JPS6145291B2 - - 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 that allows the recording medium to be held together 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 vapor deposited film of a recording medium 2 such as Te or Se is formed thereon. This uses a laser beam to record a digitized signal by providing an infinite number of bits 6 of about 1 .mu.m. Note that 5 indicates the center shaft hole. 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 (H 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 eliminates the adverse effect on the recorded pits 6 due to the adhesion of dust, the energy of the laser beam during writing increases. For example, the method shown in Figure 1 was able to form pits with 4mW-500nsec, but the method shown in Figure 2
8mW−500nsec is required. This is because when forming pits of approximately 1μφ in the Te vapor deposited film, heat was conducted only to the substrate 1 in the method shown in Figure 1, but heat was also conducted to the protective film 3 in the method shown in Figure 2. This is because more people run away. On the other hand, deterioration such as whitening of the Te vapor-deposited film on 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, so H ₂ O and
This is because it is difficult to completely prevent an active metal vapor deposited film such as Te from reacting with O ₂ or H ₂ O because O ₂ gas molecules easily pass through it.

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 medium 2 is surrounded by the substrate 1 and the spacer 4, the influence of dust adhesion on the recording pit hole 6 can be eliminated. This prevents heat loss of the laser beam due to heat conduction. In addition, by filling the hollow part with inert gas _N2 or Ar gas, Te
This has the advantage of preventing deterioration of the metal vapor deposited film. but,
Even when filled with Ar gas, the discoloration prevention effect of the Te metal evaporated film deteriorates over a long period of time. For example, an initial transmittance of 5 to 10% deteriorates to 20 to 30% in two months, making it unsuitable for preserving records over many years or even over ten years.

The present invention was made in order to solve the above-mentioned problem, that is, the problem of deterioration over many years, and by maintaining a vacuum state and installing a getter, the characteristics of the deposited thin film can be maintained for a long period of time. This is designed to maintain the performance of 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. As can be seen in this figure, a recording film 2 such as a thin metal film is formed on one side of a substrate 1 made of glass.
After vapor deposition, spacers 4 and 4' are attached, and a partition wall 13 for forming a getter chamber 10 is installed, and a ring-shaped getter 11 is installed in the center thereof. A shielding plate 12 is placed alongside this getter 11 so as not to affect the recording film 2. In this manufacturing method, the spacers 4, 4' and the fusion wall 13 with the holes 14 are made of glass, and the indium metal foil 16 is used to press them together to form an airtight structure. Before assembly, each part is heated in a vacuum and thoroughly degassed. For example, metal vapor deposition for the recording film is performed before assembly. Vacuum evacuation is performed through the exhaust pipe 15 attached to the outer spacer 4,
After evacuating to a 10 ^-5 Torr table, the getter is tipped off, and the getter support is heated by applying a high frequency electric field or current to the getter to evaporate the getter material (Ba metal, etc.) onto a part of the inner wall of the vacuum container. When heating the getter by applying electricity, the structure is such that a lead wire is taken out from the surface of the board, connected to the power supply with a clip, and the getter material is evaporated by applying electricity.

As a result, O ₂ gas and
Adsorbs H ₂ O in the form of sticks. For example, getter material
In the case of Ba metal, the reaction with O ₂ , H ₂ O, and CO ₂ is carried out as follows.

2Ba+O ₂ →2BaO Ba+2H ₂ O →2Ba(OH) ₂ +H ₂ 2Ba+2CO ₂ +O ₂ →2BaCO _3In this way, the Ba film adsorbs impurity gases over many years and prevents the recording film from deteriorating. .

FIG. 5 shows a modification in which the getter chamber 10 is installed at the circumference. This is based on the method shown in Figure 4.
Since the area on which the getter is evaporated increases, the time for maintaining a high degree of vacuum becomes longer, making it possible to create a recording member with a longer life.

As described above, according to the present invention, it is possible to provide an optical recording member that can maintain the characteristics of a recording film 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 sectional view of a recording member of the present invention which is a vacuum tube type recording member and has a getter chamber in the center; FIG. 5 is a sectional view of a recording member of the present invention which is also a vacuum tube type and has a peripheral portion. FIG. 3 is a cross-sectional view of a recording member having a getter chamber at the center thereof. 1: Substrate, 2: Recording plate, 4, 4': Spacer,
5: central shaft hole, 10: Getter chamber, 11: Getter material, 12: shielding plate, 13: Getter chamber partition, 1
4: Vent hole, 15: Vacuum exhaust pipe, 16: Joint surface (indium foil).

Claims (1)

[Claims] 1. A disk-shaped transparent substrate is hollow inside and a recording film is provided on the inner wall thereof, and the hollow portion inside the substrate is evacuated and a getter material is incorporated therein. Optical recording member. 2. The optical recording member according to claim 1, wherein the getter material is provided at the center or the periphery of the disc-shaped substrate. 3. The optical recording member according to claim 1, wherein the recording film is a recording metal thin film.