JPH0229950A - Optical disk - Google Patents

Abstract

PURPOSE:To relieve the strain of substrates and to improve reliability by changing the properties of the adhesive agent between the spacers and substrates provided on the inside circumference and outside circumference of the substrates, using the secure adhesive agent for the inside circumference and using the plastic adhesive agent for the outside circumference. CONSTITUTION:Guide grooves for an optical head for information reading and recording grooves 2 for recording information are provided to the substrates 1. The substrates 1 are disposed to face each other by interposing the inside circumferential spacer 3 and the outside circumferential spacer 4 to the regions in the inside circumferential part and outside circumferential part of the substrates 1 where there are no films 2, then the substrates are joined by the adhesive agents 5, 6. The adhesive agent 5 of an epoxy system having high adhesive strength is used for the substrate 1 and the spacer 3 and the adhesive agent 6 of an urethane system or silicone rubber system having plasticity is used for the substrate 1 and the spacer 4. The strain in the substrates and the strain of the deterioration with age by humidity in use environment are relieved in this way and the fluctuation in the light reflectivity is decreased, by which the reliability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc, and particularly to an optical disc using an air sandwich type laminated substrate.

[Conventional technology]

When a conventional optical disc uses an air sandwich type laminated substrate, as shown in FIG.
, an inner spacer 3 , an outer spacer 4 , and an adhesive 7 .

An air sandwich structure in which an inner circumferential spacer 3 and an outer circumferential spacer 4 are sandwiched between the inner circumferential spacer 3 and the outer circumferential spacer 4, which contact only the portions of the inner and outer periphery where the recording film 2 is not attached to the substrate 1 to which the recording film 2 for recording information is attached, and only those portions are bonded. It becomes.

In this case, the adhesive 7 used to bond the mating substrate 1 with the inner circumferential spacer 3 and the outer circumferential spacer 4 is a room temperature curing type or thermosetting type epoxy adhesive or an ultraviolet curing type adhesive. .

[Problem to be solved by the invention]

However, in the conventional optical disk described above, when bonding the substrates, the same type of adhesive is used to bond the inner circumferential spacer and the outer circumferential spacer to the substrate. Because a strong adhesive is used, potential distortion in the board or distortion due to moisture absorption in the usage environment accumulates on the board, inner spacer, outer spacer, and their vicinity over time, causing damage to the inner and outer peripheries of the board. There was a problem that the optical properties and mechanical properties did not meet the standards, and the yield was poor and the reliability was significantly lowered.

[Means to solve the problem]

In the optical disk of the present invention, adhesives with different properties are used for the inner circumferential spacer portion of the substrate and the outer circumferential spacer portion of the substrate, an adhesive with high adhesive strength is used for the inner circumferential spacer portion, and a plastic adhesive is used for the outer circumferential spacer portion. configured to join.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention.

In the optical disc shown in FIG. 1, a substrate 1 is provided with a group groove on one side for guiding an optical head for reading information.
Furthermore, a recording film 2 for recording information is attached. The substrate 1 is bonded with adhesives 5 and 6 to the inner and outer regions of the substrate 1 where the recording film 2 is not present, with the substrate 1 facing each other via the inner and outer spacers 3 and 4, respectively.

At this time, an epoxy adhesive 5 with high adhesive strength is used between the substrate 1 and the inner circumferential spacer 3, and a plastic urethane-based or silicone rubber-based adhesive 6 is used between the substrate 1 and the outer circumferential spacer 4.

〔Effect of the invention〕

In the optical disc of the present invention, the properties of the adhesive used to bond the substrate to the inner spacer and outer spacer provided on the inner and outer peripheries of the substrate are changed, and the substrate and the inner spacer are bonded with a strong adhesive. By using a plastic adhesive between the substrate and the outer spacer, distortion within the substrate and strain that changes over time due to moisture in the usage environment can be alleviated.
It is possible to minimize variations in the light reflectance of the substrate, improve mechanical properties and improve mechanical properties caused by these, and achieve high reliability.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view showing an example of the conventional technology. 1...Substrate, 2...Recording film, 3...
...Inner circumference spacer, 4...Outer circumference spacer, 5
, 6.7...Adhesive.

Claims (1)

[Claims] two substrates each having a recording film formed on at least one side; an inner circumferential spacer bonded to the inner periphery of the two substrates on the side where the recording film is formed with an adhesive having high adhesive strength; an outer periphery spacer portion bonded to the outer periphery of the substrate on the recording film forming surface side with a plastic adhesive.