JPH0725204B2 - Optical information recording carrier - Google Patents

Description

TECHNICAL FIELD The present invention relates to a write-once type optical information recording carrier having an organic dye thin film.

BACKGROUND ART Conventionally, as a write-once type optical information record carrier, there is a write-once type optical information recording carrier that records a signal on a recording layer of a metal thin film such as Te provided on a circular substrate by using a laser beam, and is practically used as a write-once type optical disc. Has been converted.

On the other hand, in another write-once type optical disc, one using a thin film containing an organic dye, especially a cyanine dye in a recording layer is also disclosed in JP-A-60-103532. Such an optical disc is shown in the schematic sectional view of FIG. That is, the substrate 1 is a circular substrate made of acrylic acid resin such as PMMA, on which fine pre-addresses and pre-grooves that are aligned concentrically or spirally are formed. A solution containing a cyanine dye is uniformly coated on the pre-address and pre-groove surfaces of the substrate 1 by a spin coating method, and the coating surface is dried to form the recording layer 2. A write-once optical disc is obtained by bonding a protective plate 4 via a spacer 6 on a substrate 1 having the recording layer 2 to protect the recording layer 2 with a gap 3 therebetween.

A double-sided optical disk having an air sandwich hermetically sealed structure in which a pair of substrates 1 having a recording layer 2 as shown in FIG. 3 are carried by a reinforcing plate 7 has also been proposed.

The recording layer 2 of such a conventional optical disc is a thin film made of a cyanine dye, and the surface thereof has a bronze luster or a metallic luster and is a recording layer which is convenient for reflecting a weak laser beam at the time of reproduction. Since the thin film of cyanine dye absorbs semiconductor laser light of a predetermined power and sublimes, it has a function as a recording layer in which pits are formed by irradiation with a laser light beam during recording. Further, the thin film of the cyanine dye is excellent in flexibility and is unlikely to be cracked due to temperature change like a metal film. Due to these advantages, an optical disk having a single thin film recording layer formed of a single cyanine dye component has been developed.

However, an optical disk using a thin recording layer made of only a cyanine dye cannot withstand repeated reading and reproducing because, after writing and recording, photodegradation occurs due to weak laser light during reading or due to sunlight during handling.

Therefore, it may be considered to mix a cyanine dye with a substance that suppresses photodegradation, and a benzenethiol nickel complex may be mentioned as the substance. The benzenethiol nickel complex has a structure of 800-800 as disclosed in JP-A-57-11090.
This is because it is a substance that has an absorption wavelength in the region of up to 950 nm and is a dye that has a strong action of absorbing the laser light required for recording and converting it into heat. Therefore, mixing the benzenethiol nickel complex as a recording thin film is suitable for assisting the sublimation of the organic dye by laser light.

However, even if the conventional mixture of the benzenethiol nickel complex and the cyanine dye is used, the reading may be impossible when the reading is repeated in the optical disc on which the pits are recorded and formed.

This means that, as shown in the enlarged sectional view of FIG. 4, in the optical disc, the pre-address part a and the pre-groove part b for guiding the laser beam are provided in advance on the substrate 1, and the signal recording layer is formed thereon. Since it is covered, the reflectance of the pre-address part a is reduced and the difference between the reflected light of the pit and the non-pit is reduced, so that the reflected light is not sufficient,
The cause was that pits and non-pits could not be detected. Since the pits in the pre-groove part b are perforated in the recording layer, the pits can be detected to some extent depending on the presence or absence of reflection even if the reflectance decreases.

FIG. 5 is a graph showing the repetitive durability of the recorded optical disk by the reading laser beam, that is, the number of times of repetitive reading. The vertical axis of the graph represents the number of times that repeated reading is possible, and the horizontal axis of the graph represents the reproduction power of laser light. The playback linear velocity of the disc was 2.36 m / sec. Solid line A
Shows the durability of the recording layer in the pre-address part a, and the solid line B shows the durability of the recording layer in the pre-groove part b. That is, the pre-groove portion b limits the number of times the data can be read due to the destruction of the recording layer by the laser beam, and the pre-address portion a due to the deterioration of the reflectance of the recording layer due to the light deterioration. Therefore, in the pre-groove part b in which the pit row is formed, the read power may be kept low.
It has been clarified that the pre-address part a has started to undergo photodegradation after about 3 million times of readable times, and it is not possible to secure a difference in reflection amount enough to identify an address signal.

In recent years, in practical use of a write-once optical disc using an organic dye, a disc capable of maintaining a higher readable count, that is, an optical disc having light deterioration resistance is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an information record carrier which solves the above-mentioned problems and which is excellent in resistance to light deterioration while maintaining metallic luster.

The optical information recording carrier of the present invention is a transparent circular substrate, an optical information recording carrier comprising a signal recording layer formed on the substrate, the signal recording layer is indocyanine green, Bis (4-diethylaminodithiobenzyl) represented by
It is characterized by comprising a mixture with nickel.

Example The present inventor, as a result of research on the above-mentioned substance having resistance to light deterioration, showed that the cyanine dye having absorption characteristics in a semiconductor laser oscillation wavelength region and a solvent dissolving the dye are compatible with each other, and Finding one having an effect of absorbing light in such a wavelength region to prevent photodegradation of the cyanine dye,
The present invention has been completed.

The cyanine dye is indocyanine green represented by the following formula (I).

It has absorption characteristics in the semiconductor laser oscillation wavelength region.

The substance having an effect of absorbing light in the wavelength region and preventing the photodegradation of the cyanine dye in this example is bis (4-diethylaminodithiobenzyl) nickel represented by the following formula (II).

Bis (4-diethylaminodithiobenzyl) nickel is a so-called quencher (quenching) that can suppress the decomposition of cyanine by electronically attracting the excited state of cyanine which is excited by regeneration light and is about to cause decomposition, and taking it into itself. It is presumed that it acts as a drug, and its effect is great. This is because bis (4-diethylaminodithiobenzyl) nickel is considered to have greater optical reactivity such as light absorption and deactivation of excited state than benzenedithiol nickel complex.

An embodiment of the present invention will be described below with reference to the drawings.

PM as a solution of cyanine dye and bis (4-diethylaminodithiobenzyl) nickel by spin coating
Various optical discs were prepared by the usual manufacturing method in which the signal recording layer was formed on the MA circular substrate, and their characteristics were investigated. Cyanine dye is indocyanine green (MERCK No.4839 9th E
It was confirmed that good results could be obtained by using d.).

As a result of repeating the experiment, the concentration was 0.4 mg / cc to 1.3 mg / cc with respect to the cyanine dye solution when used as a normal single component.
Bis (4-diethylaminodithiobenzyl) nickel was mixed in the range of 1.0 to 1.0 to give some effect, but 1.0 mg /
It was confirmed that cc was the most preferable concentration. 0.4 mg /
When it was mixed with less than cc, it did not show light deterioration resistance. 1.3 mg / cc
At higher mixing, the solubility in the cyanine dye solution was exceeded and bis (4-diethylaminodithiobenzyl) nickel became insoluble.

A predetermined signal was recorded on an optical disc having a bis (4-diethylaminodithiobenzyl) nickel concentration of 1.0 mg / cc for the cyanine dye solution as a signal recording layer, and thereafter,
FIG. 1 is a graph showing the repetitive durability of the already-recorded optical disk by the reading laser beam, that is, the number of times of repetitive reading. The vertical axis of the graph represents the number of times that repeated reading is possible, and the vertical axis of the graph represents the reproduction power of laser light. The playback linear velocity of the disc was 2.36 m / sec. The solid line A shows the durability of the signal recording layer in the pre-address part a, and the solid line B shows the durability of the recording layer in the pre-groove part b. As is clear from the graph, in the pre-address part a in which the guide pit row provided in advance is formed, the photodegradation starts from the number of times the data can be read out about 17 million times, and the address in the signal recording layer is started. It can be seen that the reflection is secured enough to identify the signal.

Although the substrate of PMMA is used in this example, it is made of glass, acrylic resin, vinyl resin, polyether resin, epoxy resin, polycarbonate resin, polybutyral resin, cellulose acetate butyrate resin, nitrocellulose resin, or the like. It is also possible to use a substrate formed of a selected material.

Effect As described above, according to the present invention, since a thin film of a mixture of a cyanine dye having an absorption characteristic in a semiconductor oscillation wavelength region and bis (4-diethylaminodithiobenzyl) nickel is used as a signal recording layer, light resistance deterioration is caused. It is possible to obtain an organic dye write-once type optical disc having excellent properties and stable for a long period of time.

[Brief description of drawings]

FIG. 1 is a graph showing the repetitive durability of an already recorded optical disk by a reading laser beam of the optical disk of the present invention,
2 is a partially enlarged sectional view of a conventional single-sided optical disk, FIG. 3 is a partially enlarged sectional view of a conventional double-sided optical disk, and FIG. 4 is an explanatory diagram for explaining pre-address and pre-groove of the optical disk. FIG. 5 is a graph showing the repetitive durability of a recorded optical disk by a reading laser beam of a conventional optical disk. Explanation of symbols for main parts 1 …… PMMA substrate with guide rack 2 …… Cyanine dye recording layer 3 …… Gap 4 …… Protection plate 6 …… Spacer

Claims (1)

[Claims] 1. An optical information recording carrier comprising a transparent circular substrate and a signal recording layer formed on the substrate, wherein the signal recording layer has indocyanine green and a structural formula: Bis (4-diethylaminodithiobenzyl) represented by
An optical information recording carrier comprising a mixture with nickel.