JPS61153841A - Optical memory medium and its recording and reproducing method - Google Patents

Abstract

PURPOSE:To obtain the titled high-density recording memory medium with high sensitivity by recording on a recording layer consisting of an org. substance contg. metallic atoms or ions forming a cluster with the light of specified wavelength, and reproducing with the light of the wavelength at the absorption maximum of the formed cluster. CONSTITUTION:Chloroauric acid, for example, is added to a methanol/water liq. mixture. The mixture is heated, and dried under vacuum to obtain polyvinyl alcohol contg. 0.1% gold. The alcohol is dissolved into methanol. The soln. is spin-coated on an acrylic sheet 1 on which an Al reflecting layer 2 is vapor- deposited, and the soln. is dried to obtain a memory medium 4 wherein a recording layer 3 is formed. A pigment laser beam 5 of 430nm wavelength is irradiated on the recording medium through a condenser lens 6 to form a cluster having about 100Angstrom size. Although the absorption maximum of Au at 560nm remains at the part which is not irradiated with the laser, the maximum at the irradiated part is lowered. The recording medium contg. >=2 kinds of metallic fine powder is thus formed by selecting the recording and reproducing wavelength, and a multiple chemical memory is also obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical memory medium and a recording/reproducing method thereof.

[Technical background of the invention and its problems]

2. Description of the Related Art Optical discs are known as memory media capable of recording information signals at a density of a, in which information signals are recorded as structural changes and optically reproduced. This type of optical memory medium has conventionally formed a recording layer of a metal thin film made of sulfur, tellurium, etc. on a glass or plastic substrate.
A method has been adopted in which information is recorded by forming bits using melting and evaporation using focused laser light. However, such metal thin film recording layers generally have low recording sensitivity due to their high melting point, and furthermore, since the recording density in the metal H film recording layer is regulated by the convergence area of the focused laser beam, it is difficult to improve the recording density. There was a problem that.

[Purpose of the invention]

The present invention aims to provide an optical memory medium capable of high-sensitivity and high-density recording, and a recording/reproduction method thereof.

[Summary of the invention]

A first invention of the present application is an optical memory medium characterized by comprising a recording layer made of an organic compound containing metal atoms or ions that form clusters when exposed to light of a specific wavelength.

The second invention of the present application is to irradiate an optical memory medium with a recording layer made of an organic compound containing metal atoms or ions that form clusters with light of a specific wavelength so that light of a specific wavelength is applied to the irradiated portion. 10 that has a light absorption maximum at a wavelength different from that of light
An optical system comprising a step of forming a cluster of ~1000 people and performing recording, and a step of irradiating a memory medium after recording with light having a light absorption maximum of the wavelength of the cluster to perform reproduction. This is a recording/playback method for a digital memory medium.

The present invention will be explained in detail below.

In general, many organic compounds having metal atoms or ions in their molecules have a property that their light absorption rate is high at a specific wavelength or wavelength range. Further, when an organic compound is excited at such a specific wavelength, metal clusters may be formed, and the formed metal clusters often exhibit an absorption peak at a specific wavelength. In view of the above points, the present inventors applied a compound having metal atoms or ions in the molecule to the recording layer of an optical memory medium, and the oscillation wavelength of the recording light source and the light absorption rate of the organic compound were adjusted. indicates the peak,
It was also found that by setting the wavelength to be approximately the same as the wavelength that forms metal clusters, metal clusters can be efficiently formed and recording can be performed.

Furthermore, it has been found that efficient regeneration can be achieved by making the wavelength at which the optical absorption of the formed metal cluster reaches its maximum and the oscillation wavelength of the reproducing light source substantially the same.

The organic compound having the above-mentioned metal atom or ion in its molecule is not particularly limited, and compounds having the above-mentioned characteristics can be used alone or in combination. Specifically, when a noble metal salt is treated with a resin solution such as polyvinyl alcohol, a complex of noble metal ions and polyvinyl alcohol or a mixture of noble metal and polyvinyl alcohol is formed.

Since such complexes or mixtures have a unique light absorption maximum, when light of that wavelength is irradiated onto a recording layer made of the complex etc., organic substances such as polyvinyl alcohol surrounding the noble metal ions are removed. etc., to become noble metal atoms, and the atoms combine and grow to form noble metal clusters. The formed noble metal cluster has a specific light absorption rate depending on the type of gold scrap element, particle size, dispersion density, surrounding organic matter, etc. In this case, the particle size and dispersion density of the clusters are determined by the type of polymer used, the degree of polymerization, the concentration, the type of noble metal ion, the concentration, the type and concentration of the organic compound that acts as a reducing agent, the intensity of light, and the irradiation time. changes depending on the presence or absence of heat treatment. Therefore, by controlling the manufacturing conditions and light irradiation conditions of the recording layer, a recording spot having an absorption maximum at a specific wavelength can be formed. Furthermore, since recording can be performed by simply irradiating light to form clusters on the recording layer, the sensitivity is significantly higher than in the conventional method in which bits are formed by melting and evaporating the recording layer.

Next, an optical recording/reproducing method for an optical memory medium according to the present invention will be explained with reference to FIG.

First, an optical memory medium 4 is manufactured by sequentially laminating a reflective layer 2 and a recording layer 3 made of an organic compound containing metal atoms or ions on a substrate 1. Subsequently, the laser beam 5 is focused on the recording layer 3 of the memory medium 4 using a lens 6. At this time,
In the recording layer 3 containing metal ions, the gold dust ions are excited and reduced by the n-containing compound to become metal atoms, which form clusters for further stabilization and are then recorded.

On the other hand, in the recording layer 3 containing metal atoms, the metal atoms are minutely aggregated to form clusters. The particle size of the clusters formed is preferably in the range of 10 to 1000 people. The reason for this is that if the particle size is less than 10, the maximum light absorption in the visible range does not occur;
When the number exceeds 0, the light absorption maximum becomes weak, the S/N ratio decreases, and reproduction becomes slow. Since such clusters have a light absorption wavelength different from that of the light used in the formation process, reproduction can be performed by irradiating the recorded recording layer 3 with light of this wavelength.

In addition, when using a recording layer made of an organic compound containing multiple metal ions, by irradiating the recording layer with light of wavelengths corresponding to those metal ions, it is possible to absorb light at the same irradiation position. A recording spot with selectivity can be formed. As a result, multiple recording and multiple reproduction are possible, and high-density recording and reproduction can be performed.

Furthermore, since the recording layer does not melt or evaporate, it is possible to form a recording layer with multiple layers of different metal types, and even when a recording layer with such a structure is used, the wavelength corresponding to the metal can be adjusted. By irradiating the same portion of the recording layer with the light, a recording spot having light wavelength selectivity can be formed at the same irradiation position, making it possible to perform high-density recording and reproduction.

[Embodiments of the invention]

Examples of the present invention will be described in detail below.・Example 1 First, chloroauric acid was mixed with polyvinyl alcohol (approximately 50%
The mixture was added to a methanol/water (mixing ratio 1:1) solution of 0) and heated under reflux for 5 minutes, followed by vacuum drying to obtain a polyvinyl alcohol polymer containing 0.1% gold. Next, this polymer was dissolved in methanol, spin-coded onto an acrylic plate on which a 1,000-layer aluminum reflective layer was deposited, and dried to form a recording layer with a thickness of 0.1 μm to produce an optical memory medium. .

Next, recording was performed by irradiating the recording layer of the memory medium with light of 200 μJ/#yII2 using an argon gas laser with a wavelength of 430 nm. At this time, gold clusters of 100 particles in size were formed in the laser irradiated area. Further, when the spectral absorption characteristics of the recording layer after recording were investigated, the characteristic diagram shown in FIG. 2 was obtained.

Next, when the reflection intensity of the recorded area was examined using a YAG laser having a wavelength of 560 nm, which is equal to the wavelength of maximum absorption of the gold cluster shown in FIG. 2, it was found to be 13% lower than that of the non-recorded area. Further, when similar measurements were performed after this optical memory medium was left for three months, the reflection intensity ratio between the recorded area and the non-recorded area did not change.

Example 2 First, a sodium hydroxide solution was added to an aqueous silver nitrate solution, and the resulting precipitate was washed with water, dried, and added to a methanol/water (mixing ratio 1:1) solution of polyvinylpyrrolidone (polymerization time: about 1000). The mixture was heated under reflux for 3 minutes and further dried under vacuum to obtain a polyvinylpyrrolidone polymer containing 0.05% silver. Next, this polymer was dissolved in ethanol, spin-coded onto an acrylic plate on which a 1,000-layer aluminum reflective layer was deposited, and dried to a thickness of 0.3μ.
An optical memory medium was prepared by forming a recording layer of m.

Next, recording was performed by irradiating the recording layer of the memory medium with light of 300 μJ/am'' using a dye laser with a wavelength of 350 nm.At this time, silver clusters with a particle size of about 50 particles were formed in the laser irradiated area. It was done.

In addition, when we investigated the spectral absorption characteristics of the recording layer after recording, we found that
The characteristic diagram shown in Figure 3 was drawn.

Next, when the reflection intensity of the recorded area was examined using a dye laser having a wavelength of 460 nm, which is equal to the wavelength of absorption maximum of the silver cluster shown in FIG. 3, it was found to be 18% lower than that of the non-recorded area.

Further, when similar measurements were performed after this optical memory medium was left for three months, the reflection intensity ratio between the recorded area and the non-recorded area did not change.

・Example 3 2 parts by weight of the gold-containing polymer made from y4FJL in Example 1 and 1 part by weight of the silver-containing boria made from y4 in Example 2 were dissolved in ethanol, and this solution was used to form an aluminum reflective layer for 1000 people. An optical memory medium was prepared by spin-coding the deposited acrylic plate and drying it to form a recording layer with a thickness of 0.3 μm.

Next, recording was performed by irradiating the recording layer of the memory medium with light of 30011 J/ms'' using a dye laser with a wavelength of 350 nm.At this time, silver clusters with a particle size of about 50 particles were formed in the laser irradiated area. Been formed.

Subsequently, 'recording was performed by irradiating light of 200 μJ/m 2 to the same location on the recording layer using an argon gas laser with a wavelength of 430 nm. At this time, gold clusters with a particle size of approximately 100 particles were formed in the laser irradiated area.
Next, when we examined the reflection intensity of the recorded area using a YAG laser with a wavelength of 560 nm, we found that it was 10% lower than the non-recorded area.
% had decreased. Furthermore, when the reflection intensity of the recorded area was examined using a dye laser with a wavelength of 46 Qnm at the same location, it was found to be 14% lower than that of the non-recorded area.

Furthermore, after leaving this optical memory medium for 3 months, 560
When similar measurements were performed using two wavelengths, nm and 460 nm, the same reflection intensity ratios as immediately after recording were obtained at each wavelength.

〔Effect of the invention〕

As described in detail above, according to the present invention, recording can be achieved simply by forming metal clusters in the photon mode, making it possible to significantly increase the sensitivity. In addition to being able to perform multiple recordings and reproductions with optical wavelength selectivity at the same irradiation point by using the optical wavelength selectivity of recording, it is also possible to shorten the wavelength of the irradiated light. It is possible to provide an optical memory medium and a recording/reproducing method thereof, which have remarkable effects such as being able to significantly improve the recording density even by reducing the diameter of the irradiation beam.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining the recording principle of the optical memory medium according to the present invention, FIG. 2 is a diagram showing the spectral absorption characteristics of the recording layer after recording in Example 1 of the present invention, and FIG. 2 is a diagram showing the spectral absorption characteristics of the recording layer after recording in Example 1 of the present invention. FIG. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Reflection layer, 3...Recording layer, 4...
...Optical memory medium, 5...Laser light: 6...Lens. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (4)

[Claims] (1) An optical memory medium comprising a recording layer made of an organic compound containing metal atoms or ions that form clusters when exposed to light of a specific wavelength. (2) The optical memory medium according to claim 1, wherein the organic compound contains two or more types of metal atoms or ions that form different clusters with light of different specific wavelengths. (3) An optical memory medium equipped with a recording layer made of an organic compound containing metal atoms or ions that forms clusters with light of a specific wavelength is irradiated with light of a specific wavelength, and the irradiated portion is exposed to a wavelength different from that of the light. 10-1000 Å with a light absorption maximum of
an optical memory medium characterized by comprising the steps of: forming clusters to perform recording; and reproducing by irradiating the recorded memory medium with light having a light absorption maximum of the wavelength of the clusters. How to record and play. (4) Using an optical memory medium equipped with a recording layer made of an organic compound containing two or more metal atoms or ions that form different clusters with light of different specific wavelengths; 10 to 100, which has a light absorption maximum of a wavelength different from that of the light on the irradiated part when irradiated with light.
A patent claim characterized in that after recording is performed by forming two or more types of clusters of 0 Å, reproduction is performed by irradiating the memory medium with two or more types of light having a light absorption maximum of the wavelength of each cluster. A method for recording and reproducing an optical memory medium according to item 3.