JPS6117055B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the performance of a recording medium of a high-density recording member in a device for optically recording and reproducing information at high density in a video disk, PCM audio equipment, office recording machine, etc. The present invention relates to an optical recording member having a structure capable of retaining data for many years.

Conventionally, a recording member of an optical recording device has a disk-shaped substrate 1 made of glass or plastic, as shown in FIG.
A recording layer 2 of Te, Se, etc. is formed on top by vapor deposition. Note that 5 indicates the center shaft hole. This uses a laser beam to record digitized signals by providing countless pits of about 1 μm in size.
However, if this recording member is left in the air, dust will adhere to it, causing trouble in writing and reading signals. Also, it is easily deteriorated by corrosive gases, moisture (B ₂ O), O ₂ and CO ₂ . For example, immediately after vapor deposition, Te had a metallic luster with a light transmittance of about 5 to 10%, but
If left indoors for a month, it will oxidize or turn into hydroxide, increasing to 50-60%, and recording with laser light.
The read S/N ratio deteriorates. As a countermeasure against this problem, a recording member provided with a protective film 3 as shown in FIG. 2 is being considered. However, although this method removes the negative effects of dust on the recorded pits,
The energy of the laser beam during writing increases.
For example, the method shown in Figure 1 could form a bit with 4mW - 500nsec, but the method shown in Figure 2 could form a bit with 8mW.
-500n sec is required. This is about 1 for the Te vapor deposited film.
When forming pits of μφ, heat conduction occurs only to the substrate 1 in the method shown in Figure 1, but in the method shown in Figure 2, heat is conducted to the protective film 3, which increases the amount of heat that escapes. . On the other hand, deterioration such as whitening of the Te vapor deposited film of the recording medium is slightly improved compared to the substrate of the method shown in FIG. 1, but this is not perfect either. This is because the protective film is an organic substance and easily passes gas molecules such as H ₂ O and O ₂ , so it completely prevents active metal deposited films such as Te from reacting with O ₂ and H ₂ O. This is because it is difficult to prevent.

Furthermore, as a countermeasure to this problem, a hollow type recording member having a recording layer provided inside as shown in FIG. 3 has been considered. According to this method, since the recording layer 2 is surrounded by the substrate 1 and the spacer 4, it is possible to eliminate the influence of dust adhesion on the recording pits (holes).
Since there is no sandwich damage between the protective film 3 and the substrate 1, heat loss of the laser beam due to heat conduction can be prevented. Also, inert gas _N2 or
Filling with Ar gas has the advantage of preventing deterioration of the Te metal evaporated film. However, even when filled with Ar gas, the discoloration prevention effect of the Te metal evaporated film deteriorates over the long term. For example, initial transmittance, 5~
The deterioration of 10% to 20-30% in two months shows that it is unsuitable for preserving records for many years or over 10 years.

The present invention was made to solve the above problem, that is, the problem of deterioration over many years.In order to maintain the properties of the deposited thin film for a long period of time, the present invention is made by placing a moisture absorbent in an inert gas. This is to maintain the performance of the recording layer 2.

The present invention will be explained below with reference to the drawings.

FIG. 4 is a diagram showing the cross-sectional shape of the optical recording member of the present invention. The two substrates 1 are made of transparent material (for example, glass or transparent resin material). A metal thin film is deposited as a recording layer 2 on each side of this substrate, and these are opposed to each other with spacers 4 and 4' interposed therebetween. Partition plate 1 further having ventilation holes 10
1 is provided in the hollow part, and a hygroscopic substance 1 is placed therein.
2 (e.g. silica gel, LiCl, CaCl ₂ , MgCl ₂
etc.) is installed. This manufacturing method involves depositing Te as a recording layer 2 at a predetermined position on one side of a glass plate (substrate 1), then installing ring-shaped spacers 4, 4' made of the same material as the substrate 1, and then adding a hygroscopic substance 12. After assembling the enclosed holder 13 and partition plate 11 and fixing them with a jig so that the spacers 4 and 4' do not move,
Apply epoxy resin to the joint surfaces and adhere. Next, after creating a vacuum through an exhaust pipe (not shown), inert gas (Ar or N ₂ ) is injected to seal the exhaust pipe.
By attaching two exhaust pipes, it is also possible to expel and replace the internal air by sucking inert gas from one of the exhaust pipes.

Plastic materials (polymethacrylic, polyester, polyvinyl chloride,
Vinyl acetate-PVC copolymer, acetyl cellulose, polycarbonate, polypropylene, nylon, AS
It is also possible to use resin (epoxy resin, etc.). In this case, resin is weaker than glass at the same thickness, so if it is evacuated to a vacuum, it will be pushed by atmospheric pressure and the strain applied to the bond will increase, so replacing air with inert gas will be one-sided. N ₂ gas can be flowed through the exhaust pipe of the engine to drive out and replace O ₂ , P ₂ O, CO ₂ and other corrosive gases.

FIG. 5 shows a case in which the perforated partition plate in FIG. 4 is omitted and a ring-shaped object 16 having minute holes is used instead to prevent the hygroscopic substance 12 from spilling out.

Furthermore, in order to prevent the powder of the hygroscopic substance 12 from spilling out from the minute holes, it is recommended to form a coating of a resin layer with good moisture permeability (for example, silicone resin, cellulose resin) on the surface of the ring-shaped object 16. preferable. Furthermore, Fig. 6 shows the ring-shaped object 16 in Fig. 5.
FIG.

FIG. 7 shows an example in which the moisture absorbent installation chamber is installed around the circumference. In this case, since the amount of moisture absorbent can be increased compared to the case shown in FIG. 4, the humidity can be kept low for a longer period of time.

FIG. 8 shows an example in which the ring-shaped object wrapped around the hygroscopic substance used in FIG. 5 is provided around the circumference. In this case as well, since the amount of moisture absorbing material can be increased as in the case of FIG. 7, the humidity can be kept low for a longer period of time.

As described above, according to the present invention, it is possible to construct an optical recording member that can maintain the characteristics of the metal thin film of the recording medium for many years.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional recording member without a protective film, Figure 2 is a cross-sectional view of a conventional recording member with a protective film, and Figure 3 is a conventional hollow type recording member with a recording layer provided inside. 4 is a cross-sectional view of the recording member. FIG. 4 is a diagram showing a hollow recording member having a small chamber for placing the hygroscopic substance of the present invention in the center. FIG. 5 is a modification of FIG. FIG. 6 is a plan view of a ring filled with a hygroscopic substance, and FIG. 7 is a modification of the present invention in which a ring-shaped substance filled with a hygroscopic substance is installed in the center. A diagram showing a hollow type recording member having a small chamber for installing it in the peripheral part,
FIG. 8 is a modification of FIG. 7, showing a hollow recording member in which a ring-shaped member filled with a hygroscopic substance is installed around the periphery. 1... Substrate, 2... Recording layer, 4, 4... Spacer,
5... Central shaft hole, 11... Partition plate, 12... Hygroscopic substance, 13... Holder, 16... Ring-shaped object surrounding hygroscopic substance.

Claims (1)

[Scope of Claims] 1. A recording metal thin film is provided on the inner wall of a disk-shaped transparent substrate whose interior is hollow and filled with an inert gas, and a moisture absorbent is provided in the hollow portion to keep the humidity low. An optical recording member characterized by having a built-in optical recording member. 2. The optical recording member according to claim 1, wherein the moisture absorbent is installed at the center or the periphery of the disk-shaped substrate.