JPS59171049A - Optical disc - Google Patents

Abstract

PURPOSE:To obtain an optical disc which is stable to a change in environment by providing groove or notch and filters which permit passage of outdoor air between the space between the substrates of the optical discs consisting of two sheets of the substrates stuck together and the outside. CONSTITUTION:Plastic substrates 3, 4 on which thin Te-Se films 1, 2 are deposited by evaporation are adhered via spacers 5, 6 to form a spacer 7 between the substrates 3 and 4. Four grooves 8 are provided on one surface of the spacers 5, 6 and millipore filters 9 are atached in the grooves 8. The air in the space 7 is put in and out through the filters 9 according to the change in temp. or external pressure, by which the deformation of the disc is prevented and the air in the space 7 is maintained always normally.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a video disc or a ViPCΔ4 code.
The present invention relates to a disk substrate used for a hard disk audio disk, a digital hard disk, or the like.

[Background of the invention]

Conventionally, in optical discs that record videos, digital information, etc. on a thin film made of a recording material such as metal or chalcogen glass, two opposing substrates,
For example, a ring-shaped spacer f between plastic discs:
By sandwiching and adhering the discs, a space containing only clean air is created between the discs, and a thin film made of the recording material is pre-deposited on the surface of the glass disk facing this space. There is a structure ′ (Ersandermanch structure). With this structure, since the information recording surface always faces clean air, there is no risk of information loss due to adhesion of dust, etc., and the quality of the reproduced signal can be improved.

However, in this type of structure, the air in the space is completely sealed; 4. Therefore, the entire disc swells or dents due to temperature changes and pressure differences with the outside air. 7
There is a drawback. This is because the disk as a whole is mechanically weak because this machine uses a glass disk surface with a thickness of about 1 inch as the substrate.

If the disc is uneven in this manner, the laser beam spot focused on the disc may be out of focus when recording or reproducing information. The tolerance value for this unevenness is approximately 10
It is about 0 to 200 μm υ, whereas the actual amount of change in unevenness is +501? It can reach up to about ±2 gates in the range of -50C to -50C.

[Purpose of the invention]

An object of the present invention is to solve the above problems and provide an optical disc that is stable against environmental changes.

[Summary of the invention]

In order to solve the above-mentioned problems, the air in the space inside the disk and the air in the outside world should be able to flow so that the disk does not deform even if a temperature change or a pressure difference with the outside air occurs.

First, by providing one or more grooves before pasting a part of the ring-shaped spader or the edge of the board, the space inside the Dinuku can be adjusted according to temperature changes or pressure differences with the outside air. This changes the pressure of At this time, filler is glued to the spacer so as to close each groove to prevent dust from flowing in from the outside world. This filter is preferably made of paper, polymer thin film, ceramics, glass fiber/(-, etc.).The pore size of the filter is preferably osμm or more and 2μm or less. In this case, it is more efficient to manufacture discs by making it at one place on the circumference than by making it at multiple places.

Grooves and notches can be easily formed by machining or injection molding.

The thickness of the plastic disk is preferably 10 μm or more and 20 μm or less, and preferably 500 μm or more and 2 μm or less.

Further, the thickness of the spacer is preferably 100 μm or more and 20 mIn or less, particularly preferably 1.50 μm or more and 5 mIn or less.

As the recording film formed on the substrate of the present invention, TbFe
, Rb, fx, semimetals such as 13i, semiconductors such as Te, oxides of these, and organic materials such as rough-in. Almost any type of recording film can be used.

Also, instead of providing grooves or notches in the spacer, if the material of the spacer is made flexible or expands and contracts so that the volume of the space can be changed, the pressure difference between the space and the outside air can be created. When this occurs, the volume of the space changes, keeping the internal and external pressures approximately constant and preventing the disk from deforming.

However, since this alone is not sufficient, it is better to use a method of providing grooves or notches.

On the other hand, it is also preferable to have a structure in which one or both of the plastic disks have a bulge integral with the plastic disk and are glued together at the bulge, without using a spacer. Then, a path (groove formed in the tabs before bonding) is provided that allows the disc to flow parallel to the disk surface. At this time, it is advisable to install a filter on the path through which the fluid can flow to prevent dirt from entering the space. The width of the opening at this time is preferably 1 m+n or more and 80 m+n or less, particularly preferably 3 m+n or more and 50 m+n or less. Also, the height of the protrusion is 5
It is preferably 0 μm or more and 10 #I or less, and 100 μm or more and 3 or less #I is preferable. If you create a path that allows outside air to flow in a direction parallel to the disk surface, you can achieve higher speeds than if you create a path that allows outside air to flow in a direction perpendicular to the disk surface, that is, if you make a hole in a part of the disk surface. It is superior in that it is less likely to cause vibrations of the disk due to turbulent flow during rotation.

[Embodiments of the invention]

The present invention will be explained below using examples.

Embodiment 1 FIGS. 1(a) and 1(b) show a partially cutaway top view and a vertical cross-sectional view of an optical disc according to the invention. FIGS. 2(a) to 2(C) are diagrams showing a filter portion on the outer periphery of an optical disc. In FIGS. 1(a) and 1(b), plastic disks 3 and 4 having an outer diameter of 3QOmm, an inner diameter of 35 mm, and a thickness of 1.1 mm, on which Te1Se thin films 1 and 2 are deposited, face each other on the deposition surfaces. Together, they are bonded together with ring-shaped large diameter and small diameter spacers 5 and 6 about 1 inch thick, and a space 7 is formed between the plastic discs 3.4. ing.

Here, four grooves 8 are formed on each side of the ring-shaped large-diameter and small-diameter spacers 60, and valley grooves 8 are formed.
Filter 9 was glued to the spacer so as to cover the spacer. Second
Figure (a) is a diagram showing the outer peripheral filter section at this time. Here, as the filter 9, a Millipore filter with a bore size of 0.2 μm was used so as not to pass through dust of 0.2 μIn or more contained in the air flowing in from the outside.

With the above structure, the air in the space 7 containing the thin films 1 and 2 made of recording material can easily enter and exit through the holes 8 when there is a temperature change or a pressure difference with the outside air. There is absolutely no possibility that the plastic discs 3 and 4 will be deformed due to stress due to the pressure difference between the inside and outside. As a result, the disk surface could be stably kept flat despite temperature changes and pressure differences with the outside air.

Also, since the air always passes through the filter 9 at this time, all harmful dust mixed in the outside air is removed, the air in the space 7 is always kept clean, and there is no risk of it adhering to the thin films 1 and 2.

Here, if there are grooves on both sides of the spacer as shown in Figure 2(b) (view of the disk from the outer circumferential side), or as shown in Figure 2(C).
Even if the spacer was cut in the middle as shown in the figure (view of the disc viewed from the outer circumference), the same results as when the groove was on one side were obtained.

Instead of providing grooves, the spacers 5 and 6 are made of silicone rubber with a thickness of about 1 mm, so that the volume of the space 7 changes and flexes in response to temperature changes and pressure differences with the outside air. Therefore, when a pressure difference occurs between the space 7 and the outside air, the volume of the space 7 changes, reducing the internal and external pressure to l't/'! It was possible to keep the temperature constant and prevent the disk from deforming.

Similar results were obtained even if grooves were provided in the spacer depending on the situation.

Example 2 Figure 3 (a) to (C) and (a)' to (C)
The figures up to 'A' are a longitudinal sectional view and a side view as seen from A of an optical disk as an extended embodiment of the present invention. In Fig. 3(a) and (a)', the outer diameter of 3QQmm and the inner diameter of 35 rrm on which the Te-8e thin film 10.11 was deposited, respectively.
, on the inner and outer peripheries of a plastic disk 12.13 with a thickness of 1.1 mm, there are protrusions 14 and 15 with a width of 10++ on and a height of 0.2 wn on both sides of each deposit. These plastic disks 12.13 are bonded together at the boxwood portions p14.15 with their vapor deposition surfaces facing each other, and a space 16 is formed between the plastic disks 12.13. . Here, the protrusions 14 and 15 have grooves 17 through which outside air can flow, and a filter 18 is glued to cover the grooves 17. The filter 18 used was the same as in Example 1. As a result, the disk surface could be stably kept flat against temperature changes and pressure differences with the outside air, and the air in the space 16 was always kept clean. At this time, groove 17
Similar results were obtained even if the depth of 14.15 and the height of the protrusion 14.15 were equal.

In addition, as shown in FIGS. 3(b) and (b)', the plastic disk 12 on one side has no protrusion, and the opposite plastic disk 13 has a protrusion 14.15. Even with regard to the structure, similar results to those of Example 1 were obtained.

At this time, the depth of the groove 17 and the height of the protruding portion 14.15 may be equal.

In addition, when forming a plastic disk by injection, it is better to form protrusions 14 and 15 on both sides of the substrate surface as shown in FIGS. 3(C) and 3(C)' to reduce distortion after molding. Hard to occur. When forming by injection, it is also possible to provide grooves using a mold during molding. The same results as in Example 1 were obtained with this structure as well. At this time, the depth of the groove F and the height of the protrusion p14.15 may be equal.

〔Effect of the invention〕

According to the present invention, it is possible to prevent the deformation of the disk due to the pressure difference between the inside and outside, and also to keep the internal space always in a clean state, which has a great effect.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are a partially cutaway top view and longitudinal sectional view of an embodiment of the present invention, and FIGS. 2(a) and (b) are
and (C)U, a diagram showing a filter portion on the outer periphery of an embodiment of the present invention, FIGS. 3(a), (b), (C) and (a
)'Cb)'(C)' is a vertical sectional view and a side view of another embodiment of the present invention. 1, 2... Thin film made of recording material, 3, 4... Plastic disc, 5.6... Sveza, 7... Space,
8...Groove, 9...Filter, 10, 11...Thin film made of recording material, 12.13...Plastic disc, 14° 15...Bump, 16...Space, 17.
... Groove, 18...
(b) (b' (C) (σ) Continuation of page 1 @ Inventor Motoyasu Terao 1-280 Higashi Koigakubo, Kokubunji City Hitachi, Ltd. Central Research Laboratory @ Inventor Shinkiyoshi Horikago 1-280 Higashi Koigakubo, Kokubunji City Address: Central Research Laboratory, Hitachi, Ltd. Title of the invention: Optical Disk Capture II:, IV1 with 11'l Patent Applicant'111
;'5jQ) The meeting of the dead ([l erected, I, and the third representative of the office] Kuθ,) (d)

Claims (1)

[Claims] In an optical disk having an integrated structure in which one or two substrates are aligned on the inside of a metal plate provided with a thin film made of a recording material, and a space is provided between the substrates, outside air can be circulated. 1. An optical disc characterized in that a groove or notch is provided in a direction parallel to the surface of the substrate. 2. The optical disc according to claim 1, wherein a filter is attached to the groove or notch through which the outside air can flow to remove dust from the outside air flowing into the space.