave portion of the second gate, in which a recording film or a recording film and a protective film 33 are formed outside the second gate, and an adhesive 3 is formed.
4 is designed to stop at the second gate. According to this configuration, there was a problem in that the adhesive strength could not be maintained at the portion 35 where the epoxy adhesive 34 and the substrate 11 were in direct contact, resulting in peeling.

FIG. 4 shows an improved version of this, in which a recording film or a recording film and a protective film 43 are formed over the entire surface of the substrate, and the adhesive 44 is stopped at the second gate portion 12.

According to this configuration, the adhesive strength is maintained and there is no appearance defect due to adhesive extrusion, but there is a problem that the recording film inside the second gate part oxidizes after long-term aging even if there is a protective film. Ta.

FIG. 5 is a schematic cross-sectional view of an optical disc in which both adhesive and recording film are formed on the entire surface, 53 is the recording film or recording film and protective film formed on the entire surface of the substrate, and 54 is the epoxy adhesive formed on the entire surface of the substrate. It is a drug.

However, when using an injection molded board like this, there is a recess in the second gate part formed by the inner circumferential ring for holding the stand bar, so when the entire surface is glued, the adhesive protrudes from the inner diameter part, causing the inner diameter part to become damaged. The disc was dirty, but the adhesive also protruded from the outer periphery, resulting in a defective optical disc or an optical disc with a poor appearance.

An object of the present invention is to provide an optical disc that has a good appearance and a high yield.

[Means for Solving the Problems] The optical disk of the present invention is manufactured by injection molding the substrate, and the injection molded substrate has a concave portion called a second gate formed by an inner circumferential ring that holds a stand bar on the inner circumference from the recording portion. and a recording film formed thereon, or if necessary, bond two optical recording media with a recording film and a protective film with epoxy.In a double-sided optical disc, the recording film or the recording film and the protective film are bonded together using epoxy. It is characterized by having a structure that is not formed inside the recess.

Hereinafter, the present invention will be explained in detail using examples.

[Example 1] FIG. 1 shows an embodiment of the present invention.

11 is an injection molded substrate, and 12 is a concave portion of the second gate.

Reference numeral 13 denotes a recording film or a recording film and a protective film, and in the case of the present invention, the recording film or the recording film and a protective film are formed outward from the second gate portion. According to the eight-piece configuration in which the adhesive 14 is stopped at the second gate, the oxidation of the recording film is protected by the protective film and the adhesive 14, so there is no deterioration in appearance, and the reliability is very high. We were able to provide a condylar double-sided optical disc.

[Example 2] This example is an example in which further improvements were made to achieve the object of the present invention.

FIG. 2 shows a schematic cross-sectional view.

In this embodiment, the injection molded substrate is provided with a recess 26 not only in the recess of the second gate but also in the outer periphery. According to this configuration, since the adhesive is trapped in the recesses not only on the inner periphery but also on the outer periphery, there is an advantage that stains caused by the adhesive extruding can be completely eliminated.

The recording film or the recording film and the protective film 23 may be formed from the second gate 12 to the outer peripheral recess 26 .

Edge Film and Protective Film 14.24.34.44.54 Epoxy Adhesive or More [Effects of the Invention] As described above, according to the present invention, there is no appearance defect due to adhesive extrusion, and oxidation of the recording film can be prevented. We were able to provide a high-quality optical disc that does not suffer from problems such as adhesive parts peeling off in long-term use environments.

Applicant Seiko Epson Corporation Representative Patent Attorney Masayoshi Kamiyanagi (1 other person)

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an optical disc according to an embodiment of the present invention. FIG. 2 is an embodiment according to the present invention, and is a schematic cross-sectional view of an optical disc. 3 to 5 are schematic cross-sectional views of conventional optical discs. 11 Injection molded substrate 12 Recessed portion of second gate 13.23.33.43.53 Recording film or description FIG. 3, FIG. 4, FIG. 5

Claims (1)

[Claims] The substrate is manufactured by injection molding, and the injection molded substrate has a recess called a second gate formed by an inner circumferential ring that holds the stamper on the inner periphery of the recording part, and a recording film formed thereon, or if necessary. , a double-sided optical disc in which two optical recording media having a recording film and a protective film are bonded with epoxy, the optical disc having a structure in which the recording film or the recording film and the protective film are not formed inside the recessed portion. .