JPS63129339A - Optical recording medium and optical recording and reproducing method - Google Patents

Abstract

PURPOSE:To permit erasure and reproduction by using an org. dye molecule associated body, the polarization dichroism of which is changed by photoirradiation, to form a recording layer having the polarization dichroism. CONSTITUTION:Writing of a record is executed by projecting a laser to a recording medium consisting of the org. dye molecule associated body which has an absorption band in a visible light - near IR region and exhibits the polarization dichroism and changing the polarization dichroism of the org. dye molecule associated body in said recording medium. Reading of the record is executed by detecting the dichroic ratio of the polarized light transmitted through or reflected from the photoirradiated part or a change in rotating angle. The org. dye molecule to be used is exemplified by merocyanine and cyanine dyes. Erasure and reproduction with high sensitivity are thereby permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical recording medium and a method for recording and reproducing the δ self.

BACKGROUND ART AND PROBLEMS Conventionally, many optical recording media using organic dyes have been proposed, but the recording principle of these recording media is that the dye is
Since this is based on the change in the shape of the recording medium (in some cases, bit formation) due to the heat generated by absorbing tt, <in most cases laser light), it is necessary to provide a spacing layer etc. that can absorb this change. , the structure of the recording medium was complicated.Also, since the original recording medium using conventional organic dyes detects changes in the light reflectance and transmittance of the medium after light irradiation, The rate is usually 10% or more, preferably
It is required that it be 15% or more. Therefore, it is currently considered difficult to reduce the energy consumption and irradiation time required to write a record.Furthermore, in conventional optical recording media, dye molecules vaporize due to focal point formation. It involved discreteness and was not reversible.

Recently, recording media that utilize the phase change of inorganic M crystals due to thermal mode have been proposed for optical recording media that have these problems, but since these are inorganic materials, coating, casting, etc. Simple film-forming methods cannot be used, and relatively complicated film-forming methods such as Shinshin vapor deposition and spatter must be used.

The inventors of the present invention have looked at these situations and found that the coating film can be formed by soluble in organic medium, has high sensitivity, and (
As a result of intensive studies on optical recording media that can be erased and reproduced, we found that a special association of cyanine and merocyanine dyes exhibits polarization dichroism in the solid film state, and that this material can be changed to a non-aggregated state by light irradiation. Then, he discovered φ that loses polarization dichroism and completed the present invention.

Summary of the Invention The optical recording medium according to the present invention comprises a substrate, a recording layer, and optionally a reflective layer and a protective layer, the recording layer being an organic film exhibiting polarization dichroism. It is characterized by #k, which is a dye molecule association.

Further, in the recording/reproducing method using the optical recording medium according to the present invention, recording is written by irradiating the recording medium with a laser to change the polarization dichroism of the organic dye molecule association in the recording medium. After performing this, the recording is read out by detecting changes in the dichroic ratio or rotation angle of the transmitted or reflected polarized light of the light irradiation section.

Performance of each layer in the optical self-recording medium of the present inventionj-71jl
The order may be either l) substrate - (reflective layer) - recording layer = (protective layer) and 2) -4 board - recording layer - (reflective layer) [However, the layers in parentheses are not essential] .

According to the above-mentioned method 2), it is also possible to create a structure in which the recording layer is sandwiched between the substrate and the reflective layer and hermetically protected. 'I! Among the r-layers, φ, which is optically inactive except for the recording layer, must be a female, and in particular must not exhibit anisotropy such as birefringence.

The organic dye molecules used in the present invention include, for example, merocyanine expressed by the following formula and/or mixed with other gland-forming substances, and have a sharp absorption band in the visible light region. , special aggregates that have the property of emitting fluorescence (usually
The film is coated to form a J aggregate or a 5chsibe aggregate. As the film forming method, the Langmuir 7' logiette method or the coating method is used.

Among these, the following compounds are preferred from the viewpoint of ease of acquisition.

Xn NK2560 S l 1NK262
2 S CIO, 1NK2638 S
CJo, ONK 2b65 C (C1-1,
), Z IN K 304 b Q
C1O+ 1NK2684 HS I NK 27345 CH3S I NK 2746 6-CH,S LNK2733
Formation of the aggregate by the HSe l Langmuir-Prodgett method is carried out as follows. First, a solution of the above-mentioned cyanino pigment dissolved in an organic porous medium is dropped onto the water surface of the aquarium (at this time, other molecules such as hexadecane and stearic acid are mixed to an extent that does not interfere with the formation of J-aggregates). Obtain a monomolecular group that does not mind if the monomolecular film meets (・).Next, while compressing this monomolecular film with a constant surface pressure, insert the substrate vertically into this film, and then repeat the operation of pulling it up as many times as desired. By transferring the above monomolecular film onto a substrate, a J-aggregate in which the dye molecules are oriented in the direction of infiltration and pulling up of the substrate is obtained.Also, it is also possible to form a J-aggregate using a coating method. In particular, in the case of the merocyanino dyes mentioned above, the MU of the dye alone or other matrinoxaceae (e.g. polymethyl methacrylate, polycarbonate, polyvinyl chloride, polystyrene) can be deposited on a solid material.

Vinylidene boria, polysulfone polymer materials)
By casting a mixed bath solution with , evaporating the solvent, and immersing it in alkaline water Sa, J aggregates are simply generated. At this time, by using an inorganic material (e.g., mica) or an organic polymer material (e.g., polyvinylidene fluoride, aromatic polyimide, etc.) having a highly crystallized next-plane structure as a solid substrate, the above J-aggregate can be formed. It becomes in-plane oriented on the substrate and exhibits polarization dichroism.

It was known that the light absorption spectrum of the J-aggregates formed in this way changes greatly due to changes in the microscopic structure within the molecule due to heat. Until now, it was not known that it exhibits optical properties and that it becomes optically inactive due to the heat generated by light irradiation.

In the present invention, the basic principle is φ, which utilizes such characteristics of the J aggregate and reads the difference in polarization dichroism or optical rotation between the original irradiated part and the non-irradiated part. The present invention - Polarization dichroism and Q refer to the dichroism of linearly polarized light or circular 1HD light. It is expressed centrally in pigment molecule dust or aggregates.

When these dyes form a special association like the J-aggregate mentioned above, the J-aggregate becomes 'W!' due to the heating of the laser irradiation area. #If the in-plane orientation of the dye molecules is disturbed by the separation, the dichroism of linearly polarized light will decrease. In addition, if dye molecules form J aggregates but do not originally exhibit in-plane orientation, heating of the laser irradiation area may cause J-aggregates to form.
Due to the dissociation of the coalescence, the maximum absorption wavelength (λ
The optical rotation in the max) region decreases. In any of the above cases, the recording m written by laser irradiation is distinguished from the non-recorded portion by a change in its transmission or reflection-original dichroic ratio or polarization rotation angle. As can be understood from its recording/reading principle, the recording medium of the present invention is reversible and rewritable in principle since it does not involve evaporation or dispersion of the dye in the recording area. -Also, the recording start-up does not detect single changes in reflectance or transmission, as has been the case until now.
0.50° is sufficient), the light irradiation energy and time required for writing can be significantly reduced.

The present invention will be explained below according to examples.

Example 1 Melonanine shown below (Japan Photosensitive Dyes Shiso, NK-
2733) 109 to 25 tnl pao form K f
eI, 10-' mol/73 (1) COCl
2 ZK l'G g (water temperature controlled at 17°C) 90 μl of the solution was dropped onto the surface. Thereafter, after cooling for 15 minutes, the membrane on the water surface was compressed with a pressure of 30 mN/m,
A 0.8 cm film was deposited using the Langmuir-Blodgett method on a glass substrate that had been previously treated with octadecyltrichlorosilane.
A 60-story building was constructed at a speed of /min. In this way, an optical recording layer with a thickness of about 2100 Å was formed on the glass substrate. The angle of incidence and light rotation on this optical recording medium is determined by the optical rotation angle needle (JASCO ■
When m+I was determined using an optical system (equipment), it was -8.22°, and when this was converted into specific optical rotation, it was -1.27×1070, which was an extremely large value. When this optical recording layer was instantaneously heated by Franche irradiation using a xenon lamp, the incident polarization rotation angle of the recording layer was drastically reduced to 10.90 degrees.

From this black ink, it was confirmed in principle that the recording medium can be used as a method for reading out records by changing the angle of rotation of incident polarization due to heat. Place the optically inactivated recording medium in a desiccator adjusted to 100% humidity and heat at 20C.
After cooling for 30 minutes, the angle of rotation of the incident polarized light was measured again.
”) and recovered to almost the initial value. From this φ, it was confirmed that the recording medium of the present invention is reversible and, in principle, rewritable.

Example 2 Using the optical recording medium reproduced in Example 1, a rhodamine dye laser (oscillation wavelength: 600±tonm) was used for 2. Op
When pulse irradiation was performed at 10 CPS with a power of tn &, 3 fJ my, the incident polarization rotation angle was -7,
It was confirmed that φ decreased from 37° to -2.27' and that laser recording was possible. In addition, the 6d recording sensitivity of this medium is
It reached 10mj/cij.

Example 3 Merocyanine dye 10019 used in Example 1 was dissolved in chloroform 10a/[@, and a film was formed on a clean glass plate by a spin cord method. The thickness obtained in this way is 2600
A recording medium having a dye layer of 1 wt% KOHO
After immersion in H water for 10 seconds, the dye layer changed from red to blue-purple, indicating the formation of J aggregates. This material was flash irradiated with a xenon lamp in the same manner as in Example 1, and the incident polarization rotation angle was changed from -6.35° to -0.
,05°. From this fact, the recording medium of this example in which the J-aggregate obtained by the coating method is used as the recording medium also has the ability to withstand changes in polarization dichroism due to heat, as well as the medium obtained in Example 1. It has been confirmed in principle that this method can be used as a smudging method.

Example 4 Using the following cyanine dye instead of the merocyanine dye used in Example 1, a monomolecular film was formed on distilled water,
60) was accumulated on a glass substrate in the same manner as in Example 1. -F with thickness 2200A obtained from Koushi-c! ! , a recording medium having a fiber layer was irradiated with 7 runs of light using a xenon lamp in the same manner as in Example 1, and the incident polarization rotation angle was -
4.25° color sharply decreased to 0.15°. From this, it has been confirmed in principle that the recording medium can be used as a method for reading out records based on changes in polarization dichroism caused by heat.

J: ＼-12I

Claims (1)

[Scope of Claims] 1. An optical recording medium having a substrate, a recording layer, and optionally a reflective layer and a protective layer, in which the recording layer has polarization dichroism and is polarized by light irradiation. An optical recording medium characterized by being an aggregate of organic dye molecules whose polarization dichroism can be changed. 2. The optical recording medium according to claim 1, wherein the recording layer is a cyanine or merocyanine dye aggregate exhibiting polarization dichroism. 3. The optical recording medium according to claim 1, wherein the organic dye aggregate has an absorption band in the visible light to near infrared light region. 4. When writing and reproducing records using an optical recording medium consisting of at least a recording layer and a substrate that have polarization dichroism and whose polarization dichroism can be changed by light irradiation, First, recording is written by irradiating the recording medium with a laser to change the polarization dichroism of the organic dye molecule aggregate in the recording medium. An optical recording/reproducing method characterized in that recording is read out by detecting changes in chromaticity ratio or polarization rotation angle.