JPS60118787A - Liquid crystal element - Google Patents

Abstract

PURPOSE:A liquid crystal element having the composition in which a specific polymethine 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 polymethine compound of formula I [A, B, D and E are (substituted) aryl; R1-R5 are H, halogen or alkyl; Y is a bifunctional residue having atomic group necessary for completing 5-6-membered ring; X<-> 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, it 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 devices 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 arranged between two glass substrates, and this liquid crystal When the device is irradiated with a laser beam (+1), that area is locally heated to an intropical phase, and then, by rapid cooling, a liquid crystal phase with a random alignment state different from the initial uniform alignment state is formed. As a result, light scattering occurs at the location irradiated with the laser beam, resulting in a difference in optical properties from the night crystal phase in the background region, which is in a uniformly oriented 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 all the elements of the TF'RI element with a heat source (for example, a heater) that is different from the laser beam! By heating the fk phase to the intropic phase and then applying a voltage between the aforementioned electrodes, a homeotropic structure is formed in the case of smectic liquid crystals, or a Grandshuan structure in the case of cholesteric-nematic bacteriostatics, for example. By cooling the surface to a temperature of 100.degree. C., the optical image formed by the previous writing can be completely erased.

This liquid crystal element has a matrix (reflection pole 4.
111i5. 'i is not required, just 't11. This method has the advantage that an image pattern can be formed by scanning an optical signal converted from an optical signal, and that it can be obtained on a large screen.

One way to convert electrical signals from computer terminals into optical signals is to modulate a laser beam with a drive signal that corresponds to digital image information. A method of scanning is adopted through an optical system consisting of an optical deflector such as a carpano mirror. In particular, in recent years, semiconductor lasers have come to be used as the beam of such optical signal generators.

The semiconductor laser described above generally has a long wavelength range (for example, 750 nm).
Despite having an oscillation wavelength of less than mm11), the aforementioned liquid crystal elements have low heat conversion efficiency for long wavelength beams, and therefore, when writing to liquid crystal elements using a semiconductor laser, high power is required. It was necessary to irradiate it with a laser beam. However, the power of semiconductor lasers is lower than that of cassette lasers such as argon lasers and helium-neon lasers, and therefore the optical signal from an optical signal generator using a semiconductor laser is used to scan the liquid crystal element as described above. However, there are disadvantages in that either sufficient writing cannot be performed, or writing can only be performed by slowing down the scanning speed of the optical signal sufficiently.

For this reason, conventionally, the analogy is “5ociety of I”.
nformation Display fterna
tional Symposium.

Digest of Technical Paper
"P, R34-4J172-187゜238-253 (
As disclosed in 1H2), a guest-phos I type laser thermal writing type liquid crystal element in which a black dye is added to a smectic liquid crystal by l+y has been proposed for IR.

However, even this type of liquid crystal element does not have sufficient efficiency -V to absorb a laser beam from a semiconductor laser and convert it into thermal energy, and requires high power or low speed optical pulse scanning. In this regard UK publication 2081753
This is similar to the drawback of the liquid crystal 4 of the method disclosed in the above publication. Moreover, in the liquid crystal element using the above-mentioned J and 11 color pigments, a white image pattern is formed on a black background, which has the disadvantage that it does not provide a good display in terms of human science.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the above-mentioned drawbacks and to provide a liquid crystal element capable of forming an optical image pattern in response to optical signal time scanning, particularly from an optical signal +4 laser generator using a laser oscillator. be.

The liquid crystal element of the present invention has a score of 4 to 9 in that it uses a liquid crystal composition in which a polymethinone compound represented by the following general formula (1) is dissolved in a liquid crystal.

General formula (1) In the formula, A, B, D and E are substituted or unsubstituted aryl groups (phenyl, tolyl, xylyl, ethylphenyl,
chlorophenyl, dichlorophenyl, trichlorophenyl, bromophenyl, dibromophenyl, nitrophenyl, methoxyphenyl, ethoxyphenyl, dimethylaminophenyl, diethylaminophenyl, diethylaminophenyl, dibenzylaminophenyl, diphenylaminophenyl, etc.), and R1゜1 (2 ,R,,R4
and to are hydrogen atoms, ), rogone atoms (chlorine atoms, bromine atoms), or alkyl groups (methyl, ethyl, globil,
butyl, amyl, etc.). Y is 5-membered or td6j
! A divalent residue (ethylene, propylene, 0-phenylene) having the atomic group necessary to complete tJfi'r: f.

Xe1-1:, Anion (berchlorate, fluoroborate, iodide, chloride, promy)", P
- toluene sulfonate) f.

Representative compounds represented by general formula (1) are shown below.

ZO4 FO Ma-I +ohaQ − Go to 〇 o,　r　.

0 0 0 These polymethine dyes are described, for example, in JP-A-56-81J.
It can be obtained by the synthesis method described in Publication No. 19 and the like.

/ / /″ Next, the liquid crystal element of the present invention will be explained according to the drawings.

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

The liquid crystal composition 108 has the general formula (1) of +iii
An ltM product in which a compound represented by is dissolved is used.

The liquid crystal used in the device of the present invention is suitably a smectic liquid crystal, and the A phase or C phase of a smectic liquid crystal having positive dielectric anisotropy is suitably used.

It takes smectic! The night crystals are located at Iζ6 with a laser beam.
Until it is heated, it is arranged in a smectic phase with a homeotropic M1 weave, and in a warm phase - a smectic phase with a homeotropic M1 weave → a nematic phase → an isoI-robic phase. Can change.

Next, when the phase is changed from the intropic phase to the smectic phase in a rapidly cooled state, a smectic phase with a force luconic structure having light scattering properties is formed. Therefore, when the smectic phase in a liquid crystal element is locally heated to an isotropic phase by irradiation with a laser beam, and then rapidly cooled, the smectic phase in that area becomes a focal conic structure, and this state has light scattering properties, so A still image pattern can be formed by scanning an optical signal with a laser beam.

Examples of compounds capable of forming a smectic phase having positive 8f5 electroanisotropy used in the liquid crystal element of the present invention include JP-A-56-150030 and JP-A-57-40429.
Compounds described in JP-A-57-51779 and the like can be used.

The compound represented by the aforementioned general formula (1) is contained in the liquid crystal composition 108 in an amount of 0.1% by weight or more, or in the range of 1% to 3% by weight, based on the liquid crystal. be able to.

Further, the liquid crystal element of the present invention can also use a 115 mixture liquid crystal of smectic liquid crystal and cholesteric liquid crystal having positive dielectric strength. It is suitable that the cholesteric liquid crystal is contained in the liquid crystal composition 108 in an amount of 0.5% to 15% by weight, preferably 14% to 141% by weight.

Cholesteric liquid crystals that can be used in the present invention include cholesteryl chloride, cholesteryl bromite, cholesteryl iodite, cholesteryl nitrate, cholesteryl chlorodecanoate-1, cholesteryl butyrate, cholesteryl caprate, cholesteryl oleate, cholesteryl oleate, cholesteryl laurate, cholesteryl myristate, cholesteryl heptyl carbamate,
Examples include cholesteryl compounds such as cholesteryl tesyl ether, cholesteryl lauryl ether, and cholesteryl oleyl ether.

A liquid crystal element using such a mixed liquid crystal undergoes a phase change from a smectic phase of home 1 ropic to intro pink 11 by local heating of laser beam J., and when this is rapidly cooled, a phase change occurs as described above. It is possible to form a smectified phase of M1 type.

Recorded using the method described above! The fk l'+71 element heats the entire surface of the liquid crystal composition 108 using, for example, a heater to change the phase into an iso-i-ropink phase, and then heats the liquid crystal composition 108 over the substrates +01 and 102 (for example, transparent glass) that constitute the liquid crystal element. By applying an appropriate direct current or alternating current between electrodes 103 and 104 provided on a plastic plate (such as a plastic plate or an acrylic plate) and slowly cooling, the isodropink phase→
A change can occur from the nematic phase to the smectin phase. At this time, since the liquid crystal in the nematic phase has positive dielectric anisotropy, the nematic liquid crystal is aligned in the direction of the electric field, and a smectic phase or C phase with a homeotropic structure that is further cooled is formed, leading to the writing. The image pattern will be erased. Electrodes 103 and 104 are typically made of indium oxide, tin oxide or I To (Indium
obtained by a transparent conductive film of Tin O++1de),
If necessary, it can also be obtained by using a four-electrode film made of metal such as aluminum, chromium, silver, or nickel. The upper electrodes 103 and 104 are desirably covered with Ti over the entire surface of the upper electrodes 101 and 102, and do not necessarily have to have a predetermined pattern shape or matrix electrode structure. It is also possible to design a predetermined pattern shape or matrix electrode structure depending on the situation.

The liquid crystal element of the present invention has an alignment control film 11, 1, and 8 made of an insulating material on each electrode 103 and 104.
and 107 can be provided. This orientation control film 10
6 and 107 are I+'ti that touch at these critical surfaces,
The surface 41 has a structure that allows the alignment direction of the crystal composition 108 to be controlled to a desired state. Also, this orientation control III! toe and 107 also function as an insulating film that can prevent generation of current flowing through the liquid crystal composition 108. This kind of orientation system 11111 II 10
6 and 107 are, for example, -46 silicon, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, boron nitride, polyvinyl alcohol,
Polyimide, polyamideimide, polyesterimide,
Insulating materials such as polyparaxylerin, polyester, polycarbonate, polyhinyl acecool, polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin, orcasiloxane, polyfluorinated ethylene, etc. Steaming method, dip coating 11
It can be obtained by forming a film by the + method, spinner coating method, or spray coating method.

The orientation control films 108 and 107 are formed in a J-like manner by rubbing their surfaces with cloth, paper, velvet, etc., or by using a diagonal non-adhesive method when forming the film, depending on a predetermined method. A silane compound having a surface structure that homogeneously aligns the crystal composition 108, or a silane compound having a perfluoroalkyl group described in JP-A No. 50-50947, for example, Alkyltrialco and Shinran described in JP-A-11? (By treating the liquid crystal composition 108 with a compound such as tetraalkoxysilane described in Japanese Patent No. 50-63955, the liquid crystal composition 108 can be
It is possible to have a surface structure with a pink orientation.

The optimum thickness of the alignment control films 106 and 107 varies depending on the type of insulating material used.
It is suitable to set the alignment control films 106 and 107 in the range of 0 OA, and it is better to set the film thickness so that the alignment control films 106 and 107 also act as anti-fouling films. As shown in the figure, the above-mentioned still image is formed by irradiating the element with a laser beam 110 from the rear surface, and observation light 109 such as natural light, halogen lamp light, xenon lamp light, fluorescent lamp light, etc. is incident into the element from the front direction. Then, using this light beam as reflected light from the cold mirror 105, the above-mentioned still image can be observed. This cold mirror 105 generally has a high reflectance of 1:1 for visible light, and has a transmittance characteristic of 1::1 for long wavelength light of eQOmm or more.

Specifically, Ge/MgF2 (1/4 person) /C:e0
2 (1/4λ) /MgF2 (1/4 person) /Ce07
A multilayer film consisting of (1/4 person) is known.

However, in the present invention, the use of cold mirror 105 can also be omitted. In addition, the device of the present invention has a cold filter (not shown) connected to the electrode 103 and orientation control +1AI0.
It can also be provided between 6 and 6. This cold filter has a sufficiently high transmittance for visible light and a sufficiently high fouling rate for long wavelength light. It has Y-character.

Next, a second example in which a display pattern was formed using the liquid crystal element of the present invention will be shown.

Among the compounds represented by the above-mentioned general formula (1), compounds No., At this time, the liquid crystal composition was heated until it became an intropic phase, and then
The above-mentioned compound was added, and this liquid was injected into a cell whose inner wall surface had been subjected to a homeotropic alignment treatment, and then slowly cooled to form a liquid crystal of a Smectifuku phase with a Homeo-I-Robinck structure.

The laser oscillator 202 that emits the laser beam used to write an image on the liquid crystal cell 201 can be selected from those with a wavelength that is I5 relative to the absorption efficiency of the above-mentioned compound containing 1f in the crystal. In particular, a long laser beam emitted from a helium-neon laser, a semiconductor laser or a YAG laser, or a laser beam of known wavelength emitted from an argon laser can be used. The laser beam emitted from the laser oscillator 202 is transmitted to a modulator 203, a pickpocket 71204, and a Y deflector 2.
05, the light passes through the X beam deflector 20G, is modulated and deflected, is focused by the Vl focusing lens 208, and is irradiated from the back of the liquid crystal element 201 via the tychroic mirror 208. The aforementioned modulator 203 and Y-carriage deflector 20
5, the X vehicle deflector 206 is connected to the ij'r+', r source 211 via the driving amplifier 210,
This causes the laser beam to be controlled and ft!
'3p: Digital from I211'ili: Converts air signals into optical signals. This optical signal causes static crystal element r-20+
An image pattern is written to the image.

After 17 days, the Bertier element 212, which had been removed from the periphery 81 of the liquid crystal element 201, was activated by H2+3 to rapidly cool the liquid crystal element 201.
When cooled, a smectic phase with a focal conic structure was formed, and an image pattern was formed where the light beam was irradiated, resulting in a light scattering pattern. At this time, Benilche, IJ, R212 is controlled by temperature controller 214 for 1.1 items and 18 images. can.

Next, in order to erase the image pattern described above in 11], a transparent heater 216 (for example, an indium oxide film, a tin oxide film, an ITO film) provided on the liquid crystal element 201 is heated using a heater mold via a temperature controller 217. Heating is performed by z+2+e to cause phase collapse from the liquid crystal phase to the isoI-ropic phase. After that, while applying voltage from the AC power supply 221 between the electrodes 218 and 220 provided on the liquid crystal element 201,
The liquid crystal element 201 was slowly cooled to form a smectic phase with a homeo]ropic structure.

As a result, both written image patterns were erased.

The liquid crystal element of the present invention can be applied as a large screen display, and is also a recording type optical display system in which pits are formed by scanning an optical signal containing predetermined information onto a track. Also 14-: can be a river.

[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 the small table j type using the liquid crystal element f of the present invention. 101, 102; Substrate +03, 104; Electrode 105; Cold mirror 1013, 107; Alignment control film 108; Liquid crystal composition 108; Observation light 110; Laser beam ↓ ~ lθq 1 ~ l/θ

Claims (1)

[Scope of Claim] A liquid crystal element comprising a liquid crystal composition containing a liquid crystal and a compound represented by the following general formula (1). General formula (1) (wherein A, B, D and E represent substituted or unsubstituted aryl groups. R1, R2, R,, R4 and R5 are
Indicates a hydrogen atom, a halogen atom, or an alkyl group. Y represents a divalent residue having the necessary atomic groups to complete a 5-membered structure or a 6-membered structure. Xo represents an anion. )