JPH06251539A - Optical disk and cartridge housing this disk - Google Patents

Abstract

PURPOSE:To provide an optical disk which prevents the generation of a defect by an arc discharge through the spacing of the joint surfaces of the cartridge and the cartridge housing this optical disk. CONSTITUTION:This cartridge is constituted by joining a flat upper shell 1a and lower shell 1b in a position where an optical recording layer 2b does not exist flush with the plane inclusive of the joint surfaces 3 of the both shells within a range where the optical disk 2 housed between both shells moves vertically. The resin protective layer 2d in the peripheral edge of the optical recording layer 2a of the optical disk 2 provided with at least the optical recording layer 2b and the resin protective layer 2c covering this layer on the main plane of the substrate 2a is formed thicker than the other part. As a result, the arc discharge on the optical recording layer 2b is hardly generated and the generation of the defect is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc having an optical recording layer formed on a substrate made of resin or the like, and a cartridge for accommodating the optical disc.

[0002]

2. Description of the Related Art Conventionally, in a cartridge such as a CD-ROM, a write-once optical disk, and a rewritable optical disk, a shutter opens and closes an opening window formed in the shell in order to protect the optical disk contained in the shell. A disc drive device, which is provided so that the cartridge can be inserted into the disc drive device, opens and closes the disc drive device to read information written in the optical disc in the opening window or write information in the optical disc.

That is, as shown in FIG. 7, a cartridge 1 having a flat upper shell 1a and a lower shell 1b joined together accommodates an optical disk 2 having a structure in which an optical recording layer 2b is formed on a substrate 2a. In general, the joint surface 3 of the cartridge 1 is a plane parallel to the surface of the cartridge 1 as shown in the drawing, and linearly traverses the outer peripheral portion from the outer surface to the inner surface, and a gap of several μm is formed here. There is. The optical recording layer 2b is provided with a protective resin layer 2c made of a resin such as an ultraviolet curable resin or a thermosetting resin on the surface thereof, but it is very thin, and as described above, it is connected to the inside and outside of the joint surface 3. If there is a gap, charged people or things, that is, charged body 4
When the disk contacts the peripheral surface of the cartridge 1, a minute arc discharge is generated between the disk and the optical disk 1 inside through the gap. Therefore, despite the presence of the protective resin layer 2c, the optical recording layer 2b may be damaged and a pinhole may be generated, which may become a defective portion.

[0004]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a highly reliable cartridge and optical disk which prevent the occurrence of defects due to arc discharge through a gap in the joint surface of the cartridge, focusing on the above-mentioned problems.

[0005]

[Means for Solving the Problems] First to achieve the above object
The invention described in (1) is a cartridge in which a flat upper shell and a lower shell are joined and an optical disk is housed therein, wherein the joint surfaces of the both shells are bent.

According to a second aspect of the present invention, in a cartridge in which a flat upper shell and a flat lower shell are joined and an optical disc is housed therein, the joint surface of both shells is a plane different from the optical recording layer of the optical disc. The cartridge is characterized in that it is located at.

A third aspect of the present invention is an optical disc in which at least an optical recording layer and a resin protective layer covering the optical recording layer are provided on the main surface of a substrate, and the resin protective layer at the peripheral portion of the optical recording layer is different from that of the other. The optical disk is characterized in that it is formed thicker than the portion.

[0008]

According to the first and second aspects of the invention, for example, the joint surface of both shells has a shape with a bent portion, or the joint surface is provided at a position which is always located below the optical disc within the moving range of the optical disc. By doing so, the discharge path through the gap between the shells becomes longer, arc discharge to the optical recording layer is less likely to occur, and defects are prevented from occurring.

According to the third aspect of the invention, since the resin protective layer at the outer peripheral edge of the optical recording layer is thicker than the other portions, damage that would cause a defect even if a discharge occurs would occur. The optical recording layer becomes hard to receive, and the occurrence of defects is prevented.

[0010]

Embodiments of the present invention will be described in detail with reference to the drawings. First, embodiments of the first and second inventions will be described. The same parts as those in FIG. 7 are designated by the same reference numerals, and mainly different points will be described. FIG. 1 shows a V-shaped embodiment in which a V-shaped convex portion 3a is formed on one of the outer peripheral portions of the upper shell 1a and the lower shell 1b, and correspondingly a V-shaped concave portion on the other side. 3b is formed and these are combined with each other to form a V-shaped joint surface 3.

Here, the above-mentioned shape is only an example, and the joining surface 3 has an appropriate shape so as not to be a simple flat surface parallel to the surface of the cartridge 1, and the joining surface 3 is bent from the outer surface to the inner surface. You can do so. By doing so, it is possible to prevent the optical recording layer 2b from being positioned on the plane including the bonding surface 3 within the vertical movement range of the optical disc 2 housed between the shells.
2 to 5 exemplify such another shape, and in FIG. 2, the projection surface 3c is provided on one of the outer peripheral portions of the upper shell 1a and the lower shell 1b to make the joint surface 3 L-shaped. Example, Figure 3
Is an example in which both the upper shell 1a and the lower shell 1b are L-shaped, FIG. 4 is an example in which the bonding surface 3 is provided below the main surface on which the optical recording layer 2b is not formed, and FIG. This is an example in which 4 and 4 are combined. 6 is a comparative example, which is an example in which a bonding surface is provided above the main surface on which the optical recording layer 2b is formed, and the optical recording layer 2b within the moving range of the optical disk 2 is shown.
May be located on a plane including the joint surface 3.

In this way, the defect is prevented by lengthening the discharge path to make arc discharge less likely to occur. As shown in FIG. 8, the cartridge 1 is placed upright on the conductor plate 5 and the outer peripheral portion is provided. Electrostatic tester probe 6 (330Ω,
Table 1 shows the results of an electrostatic breakdown voltage test conducted by applying 150 pF, 15 kV).

[0013]

[Table 1]

Here, when an arc discharge occurs, the two places of the entrance and the exit of the discharge are destroyed, and pinholes are generated in the optical recording layer. 6, the pinholes were generated in about 50% of the samples in the comparative example shown in FIG. 6 and about 80% in the conventional example shown in FIG.
No pinholes were generated, and the remarkable effect of the present invention could be confirmed.

Next, an embodiment of the second invention will be described. FIG. 9 is an enlarged view of the peripheral portion of the optical disc 2 of the embodiment. The substrate 2 is, for example, a disk made of a resin such as polycarbonate having a diameter of about 86 mm, and has an optical recording layer 2b on its main surface.
As a protective resin layer, a magneto-optical recording layer is formed by sequentially stacking, for example, silicon nitride, a magnetic layer, silicon nitride and an aluminum reflective layer by sputtering, and a urethane acrylic ultraviolet curable resin is laminated thereon by a spin coating method. 2c is formed, and a peripheral edge protective layer 2d that is thicker than the inner portion is formed on the peripheral edge.

Concretely, a plurality of samples of several kinds having different thicknesses of the peripheral edge protection layer 2d are prepared, and each sample is assembled into a conventional cartridge having the structure shown in FIG. The test was conducted. That is, viscosity 500c
Samples A and B having a thickness t of the peripheral edge protection layer 2d of 23 μm and 20 μm at a position of radius r = 42 mm were prepared as an example using a urethane acrylic ultraviolet curable resin of ps, and r = 42 mm. As a comparative example, a sample D in which the thickness t of the peripheral edge protective layer 2d was 6 μm at the position of, and a sample E in which the protective resin layer 2c including the peripheral edge protective layer 2d was not formed were prepared.

[0017]

[Table 2]

Table 2 shows the results of the electrostatic breakdown voltage test of these samples. As is clear from Table 2, sample A and B have no pinholes, whereas
In Samples C to D, the smaller the thickness t is, the higher the occurrence rate is, and particularly in Sample E, the occurrence rate is 100%, which is not the cartridge of the first invention but the conventional cartridge. Also, the thickness of the peripheral protection layer 2d is 20 μm.
It was confirmed that the occurrence of pinholes could be prevented as much as possible in the above cases. The optical disc of the second invention is the first
When combined with the cartridge of the present invention, the occurrence of pinholes can be prevented more reliably, and the thickness of the peripheral edge protection layer 2d can be reduced to 2 mm.
It is also possible to make it thinner than 0 μm.

The peripheral edge protection layer 2d which is thicker than the other portions
The above-mentioned spin-coating method is suitable for forming the resin, and when a resin such as an ultraviolet-curing resin is applied, it is desirable that the viscosity is about 100 to 500 cps, and the viscosity is lower than this. However, it was difficult to apply the coating with high reproducibility even at high cost. Further, as the shape of the substrate 2a, a shape in which the outer peripheral edge is left or a shape in which the outer peripheral edge is raised is preferable, and it is difficult to apply with good reproducibility if the outer peripheral edge is cut off. It should be noted that the mechanical characteristics of the optical disk (Ti
(lt; tilt) was not adversely affected.

[0020]

As is apparent from the above embodiment, the first
In the cartridge of the second invention, the joint surface between the upper shell and the lower shell is provided with a bent portion, so that a flat surface including the joint surface is formed within the moving range of the optical disc housed between the shells. The surfaces on which the optical recording layers are formed do not coincide with each other. Therefore, when the charged body comes into contact with the peripheral surface, the discharge path to the optical disk becomes long, arc discharge hardly occurs, and the occurrence of defects is prevented.

Further, in the optical disc of the third invention, the resin protective layer at the peripheral portion of the optical recording layer is made thicker than the other portions, and the charged body is the peripheral surface of the cartridge without changing the shape of the cartridge. It is possible to prevent the occurrence of defects due to arc discharge in the case of contact with, and the effect is certain if the film thickness is 20 μm or more. Further, by combining with the cartridge of the first aspect of the present invention, the occurrence of defects can be prevented more reliably.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a first embodiment according to the first invention.

FIG. 2 is a sectional view of an essential part of the second embodiment.

FIG. 3 is a sectional view of an essential part of the third embodiment.

FIG. 4 is a cross-sectional view of a main part of a fourth embodiment according to the second invention.

FIG. 5 is a sectional view of a main part of the fifth embodiment of the present invention.

FIG. 6 is a cross-sectional view of a main part of a comparative example.

FIG. 7 is a cross-sectional view of a main part of a conventional example.

FIG. 8 is a perspective view illustrating an electrostatic breakdown voltage test.

FIG. 9 is an enlarged sectional view of an essential part of an embodiment of the third invention.

[Explanation of symbols]

 1 ... Cartridge 1a ... Upper shell 1b ... Lower shell 2 ... Optical disk 2a ... Substrate 2b ... Optical recording layer 2c ... Protective resin layer 2d ... Peripheral protective layer 3 ... ..Joining surface 4 ... Charged body

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Shibata 6 1166, Haseno Hachimizo, Yokaichi-shi, Shiga Prefecture 6 Kyocera Co., Ltd. Shiga Yokaichi Factory

Claims (3)

[Claims] 1. A cartridge comprising a flat upper shell and a lower shell joined together to accommodate an optical disk therein, wherein the joining surfaces of the two shells are bent. 2. A cartridge comprising a flat upper shell and a flat lower shell joined together to accommodate an optical disc therein, wherein the joint surface of the two shells is located on a plane different from the optical recording layer of the optical disc. Characteristic cartridge. 3. In an optical disc having at least an optical recording layer and a resin protective layer covering the optical recording layer on a main surface of a substrate, the resin protective layer at the peripheral edge of the optical recording layer is formed thicker than other portions. An optical disc characterized in that