JPS60118789A - Liquid crystal element - Google Patents

Abstract

PURPOSE:A liquid crystal element having the composition in which a specific pyrylium compound is dissolved in a liquid crystal, and capable of forming optical images corresponding to optical signals given from He-Ne laser, YAG laser, semiconductor laser or Ar laser. CONSTITUTION:A liquid crystal element containing a liquid crystal composition of a compound of formula I [R1-R4 are (substituted) aryl or (substituted) heterocyclic ring; R5 is H, alkyl or (substituted) aryl; X1 and X2 are O, S or Ce; A<-> is anion], e.g. the compound of formula II, preferably in an amount of 1-3wt% dissolved in the phase A or C of preferably a smectic liquid crystal having positive dielectric anisotropy. USE:Optical disk systems of the recording method forming a large scope display and pit.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal element that can be used in a thermal writing method.
More specifically, the invention relates to a liquid crystal element capable of forming an optical image corresponding to an optical signal generated from a laser beam, specifically a helium-neon laser, a YAG laser, a semiconductor laser, or an argon laser.

Until now, we have prepared liquid crystal elements in which a mixed liquid crystal of nematic liquid crystal and cholesteric liquid crystal with negative dielectric anisotropy or smectic liquid crystal with positive dielectric anisotropy is notated between two glass substrates. When this liquid crystal element is irradiated with a laser beam, the area is locally heated to an intropic phase, and then rapidly cooled to form a liquid crystal phase with a random orientation different from the initial uniform orientation. . As a result, light scattering occurs at the location where the laser beam is irradiated with μ-rays, resulting in a difference in optical properties from the liquid crystal phase in the background region, which is in a uniformly aligned state.

This type of liquid crystal element can also erase an optical image formed by laser writing using the method described above.

That is, by providing electrodes on each of the two substrates that make up the liquid crystal element, and heating the entire liquid crystal element using a heat source other than the laser beam (for example, a heater),
The liquid crystal phase is heated to the introtropic phase, and then the process described in 1.
T1. With a voltage applied between the electrodes, the optical structure formed by the previous writing is cooled until a homeotropic structure is formed in the case of a smectic liquid crystal, or a Grandshuan structure in the case of a cholesteric-nematic liquid crystal. Images can be erased.

This liquid crystal element does not require a matrix electrode structure to form pixels; it can form an image pattern simply by scanning 4g of light converted from an electrical signal, and has the advantage that it can be obtained on a large screen. 6 On the other hand, conventional methods for converting electrical signals from computer terminals into optical signals involve modulating a laser beam with a drive signal that corresponds to digital image information, and using this modulated laser beam to form an image. A method of scanning is adopted through an optical system consisting of a lens, a light deflector such as a carpano mirror, etc. In particular, in recent years, semiconductor lasers have come to be used as beam sources for such optical signal generators.

The semiconductor laser described above generally has a long wavelength wavelength (for example, 750 nm).
Despite having an oscillation wavelength of 1 mm or more, the above-mentioned liquid crystal elements have low heat conversion efficiency for long wavelength beams, so when writing to liquid crystal elements using a semiconductor laser, a high-power laser is required. It was necessary to irradiate the beam. However, semiconductor lasers generally have lower power than gas lasers such as argon lasers and helium-neon lasers, so it is sufficient to scan an optical signal from an optical signal generator using a semiconductor laser on a liquid crystal element such as the one shown in the previous J. There is a drawback that writing cannot be performed, or writing can only be performed by slowing down the scanning speed of the optical signal sufficiently.

For this purpose, conventionally, for example, 5ociety ofIn
display format
tional Symposium.

Digest of Technical Paper
"P, R34-49, 172-187.

238-253 (IH2), a guest-post type laser thermal writing type liquid crystal element in which a black dye is mixed into a smectic liquid crystal has been proposed.

However, even this type of liquid crystal element does not have a high efficiency in absorbing a laser beam like a semiconductor laser and converting it into thermal energy, and requires high power or low speed optical signal scanning. This point is common to the drawbacks of the liquid crystal element of the type disclosed in Japanese Publication No. 2091753. However, in the liquid crystal element using the above-mentioned black dye, a white image pattern is formed on a black background, so there is a drawback that the display does not have good ergonomics.

Therefore, it is an object of the invention to overcome the above-mentioned drawbacks and to provide a liquid crystal element capable of forming an optical image pattern in response to scanning of an optical signal from an optical signal generator using, in particular, a laser oscillator. .

The liquid crystal element of the present invention is characterized in that it uses a liquid crystal composition in which a beryllium-based compound represented by 11 is dissolved in liquid crystal.

General formula (1) In the formula, 几+, R2, ■, and 1 also represent substituted or unsubstituted aryl groups such as ketphenyl, tolyl, xylyl, chlorophenyl, methoxyphenyl, naphthyl, and 2-pyridyl, 3-pyridyl, 2 -furyl, 2-chenyl, 2-
Thiazolyl, 3-carbazolyl, 2-quinolyl, 3-quinolyl, 2-imidazolyl, 2-levidyl, 3-methoxy-2-pyridyl, 6-methyl-2-pyridyl, 4.5
-dimethyl-2-thiazolyl, 4,5-Schiff x = /
1/-Represents a substituted or unsubstituted heterocyclic group such as -2-thiazolyl, 4-phenyl-2-thiazolyl, and 9-ethyl-3-carbazolyl. ``5'' represents a hydrogen atom, any alkyl group such as methyl, ethyl, butyl, and (2) substituted or unsubstituted aryl group such as phenyl, tolyl, xylyl, chlorophenyl, fromophenyl, and naphthyl.

Xl and Xl represent an oxygen atom, a sulfur atom or a selenium atom. A is chloride ion, bromide ion, (3) iodide ion, perchlorate ion, benzenesulfonate ion, P-toluenesulfonate ion, methyl sulfate ion, ethyl sulfate ion, globil sulfate Represents anions such as ions. (4) Next, typical examples of pyrylium dyes, thiopyrylium dyes, and selenapyrylium dyes used in the liquid crystal element of the present invention are listed below.

(21) Among these compounds represented by the general formula (1), in the case of a symmetric type, the compound represented by the general formula (2) (wherein, , R, , X, and Ao are as defined above) The compound represented by the general formula (3) or the general formula (4) has the same definition as the general formula (3) (wherein, R6 is a hydrogen atom, and methyl, ethyl, propyl, (Represents an alkyl group such as butyl.) General formula (4) %Formula% (In the formula, 几 represents a substituted or unsubstituted aryl group such as phenyl, tolyl, xylyl, rylorophenyl, fromophenyl, or naphthylnato.) Suitable solvent It is obtained by reacting in When the compound represented by the general formula (1) is asymmetric, the compound represented by the general formula (2) and the compound represented by the general formula (5) i or the general formula (6) are mixed in a suitable solvent. General formula (5) (In the formula, 111 hR6, X, and Aθ have the same definitions as defined above.) General formula (6) (In the formula, , and Xl have the same definitions as defined above).

Next, one liquid crystal element of the present invention will be explained with reference to the drawings.

FIG. 1 shows a cross-sectional view of a liquid crystal element of the present invention.

As the liquid crystal composition +08, a liquid crystal in which a compound represented by the above-mentioned general formula (1) is dissolved is used. The liquid crystal used in the device of the present invention is suitably a smectic liquid crystal, particularly the A phase or C phase of a smectic liquid crystal having positive dielectric anisotropy.
phase is suitable.

Such a smectic liquid crystal is arranged in a smectic phase of a homeotropic structure until it is heated by a laser beam, and the smectic phase of a homeotropic structure with no difference in temperature → nematic phase → isotropic phase It can undergo a phase change to the tropic phase and then quench from the intropic phase.

When the phase changes to a smectic phase, a smectic phase with a focal conic structure having light scattering properties is formed. Therefore, the laser beam is 1! ζ(.

to locally inject the smectic phase in the liquid crystal element.
When heated to a tropic phase and then rapidly cooled, that area becomes a smectic phase with a focal conic structure, and since this state has light scattering properties, a still image pattern can be formed by scanning the optical signal with the laser beam described above.

Examples of compounds capable of forming a smectine phase having positive dielectric anisotropy used in the liquid crystal element of the present invention include:

For example, JP-A-56-150030, JP-A-57-
Compounds described in JP-A No. 40428, JP-A No. 57-51778, etc. can be used.

The compound represented by the above general formula (1) is present in an amount of 0.1% by weight or more, preferably 1'% to 3% by weight, based on the liquid crystal.
It can be contained in the liquid crystal composition 108 within the range of .

Further, the liquid crystal element of the present invention can also use a mixed liquid crystal of a smectic liquid crystal and a cholesteric LTK product having positive dielectric anisotropy. Cholesteric j? It is suitable that the compound is contained in the liquid crystal composition 108 in a range of 0.5% to 15% by weight, preferably in a range of 1% to 5% by weight.

Cholesteric liquid crystals that can be used in the present invention include cholesteryl chloride, cholesteryl bromide, cholesteryl yogate, cholesteryl nitrate, and cholesteryl chlorodecanoate.

Examples include cholesteryl compounds such as cholesteryl butyrate, cholesteryl caprate, cholesteryl oleate, cholesteryl caprate, cholesteryl laurate, cholesteryl myristate, cholesteryl heptyl carbamate, cholesteryl decyl ether, cholesteryl lauryl ether, and cholesteryl oleyl ether.

A liquid crystal element using such a mixed liquid crystal undergoes a phase change from a homeo (lobing) smectic phase to an intropic, smectic phase by local heating with a laser beam, and when this is rapidly cooled, a smectic phase with a focal conic structure occurs as described above. can be formed.

The liquid crystal element recorded by the method described above is manufactured by heating the entire surface of the composition 108 with a heater to change the phase to the intropic phase, and then forming the substrates 101 and 102 forming the liquid crystal element r. Electrodes 103 and 10 provided on (for example, a plastic plate such as a transparent glass plate or an acrylic plate)
By applying a suitable direct current or alternating current during step 4 and slow cooling, a phase change can be caused from an isotropic phase to a nematic phase to a smectic phase. At this time, since the liquid crystal in the nematic phase has a stop dielectric anisotropy, the nematic liquid crystal is aligned in the direction of the electric field, and a smectic A phase or C phase with a homeotropic structure is formed to further cool the written image. The pattern will be erased. Electrodes 103 and 104 are typically made of indium oxide, tin oxide or ITO (L++dium Tan Oxid).
The transparent conductive film of e) is obtained, and if necessary, a metal such as aluminum, chromium, silver or dielectric metal 11 can be used.
obtained by The electrodes 103 and 104 are desirably coated over the entire surface of the substrates 101 and 102, and do not necessarily have to have a predetermined pattern shape or matrix electrode structure. However, it is possible to provide a predetermined pattern shape or matrix electrode structure 81 as desired.

The liquid crystal element of the present invention has a 10 ft.
and 107 can be provided. This orientation control 11g1
O6 and 107 are in liquid crystal composition 1 that are in contact with each other at these critical surfaces.
It has a surface structure that allows the arrangement direction of 08 to be controlled to a desired state. Moreover, this orientation f+i control film 106
and 107 also function as an insulating film that can prevent the generation of current flowing through the liquid crystal composition +08. This type of alignment control films 10fl and 107 can be made of, for example, silicon oxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, boron nitride, polyvinyl alcohol, polyimide. , polyamideimide, polyesterimide, polyparaxylerin, polyester, polycarbonate, polyvinyl acecool, polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin, organosiloxane, polyfluorinated ethylene, etc. The substance is applied by vapor deposition, dip coating, spinner coating, or spray coating. S! Obtained by forming.

The alignment control films 106 and 107 homogeneously align the liquid crystal composition 108 by rubbing the surface with cloth, paper, velvet, etc., or by using an oblique vapor deposition method when forming the film, depending on a predetermined writing method. A silane compound that can have a surface structure, or has a barfluoro alkyl group on its surface, for example, as described in JP-A-50-3fil'liO;
By treatment with compounds such as alkyltrialkoxysilanes described in Japanese Patent Publication No. 50947 and tetraalkoxysilanes described in JP-A-50-133955.

Liquid crystal composition! It is possible to have a surface structure that causes 08 to have a Home-I-Robic orientation.

The optimum thickness of the alignment control films 106 and 107 varies depending on the type of insulating material used, but generally it is 10.
It is suitable to set the thickness in the range of 0A to 1L, preferably in the range of 500A to 200OA, and furthermore, it is preferable to set the film thickness so that the alignment control films 10B and 107 also function as antireflection film 11. Preferably, the liquid crystal element of the present invention forms the above-mentioned still image by irradiating the laser beam 110 onto 11 from the back iA1 direction, and receives natural light, halogen lamp light, or xenon lamp light from the front direction. By making observation light 108 such as fluorescence burning light enter the element and using this light as reflected light from the cold mirror 105, the still image described by fIU can be observed. This cold mirror 105 generally has a sufficiently high reflectance for visible light and a high transmittance for long wavelength light of f (00 mm or more). is Ge/MgF2 (1 electric 4 people) /CeO2 (1
(4 people) /MgF2 (4 people per electric) /CeO2 (1 /
A multilayer film consisting of 4λ) is known.

However, in the present invention, the use of cold mirror 105 can also be omitted. Further, in the device of the present invention, a cold filter (not shown) can be provided between the electrode +03 and the alignment control film +06. This cold filter is
It has a sufficiently high transmittance for visible light and a sufficiently high reflectance for long wavelength light.

Next, a Pt5Z diagram shows an example in which a display pattern was formed using the liquid crystal element of the present invention.

Among the compounds represented by the aforementioned general formula (1), compound No. 2 was added at a ratio of 2% by weight to the smectic liquid crystal (4,4'-cyanooctylbiphenyl: having positive dielectric anisotropy). It was dissolved as follows. At this time, the liquid crystal composition is・After heating until it becomes a lobic phase, the above-mentioned compound is added, and this liquid is injected into a cell whose inner wall surface has been subjected to homeotropic alignment treatment, and then slowly cooled to create a homeotropic structure. A smectic phase liquid crystal was formed.

The laser oscillator 202 that emits the laser beam 1 used to write an image on the liquid crystal cell 201 can be selected from wavelengths that correspond to the absorption efficiency of the above-mentioned compounds contained in the liquid crystal. - A long-wavelength laser beam emitted from a neon laser, a semiconductor laser, or a YAG laser, or a single-wavelength laser beam emitted from a laser beam (a single wavelength laser beam can be used; a laser beam emitted from a laser oscillator 202) are a modulator 203, a slint 204, a Y vehicle deflector 20
5. After passing through an X-axis deflector 206 and being modulated and deflected, the light is focused by a writing lens 208 and irradiated from the back side of the liquid crystal element 201 via a gicroic mirror 209. The aforementioned modulator 203 and Y-axis deflector 20
5. The X-axis deflector 206 is connected to the signal source 21+ via the driving amplifier 210, thereby controlling the laser beam and converting the digital electrical signal from the signal source 211 into an optical signal. An image pattern is written on the liquid crystal element 201 by this optical signal.

Thereafter, the Peltier element 212 placed around the liquid crystal element 201 (= J digit) is operated by the power source 213 to bring it into a rapid cooling state, thereby cooling the liquid crystal element 201 to form a smectic phase with a focal conic structure, and to generate light. An image pattern was formed in which the areas irradiated with the signal were in a light scattering state.At this time, the Venirtier element 212 was
The temperature is controlled by a roller device 214.

This image pattern can be observed by turning on the illumination source 215 placed in front of the liquid crystal element 20+.

Next, in order to erase the above-mentioned image pattern, a transparent heater 216 (for example, an indium oxide film, a tin oxide film, an ITO II film) provided on the liquid crystal element 201 is heated by a heater power source 218 via a temperature controller 217. , causing a phase change from the bacteriostatic phase to the isotropic phase. Thereafter, the liquid crystal element 201 was slowly cooled while applying a voltage from the AC power source 221 between the upper electrodes 219 and 220 provided in the liquid crystal element 20+ to form a smectic phase with a homeotropic structure.

As a result, the written image pattern was erased.

The liquid crystal element of the present invention can be applied to a large screen display, and can also be applied to an optical disk system using a recording method in which pits are formed by scanning an optical signal containing predetermined information along a track. I can do it.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a liquid crystal element of the present invention. FIG. 2 is an explanatory diagram showing an example of a display method using the liquid crystal element of the present invention. 101.102. Substrate +03,104; Electrode 105; Cold mirror 106, IO7; Alignment control film 108; Liquid crystal composition 108; Observation light +10. laser beam

Claims (1)

[Scope of Claims] A liquid characterized by having a liquid crystal composition containing a liquid crystal and a compound represented by the following general formula (1). , It, and R1 represent a substituted or unsubstituted aryl group and a substituted or unsubstituted heteroterminal group. 几 represents a hydrogen atom, an alkyl group, or an unsubstituted aryl group. X and X2 represent an oxygen atom and a sulfur group, respectively. atom or selenium atom. A indicates an anion residue.)