JPH0452239B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION Technical Field The present invention relates in particular to optical recording media having a liquid crystal layer. Prior art and its problems In recent years, the development of erasable and rewritable optical recording media has become active, and one known one is one that utilizes the phase transition of liquid crystals (SPIC 420 p194~
p199 etc.) Such a medium is constructed by providing, for example, a liquid crystal layer such as a smectic layer between a substrate having a light-absorbing electrode layer and a transparent electrode having a transparent electrode layer. By irradiating such a medium with a laser beam, the light-absorbing electrode layer generates heat and is rapidly cooled, causing a smectic-nematic phase transition, etc., to occur in the irradiated area, and a recording point is formed. , writing is performed. Further, when the medium after writing is irradiated with a reading laser beam, reading can be performed by light scattering at the recording point. Furthermore, by applying an electric field between the electrodes of the medium after writing, or by heating or slowing down, the transition to the original smectic phase, etc. is performed.
The data is erased and can be rewritten. In addition, it is also possible to perform laser irradiation while applying a voltage, or to perform erasing by heating without applying a voltage. In addition, dichroic dyes may be included in the liquid crystal phase,
An alignment agent layer may also be provided between the electrode layer and the liquid crystal phase. In such media, metals such as Cr, Cr alloy, Au, Al, etc. are usually used as the light-absorbing electrode layer, which has the drawbacks of low recording sensitivity and low readout S/N ratio. There is. OBJECT OF THE INVENTION An object of the present invention is to improve the recording sensitivity and read S/N ratio in a heat mode rewritable optical recording medium having a liquid crystal layer. These objects are achieved by the invention described below. That is, the first invention comprises a base body having a light-absorbing electrode layer and a transparent base body having a transparent electrode layer, and the two base bodies are integrated so that the two electrode layers face each other to form a cell. The optical recording medium is characterized in that a liquid crystal is stored therein as a recording layer, and the light absorption electrode layer has a phthalocyanine layer. Further, the second invention comprises a base body having a light-absorbing electrode layer and a transparent base body having a transparent electrode layer, and the two base bodies are integrated so that the two electrode layers face each other to form a cell, and this cell The optical recording medium is characterized in that a liquid crystal is stored therein to form a recording layer, the recording layer contains a dye, and the light absorption electrode layer has a phthalocyanine layer. The third invention comprises a base body having an electrode layer and a transparent base body having a transparent electrode layer, and the two base bodies are integrated so that the two electrode layers face each other to form a cell, and in this cell, This optical recording medium is characterized in that it stores liquid crystal as a recording layer, this recording layer contains a dye, and this dye contains phthalocyanine. Furthermore, a fourth invention comprises a cell having a liquid crystal between a base body having an electrode layer and a transparent base body having a transparent electrode layer, and integrating both base bodies so that both electrode layers face each other, Either a liquid crystal is stored in this cell and used as a recording layer, or a dye is added to this recording layer, and the electrode layer has a phthalocyanine layer.
Alternatively, the optical recording medium is characterized in that the dye is phthalocyanine, and an alignment agent layer is provided on one or both of the electrode layer and the transparent electrode layer. Specific Configuration of the Invention The specific configuration of the present invention will be described in detail below. The medium of the invention has first and second substrates. The first substrate is made of glass, various resins such as polycarbonate, various photosensitive resins, various metals, etc., and an electrode layer is formed on its surface. This electrode layer also functions as a light absorption layer, and phthalocyanine is used as the light absorption agent. Therefore, the electrode layer may be formed using phthalocyanine alone. However, usually indium tin oxide (ITO),
Metal oxides such as indium oxide and tin oxide; Single metals such as Al, Au, Cr, Pd; Cr alloys, TbFeCo, TbDyFe, GdTbFe, GdFe,
Rare earths (Gd, Tb, Dy, Ho, etc.) and transition metals (Fe, Co, etc.) such as GdCo, TbFe, GdFe, TbFeO ₃
It is preferable to have a phthalocyanine light-absorbing layer on a base layer with a thickness of about 0.01 to 2 μm, such as an alloy thin film of MnBi, MnCuBi, etc.; or a chalcogenide system such as SbSe, TeAsGe, TeOx. In such cases, the phthalocyanine used is
There is no particular restriction, and the central atoms include Cu, Fe,
Co, Ni, In, Ga, Al, InCl, InBr, InI,
GaCl, GaBr, GaI, AlCl, AlBr, Ti, TiO,
Si, Ge, H, _H2 , Pb, Vo, Mn, Sn, etc. are possible. In addition, -OH, halogen,
−COOH, NH ₂ , −COCl, −COOR′, −
OCOR′ (where R′ is various alkyl or aryl, etc.), −SO ₂ Cl, −SO ₃ H, −CONH ₂ , −CN, −
Various substituents such as NO ₂ , -SCN, -SH, -CH ₂ Cl, etc. may be bonded thereto. Furthermore, phthalocyanine can be added to polymer chains such as polystyrene, polyvinyl alcohol, styrene-vinylpyridine copolymer, and polybenidyl glutamate, such as -COO-, -OCO-, -CONH-, -
NHCOO-, _-SO2- , _-SO2NH- , -O-, etc.
Alternatively, they may be bonded to these through divalent groups such as alkyl groups, or polymerized in two or three dimensions as polyamide, polyimide, polyester, polyurethane, epoxy resin, polyvinyl alcohol, polyacrylic acid, silicone resin, etc. It may be a condensed one. The phthalocyanine layer as such a light absorption layer has a thickness of about 0.005 to 5 μm, and is formed by vapor deposition, sputtering, coating, or the like. Note that the phthalocyanine layer contains other pigments,
Other polymers or oligomers, various plasticizers, surfactants, antistatic agents, stabilizers, crosslinking agents, catalysts,
An initiator, sensitizer, alignment agent, alignment treatment agent, etc. may be contained. Note that, as described later, when phthalocyanine is contained in the liquid crystal layer, the electrode layer on the first substrate does not necessarily have a layer containing phthalocyanine. On the other hand, the second substrate is a transparent substrate, and is formed from glass, polycarbonate, acrylic, epoxy, various transparent resins such as various photocurable resins, and the like. Then, on this second substrate, indium oxide, ITO (indium tin oxide), tin oxide, Al,
A transparent or semitransparent electrode layer of various metals such as Au, Cr, Cr alloy, Pb, etc. is formed to a thickness of about 0.001 to 10 μm. The first and second substrates are integrated via a spacer or the like so that the electrode layers supported by both substrates face each other, and form a cell, in which a liquid crystal is stored. . The liquid crystals used are nematic, cholesteric,
There are no particular restrictions such as smectic liquid crystal, but the sensitivity,
In terms of the S/N ratio, it is preferable that the liquid crystal be a smectic liquid crystal and undergo a smectic-to-isotropic transition, a smectic-to-nematic transition, or a smectic-to-nematic to isotropic transition. As such liquid crystal compounds, the following are suitable. Such liquid crystals are usually poured into the cell either singly or in combination, with the addition of other nematic or cholesteric liquid crystals, and optionally with electrolytes, such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. ketone type, butyl acetate, ethyl acetate, carbitol acetate, ester type such as butyl carbitol acetate, ether type such as methyl cellosolve, ethyl cellosolve, aromatic type such as toluene, xylene, halogenated alkyl type such as dichloroethane , dissolved in a solvent such as alcohol, and stored in a cell. Note that the thickness of the liquid crystal layer is approximately 0.01 to 100 μm. Furthermore, the liquid crystal layer may contain one or more types of dyes. At this time, sensitivity improves. Examples of such dyes include dichroic dyes. The following dichroic dyes are particularly suitable. 6. Others include tetrazine type, methine type, squarylium type, etc. Furthermore, as the dye, the above-mentioned phthalocyanine can be mixed with the liquid crystal, and in this case, the sensitivity is improved. The mixing ratio of liquid crystal and dye is 1:1 in molar ratio.
It should be about 0.01 to 0.8. Furthermore, the liquid crystal layer may contain various alignment agents, various polymers or oligomers such as polycarbonate, various plasticizers, various stabilizers, and the like. In addition, on either or both of the electrode layer on the first substrate and the electrode layer on the second substrate,
Sensitivity is further improved by providing an alignment agent layer. In such a case, it is preferable that the alignment agent on the first substrate be horizontally aligned and the alignment agent on the second substrate be vertically aligned. The following alignment agents are suitable for use. (1) Solution application (physical adsorption) (1) Vertical orientation Lecithin, stearic acid, CTAB (hexadecyltrimethylammonium bromide),
Octadecylamine hydride, etc. (2) Parallel alignment Carbon, polyexyethylene, Versamide 125, polyvinyl alcohol, polyimide, etc. (1) Solution coating (chemical adsorption) (1) Vertical alignment Monobasic carboxylic acid chromium complex (e.g. myristic acid) chromium complex, perfluorononanoic acid chromium complex), organic silane (e.g. DMOAP)
etc. (2) Parallel alignment dibasic carboxylic acid chromium complex (e.g. chromium brassylate complex), organic silane (e.g.
MAP), etc. (3) Plasma polymerization (1) Vertical orientation Hexamethyldisiloxane, perfluorodimethylcyclohexane, tetrafluoroethylene, etc. (2) Parallel orientation Acetylene, etc. (4) Sputtering (1) Vertical orientation Polytetrafluoroethylene, etc. (5 ) Liquid crystal dissolution injection (physical adsorption) (1) Vertical alignment Lecithin, CTAB, Versamide 100, Odecylmalonic acid, etc. (2) Parallel alignment Dibasic fatty acids (e.g. HOOC (CH ₂ )
nCOOH, n=3-11), Versamide 125, Crown Ether, etc. (1)' Rubbing method The surface is rubbed in one direction with cotton cloth, absorbent cotton, etc., and oriented in parallel. (2)′ Oblique evaporation method (1) Single evaporation Planar oxides such as SiO are evaporated from an oblique angle, resulting in oblique parallel orientation (shallow evaporation angle) or parallel orientation (deep evaporation angle). (2) Double evaporation The first layer of oxide such as SiO is deposited on the surface at a shallow deposition angle, and the second layer is deposited at a deep deposition angle by rotating the substrate surface by 90 degrees, resulting in an inclined parallel orientation. (3) Rotary evaporation While rotating the surface, oxides such as SiO are deposited from an oblique angle and oriented vertically. (3)′ Ion beam method: The surface is etched by irradiation with an ion beam from an oblique angle, and the surface is oriented in parallel. (4)′ Plasma method Etch the surface using oxygen plasma, etc., and align it in parallel. (5)' Pull-up coating method The substrate may be immersed in a solution of polymer or the like, pulled-up coated, and aligned in parallel. Note that it is preferable that a tracking groove be provided on the surface of the first base. In this case, the groove may be concave or convex. In addition, its shape is square, semicircular, semielliptical,
In addition to the V-shape, it is also preferable to have no corners, and various selections may be made depending on the alignment characteristics of the liquid crystal material. Furthermore, a heat insulating layer may be provided on the electrode layer of the first base. Further, a reflective layer or a semi-transparent reflective layer may be provided on the first substrate. Specific Effects of the Invention The medium of the present invention is irradiated with a laser beam from its transparent or translucent base side. This results in the smectic-isotropic, smectic-nematic, or smectic-nematic transition.
An isotropic transition or the like occurs in response to the irradiation beam and a recording point is formed. Reading of recording points is performed by detecting reflected light or transmitted light, usually reflected light. In order to partially erase the area, for example, an erasing laser beam may be irradiated while applying an electric field. Further, in order to erase the entire area, it is sufficient to heat the entire area while applying an electric field or to irradiate erasing light. In addition, writing may be performed while applying an electric field, or erasing may be performed by heating without applying a voltage. Furthermore, the laser pulse width, the shape of the laser spot, and the intensity of the laser beam may be changed for erasing. Specific Effects of the Invention According to the present invention, recording sensitivity is significantly improved. Furthermore, the read S/N ratio is also improved. The present inventors conducted various experiments to confirm the effects of the present invention. An example is shown below. Example ITO was deposited on a glass substrate, and the first and second
It was used as the base of Then, vanadyl phthalocyanine was deposited to a thickness of 0.1 μm on the electrode of the first base. Both substrates were integrated with an inter-electrode spacing of 8 μm, and a smectic liquid crystal mixture S2 (manufactured by British Dry House Co., Ltd., etc.) was housed inside to obtain sample No. 1. Furthermore, 0.08wt% dichroic dye is added to the liquid crystal compound.
Containing NK-2772 (manufactured by Nihon Kanko Shiki Co., Ltd.) and 0.05% vanadyl phthalocyanine, sample No. 2,
I got 3. In addition, in sample No. 2, after coating an acrylic photopolymer on the vanadyl phthalocyanine layer of the first substrate and photocuring, KBM403
A horizontal alignment agent (manufactured by Shin-Etsu Chemical Co., Ltd.) was formed to a thickness of 500 Å, and a vertical alignment agent FS-150 (manufactured by Dainippon Ink Co., Ltd.) was formed to a thickness of 600 Å on the ITO layer of the second substrate. I got sample No.4. Separately, for comparison, we added a phthalocyanine layer.
Sample No. 5 was added instead of the CdTe layer. For each of these samples, writing was performed from the transparent electrode side using a GaAlAs laser as a light source and a condenser output of 15 mW. Next, GaAlAs laser (concentrator output
Using a reading light of 0.8 mw), the writing light pulse width at which the S/N ratio of the reflected light was 50 dB was measured, and the reciprocal of the sensitivity was calculated. Further, writing was performed using a writing light having a pulse width of 200 nsec, and then reading was performed using the above-mentioned reading light, and the read S/N ratio was measured. The results are shown in Table 1.

[Table] From the results shown in Table 1, the effects of the present invention are clear.

Claims (1)

[Scope of Claims] 1. A cell having a base body having a light-absorbing electrode layer and a transparent base body having a transparent electrode layer, the two base bodies being integrated with the two electrode layers facing each other, and comprising a cell. 1. An optical recording medium, wherein a liquid crystal is stored therein as a recording layer, and the light absorption electrode layer has a phthalocyanine layer. 2. A cell having a substrate having a light-absorbing electrode layer and a transparent substrate having a transparent electrode layer, and integrating both substrates so that the electrode layers face each other to form a cell, and storing a liquid crystal in the cell. An optical recording medium characterized in that the recording layer is a recording layer, the recording layer contains a dye, and the light absorption electrode layer has a phthalocyanine layer. 3. A cell is formed by having a base body having an electrode layer and a transparent base body having a transparent electrode layer, and the two base bodies are integrated so that both electrode layers face each other, and a liquid crystal is stored in this cell for recording. An optical recording medium characterized in that the recording layer contains a dye, and the dye contains phthalocyanine. 4. A cell is formed by having a liquid crystal between a base body having an electrode layer and a transparent base body having a transparent electrode layer, and integrating both base bodies so that both electrode layers face each other,
Either a liquid crystal is stored in this cell and used as a recording layer, or a dye is added to this recording layer, and the electrode layer has a phthalocyanine layer.
Alternatively, the optical recording medium is characterized in that the dye is phthalocyanine, and an alignment agent layer is provided on one or both of the electrode layer and the transparent electrode layer.