JPS61293288A - Liquid crystal element for time-division drive - Google Patents

Abstract

PURPOSE:To provide the title liq. crystal element which is ferroelectric and free from reversal, by applying signals for writing and holding the written-in state of specific image elements arranged over a plurality of lines until a next period of signals for writing are applied. CONSTITUTION:Counter electrodes and image elements having a liq. crystal compd. (a) contg. an optically active group of the formula I [wherein R is a 1-20 C straight-chain, branched or cyclic (un) satd. hydrocarbon group; and *is an asymmetric carbon atom] such as a compd. of any of the formula II-VI (wherein R1-R5 are each independently a 1-20 C alkyl or alkoxyl) or a liq. crystal compsn. (b) contg. the component (a) which is in a bistable state are arranged over a plurality of lines. The signals for writing are applied to each line. The written-in state of the image element is held for a period of 1 frame or 1 field until a next period of signals for writing are applied.

Description

[Detailed Description of the Invention] Field of Application] The present invention relates to a ferroelectric liquid crystal device in a bistable state, and more specifically, to a ferroelectric liquid crystal device using a memory drive method that maintains a written state during a frame or l-field period. This invention relates to a time-division driving liquid crystal element.

[Conventional technology]

As a conventional liquid crystal element, for example, M-Shut (M,
5chadt) and W. Helfrich (W,
He1frich) ``Applied Physics
Applied Physics
Letters") No. 188.ff54 (19714
F February 150Q line).

``Voltage Dependent Optical Activities - Twisted Nematic Liquid Crystals'' on pages 127-128
oltage Dependent 0pticalA
activity of a twisted
Twisted nematic shown in “NematicLiquid Crystal”
A device using a nematic liquid crystal is known. This TN liquid crystal has a problem in that crosstalk occurs during time division driving using a matrix electrode structure with high pixel density, so the number of pixels is limited.

Furthermore, a display element is known in which a switching element using a thin film transistor is connected to each pixel, and each pixel is switched. However, the process of forming the thin film transistor on the substrate is extremely complicated, and it is difficult to use a display element with a large area. There are some problems that make it difficult to create.

In order to improve the drawbacks of conventional liquid crystal elements, C1ark and Lage
rwa l 1) The helical structure of the ferroelectric liquid crystal can be unraveled by making the film thickness of the ferroelectric liquid crystal five times or less than its helical pitch, and as a result, bistable properties are expressed. has been published, for example, in US Pat. No. 4,367,924. Liquid crystals with this bistability generally include chiral smectate C phase (SmC).
Alternatively, a ferroelectric liquid crystal having an H phase (S mHX) is used.

This liquid crystal has a bistable state consisting of a first optically stable state and a second optically stable state with respect to an electric field, and therefore, unlike the optical modulation element used in the above-mentioned TN type liquid crystal,
For example, a liquid crystal is aligned in a first optically stable state for one electric field vector, and a second optically stable state for the other electric field vector.
The liquid crystal is aligned in an optically stable state. Furthermore, this type of liquid crystal has the property of very quickly taking one of the above two stable states in response to an applied electric field, and maintaining that state when no electric field is applied. By utilizing such properties, considerable improvements can be obtained in many of the problems of the conventional TN type elements mentioned above.

[Problem that the invention seeks to solve]

However, when time-division driving is performed using the memory drive method described later using the above-mentioned bistable liquid crystal element, some of the pixels written in accordance with the information signal on the screen may change in the liquid crystal alignment at the time of writing. There is a problem in that a writing pixel inversion phenomenon occurs due to changing the stable alignment state from one liquid crystal alignment direction to another liquid crystal alignment direction. This is for example.

There are pixels written as "white" signals on the screen.

This is a phenomenon of reversing to a "black" state. The occurrence of such an inversion phenomenon actually makes it difficult to apply this ferroelectric liquid crystal element to a display device.

It is an object of the present invention to prevent the above-mentioned inversion phenomenon and change the written state of pixels written in accordance with information signals in one frame or one frame.
An object of the present invention is to provide a time-division driving liquid crystal element that can be maintained during a field period.

[Means for Solving the Problems] and [Operation] The present invention provides a pair of opposing electrodes and the following general formula (I) under a bistable state.
Pixels containing a liquid crystal compound having an optically active group or a liquid crystal composition containing the same are arranged in a plurality of rows, and a write signal is applied to each row of pixels in the plurality of rows. The device is characterized by a time-division drive liquid crystal element that performs time-division driving in which the write state of pixels in a row to which a write signal is applied is held until a write signal of the next cycle is applied. be.

General formula % Formula % () [In the general formula (I), R represents a linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, * represents an asymmetric carbon atom ] [Example] Specific examples of liquid crystalline compounds having an optically active group represented by general formula (I) are shown below, but the present invention is not limited thereto.

general formula R in the above formula is a straight chain having 1 to 20 carbon atoms.

It is a branched or cyclic saturated or unsaturated hydrocarbon group. If the number of carbon atoms is less than 3, the properties as a terminal group are likely to be impaired, and if it is more than 21, the viscosity and molar volume of the final functional material will increase, which is undesirable. It is 16. Specific examples of H include linear alkyl groups, branched alkyl groups, cycloalkyl groups, linear alkenyl groups, branched alkenyl groups,
Cycloalkenyl group, linear alkabienyl group, branched alkabuenyl group, cycloalkabuenyl group, linear furkatrienyl group, branched alkabienyl group,
There are linear alkynyl groups, branched alkynyl groups, and aralkyl groups. The book also shows asymmetric carbon atoms.

R1-R5 represent an alkyl group or an alkoxy group having 1 to 20 carbon atoms.

In addition, azo-, azoxy derivatives, ring-assembled hydrocarbon derivatives into which an optically active group represented by the general formula (I) is introduced,
Condensed polycyclic hydrocarbon derivatives, heterologous conductors, fused heterocyclic derivatives, ring-assembly heterocyclic derivatives, etc. can be used, and specifically, optically active groups represented by the above general formula (I) have been introduced. Azobenzene conductor, azoxybenzene derivative,
Biphenyl rust conductors, terphenyl derivatives, phenylcyclohexane derivatives, benzoic acid derivatives, pyrimidine derivatives, pyrazine derivatives, pyridine derivatives, stilbene derivatives, tolan derivatives, carhoun rust conductors.

Bicyclohexane derivatives, cinnamic acid derivatives, etc. can also be used as liquid crystal compounds.

The lactic acid derivative used in synthesizing these liquid crystal compounds can be synthesized by the following method.

(a) Honko (b) Wood 1 (c) RI in the above reaction formula can be selected from a wide range of carbon numbers, and specifically, iodobutane,
Iodohentane, iodohexane.

Linear saturations such as iodohebutane, iodooctane, iodononane, iodothicane, iodoundecane, iodododecane, iodotridecane, iodobutrabucan, iodopentadecane, iodohexadecane, iodoheptadecane, iodooctadecane, iodononadecane, iodoeicosane, etc. Hydrocarbon iodide, 2-iodobutane, 1-
Branched saturated hydrocarbon iodides such as iodo-2-methylpropane and 1-iodo-3-methylbutane; cyclic unsaturated hydrocarbon iodides such as iodobenzyl, iodophenacil, and 3-iodo-1-cyclohexene; iodocyclopentane; There are cyclic saturated hydrocarbon iodides such as iodocyclohexane, 1-iodo-3-methylcyclohexane, iodocyclohebutane, and iodocyclooctane.

From various milk melt derivatives obtained by such methods, the following general formula (Il) or (tI
A liquid crystalline compound shown in [) was obtained.

H3 CH3 ([) [However, in the above general formulas (II) and (m), R represents a linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms. , R1 and R2 represent an alkyl group or an alkoxy group having 1 to 20 carbon atoms.] The specific liquid crystal compound described below or the liquid crystal composition containing the same has good threshold characteristics as a ferroelectric liquid crystal. By applying this to a liquid crystal element, the above-mentioned inversion phenomenon can be effectively prevented.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

The liquid crystal used in the present invention has ferroelectricity, and specifically has a chiral smectic C phase (SmC).
), H phase (SmH)k), I phase C5m1*), J phase (S
A liquid crystal having a phase (SmK)k), a phase G (SmG)k), or an F phase (SmF*) can be used.

Representative examples of liquid crystal compounds used in the liquid crystal element of the present invention are as follows.

(1) 4'-hexyl-4-α-butoxypropanoyloxyazobenzene (2), 4'-hebutyl-4-α-butoxypropanoyloxyazobenzene (4) 4'-hexyl-4-α- Butoxypropanoyloxyazobenzene (5) 4'-hexyloxy-4-α-butoxypropanoyloxyazobenzene (6) 4'-octyl-4-α-hebutyloxypropanoyloxyazobenzene (7) 4'-hexyloxy -4-α-hebutyloxypropanoyloxyazobenzene (8) 4'-hexyloxy-4-α-butoxypropanoyloxyazoxybenzene (9) 4'-ctyl-4-α-hebutyloxypropanoyl Oxyazoxybenzene (10) 4'-hexyloxy-4-α-hebutyloxypropanoyloxyazoxybenzene (11) 5-decyl-2-(4'-α-pentyloxypropanoyloxyphenyl)pyrimidine ( 12) 4-octyloxybenzoic acid (4'-α-
Octadecyloxypropanoyloxyphenyl) ester (13) 4-octyloxybenzoic acid (4'-
α-dodecyloxypropameyloxyphenyl) ester (14) 4-hebutylbiphenylcarboxylic acid (
4″-α-hebutyloxypropanoyloxyphenyl) ester (15) 4-octyloxybiphenylcarboxylic acid (4′-(4″-α-octyloxypropanoyloxybenzoyloxy)phenyl) ester (1B) 4- Pentyloxybenzoic acid (4'-(4
″-α-nonyloxypropanoyloxybiphenylcarboxyl)phenyl) ester (17) 4-hebutylbiphenylcarboxylic acid (4'
-(4"~α-dodecyloxypropanoyloxybenzoyloxy)phenyl) ester (1B) 4-hebutylbiphenylcarboxylic acid (4'
-(4″-α-pentyloxyprobanoyloxybiphenylpoxyl)phenyl) ester (19) 5-nonyl-2-(α-propyloxybrovanoyloxyphenyl)primidine (20) 4-pentylbiphenylcarboxylic acid (4 '
-(4″-α-ethoxybrovanoyloxybenzoyloxy)phenyl) ester [Synthesis Example 1] 5-decyl-2-(4′-α-pentyloxypropanoyloxyphenyl) pyrimidine P-hydroxybenzonitrile 40g to 100mM of ethanol and 125 mfL of benzene and dry H
(It was saturated with I and left at room temperature for 1 to 2 days. The precipitated crystals were diluted with ether and separated into ethanol after a day. Ammonia-saturated ethanol was added, and the mixture was left to stand for 1 to 2 days. After that, ether was added and recrystallized. 4-Hydroxybenzamidine hydrochloride was obtained.
．． 9 g of 4-hydroxybenzamidine hydrochloride and 12 g of α-decyl-β-dimethylaminoacrolein were added to 0 g of sodium metal, and 1
It was refluxed for 0 hr. Methanol was distilled off, the residue was poured into dilute acetic acid, extracted with ether, and purified by silica gel column chromatography to obtain 5-decyl 2(4-)\idroxyphenyl)pyrimidine.

10 mM of thionyl chloride was added to 2.0 g of α-pentyloxypropionic acid, and after heating under reflux for 2 hours, excess thionyl chloride was distilled off to obtain α-pentyloxypropionic acid chloride. 20 mM dry pyridine was added, and 7.0 g of 5-decyl 2(4-hydroxyphenyl)pyrimidine dissolved in 50 mJl of dry benzene was added dropwise. After the completion of the dropwise addition, the mixture was heated under reflux for 8 hours, then poured into ice water and extracted with benzene. Purification was performed using silica gel column chromatography to obtain 5-decyl-2-(4'-α-pentyloxypropanoyloxyphenyl)pyrimidine.

[Synthesis Example 2] 4-octyloxybenzoic acid (4'-α-dodecyloxypropameyloxybiphenyl) ester α-dodecyloxypropionic acid 2. One thionyl chloride was added to Og, and after heating under reflux for 2 hours, excess thionyl chloride was distilled off to obtain α-dodecyloxypropionic acid chloride. 20m! Add L dry pyridine, 40ml
After dropping 5.0 g of 4,4' dihydroxybiphenyl dissolved in dry benzene, the mixture was heated under reflux for 3 hours, poured into ice water, and extracted with benzene.

Purification was performed using silica gel column chromatography to obtain 4-hydroxy-4'-α-dodecyloxypropanoyloxybiphenyl.

p-octyloxybenzoic acid 2. Thionyl chloride 4 to Og
After adding 0 mJ1 and heating under reflux for 2 hours, excess thionyl chloride was distilled off to obtain p-octyloxybenzoic acid chloride. 20 mL of dry pyridine was added, and 4-hydroxy-4'-α-dodecyloxypropanoyloxybiphenyl dissolved in 40 mL of dry benzene was added dropwise. After heating under reflux for 5 hours, the mixture was poured into ice water and extracted with ether.

The product was purified by silica gel column chromatography to obtain 4-octyloxybenzoic acid (4'-α-dodecyloxypropanoyloxybiphenyl) ester.

[Synthesis Example 3] 4-octyloxybiphenylcarboxylic acid (4'(4")
α-octyloxypropanoyloxybenzoyloxy)phenyl) ester 40m of thionyl chloride to 5.0g of 4-octyloxybiphenylcarboxylic acid! 2. After adding and heating under reflux for 3 hours, excess thionyl chloride was distilled off to obtain 4-octyloxybiphenylcarboxylic acid chloride. 4-octyloxybiphenylcarboxylic acid chloride was added dropwise to a solution of 5.0 g of p-hydroquinone in 50 mfL of pyridine, and the mixture was reacted for 2 hours and then heated under reflux for 10 hours. The mixture was poured into ice water, extracted with benzene, and purified by silica gel column chromatography to obtain 4-octyloxybiphenylcarboxylic acid (4'-hydroxyphenyl) ester.

10 m of thionyl chloride was added to 2.0 g of α-octyloxypropionic acid, and after heating and refluxing for 2 hours, excess thionyl chloride was distilled off to obtain α-octyloxypropionic acid chloride. Add 20mJl of dry pyridine, add 40mJl
5.0 g of p-hydroxybenzoic acid dissolved in 1 of dry pyridine was added dropwise.

After the dropwise addition was completed, the mixture was heated under reflux for 2 hours, then poured into ice water and extracted with benzene. Purified by silica gel column chromatography 4
-(α-octyloxypropanoyloxy)benzoic acid was obtained.

4-(α-octyloxypropanoyloxy)benzoic acid2. 5 g of Og and 2.5 g of 4-octyloxybiphenylcarboxylic acid (4'-hydroxyphenyl) ester
The reactant was added to 0 g of polyphosphoric acid and reacted at 100° C. for 1 Ohr, then poured into ice water and extracted with benzene. Recrystallization from ethanol gave 4-octyloxybiphenylcarboxylic acid (4'-(4--α-octyloxypropanoyloxybenzoyloxy)phenyl) ester.

These liquid crystal compounds can be obtained by the synthesis method described in Japanese Patent Application No. 195770/1984 or by conventional synthesis methods.

In the present invention, a ferroelectric chiral smectic liquid crystal having an optically active group represented by the general formula (I) is manufactured by N. Clark (N.A.).

When used as a display element as shown by C1ark et al., it has excellent threshold characteristics for electric field response, so when used in a display driven by a simple matrix electrode, ferroelectric chiral smect liquid crystals are free from crosstalk. This makes it possible to prevent this and provide good contrast. These characteristics also apply to liquid crystal compositions containing the liquid crystal compound of the present invention, and when ferroelectric chiral smect liquid crystals are used as high-definition, large-screen display elements, the liquid crystal compound of the present invention is particularly effective. Are better.

In addition, in the present invention, even if the liquid crystal compound does not exhibit a chiral smectic phase, it is possible to obtain a ferroelectric liquid crystal by mixing a liquid crystal compound having a chiral smectic phase as shown in Table 4. It is also possible to use liquid crystal compounds that contain optically active groups as shown in Table 5 but do not exhibit a chiral smectate phase, instead of mixing liquid crystalline compounds that have a ferroelectric chiral smectate phase. A liquid crystal compound or a liquid crystal composition prepared by simply mixing a liquid crystal compound containing an optically active group can also be used as a ferroelectric chiral smect liquid crystal. The ferroelectric chiral smect liquid crystal compositions thus prepared exhibited excellent threshold properties conferred by the basic framework presented in the present invention.

As mentioned above, the liquid crystal compound used in the present invention can be used alone as a material for a ferroelectric liquid crystal element, but when mixed with other components to form a composition with improved performance of a ferroelectric liquid crystal element, The content of the liquid crystal compound having an optically active group represented by general formula (I) in the composition is preferably 1% to 99% by weight, more preferably 5% to 95% by weight.

At this time, other liquid crystal compounds that can form a mixed ferroelectric liquid crystal composition with the liquid crystal compound used in the present invention are shown in Tables 4 and 5.

Table 4 Specific examples of liquid crystals exhibiting chiral smectate phase (compound groups, structural formulas, and phase transition points) -Chlorpropylcinnamate (HOBACPC) -Methylbutyl-α-cyanosinnamate) (DOBAMB
CC)-Methylbutyl-α-methylcinnamate-CO
0CH2CHC2H5 4.4'-7 Zoxycinnamic acid bis(2-
Methylbutyl) ester H 4-(2'-methylbutyl)phenyl-4'-octyloxybiphenyl-4-carboxylate; = cholesteric phase; 4'-Lupoxylate 4-year-old Ctyloxyphenyl-4-(2''-methylbutyl)biphenyl-4'-Lupoxylate 91.5℃ 93℃ Crystal;= SmC wood: SmA 112℃ 131℃ == Cholesteric phase;- Isotropic phase table-5 Specific examples of liquid crystals exhibiting cholesteric phase (compound name, structural formula, and phase transition point) (A) Cholesteryl propionate (B)
Cholesteryl nonanate (C) Cholesteryl palmitate (D) Cholesteryl nonanate 4-(2''-methylbutyl)-4'-cya/biphenyl 4-(2''-methylbutyloxy)-4'-cyanobiphenyl 4-octylphenyl -4'- -(4-β-Methylbutylbenzoyloxy)benzoate 4-cyanobenzylidene-4'-(2-methylbutyl)aniline 4-(2-methylbutyl)-4'-hexyloxyazobenzene 35.9°C 58
．． 2℃ crystal ;= cholesteric phase ;= Tokichi phase 4
- (2-Methylbutyl)phenyl-4'-decyloxybenzoate 4-hexyloxy to 4'-(2-methylbutyl)benzoate When constructing an element using these materials.

In order to maintain the temperature state such that the liquid crystal compound becomes the SmC" phase or the SmH" phase, the element can be supported by a copper block or the like in which a heater is embedded, if necessary.

Figure 1 schematically depicts an example of a ferroelectric liquid crystal cell. ll and 11' are I n203゜5n02 and I
TO(Indium-Tin-Oxid
It is a substrate (glass plate) coated with a transparent electrode such as e), and a SmC'' phase liquid crystal with a liquid crystal molecular layer 12 oriented perpendicular to the glass surface is sealed between the substrates. 13 represents a liquid crystal molecule, and this liquid crystal molecule 13 has a dipole moment (
P engineering) has 14. When a voltage higher than a certain threshold is applied between the electrodes on the substrates 11 and 11', the helical structure of the liquid crystal molecules 13 is unraveled.

The alignment direction of the liquid crystal molecules 13 can be changed so that all the dipole moments (on P) 14 are oriented in the direction of the electric field.

The liquid crystal molecules 13 have an elongated shape and exhibit refractive index anisotropy in the long axis direction and the short axis direction. Therefore, for example, if polarizers are placed above and below the glass surface in a crossed nicol positional relationship, It is easily understood that the liquid crystal optical modulation element is a liquid crystal optical modulation element whose optical characteristics change depending on the polarity of applied voltage.

Furthermore, if the thickness of the liquid crystal cell is made sufficiently thin (for example, 1
As shown in Figure 2, even when no electric field is applied, the helical structure of the liquid crystal molecules unwinds and becomes a non-helical structure, with the dipole moment P or y pointing upward (24
) or downward (24'). When an electric field E or E' with a different polarity above a certain threshold value is applied to such a cell as shown in FIG. ', and accordingly, the liquid crystal molecules are oriented to either the first stable state 23 or the second stable state 23'.

There are two advantages to using such a ferroelectric liquid crystal as an optical modulation element.

The first advantage is that the response speed is extremely fast, and the second advantage is that the alignment of liquid crystal molecules has bistability.

To explain the second point with reference to FIG. 2, for example, the electric field E
When the voltage is applied, the liquid crystal molecules are aligned in a first stable state 23, and this state remains stable even when the electric field is turned off. Moreover, when an electric field B in the opposite direction is applied, the liquid crystal molecules enter the second stable state 23.
', and changes the orientation of the molecule, but it remains in this state even when the electric field is turned off. Also, the applied electric field E
The respective orientation states are maintained as long as the values do not exceed a certain threshold. In order to effectively realize such fast response speed and bistability, it is preferable that the cell be as thin as possible, and generally 0.5. ~20p, especially lJL~5#L are suitable.

Next, a specific example of a method for driving a ferroelectric liquid crystal will be explained using FIGS. 3 to 5.

FIG. 3 is a schematic diagram of a cell 31 having a matrix electrode structure in which a ferroelectric liquid crystal compound (not shown) is sandwiched between. 32 is a scanning electrode group, and 33 is a signal electrode group. First, the case where scanning electrode S1 is selected will be described.

FIG. 4(a) and FIG. 4(b) are scanning signals, and are electrical signals applied to the selected scanning electrode S1 and other scanning electrodes (unselected scanning electrodes) S2, respectively. S3
．． 54 shows an electrical signal applied to 54--. FIG. 4(C) and FIG. 4(d) show information signals of selected signal electrodes 11. I3. I5 and the unselected signal electrode I2. It shows the electrical signal applied to I4.

In FIGS. 4 and 5, the horizontal axis represents time and the vertical axis represents voltage. For example, when displaying a moving image, the scanning electrode groups 32 are sequentially and periodically selected.

Now, the predetermined voltage application time t1. Or, if the threshold voltage t for providing the first stable state of a liquid crystal cell having bistability with respect to tz is -vt hl, and the threshold voltage for providing the second stable state is +vt h2, then the selection As shown in FIG. 4(L), the electrode signal applied to the scanning electrode 32 (Sl) has a phase (time) tz of 2v,
At phase (time) tz, the voltage is -2V, which alternates. When a plurality of electrical signals having different voltages and a phase interval are applied to the scanning electrodes selected in this way, the transition occurs between the first or second stable state of the liquid crystal corresponding to the optical "dark" or "bright" state. The important effect is that the state change can be caused quickly.

On the other hand, the other scanning electrodes S2 to s5---- are the fourth
As shown in Figure (b), it is in a grounded state and the electrical signal is O. Also, one selected signal electrode 11. I3. I5
The electrical signal given to gS4 is v as shown in Figure (C), and the unselected signal electrode I2. The electrical signal given to I4 is as shown in Figure 4(d).
Each voltage value above 0 is set to a desired value that satisfies the following relationship.

v<vt h2<3V -3V(-Vthl<-V When such an electric signal is applied, the voltage waveforms applied to each pixel and B in FIG. 3, for example, are the 5th As shown in Figures (a) and (b), namely, Figure 5 (
As is clear from a) and (b), a voltage of 3v exceeding the threshold value vth2 is applied to the pixel A on the selected scanning line at phase t2. Furthermore, a voltage of -3v exceeding the threshold value -Vthl is applied to the pixel B existing on the same scanning line at phase t1.

Therefore, depending on whether a signal electrode is selected on the selected scanning electrode line, if one is selected, the liquid crystal molecules are aligned in the first stable state, and if not selected, the liquid crystal molecules are aligned in the first stable state. Align the orientation to the stable state of 2.

On the other hand, as shown in FIGS. 5(C) and (d), on unselected scanning lines, the voltage applied to all pixels is V.
or -■, neither of which exceeds the threshold voltage. Therefore, the liquid crystal molecules in each pixel other than those on the selected scanning line maintain an orientation corresponding to the signal state when scanned last time without changing the orientation state. , is kept as is. That is, when a scan electrode is selected, signals for i's one life are written, and until the scan electrode is selected next time after one frame is completed.

This means that the signal state can be maintained. Therefore, even if the number of scanning electrodes increases, the actual duty ratio does not change and the contrast does not deteriorate at all.

Next, let us consider the problems that may actually occur when the device is driven as a display device. In Figure 3,
Scanning electrodes S1 to s5---- and signal electrodes 11 to l5-
Among the pixels formed at the intersection of ---, the pixels in the shaded area are "
It is assumed that the pixels shown in white in the "bright" state correspond to the "dark" state.If we pay attention to the display on the signal electrode Il in FIG. 3, the pixels (A ) is in the "bright" state, and all other pixels CB) are in the "dark" state. As an example of the driving method in this case, FIG. 6 shows a time series representation of the scanning signal, the information signal applied to the signal electrode 11, and the voltage applied to the pixel A.

For example, when driven as shown in FIG.

When the scanning signal S1 is scanned, the pixel A at time t2
Since a voltage of 3V exceeding the threshold value vt h2 is applied to , one pixel A transitions (switches) to a stable state in one direction, that is, a "bright" state, regardless of the previous history.
While s 5 ---- is being scanned, as shown in FIG.
-V voltage continues to be applied, but this is the threshold value -Vthl
Pixel A should be able to maintain a "bright" state because the current value does not exceed 100%, but in reality, one signal (corresponding to "dark" in this case) continues to be given on one signal electrode. When displaying such information, when the number of scanning lines is extremely large and high-speed driving is required, an inversion phenomenon occurs. However, by using the above-mentioned specific liquid crystal compound or a liquid crystal composition containing the same, this phenomenon can be avoided. Such reversal phenomena are completely prevented.

Furthermore, in the present invention, in order to prevent the above-mentioned reversal phenomenon, it is preferable to provide an insulating film formed of an insulating material on at least one of the opposing electrodes constituting the liquid crystal cell.

The insulating materials used in this case are not particularly limited, but include silicon nitride, hydrogen-containing silicon nitride, silicon carbide, hydrogen-containing silicon nitride, silicon oxide, boron nitride, Inorganic insulating materials such as hydrogen-containing boron nitride, cerium oxide, toughened aluminum, zirconium oxide, titanium oxide and magnesium fluoride, or polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylene, polyester Organic insulating materials such as polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin, and photoresist resin are used as the insulating film. The thickness of these insulating films is 5000 Å or less, preferably 100 Å or less.
Suitable ranges are from 500 to 3000 people, particularly from 500 to 3000 people.

〔Example〕

Hereinafter, the present invention will be explained according to examples.

Example 1 Polyimide I! having a film thickness of 1000 nm was applied to each of the opposing matrix electrodes formed of crossed strips of ITO. (
5wt% of polyamic resin from the combination of pyromellitic anhydride and 4゜4'-diaminodiphenyl ether
, N-methylpyrrolidone solution was applied and formed by a heating ring-closing reaction at a temperature of 250° C.), and the surfaces of this polyimide film were rubbed so as to be parallel to each other to create a cell having a cell thickness of ljL.

Next, the following composition A was injected into the above-mentioned cell by a vacuum injection method and the cell was sealed.

Thereafter, a liquid crystal cell of SmC)H was prepared by slow cooling (5° C./hour).

A crossed Nicol polarizer and an analyzer were placed on both sides of this liquid crystal cell, and signals having the waveforms shown in FIGS. 4 and 5 were applied between opposing matrix electrodes.

At this time, the scanning signal is an alternating waveform of +8 volts and 18 volts shown in FIG. 4(L), and the write information is +4 volts, respectively.
volt and 14 volt.

Further, the 171/-m period was set to 30 m*sec.

As a result, even when this liquid crystal element was subjected to the above-mentioned memory-driven time-division driving, the written state was not reversed and a normal moving image display was obtained.

Examples 2 to 4 In place of the liquid crystal used in Example 1, the following liquid crystal composition B (
A liquid crystal element was created in the same manner as in Example 1, except that Example 2), C (Example 3), and D (Example 4) were used.
As a result of displaying a moving image using a driving method similar to that used in Example 1 for each liquid crystal element, no inversion phenomenon was observed on the screen in any of the examples.

Comparative Examples 1 and 2 Comparative Examples 1 and 2 In the liquid crystal compositions A and C used in preparing the liquid crystal elements of Examples 1 and 3, the general formula (I ) Comparative liquid crystals A' (Comparative Example 1) and C'' (Comparative Example 2) having the following compositions were prepared by omitting the liquid crystal compound corresponding to the compound having an optically active group shown in These liquid crystal elements were driven in the same manner as described above, but due to an inversion phenomenon, normal moving images were not displayed.

[Brief explanation of the drawing]

72.0wt% [Effects of the Invention] The ferroelectric liquid crystal element of the present invention comprises a liquid crystal compound having an optically active group represented by the above-mentioned general formula (I) or a liquid crystal compound having an optically active group represented by the general formula (I) described above. By using the liquid crystal composition containing the liquid crystal composition, it is possible to effectively prevent the reversal phenomenon that occurs when switching or displaying is performed by a memory-driven time-division driving method. 33---- (I 1. I 2. I 3----
-1") = - signal electrode group. Figures 1 and 2 are perspective views schematically showing a time-division drive liquid crystal element used in the present invention, and Figure 3 is a diagram showing a matrix electrode structure used in the present invention. Plan view, Figures 4(a) to (d)
) is an explanatory diagram showing the electric signal applied to the matrix electrodes, FIGS. 5(a) to (d') are explanatory diagrams showing the waveform of the voltage applied between the matrix electrodes, and FIG. FIG. 2 is an explanatory diagram of a time chart showing signals applied to the liquid crystal element of the present invention. 11, ll'---one substrate, 12---one liquid crystal molecule layer, 13---one liquid crystal molecule, 14---one dipole moment (P engineering). 23-----First stable state. 23'-----Second stable state, 24----Upward dipole moment, ゛24'----
-Downward dipole moment, 31-1--cell. 32-= (S 11 S2. S3-----1)
--Issho iden aa. Pressing signal type I sheep Section 4 Section 5 Figure 5

Claims (6)

[Claims] (1) The following general formula (
Pixels containing a liquid crystal compound having an optically active group shown in (I) or a liquid crystal composition containing the same are arranged in a plurality of rows, and a write signal is applied to each row of pixels in the plurality of rows, The write state of pixels in the row to which the write signal is applied is
A liquid crystal element for time-division driving, characterized in that it performs time-division driving in which a write signal of the next cycle is held until it is applied. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (I) [In the formula, R represents a linear, branched, or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, * indicates an unsaturated Indicates a carbon atom. ] (2) A liquid crystal element for time-division driving according to claim 1, wherein the liquid crystal compound is a compound represented by the following general formula (1). General formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R_1 is an alkyl group or alkoxy group having 1 to 20 carbon atoms, R is a linear It is a branched or cyclic saturated or unsaturated hydrocarbon. * indicates an asymmetric carbon atom. ] (3) The liquid crystal element for time-division driving according to claim 1, wherein the liquid crystal compound is a compound represented by the following general formula (2). General formula (2) ▲There are numerical formulas, chemical formulas, tables, etc.▼ [In the formula, R_2 is an alkyl group or alkoxy group having 1 to 20 carbon atoms, R is a linear It is a branched or cyclic saturated or unsaturated hydrocarbon. * indicates an asymmetric carbon atom. ] (4) The liquid crystal element for time-division driving according to claim 1, wherein the liquid crystal compound is a compound represented by the following general formula (3). General formula (3) ▲There are numerical formulas, chemical formulas, tables, etc.▼ [In the formula, R_3 is an alkyl group or an alkoxy group having 1 to 20 carbon atoms. R is a linear, branched or cyclic saturated or unsaturated hydrocarbon having 1 to 20 carbon atoms. * indicates an asymmetric carbon atom. ] (5) The liquid crystal element for time-division driving according to claim 1, wherein the liquid crystal compound is a compound represented by the following general formula (4). General formula (4) ▲ Numerical formulas, chemical formulas, tables, etc. are available▼ [In the formula, R_4 is an alkyl group or an alkoxy group having 1 to 20 carbon atoms. R is a linear, branched or cyclic saturated or unsaturated hydrocarbon having 1 to 20 carbon atoms, m_1 and n_
1 is 1 or 2, * indicates an asymmetric carbon atom. ] (6) A liquid crystal element for time-division driving according to claim 1, wherein the liquid crystal compound is a compound represented by the following general formula (5). General formula (5) ▲ Numerical formulas, chemical formulas, tables, etc. are included ▼ [In the formula, R_5 is an alkyl group or an alkoxy group having 1 to 20 carbon atoms. R is a linear, branched or cyclic saturated or unsaturated hydrocarbon having 1 to 20 carbon atoms. m_2 and n_
2 is 1 or 2. * indicates an asymmetric carbon atom. ]