JPH0246442A - Organic medium functioning as optical disc - Google Patents

Abstract

PURPOSE:To prevent an optical disc from oxidation and deterioration due to an effect of an air layer by pasting two sheets of org. medium formed by providing a reflection layer on a photochromic thin film by arranging each inside surface of each reflection layer to face each other. CONSTITUTION:A recording medium layer 12 comprising a compd. causing reversible change of extinction which is different for two kinds of light having different wavelength (e.g. two kinds of laser light) on a substrate 11, and a light reflecting layer 13 is formed on the layer 12 by the vapor-deposition of Al, etc. Then, obtd. two sheets of the optical disc are pasted together by arranging each layer 13 to the inside with an adhesive agent 14. Thus, the title medium is formed. Further, it is also preferred that a recording medium layer and a reflection layer are formed successively on a substrate, and that a rigid substrate is further pasted on the reflection layer for the formation of the medium. The repeatability for recording and erase are improved by forming the layer 13, and the prepn. is simplified since no spacer is inserted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an organic optical disk medium using an organic compound as a recording medium.

[Prior Art] Optical disk media such as compact discs (CDs) are attracting attention as large-capacity external recording media, and currently on the market there are read-only optical disks such as CDs. There are two types of optical disc media: write-once type optical disc media that can be written only once.

The recording media used for write-once optical discs that users can write to include infrared regions (semiconductor laser light regions).
Substances that absorb T are used, and for inorganic compounds, T
A dispersion film based on e-based material is used, and a dye-based spin code film is used for organic compounds.

Among organic compounds, organic dyes can be produced at a lower cost than expensive inorganic compounds, and when disposing of disused optical dyes, they do not require special disposal equipment due to their low toxicity. It has several advantages.

[Problems to be solved by the invention] However, compared to inorganic materials, organic dyes have poor durability and
It had poor weather resistance, and there were concerns about the storage stability and reliability of records. Furthermore, some recording materials are degraded by laser light irradiated during recording and reading, which poses problems in the application of organic compounds to optical discs.

As shown in Figure 3, conventional write-once optical disc media that use organic compounds as recording media use laser beams to make holes in the recording medium, so the scum and debris generated when the holes are formed are eliminated. It had an air sandwich structure with an air layer 34 to allow dust to escape. In FIG. 3, 31 is a disk substrate, 32 is a recording medium layer, and 33 is a scrubber for creating an air layer 34.

On the side surface of the optical disk medium with the air sun structure shown in FIG. 3, there is an air layer 34 provided inside the disk.
It is common practice to provide a small hole to eliminate the pressure difference between the air and the outside air. Therefore, the recording medium layer 32 made of an organic compound comes into direct contact with the outside air through the small holes in the side surface scrubber 33 and is exposed to laser light, which may cause accelerated deterioration of the recording medium such as oxidation due to oxygen. It had become. Additionally, the manufacturing method for optical discs is complicated;
There is also the problem of deterioration in signal quality due to contamination of the recording medium layer 32 by dust and the like that enter through the small holes provided on the sides.

In order to solve these problems, is it desirable to have a disk structure that eliminates the air layer of this optical disk?In the conventional hole punching method, the air layer is created by gas and dust generated when the holes are formed. Optical discs that do not have an air layer and have an organic compound as a recording medium layer have not been developed since this is essential for allowing the air to escape.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and provide an optical disc medium that can be written without creating an air layer that causes deterioration of the recording medium layer. be.

[Means for Solving the Problems] In order to achieve such an object, a first aspect of the present invention includes a photochromic thin film that reversibly exhibits different absorbance changes depending on two wavelengths of light on a disk substrate. The present invention is characterized in that two optical disc media are provided with a photochromic thin film and further provided with a reflective layer that reflects light, and are bonded together with the reflective layer surfaces facing inside.

In a second embodiment of the present invention, a photochromic thin film that reversibly exhibits different absorbance changes depending on two wavelengths of light is provided on the disk substrate, a reflective layer that reflects light is provided on the photochromic thin film, and further, It is characterized by a rigid base material being bonded to the reflective layer.

[Function] According to the present invention, since no air layer is provided inside the optical disc, the recording medium layer does not come into direct contact with air and is not subject to deterioration such as air oxidation.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Example 1 1,3',3'-1-methyl 6-hydroxyspiro[2H-]-benzobilane 2,2'-indoline] (abbreviation: A recording medium layer 12 was prepared by pin-coding HBPS) onto a PMM eight-substrate substrate, which is a disk substrate 11, on which grooves were formed by a photopolymer method. The spin code is HBPS at a concentration of 1g/10mu to 10g/10mu
An ethanol solution was prepared and applied onto the disk substrate 11 at a temperature of 40 to 80 degrees. The rotation speed of the PMMA substrate is 1000
~110000rp. The thickness of the recording medium layer 12 was controlled to a predetermined thickness.

Next, an aluminum layer was formed directly on the HBPS film, which is the recording medium layer 12, by a vacuum evaporation method as an anti-resistant layer/protective layer 13.

Two optical discs produced in this manner and having different thicknesses of HBPS were bonded together using adhesive 14 with the aluminum surfaces facing inside to form an optical disc configuration as shown in FIG. 1.

Apart from the optical disk medium having the configuration shown in Figure 1, there is also an optical disk medium in which the film thickness of the HBPS film is changed without bonding two optical disk media together, an optical disk medium in which /l is not deposited, and a film thickness of 81. A modified optical disk medium was produced.

Recording and erasing characteristics were measured for a double-sided recordable optical disk medium having the configuration shown in FIG. 1 under different manufacturing conditions and a single-side recordable optical disk medium having different manufacturing conditions and having the configuration shown in FIG. 1. The results obtained are shown in Table 1.

Table 1 Here, two types of laser beams with different wavelengths were used for recording and erasing. That is, for recording, He-Ne laser light (wavelength 6
32.8 nm, pulse width 300 n sec, duty 5091;, 6 mW, spot diameter 1.2 μmφ), and UV (Ar+laser light, wavelength 360 nm) was used as the erasing light.
A continuous pulse of 1.0 μm in diameter, 6 mW, and a spot diameter of 1.0 μm was used. Recording is performed by irradiating a pulse of He-Ne laser light onto a track that has been colored with UV light.
e A decoloring portion corresponding to the pulse width of the laser beam is formed, and the color erasing portion is 0.
Reading was performed using a weak laser beam of 0.05 to 0.5 mW.

In the repeated recording, the track was colored again with UV light, then recorded with He-Ne pulsed light, and read out with weak He-Ne light.

As can be seen from the comparison of experiment numbers (1) and (2), the recording and reproducing signals were improved by reflection readout by the 12 layers A, . . . of the protective layer/reflection layer 13 compared to the conventional configuration. Comparison of experiment numbers (4) and (6), experiment number (5)
) and (7), as well as experiment numbers (8) and (9), it can be seen that the number of times recording and erasing is repeated is significantly improved by pasting. This indicates that thermal deformation during recording is suppressed by bonding.

In addition, by bonding the reflective surfaces of the optical disk medium with adhesive, the rigidity is increased, and at the same time, surface runout is suppressed, and the C/N ratio is improved by reducing the effect on the servo system of the optical recording head. It is thought that this includes the effects of

As shown in FIG. 2, writing and reading data using a laser beam is performed by transmitting the laser beam through the recording medium layer 22.
Since it is a reflected light readout type in which it is reflected by the reflective layer/protective layer 21 and transmitted through the recording medium layer 22, the laser beam in reciprocates inside the recording medium layer 22, so it is as if the thickness of the recording medium layer 22 is 2. We were able to increase the thickness of the recording layer to 172 mm in order to achieve twice as much effect and obtain contrast due to the same change in absorbance. Since this optical disc does not have an air layer inside the disc, the HBPS is not exposed to air, and the HBPS film does not suffer from oxidation or other deterioration even after repeated recording and reading with laser light. .

Example 2 A compound 1', 3', 3'-1-methyl-6 nitrose [2N-1-benzobilane-2,2'indoline] (abbreviated as NBPS) that reversibly changes absorbance depending on the wavelength of light was prepared. , under irradiation with ultraviolet light with a wavelength of 360 nm, and at a vacuum degree of 1. After lowering the temperature to
A PS film (thickness: 2,000 layers) was formed. After forming an An layer on the NBPS film to a thickness of 2,000 layers by vacuum evaporation, the optical disk substrate was divided into two.

The other was sealed with PMM8 for bonding via a resin adhesive layer with a thickness of 10 μm (experiment number (10)). The other side was not sealed with PMMA for bonding (experiment number (11)
)). When recording and reproducing were performed on two types of optical disk media, the optical disk medium of experiment number (11) was 102
While the recording and erasing characteristics began to change after approximately 10' cycles, the optical disk medium of experiment number (10) showed recording and erasing properties after 10' cycles or more. In this case as well, the PMM for bonding was sealed in the same way as in Example 1, and thermal deformation during recording was suppressed, and oxidative deterioration of the NBPS recording layer was prevented, resulting in significantly improved recording and erasing characteristics. Improved.

[Effects of the Invention] As explained above, according to the present invention, since an air layer is not provided inside the optical disc, the recording medium layer does not come into direct contact with air, and is thus prevented from being subject to deterioration such as air oxidation.
J.

Furthermore, by providing the reflective layer, the repeatability of recording and erasing is greatly improved. Unlike the air sandwich structure, there is no step of inserting a spacer, which simplifies the process of manufacturing an optical disc, leading to cost reductions. Since thermal deformation of the recording layer itself is also suppressed by bonding, irreversible components during repeated recording and reproduction can also be suppressed.

Furthermore, since the rigidity of the optical disk substrate is increased by bonding, substrate surface runout is reduced, and the burden on the servo for optical head recording constituted by a servo system is reduced, so the CZN ratio is also improved.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway sectional view of an embodiment of the present invention, FIG. 2 is a schematic diagram showing how a laser beam passes through an optical disk, and FIG. 3 is a partially cutaway sectional view of a conventional optical disk medium. . 112331...Disc substrate, 12.22.32...Recording medium layer, 13.21...Reflection layer and protective layer, 14...Adhesive, 24...Laser light, 33...Spacer .

Claims (1)

[Claims] 1) A photochromic thin film that reversibly exhibits different absorbance changes depending on two wavelengths of light is provided on the disk substrate, and a reflective layer that reflects the light is further provided on the photochromic thin film. An organic optical disk medium characterized in that two optical disk media are bonded together with the reflective layer surfaces facing inside. 2) A photochromic thin film that reversibly exhibits different absorbance changes depending on two wavelengths of light is provided on the disk substrate, a reflective layer that reflects the light is provided on the photochromic thin film, and a rigid An organic optical disk medium characterized by having base materials bonded together.