JPH0433553Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Technical Field] The present invention relates to a disk-shaped information recording medium having a so-called air sandwich structure in which a recording layer is provided on the surface of a disk-shaped substrate to optically record and reproduce information. [Prior Art] Conventionally, an air sandwich type sealed information recording medium is known, in which two disks each having a recording layer of metal, organic dye, etc. formed on a disk-shaped substrate made of plastic or the like are bonded together via a spacer. It is being For example, a radius of 100 as a disk-shaped information recording medium.
When using a mm disk, the information recording area is provided within a radius of about 50 to 95 mm. Therefore, if we use a so-called air sandwich type sealing structure, the width of the inner circumferential spacer can be made sufficiently wide, but the width of the outer circumferential spacer cannot be made very wide, so special care must be taken to ensure that the outer circumferential spacer is properly bonded. There is. That is, the adhesion should be carried out as shown in FIG. 1a, and there should be no uncoated adhesive as shown in FIG. 1b. Also, if you are worried about getting into the situation shown in Figure 1b, and use too much adhesive, resulting in the situation shown in Figure 1c, the strength will be satisfied, but the adhesive will not be able to record information. There is a greater risk that the recording material will protrude into the area, and if an adhesive that is generally anaerobic, such as a photo-curing adhesive, is used, the degree of curing of the protruding portion will be poor, and there is a risk that the recording material will be adversely affected. Therefore, as shown in Figure 1a, in order to achieve reliable adhesion, it is necessary to precisely control the amount of adhesive applied, and to precisely control the pressure applied when overlapping the spacer and substrate and spreading the adhesive. is necessary. Control of the amount of application is determined by the performance of the adhesive dispenser, but control of the pressure is determined by the thickness of the inner and outer circumferential spacers. That is, the adhesion is carried out in the order shown in FIG. 2, but the pressure by the pressing plate shown in FIG. 2c is applied to both the inner circumferential spacer and the outer circumferential spacer. If the thickness of the inner circumferential spacer is thicker than the outer circumferential spacer, the pressure will be mainly applied to the inner circumferential spacer, and therefore the outer circumferential spacer will be under-pressed, which tends to cause the situation shown in Figure 1b. . Conventionally, the inner spacer and the outer spacer have the same thickness, but due to dimensional tolerances, the inner spacer is often thicker than the outer spacer depending on the combination. A defective state as shown in Figure b occurred. [Purpose] The present invention has been made in view of the above problems, and its purpose is to improve sealing reliability and manufacturing yield of information recording media. [Structure] The above object of the present invention is to record a pair of substrates having a recording layer on one side of at least one of two disc-shaped substrates through an inner spacer and an outer spacer arranged concentrically. This is achieved by making the thickness of the inner circumferential spacer thinner than the thickness of the outer circumferential spacer in a sealed information recording medium having an air-sandwich structure in which the layers are laminated on the inside. In the present invention, the difference between the thickness of the outer circumferential spacer and the inner circumferential spacer is in the range of 10 μm to 300 μm, preferably 40 μm to 200 μm. This allows the outer spacer to be stably bonded to the state shown in FIG. 1a. Furthermore, the adhesion state of the inner circumferential spacer is also within an acceptable range as a recording medium. Next, the information recording medium of the present invention will be explained with reference to the drawings. As shown in FIG. 3, the disk-shaped substrates 1 and 1' are formed of, for example, a transparent plastic plate and have a fitting hole 2 in the center thereof. A recording layer 3 is formed on one side of the substrate 1. These substrates 1,
1' are arranged concentrically with the recording layer 3 inside through the inner circumferential spacer 4 and the outer circumferential spacer 5, and using an adhesive 7 while a space 6 is formed between the mutually facing surfaces of each substrate. It has a bonded structure.
The thickness t of the inner spacer 4 is the thickness of the outer spacer 5
It is becoming fainter than t′. That is, the relationship t<t' should be maintained. Moreover, the recording layer 2 is the substrate 1'
It may be formed on one side of the. As the material of the recording layer, any material conventionally used for information recording media can be used, and there is no restriction to a specific material.
Examples include metals, semimetals, metal compounds, and organic dyes. Furthermore, the effect of making the inner circumferential spacer thinner than the outer circumferential spacer according to the present invention was compared with the case where conventional inner and outer circumferential spacers of equal thickness were used and the case where the inner circumferential spacer was thicker than the outer circumferential spacer. Use the same adhesive in each case to
Twenty sealed disks were manufactured and the yields were compared. The results are shown in the table below.

〔effect〕

According to the present invention configured as described above,
Since the adhesive state between the outer spacer and the inner spacer can be maintained in good condition, the sealing reliability and manufacturing yield of the information recording medium can be improved.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view showing the adhesion state of the outer circumferential spacer, FIG. 2 is a schematic view showing the order in which the spacers are attached, and FIG. 3 is a cross-sectional view showing an example of the information recording medium of the present invention. . 1... Substrate, 2... Fitting hole, 3... Recording layer, 4
...Inner circumference spacer, 5...Outer circumference spacer, 6...
Space, 7...adhesive.

Claims (1)

[Scope of utility model registration request] A pair of substrates having a recording layer on one side of at least one of two disc-shaped substrates are bonded together with the recording layer on the inside through an inner circumferential spacer and an outer circumferential spacer arranged concentrically. 1. A sealed information recording medium having an air sandwich structure, wherein the thickness of the inner spacer is thinner than the thickness of the outer spacer.