JPS6369048A - Optical recording medium - Google Patents

Abstract

PURPOSE:To decrease jitter quantity of signals as against a temp. and humidity change of external environment by coating the section of an optical recording medium where the medium contacts the outside field with a UV curing resin in which fine dielectric particles are incorporated. CONSTITUTION:A composite dielectric film 2 composed of Al nitride and Si nitride is sputtered to 1,000Angstrom thickness on a polycarbonate substrate 1 with guide grooves and a magneto-optical recording film 3 consisting of NdDyFeCoTi is formed thereon to 400Angstrom thickness. A composite dielectric film 4 composed of Al nitride and Si nitride is then formed thereon to 1,000Angstrom thickness. A composite dielectric film 6 composed of Al nitride and Si nitride is formed on a grooveless polycarbonate substrate 5 to 500Angstrom thickness. The substrates 1, 5 are tightly stuck to each other by the UV curing resin 7. The entire surface of the section of such magneto-optical recording medium where the medium contacts the outside field is coated with the UV curing resin layer 8 contg. the fine SiO2 particles to 15mum thickness. The fine SiO2 particles are contained therein at 50vol%, by which the change of the jitter is obviated in spite of the temp. and humidity change of the outside.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to the structure of an optical recording medium.

[Conventional technology]

Optical recording media that can be optically recorded, reproduced or erased are:
Research and development has been actively conducted. In particular, in recent years, magneto-optical recording media using magneto-optic gold are on the verge of being put into practical use as erasable and rewritable optical recording media. However, since the recording film of magneto-optical recording media is a rare-earth transition metal film, it has poor weather resistance.Thus, as a result of intensive research efforts, the present inventors have developed a composite dielectric film (specially Through the development of the patent application No. 61-74794) and the laminated structure (No. 61-122767), we hope to be able to provide magneto-optical recording media with sufficient long-term reliability for practical use.

[Problem that the invention seeks to solve]

However, with the above-mentioned conventional technology, it has become possible to provide a medium with long-term reliability, but the substrate is a translucent resin substrate (PC,
PMMA, epoxy resin, etc.), it had serious drawbacks such as large humidity and temperature expansion and increased signal deviation (jitter) once written. Previously, when conducting accelerated sound testing, it was necessary to take the medium out of the constant temperature and humidity chamber and leave it at room temperature and humidity all day and night.

Furthermore, since the transparent resin is exposed on the surface of the substrate, it has poor scratch resistance and is easily scratched.

The present invention is intended to solve these problems, and its purpose is to provide an optical recording medium that does not change the amount of signal jitter even when the humidity of the environment in which it is used changes, and that is not easily damaged. It is in.

[Means to solve all problems]

In an optical recording medium formed on a transparent resin substrate and in which recording, reproduction, or erasing is performed by irradiating the optical recording medium with light, the portion of the optical recording medium that comes into contact with the outside world is exposed to ultraviolet light containing dielectric fine particles. It is characterized by being coated with a hardened resin.

[Effect]

According to the above structure of the present invention, the portion of the optical recording medium that comes into contact with the outside world is coated with the ultraviolet curing resin containing dielectric fine particles, thereby preventing moisture (moisture) from penetrating into the translucent resin foil plate. To prevent. Furthermore, the ultraviolet curable resin that covers the entire medium has a small coefficient of thermal expansion because it contains a dielectric (ceramic), and by suppressing all of the thermal expansion of the translucent resin substrate, changes in the amount of jitter in the signal are eliminated. Furthermore, since the medium surface hardness also increases, the scratch resistance improves.

The present invention will be described in detail below based on examples.

〔Example〕

FIG. 1 is a schematic cross-sectional view of the magneto-optical recording medium of the present invention. 1 is a polycarbonate (PC) substrate with guide grooves, on which a composite dielectric film 2 of aluminum nitride and silicon nitride of 1000Ai is formed by sputtering (all films are formed by sputtering), and 3 NdDyFe0o.
A Ti magneto-optical recording film of 400 Ai was formed, and a composite dielectric film of 4 aluminum nitride and silicon nitride of 1000 A' was formed.
90 Next, 500Ai composite electrolyte film of aluminum nitride and silicon nitride was formed on the grooveless PC board of No. 5, and these films were formed on the 3PC substrate with guide grooves and the PC without groove.
All seven substrates were closely bonded using ultraviolet (U/V) curing resin. Finally, the entire surface of the bonded magneto-optical recording medium in contact with the outside world was coated with an ultraviolet curable resin layer containing 5102 fine particles. Film thickness is 15μm
It is thick and contains 50Vot% of BLO2 fine particles.

The amount of jitter in the signal was measured by recording and reproducing the medium of the present invention prepared in this way and the uncoated conventional American medium. The temperature during recording was 25° C. and the humidity was 50%. FIG. 2 is a diagram showing the humidity dependence of the jitter amount when the media of the present invention and the conventional media are kept at a constant temperature of 25° C. and the humidity is changed to see the changes in the amount of jitter. 21 is 810□ microparticle-containing ultraviolet curing resin coated medium according to the present invention, 2
2 is a conventional uncoated medium, and as is clear from this figure, the jitter of the present invention medium is 50nθθC regardless of humidity.
However, in conventional media, the jitter increases as the humidity changes. This is because a signal shift occurs due to humidity expansion (contraction).

Jitter at reduced humidity of 50CX is 3, the same as the inventive media.
0 nB@Q, but this is because the humidity at the time of recording is 50X
This is a reminder.

Next, the jitter amount of these two media was measured by raising the temperature while keeping the absolute humidity constant, and FIG. 3 shows the temperature dependence of the jitter amount.

21' is a coated medium of the present invention, and 22' is a conventional uncoated medium. As is clear from this figure, it can be seen that the medium of the present invention shows little change in the amount of jitter.

- It can be seen that the amount of jitter in conventional media has a large temperature dependence. The reason why the amount of jitter between the medium of the present invention and the conventional medium is the same at 25°C is due to the fact that the recording temperature is 25°C.

It can be seen from these FIGS. 2 and 3 that the medium of the present invention is extremely stable against changes in temperature and humidity in the external environment.

Next, we examined the changes in the amount of jitter due to temperature rise using a variety of media (with a constant coating thickness of 15 μm) using different types of media, including Sin and 5102 microparticles of ultraviolet curable resin containing microparticles.

That is, the amount of jitter was measured by recording at 25°C and reproducing the signal at a total temperature of 80°C.

FIG. 4 is a diagram showing the dependence of the jitter amount 810 on the amount of fine particles. The horizontal axis is the fine particles t (Vot%).

What is important to note in this figure is that the amount of fine particles is up to 80 VotXO, but this is because an ultraviolet curable resin having a content exceeding 80 Vot% cannot be uniformly coated.

This figure shows that if the amount of fine particles is zvozX or more, there is no temperature dependence of the amount of jitter. But 27ot
Even if it is less than %, the effect is large.

All 810. used in this example. The average particle size of fine particles is 1
It is 000A. The surface hardness of the medium of the present invention was 2H on a pencil hardness, and the scratch resistance was improved compared to the conventional uncoated medium B-HB.

The dielectric material contained in the ultraviolet curing resin used in this example was S10. However, it is not limited to Sin, Altoz, C! aF! , OeF, KBr,
Kc4LaF1, NdFl, 810. Th
F4. WOs, 0sBr.

C8 Engineering, MgO, NaF, The, , MgF!
, AtN, Bi, @N, .

81N, ZnS, SiC! There is no problem in using fine particles such as , TiN, or a mixture thereof.

Also, the average particle size is not limited to 1000A (10
There is no problem with a diameter of 0A, a diameter of 1 μm, etc.

Furthermore, although the structure of the recording medium used in this example is a closely bonded structure, the present invention is also effective with an air sandwich structure and a single plate, and is applicable to write-once optical recording media instead of magneto-optical recording media. The present invention is also effective. Furthermore, the structure on the recording layer side of this example is a three-layer structure in which the magneto-optical recording layer is sandwiched between dielectric films, but it is possible to add a reflective film other than this to a four-layer structure or a third layer structure. A three-layer structure in which the dielectric film is replaced with a reflective film is also effective.

〔Effect of the invention〕

As described above, according to the present invention, the part of the optical recording medium that contacts the outside world is coated with an ultraviolet curable resin containing dielectric fine particles, thereby reducing signal jitter and noise due to changes in temperature and humidity in the external environment. Bi -1
-'F, rror Changes in Ratθ can also be reduced. Furthermore, since the substrate surface becomes hard, scratch resistance is also improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the magneto-optical recording medium of the present invention. FIG. 2 is a humidity dependence diagram of the amount of jitter. FIG. 3 is a temperature dependence diagram of the amount of jitter. Figure 4 shows the jitter amount of 810! Fine particle amount dependence diagram. 1... Polycarbonate (PC) board with guide groove 2.
...Composite dielectric film of aluminum nitride and silicon nitride 1
000A thickness 3--NdDyF'eCoTi magneto-optical recording film 400A
Thickness 4... Composite dielectric film of aluminum nitride and silicon nitride 1000A Thickness 5... Grooveless PC board 6... Composite dielectric film of aluminum nitride and silicon nitride 500A Thickness 7... Ultraviolet (U/V) ) Cured resin layer 8...Sin
, fine particle-containing ultraviolet curable resin layer 21...S10. according to the present invention. Covered cloth medium 22...Conventional uncoated medium 21'...S10. according to the present invention. Covered cloth medium 22'・
...Conventional uncoated media. Part 2 Diagram 3

Claims (1)

[Claims] In an optical recording medium in which recording, reproduction, or erasing is performed by irradiating an optical recording layer formed on a transparent resin substrate with light, the portion of the optical recording medium that comes into contact with the outside world is exposed to ultraviolet light containing dielectric fine particles. An optical recording medium characterized by being coated with a cured resin.