JPH10195440A - Liquid crystal element and liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal element capable of preventing a local abnormality in switching, a change in the switching state with time and sticking and excellent in reliability and durability by sandwiching a specific chiral smectic liquid crystal composition capable of manifesting plural stable states between a pair of substrates. SOLUTION: This liquid crystal element comprises a chiral smectic liquid crystal composition capable of manifesting two or more stable states sandwiched between a pair of substrates. The chiral smectic liquid crystal composition has no cholesteric phase and the relationship between the layer spacing (dA) at the first transition point where the layer spacing starts reducing near the temperature for changing the smectic A phase into the chiral smectic C phase and the minimum value (dmin ) of the layer spacing at the second transition point where the layer spacing is reduced with decreasing temperature from the first transition point and then rechanged to an increase satisfies formula I. A compound represented by the formula II [A and B are each a (substituted) aromatic or a (substituted)alicyclic group] is contained in the chiral smectic liquid crystal composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal element used for a light valve used in a flat panel display, a projection display, a printer, and the like, and a liquid crystal device using the same.

[0002]

2. Description of the Related Art A CRT is known as the most widely used display. CRT
Is widely used as a moving image output for televisions and VTRs, or as a monitor for personal computers. However, C
Due to the characteristics of RT, when a still image is displayed, flicker or scanning line stripes due to insufficient resolution lowers the visibility, or the phosphor deteriorates due to burn-in. In addition, it has recently become clear that the electromagnetic waves generated by the CRT give a bad impression to the human body, and there is a concern that the health of VDT workers may be impaired. And the CRT is structurally
Since it has a large volume behind the screen, it may hinder space saving in offices and homes, and may not be able to fulfill its responsibility as a display in a highly information-oriented society.

As a solution to such a drawback of the CRT, there is a liquid crystal element. For example, M. Shut (MS
chadt) and W. Helfrich
Frich), "Applied Physics Letters"
s) A liquid crystal device using a twisted nematic liquid crystal disclosed in Vol. 18, No. 4 (issued on Feb. 15, 1971), pp. 127 to 128 is known. When such liquid crystal elements are classified by driving method, one of them is a simple matrix type liquid crystal element which has an advantage in cost. This liquid crystal element has a problem that crosstalk occurs in time-division driving using a matrix electrode structure with a high pixel density, and thus the number of pixels is limited. In addition, since the response speed is as slow as several tens of milliseconds, the use as a display has been limited. In recent years, an active matrix type liquid crystal element using a TFT (thin film transistor) or the like has been developed to improve the disadvantages of such a simple matrix type liquid crystal element. This type of liquid crystal element
Since switching elements such as transistors are created for each pixel, the problems of crosstalk and response speed are solved.However, the larger the area, the more industrially it is extremely difficult to create a liquid crystal element without defective pixels. And costly if possible.

In order to improve the disadvantages of the conventional liquid crystal device, a liquid crystal device using a liquid crystal having bistability has been developed by Clark and Lagawell.
rwall) (JP-A-56-10).
7216, U.S. Pat. No. 4,367,924).
As the liquid crystal having the bistability, a ferroelectric liquid crystal which is a chiral smectic liquid crystal exhibiting a chiral smectic C phase or a chiral smectic H phase is generally used. Since the ferroelectric liquid crystal performs inversion switching by spontaneous polarization, it has a very fast response speed and can exhibit a bistable state with memory properties. Furthermore, since it has excellent viewing angle characteristics when used for a display element, it is considered to be suitably used for a high-speed, high-definition, large-area display element or light valve. Recently, a chiral smectic antiferroelectric liquid crystal device exhibiting three stable states has also been proposed by Chandani, Takezoe et al. (Japanese Journal of Applied Physics (Japanese J
own of Applied Physic
s) 27, 1988 L729).

In such a chiral smectic liquid crystal element, when the liquid crystal molecules are aligned using, for example, a general rubbed polyimide alignment film, the apparent tilt angle (the two stable state molecules of the liquid crystal molecules) is obtained. (1/2 of the angle formed by the axes) is generally at most about 3 ° to 8 °, and therefore, the transmittance of the liquid crystal element is 3 to 5%, and the contrast is a very low value of about 10. Also,
"Kozo and Ferroelectric Liquid Crystals" (Corona, Atsuo Fukuzawa,
As described in Hideo Takezoe, 1990), there is also a problem that zigzag alignment defects are generated and the contrast is remarkably reduced. This alignment defect (zigzag defect) is caused by the fact that the layered structure (smectic layer structure) of the liquid crystal sandwiched between a pair of substrates is composed of two types of chevron-like structures (chevron structure). Hanyu et al. Of the present inventor solved a zigzag defect by increasing a pretilt angle of liquid crystal molecules at an interface of an alignment film, and obtained a liquid crystal element having a large recontrast by increasing an apparent tilt angle. (Japanese Patent Laid-Open No. 3-2)
No. 52624). However, even if the technique of Hanyu et al. Is used, in order to obtain a good driving state, for example, the tilt angle must be set to 16 ° or less, and the tilt angle (22.5 ° There is room for further improvement when compared to (). In addition, the inclination of the smectic layer peculiar to the chevron structure also lowers the transmittance, and causes a reduction in contrast.

On the other hand, recently, a chevron structure which is a cause of low contrast has been eliminated, and a layered structure called a bookshelf (hereinafter, this structure is referred to as a bookshelf structure),
Alternatively, there has been a movement to realize a structure close to that and realize high contrast (for example, "Next Generation Liquid Crystal Display and Liquid Crystal Materials", edited by CMC, Atsuo Fukuda, 1992). As a means for realizing such a structure, there is a method using a naphthalene-based liquid crystal material. In this case, the tilt angle is about 10 °, which is smaller than 22.5 ° at which an ideal maximum transmittance can be obtained. There is a problem that the transmittance is very small and the transmittance is low. Furthermore, there is a problem that the bookshelf structure cannot be reversibly exposed to temperature. Another typical method is to apply a high electric field to a liquid crystal device having a chevron structure from the outside to induce a bookshelf structure. However, this method also has a problem in that it is unstable to external stimuli such as temperature. It has become a problem. A liquid crystal having a bookshelf structure has only recently been discovered in recent years, and there are various other problems for practical use.

[0007]

Further, a liquid crystal compound having a fluorocarbon terminal has been proposed as a component of a liquid crystal composition having a book shelf or a structure close thereto (US Pat. No. 5,262,082, International Application Publication WO 93/93). / 22396, 1993 4th International Conference on Ferroelectric Liquid Crystal P-46, Mark D. Radcli
ffe et al.). By mixing this liquid crystal compound with an optically active compound, a bookshelf or a structure with a small layer tilt angle close thereto can be exhibited without using an external field such as an electric field. Suitable for liquid crystal elements and liquid crystal devices. However, further improvements are required in terms of the speed, alignment, contrast, drive stability and the like of the liquid crystal element.

In particular, in a liquid crystal device in which the liquid crystal has a book shelf (without adding an external field or the like) or a structure close to the bookshelf with a small layer tilt angle, local switching abnormality, change in the switching state over time, burn-in. ,
There is a big problem. Such a problem,
In many cases, it is caused by an electrostatic factor. Such problems have been a major cause of impairing the performance, reliability, and durability of the liquid crystal element and the liquid crystal device.

In a liquid crystal device having a bookshelf liquid crystal structure, especially in a liquid crystal device using the above-mentioned liquid crystal compound having a fluorocarbon terminal portion, the liquid crystal has a large tilt angle unlike the case of the chevron structure. In such a liquid crystal element, a means of using a liquid crystal composition having a large spontaneous polarization in order to increase the switching speed of the liquid crystal can be considered. However,
When a liquid crystal composition having a large spontaneous polarization is used, the influence of an electrostatic factor on a liquid crystal element increases. For example, there is an influence of an anti-electric field which is presumed to be caused by impurity ions in the liquid crystal. Here, the anti-electric field is a phenomenon in which an electric field in the opposite direction to the switching pulse occurs immediately after the application of the switching pulse. When a liquid crystal composition having a large spontaneous polarization is used, the anti-electric field becomes large. In a liquid crystal element using a liquid crystal composition having a large spontaneous polarization exhibiting a bookshelf structure, the adverse effect of a large anti-electric field on the orientation of liquid crystal molecules and the like is considerably larger than in the case of a chevron structure. In the case of a liquid crystal element using a liquid crystal having a chevron structure, the disturbance in alignment over time, which is considered to be affected by an anti-electric field, was not so large, but is remarkable in a liquid crystal element using a liquid crystal having a bookshelf structure. Therefore, it is necessary to reduce the influence of an electrostatic factor such as an anti-electric field on the liquid crystal element.

The present invention has been made in view of the above-mentioned problems, and is directed to a liquid crystal device which exhibits a bookshelf or a structure having a small layer tilt angle close to the bookshelf, which has a local switching abnormality, The purpose of the present invention is to provide a liquid crystal element in which problems such as a change in switching state and burn-in are suppressed and a liquid crystal device using the liquid crystal element, and greatly improve the performance, reliability, and durability of the liquid crystal element and the liquid crystal device. What you want to do.

[0011]

The present invention relates to a liquid crystal device having a chiral smectic liquid crystal composition having at least two stable states sandwiched between a pair of substrates, wherein the chiral smectic liquid crystal composition has a cholesteric phase. Layer gap (d _A ) at the first transition point where the layer gap starts to decrease near the temperature at which the phase shifts from the smectic A phase to the chiral smectic C phase, and the above-described temperature drop from the first transition point. The relation with the minimum value (d _min ) of the layer interval at the second transition point where the layer interval decreases and starts to increase again is as follows.

[0012]

_A liquid crystal element satisfying 0.990 ≦ d _min / d _A , wherein the chiral smectic liquid crystal composition contains a compound represented by the following general formula (V): It is.

[0013]

HO-AB-OH (V) (wherein A and B each represent an aromatic or aliphatic ring structure which may be substituted.)

The present invention also relates to a liquid crystal device having a chiral smectic liquid crystal composition exhibiting at least two stable states sandwiched between a pair of substrates, wherein the chiral smectic liquid crystal composition has a fluorocarbon terminal portion and a hydrocarbon terminal portion. A liquid crystal composition comprising at least one fluorine-containing liquid crystal compound having a smectic mesophase or a potential smectic mesophase, wherein both terminal portions are bound by a central nucleus, wherein the chiral smectic liquid crystal composition has the A liquid crystal element including a compound represented by the general formula (V).

Further, the present invention is a liquid crystal device in which a chiral smectic liquid crystal composition exhibiting at least two stable states is sandwiched between a pair of substrates, wherein one of the pair of substrates is subjected to a uniaxial alignment treatment. An oriented film is provided, and the other substrate is provided with an oriented film that has not been subjected to uniaxial orientation treatment, and is represented by the general formula (V) in the chiral smectic liquid crystal composition. A liquid crystal element comprising a compound.

In addition, the present invention is a liquid crystal device having at least the above liquid crystal element and means for driving the liquid crystal element.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the specific liquid crystal device as described above, the present inventors have incorporated a compound represented by the following general formula (V) into a chiral smectic liquid crystal composition to obtain a bookshelf or a book shelf. It has been found that problems such as local switching abnormalities, changes in the switching state over time, and image sticking are suppressed in a liquid crystal element exhibiting a structure with a small layer tilt angle close to that.

[0018]

HO-AB-OH (V) (wherein A and B each represent an aromatic or aliphatic ring structure which may be substituted.)

This is because the diol compound represented by the following general formula (V) interacts with impurity ions and / or polar impurities in the liquid crystal composition to suppress the activity of these impurities. It is estimated that there is.

The diol compound represented by the general formula (V) can be appropriately selected and used according to the required properties of the liquid crystal composition or the liquid crystal element.

Next, a chiral smectic liquid crystal composition containing at least two stable states, which contains the diol compound represented by the above formula (V), used in the present invention will be described.

The chiral smectic liquid crystal composition used in the present invention has no cholesteric phase,
And chiral smectic C from smectic A phase
The layer interval (d _A ) at the first transition point where the layer interval starts to decrease near the temperature at which the phase shifts, and the layer interval decreases with the temperature drop from the first transition point and starts increasing again. 2
The relationship with the minimum value (d _min ) of the layer interval at the transition point of

[0023]

## EQU3 ## _A liquid crystal composition satisfying 0.990 ≦ d _min / d _A is used. By using the chiral smectic liquid crystal composition, it is possible to exhibit a bookshelf or a structure close to the bookshelf with a small layer tilt angle. . As a specific example of this chiral smectic liquid crystal composition, for example, “Next-generation liquid crystal display and liquid crystal material” (edited by CMC Corporation and Atsuo Fukuda, 1992)
Year)).

Further, the chiral smectic liquid crystal composition used in the present invention preferably has a fluorocarbon terminal portion and a hydrocarbon terminal portion, and both terminal portions are bound by a central nucleus to form a smectic intermediate phase or a potential smectic. Those containing a fluorine-containing liquid crystal compound having an intermediate phase are desirable.

In the fluorine-containing liquid crystal compound, the terminal portion of the fluorocarbon is a group represented by -D ¹ -C _xa F _2xa -X (provided that xa is 1 to 20;
It represents -H or -F, D ¹ is, -CO-O- (C
_{H 2) ra -, - O-} (CH 2) ra -, - (CH 2) ra -,
_{-O-SO 2 -, - SO} 2 -, - SO 2 - (CH 2) ra -,
_{-O- (CH 2) ra -O- (} CH 2) rb -, - (CH 2)
_{ra -N (C pa H 2pa +} 1) -SO 2 -, or - (CH _{2) ra
-N (C pa H 2pa + 1} ) represents the -CO-. ra and r
b is independently 1 to 20; pa is 0 to 4; ), _{^{Or, -D 2 - (C xb F}} 2xb -O) za -C ya F
A group represented by _{2ya + 1} , wherein xb is independently 1 to 10 for each (C _xb F _2xb -O);
Is 1 to 10, za is 1 to 10, and D ² is-
_{CO-O-C rc H 2rc} -, - O-C rc H 2rc -, - C rc H
_{2rc -, - O- (C sa} H 2sa -O) ta -C rd H 2rd -, -
_{O-SO 2 -, - SO} 2 -, - SO 2 -C rc H 2rc -, - C
_rc H _2rc -N (C _pb H _{2pb + 1} ) -SO _2- , -C _rc H _{2rc-
Selected from} N (C _pb H _{2pb + 1} ) —CO— and a single bond;
And rd are independently 1 to 20, sa is independently 1 to 10 for each (C _sa H _2sa -O), and ta is 1
And pb is 0-4. ) Can be used.

Particularly preferably, a fluorine-containing liquid crystal compound represented by the following general formula (I) or (II) can be used.

[0027]

Embedded image In the formula, A ¹ , A ² and A ³ are each independently:

[0028]

Embedded image Represents

Ga, ha and ia each independently represent an integer of 0 to 3 (provided that ga + ha + ia is at least 2). L ¹ and L ² are each independently a single bond, —CO—O
-, -O-CO-, -COS-, -S-CO-, -CO
-Se-, -Se-CO-, -CO-Te-, -Te-
_{CO -, - CH 2 CH 2} -, - CH = CH -, - C≡C
-, - CH = N -, - N = CH -, - CH 2 -O -, -
O-CH ₂ -, - CO- or represent -O-.

Each of X ¹ , Y ¹ , and Z ¹ is a substituent of A ¹ , A ² , and A ³ and independently represents —H, —Cl, —F, —Br, —
_{I, -OH, -OCH 3, -CH} 3, -CN, or -NO
₂ and each of ja, ma and na independently represents an integer of 0-4. J ¹ is -CO-O- (CH ₂ ) _ra -,-
_{O- (CH 2) ra -,} - (CH 2) ra -, - O-SO
_{2 -, - SO 2 -,} - SO 2 - (CH 2) ra -, - O- (C
H ₂ ) _ra -O- (CH ₂ ) _rb -,-(CH ₂ ) _ra -N (C
_pa H _{2pa + 1} ) -SO _{2- or-} (CH ₂ ) _ra -N (C _{pa
H2pa + 1} ) -CO-. ra and rb are independently 1-20, and pa is 0-4.

R ¹ is _{-OC qa} H _{2qa -OC qb} H
_{2qb + 1, -C qa H 2qa} -O-C qb H 2qb + 1, -C qa H 2qa -
_{^{R 3, -O-C qa H}} 2qa -R 3, -CO-O-C qa H 2qa -
R ³ or —O—CO—C _qa H _2qa —R ³ , which may be linear or branched (where R ³ _{is-
O-CO-C qb H 2qb} + 1, -CO-O-C qb H 2qb + 1, -
_{H, -Cl, -F, -CF 3} , -NO 2, represents a -CN, qa and qb are 20 independently). R ² is C
_xa F _2xa -X (X represents -H or -F, x
a is an integer of 1 to 20).

[0032]

Embedded image Wherein A ⁴ , A ⁵ and A ⁶ are each independently

[0033]

Embedded image Represents

Gb, hb and ib are each independently 0 to 3
(Where gb + hb + ib is at least 2). Each of L ³ and L ⁴ is independently a single bond, -C
O-O-, -O-CO-, -CO-S-, -S-CO
-, -CO-Se-, -Se-CO-, -CO-Te
-, - Te-CO -, - (CH 2 CH 2) ka - (ka is 1
To 4), -CH = CH-, -C≡C-, -CH = N-,
_{-N = CH -, - CH 2} -O -, - O-CH 2 -, - CO
-Or -O-.

Each of X ² , Y ² and Z ² is a substituent of A ⁴ , A ⁵ and A ⁶ and independently represents —H, —Cl, —F, —Br,
_{I, -OH, -OCH 3, -CH} 3, -CF 3, -OC
F ₃ , —CN, or —NO ₂ , and each jb, m
b and nb each independently represent an integer of 0 to 4;

J ² represents —CO—O—C _rc H _2rc —, —O—
_{C rc H 2rc -, - C} rc H 2rc -, - O- (C sa H 2sa -
O) _ta -C _rd H _2rd- , _-O -SO _2- , -SO ₂ -,-
_{SO 2 -C rc H 2rc -,} - C rc H 2rc -N (C pb H 2pb + 1)
_{-SO 2 -, - C rc H} 2rc -N (C pb H 2pb + 1) -CO-
_Where rc and rd are independently 1-20, sa is independently 1-10 for each (C _sa H _2sa -O), ta is 1-6, pb is 0-4. is there.

[0037] R ⁴ _{is, -O- (C qc H 2qc -O} ) wa -C qd
_{H 2qd + 1, - (C} qc H 2qc -O) wa -C qd H 2qd + 1, -C
_qc H _2qc -R ⁶ , _{-OC qc} H _2qc -R ⁶ , -CO- _OC
qc H _2qc -R ^6, or represents _{-O-CO-C qc H 2qc} -R 6, linear, may be either branched (Here, R
⁶ is _{-O-CO-C qd H 2qd} + 1, -CO-O-C qd H
_{2qd + 1, -Cl, -F,} -CF 3, -NO 2, represents -CN, or -H, qc and qd are independently an integer of 1 to 20, the wa is an integer of 1 to 10). R ⁵ is (C _xb F _2xb
-O) _za -C _ya F _{2ya + 1} (where xb is independently 1 to 10 for each (C _xb F _2xb -O)
And ya is 1 to 10, and za is 1 to 10.)

The compound represented by the above general formula (I) is
JP-A-2-142755, U.S. Pat.
2,587.
Specific examples of such compounds are listed below.

[0039]

Embedded image

[0040]

Embedded image

[0041]

Embedded image

[0042]

Embedded image

[0043]

Embedded image

[0044]

Embedded image

[0045]

Embedded image

[0046]

Embedded image

[0047]

Embedded image

[0048]

Embedded image

[0049]

Embedded image

[0050]

Embedded image

The compound represented by the above general formula (II) is described in International Publication WO 93/22396, JP-T-Hei 7-506.
368 can be obtained.
Specific examples of such compounds are listed below.

[0052]

Embedded image

[0053]

Embedded image

[0054]

Embedded image

[0055]

Embedded image

[0056]

Embedded image

In the present invention, in particular, the chiral smectic liquid crystal composition is preferably a liquid crystal composition containing at least 50% by weight or more of a fluorine-containing liquid crystal compound containing at least one ether oxygen in the chain in the terminal portion of the fluorocarbon.

Further, specific examples of the optically active liquid crystalline compound as other constituents include those having the following structures, but the present invention is not limited thereto.

化合物 A compound represented by the following general formula (III).

[0060]

Embedded image

[0061]

[Table 1]

[0062]

[Table 2]

[0063]

[Table 3]

[0064]

[Table 4]

[0065]

[Table 5]

The abbreviations used in the specific examples of the compound of the general formula (III) are as follows.

[0067]

Embedded image

[0068]

Embedded image

化合物 A compound represented by the following general formula (IV).

[0070]

Embedded image

[0071]

[Table 6]

[0072]

[Table 7]

[0073]

[Table 8]

[0074]

[Table 9]

[0075]

[Table 10]

The abbreviations used in the specific examples of the compound of the general formula (IV) are as follows.

[0077]

Embedded image

[0078]

Embedded image

[0079]

Embedded image

[0080]

Embedded image

[0081]

Embedded image

[0082]

Embedded image

N = 6,2R, 5R n = 6,2S, 5R n = 4,2R, 5R n = 4,2S, 5R n = 3,2R, 5R n = 2,2R, 5R n = 2,2S , 5R n = 1,2R, 5R n = 1,2S, 5R

[0084]

Embedded image

N = 1 n = 2 n = 3 n = 4 n = 6 n = 10

[0086]

Embedded image

N = 8 n = 10

[0088]

Embedded image

[0089]

Embedded image

[0090]

Embedded image

[0091]

Embedded image

[0092]

Embedded image

[0093]

Embedded image

Next, in the present invention, the specific diol compound contained in the chiral smectic liquid crystal composition is represented by the following general formula (V)

[0095]

Embedded image This is a compound represented by HO—A—B—OH (V). In the general formula (V), A and B represent an aromatic or aliphatic ring structure which may be substituted.

A and B in the general formula (V) are preferably
Is 1,4-phenylene having one or two substituents selected from 1,4-phenylene, F, Cl, CN and CF ₃ , 1,4-cyclohexylene, pyrimidine-
2,5-diyl, pyridine-2,5-diyl, 2,6-
Selected from naphthylene. Specific examples of the compound represented by the general formula (V) are shown below.

[0097]

(V-1) HO-Ph-Ph-OH (V-2) HO-Py1-Ph-OH (V-3) HO-Py2-Ph-OH (V-4) HO-Pr1-Ph -OH (V-5) HO-Pr2-Ph-OH (V-6) HO-Cy-Ph-OH (V-7) HO-Np-Ph-OH (V-8) HO-Np-Py1-OH (V-9) HO-Np-Py2-OH (V-10) HO-Np-Pr1-OH (V-11) HO-Np-Pr2-OH (V-12) HO-Ph-Tn-OH (V -13) HO-Ph-Tzl-OH (V-14) HO-Ph2F-Ph-OH (V-15) HO-Ph3F-Ph-OH (V-16) HO-PhdF-Ph-OH (V-17) ) HO-Ph2CN-Ph-OH (V-18) HO-Ph3CN-Ph- H (V-19) HO-PhdCN-Ph-OH (V-20) HO-Ph2F-Pyl-OH (V-21) HO-Ph3F-Pyl-OH (V-22) HO-PhdF-Pyl-OH ( V-23) HO-Ph2CN-Pyl-OH (V-24) HO-Ph3CN-Pyl-OH (V-25) HO-PhdCN-Pyl-OH

The abbreviations used in the specific examples of the compound represented by formula (V) are as follows.

[0099]

Embedded image

Next, the content of the compound represented by the general formula (V) contained in the chiral smectic liquid crystal composition of the present invention in the liquid crystal composition is determined from the viewpoints of both the effect and not impairing the liquid crystallinity. Less than 10 wt%, preferably 5
wt%, more preferably 1.0 × 10 ^{−9 to} 1.0
wt%. The compound represented by the general formula (V) is characterized in that it is effective in a very small amount. For this reason, the effect on liquid crystallinity and other driving characteristics is very small, and depending on the liquid crystal composition, even a very small amount is effective. Another feature is that the compound represented by the general formula (V) is excellent in dispersibility in liquid crystal, which enhances the reliability of the liquid crystal element.

In the present invention, since the compound represented by the general formula (V) is contained in the chiral smectic liquid crystal composition, local switching abnormality of the liquid crystal element, change of the switching state over time, The problem of burn-in is well suppressed and the performance, reliability and durability of the liquid crystal element are improved. Although the mechanism of this action is not clearly understood, it is thought that the compound represented by the general formula (V), which is contained in a small amount, has an adverse effect near the interface between the liquid crystal layer and the alignment film or spacer. It is considered that the influence of electrostatic factors such as impurities having polarity and / or the like is suppressed. Therefore, the present invention is particularly effective for a liquid crystal material or a liquid crystal element in which impurity ions and / or impurities having polarity are easily generated or easily biased. Specifically, “a liquid crystal element having bistability” and “ferroelectricity” Or "Anti-ferroelectric liquid crystal element", "Liquid crystal element having a structure in which the element structure sandwiching the liquid crystal layer is vertically different", "Having a fluorocarbon terminal chain part and a hydrocarbon terminal chain part, both terminal chain parts being formed by a central nucleus. 70% by weight combined and having a smectic or potential smectic mesophase
The liquid crystal composition occupied above has an advantageous effect.

Further, as a more effective liquid crystal element in combination with the compound represented by the general formula (V) in the present invention, a neutral molecule and / or an ionic compound may be formed at the interface formed between the liquid crystal and the alignment film. It is more effective to adsorb molecules.
Water or the like is used as the ionic molecule.

The chiral smectic liquid crystal composition used in the present invention may contain other compounds, for example, additives such as dyes, pigments, antioxidants and ultraviolet absorbers.

Hereinafter, the liquid crystal device of the present invention will be described in detail.
FIG. 1 is a schematic view showing an example of the chiral smectic liquid crystal device of the present invention. In the figure, reference numeral 1 denotes a liquid crystal layer composed of a chiral smectic liquid crystal composition. When a chiral smectic liquid crystal is used as the liquid crystal, the layer thickness is usually preferably 5 μm or less in order to realize bistability. 2a,
2b is a substrate made of glass, plastic, or the like. 3a and 3b are transparent electrodes such as ITO. 4a, 4
b is an alignment film, and a uniaxial alignment film obtained by performing a uniaxial alignment treatment on at least one substrate is required. As a method of forming the uniaxial alignment film, for example, by solution coating or vapor deposition or sputtering on a substrate, silicon monoxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride,
Silicon carbide, inorganic substances such as boron nitride, polyvinyl alcohol, polyimide, polyimide amide, polyester, polyamide, polyester imide, polyparaxylene, polycarbonate, polyvinyl acetal,
After a film is formed using an organic material such as polyvinyl chloride, polystyrene, polysiloxane, cellulose resin, melamine resin, urea resin, and acrylic resin, the surface is rubbed with a fibrous material such as velvet, cloth or paper. It can be obtained by: Also, an oblique deposition method of depositing an oxide or a nitride of SiO or the like from an oblique direction of the substrate may be used. These materials and forming methods can be used without imparting uniaxial orientation such as rubbing on one substrate side. In addition, it is also possible to provide a short-circuit prevention layer. The structure of the liquid crystal element of the present invention is not limited as long as the chiral smectic liquid crystal composition containing the compound represented by the general formula (V) is controlled to have a predetermined function.

In particular, the liquid crystal device of the present invention comprises a pair of substrates sandwiching a chiral smectic liquid crystal composition containing at least two stable states and containing a compound represented by formula (V). In one of the pair of substrates, one substrate is provided with an alignment film that has been subjected to a uniaxial alignment treatment, and the other substrate is provided with an alignment film that has not been subjected to a uniaxial alignment treatment. Preferably, the liquid crystal element has an alignment film that has been subjected to the uniaxial alignment treatment made of polyimide and an alignment film that has not been subjected to the uniaxial alignment treatment made of a silane coupling agent or polysiloxane. 8a, 8
b indicates a polarizing plate, 5 indicates a sealing material, and 9 indicates a light source.

The liquid crystal device of the present invention constitutes a liquid crystal device having various functions. The most suitable example is the case where the liquid crystal device is used for a display panel and the scanning line address shown in FIGS. 2 and 3 is used. The liquid crystal display device is realized by using a data format including image information having information and a communication synchronization unit using a SYN signal.

The reference numerals in the figure are as follows. Reference Signs List 101 Chiral smectic liquid crystal display device 102 Graphic controller 103 Display panel 104 Scan line drive circuit 105 Information line drive circuit 106 Decoder 107 Scan line signal generation circuit 108 Shift register 109 Line memory 110 Information signal generation circuit 111 Drive control circuit 112 GCPU 113 Host CPU 114 VRAM

The image information is generated by the graphic controller 102 of the main unit, and is transferred to the display panel 103 according to the signal transmission means shown in FIGS. The graphic controller 102 includes a CPU (central processing unit, abbreviated as GCPU 112) and a VRAM.
(Image information storage memory) Host CPU 1 with 114 as a core
13 manages image information and communicates with the liquid crystal display device 101. Note that a light source is disposed on the back surface of the display panel.

In the display device of the present invention, since the liquid crystal element as the display medium has good switching characteristics as described above, it exhibits excellent driving characteristics and reliability, and has high definition.
A high-speed, large-area display image can be obtained.

As a method of driving a chiral smectic liquid crystal element which is an example of the liquid crystal element of the present invention, for example, JP-A-59-193426 and JP-A-59-19342.
7, JP-A-60-156046, JP-A-60-156046
The driving method disclosed in Japanese Patent Application No. 0-156047 can be applied.

FIG. 6 is a diagram showing an example of a waveform diagram of the driving method. FIG. 5 is a plan view showing an example of a ferroelectric liquid crystal panel in which matrix electrodes are arranged. The liquid crystal panel 51 shown in FIG.
And three data lines intersecting each other, and a ferroelectric liquid crystal is arranged between the scanning line and the data line at the intersection.

[0112] The S _S is selected scan waveform applied to the selected scanning line in FIG. 6 (A), the non-selection scanning waveform S _N is not selected, I _S is applied to the selected data line The selected information waveform (black), and _IN indicates a non-selected information signal (white) applied to an unselected data line. Also,
In Figure at _{(I S} -S S) and _(I N -S _S) is the voltage waveform applied to pixels on a selected scanning line, the voltage _(I S _-S S)
The pixel to which is applied a black display state, and the voltage ( _IN −
The pixel to which _{S s} ) is applied becomes a white display state.

FIG. 6B shows the driving waveform shown in FIG. 6A, which is a time-series waveform when the display shown in FIG. 4 is performed. In the driving example shown in FIG. 6, the minimum application time of a single polarity voltage Δt corresponds to the time the write phase t ₂ applied to a pixel on a selected scanning line, one line clearing phase t ₁ time 2
It is set to Δt. Now, the values of the parameters V _S , V _R , and Δt of the drive waveform shown in FIG. 6 are determined by the switching characteristics of the liquid crystal material used.

FIG. 7 shows the transmittance T when the drive voltage (V _S + V _I ) is changed while the bias ratio described later is kept constant.
, Ie, the VT characteristic. Here, Δt = 50 μsec, and the bias ratio V _I / (V _I + V
_S ) is fixed at 1/3. The positive side of Fig. 7 is shown in FIG. 6 _(I N _-S S), the negative side _{(I S} -S S) at the indicated waveform when applied _(V S + V _I) final transmission The relationship between the rates is shown.

Here, V ₁ and V ₃ are called an actual driving threshold voltage and a crosstalk voltage, respectively. Also, V ₂ <V ₁ <
When V _3, and referred to, is an important parameter of the matrix drivable voltage range _{(V 3 -V 1) / (} V 3 + V 1) voltage variable margin ([Delta] V).

[0116] V ₃ is a ferroelectric liquid crystal display element drive on, it may be said that generally present. Specifically, FIG.
A voltage value causing switching by _{V B} in _N -S _S) of the waveform. Of course, by increasing the bias ratio, it is possible to increase the value of V _3, increasing the bias ratio corresponds to a large amplitude of a data signal, an increase in flickering in image quality, This leads to a decrease in contrast, which is not preferable.

The present inventors have examined that the bias ratio is 1/3 to
About 1/4 was appropriate. By the way, if the bias ratio is fixed, the voltage margin ΔV strongly depends on the switching characteristics of the liquid crystal material and the element configuration, and it goes without saying that an element having a large ΔV is very advantageous for matrix driving.

Similarly, when the drive voltage is fixed and the voltage application time Δt is changed, the voltage application time threshold is set to Δt ₁ , the voltage application time crosstalk value is set to Δt ₂ , and (Δt ₂ −Δt ₁ ) / (Δt ₂ + Δt ₁ ) is defined as a voltage application time margin.

At a certain temperature, it is possible to write two states, black and white, on the selected pixel according to the two directions of the information signal, and the non-selected pixels maintain the black or white state. The voltage margin or voltage application time margin that can be obtained differs depending on the liquid crystal material and the element configuration, and is unique. In addition, since the drive margins are different depending on the change in the environmental temperature, in the case of an actual display device, it is necessary to set optimal drive conditions for the liquid crystal material, the element configuration, and the environmental temperature.

[0120]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to the following examples.

The liquid crystal composition used in this example is shown below.

[0122]

Embedded image

[0123]

Embedded image

The physical parameters of the liquid crystal composition N are shown below.

[0125]

(Equation 4)

[0126]

(Equation 5)

Further, the following liquid crystal cells were prepared. (Liquid crystal cell) A glass substrate with ITO, spin-coated with Toray's polyimide precursor LP64 with an NMP / nBC = 2/1 solution, baked to obtain polyimide, and then subjected to a rubbing treatment, and a glass with ITO The substrate is spin-coated with a silane coupling agent (octadecyltriethoxysilane) on the substrate and heat-treated. A silica space bead spacer is sprayed on the substrate to form a gap of about 2 μm.

Example 1 The diol compounds A, B and C represented by the general formula (V) added to the liquid crystal composition are shown below. (Diol compound A) Exemplary compound (V-1) HO-Ph-Ph-OH (Diol compound B) Exemplary compound (V-18) HO-Ph3CN-Ph-O
H (diol compound C) Exemplified compound (V-22) HO-PhdF-Pyl-O
H

As shown in Table 11 below, diol compounds A, B and C were each added to the above-mentioned liquid crystal composition N in an amount of 0.1 wt%
The liquid crystal compositions 1 to 3 were prepared by the addition.

[0130]

[Table 11]

These adjusted liquid crystal compositions 1 to 3 and N
Was injected into a liquid crystal cell. The injection was performed under the condition of an environmental humidity of 20%.

The driving waveform of the liquid crystal cell in this embodiment uses the waveform shown in FIG. 6, the bias ratio is reduced to 1/3, and (V
_I + V _S ) was fixed at 20 V, and the initial margin was measured with the voltage application time varied. In addition, each cell is 30
The margin after storage for 500 hours in a constant temperature layer at ° C. was measured as the post-storage margin, and the margin storage ratio was calculated. The results are shown in Table 12 below.

[0133]

[Table 12]

Here, in the liquid crystal composition to which the diol compounds A, B, and C were added, the liquid crystal composition N to which nothing was added was used.
It can be seen that the margin preservation ratio is higher in each case.

Example 2 Next, in order to adsorb water molecules as neutral molecules at the interface formed between the liquid crystal composition and the alignment film, the liquid crystal composition was injected into the liquid crystal cell under steam humidification ( Table 13 below shows the results of the liquid crystal compositions 1 to 3 and N when conducted at a humidity of 80%).
Shown in

[0136]

[Table 13]

Here, too, it can be seen that the liquid crystal composition to which the diol compounds A, B, and C are added has a high margin preservation rate. Furthermore, as compared with Example 1, it turns out that the diol compound represented by the general formula (V) is more effective in the presence of water molecules.

Example 3 Next, the same experiment as in Examples 1 and 2 was carried out except that the addition ratios of the diol compounds A, B and C were each 0.5% by weight.
After all, the same effect was confirmed.

[0139]

As described above, in the liquid crystal composition having bistability and the liquid crystal element of the present invention, the driving stability of display is improved at the initial stage, and the margin preservation rate after aging is also improved. Have been. In addition, the effect is more remarkable when water molecules, which are neutral molecules, are present at the interface between the alignment film and the liquid crystal composition. Therefore, a display device with high display quality and high reliability can be provided by using the liquid crystal element of the present invention.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one example of a chiral smectic liquid crystal device of the present invention.

FIG. 2 is a block diagram showing a display device provided with a liquid crystal element using the chiral smectic liquid crystal composition of the present invention and a graphic controller.

FIG. 3 is a diagram showing a timing chart of image information communication between a display device and a graphic controller.

FIG. 4 is a schematic diagram of a display pattern when actual driving is performed with the time-series driving waveform shown in FIG.

FIG. 5 is a plan view of an example of a ferroelectric liquid crystal panel on which matrix electrodes are arranged.

FIG. 6 is an example of a waveform diagram of a driving method used in the present invention.

FIG. 7 is a graph (VT characteristic diagram) showing a change in transmittance when a drive voltage is changed according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Liquid crystal layer using chiral smectic liquid crystal composition 2a, 2b Substrate 3a, 3b Transparent electrode 4a, 4b Alignment film 8a, 8b Polarizer 5 Sealing material 9 Light source I ₀ Incident light I Transmitted light 51 Liquid crystal panel 52 Scanning electrode group 53 Information electrode group 101 Chiral smectic liquid crystal display device 102 Graphic controller 103 Display panel 104 Scan line drive circuit 105 Information line drive circuit 106 Decoder 107 Scan signal generation circuit 108 Shift register 109 Line memory 110 Information signal generation circuit 111 Drive control circuit 112 GCPU 113 Host CPU 114 VRAM

Continued on the front page (72) Inventor Yukio Hanyu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Koichi Sato 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kenji Shinjo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Makoto Mori 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (16)

[Claims] 1. A liquid crystal device having a chiral smectic liquid crystal composition exhibiting at least two stable states sandwiched between a pair of substrates, wherein the chiral smectic liquid crystal composition does not have a cholesteric phase, and has a chiral smectic A phase to a chiral smectic liquid crystal composition. The layer interval (d) at the first transition point where the layer interval starts to decrease near the temperature at which the phase shifts to the smectic C phase
_A ) and the minimum value (d _min ) of the layer interval at the second transition point where the layer interval decreases and starts increasing again with the temperature drop from the first transition point. _A liquid crystal device satisfying 0.990 ≦ d _min / d _A , wherein the chiral smectic liquid crystal composition contains a compound represented by the following general formula (V). HO-AB-OH (V) (wherein A and B each represent an aromatic or aliphatic ring structure which may be substituted.) 2. The compound represented by the general formula (V), wherein A and B are 1,4-phenylene, F, Cl, CN, C
1, having 1 or 2 substituents selected from F ₃
4-phenylene, 1,4-cyclohexylene, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 2,
The liquid crystal element according to claim 1, wherein the liquid crystal element has a structure selected from 6-naphthylene. 3. A liquid crystal element in which at least two chiral smectic liquid crystal compositions exhibiting a stable state are sandwiched between a pair of substrates, wherein one of the pair of substrates is subjected to a uniaxial alignment treatment. A film is provided. The other substrate is provided with an alignment film that has not been subjected to a uniaxial alignment treatment. The chiral smectic liquid crystal composition contains a compound represented by the following general formula (V). A liquid crystal element characterized by the following. HO-AB-OH (V) (wherein A and B represent aromatic and aliphatic ring structures which may be substituted.) 4. The liquid crystal device according to claim 3, wherein the alignment film subjected to the uniaxial alignment treatment is made of polyimide. 5. The liquid crystal device according to claim 3, wherein the alignment film that has not been subjected to the uniaxial alignment treatment is made of a silane coupling agent or polysiloxane. 6. The compound represented by the general formula (V), wherein A and B are 1,4-phenylene, F, Cl, CN, C
1, having 1 or 2 substituents selected from F ₃
4-phenylene, 1,4-cyclohexylene, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 2,
The liquid crystal element according to claim 3, wherein the liquid crystal element has a structure selected from 6-naphthylene. 7. A liquid crystal device having a chiral smectic liquid crystal composition exhibiting at least two stable states sandwiched between a pair of substrates, wherein the chiral smectic liquid crystal composition has a fluorocarbon terminal portion and a hydrocarbon terminal portion, A liquid crystal composition comprising at least one fluorine-containing liquid crystal compound having a smectic mesophase or a potential smectic mesophase in which both terminal portions are bound by a central nucleus; A liquid crystal device comprising a compound represented by the formula (1): HO-AB-OH (V) (wherein A and B each represent an aromatic or aliphatic ring structure which may be substituted.) 8. The compound represented by the general formula (V), wherein A and B are 1,4-phenylene, F, Cl, CN, C
1, having 1 or 2 substituents selected from F ₃
4-phenylene, 1,4-cyclohexylene, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 2,
The liquid crystal element according to claim 7, wherein the liquid crystal element has a structure selected from 6-naphthylene. 9. The liquid crystal device according to claim 7, wherein a terminal portion of the fluorocarbon in the fluorine-containing liquid crystal compound is a group represented by -D ¹ -C _xa F _2xa -X. (Where xa in the above formula is 1 to 20, and X is -H or -F
And D ¹ represents —CO—O— (CH ₂ ) _ra —, —O—
(CH ₂ ) _ra -,-(CH ₂ ) _ra- , -O-SO ₂ -,-
SO _2- , -SO _2- (CH ₂ ) _ra- , -O- (CH ₂ ) _{ra
-O- (CH 2) rb -,} - (CH 2) ra -N (C pa H
_2pa + 1) -SO ₂ -, or _{- (CH 2) ra -N (} C pa H
_{2pa + 1} ) represents -CO-. ra and rb are independently 1 to 20, and pa is 0 to 4. ) 10. The fluorocarbon terminal in the fluorine-containing liquid crystal compound is -D ^2- (C _xb F _2xb -O).
_za -C _ya F _{2ya + 1} liquid crystal device according to claim 7 or 8, wherein the group represented by. (Where xb in the above formula is independently 1 to 10 for each (C _xb F _2xb -O), and ya is 1
Za is 1 to 10, and D ² is -CO
_{-O-C rc H 2rc -,} - O-C rc H 2rc -, - C rc H 2rc
_{-, - O- (C sa H} 2sa -O) ta -C rd H 2rd -, - O-
SO _2- , -SO _2- , -SO ₂ -C _rc H _2rc- , -C _rc H
_{2rc -N (C pb H 2pb +} 1) -SO 2 -, - C rc H 2rc -N
(C _pb H _{2pb + 1} ) —CO— or a single bond, rc and rd are independently 1 to 20, and sa is each (C
_sa H _2sa -O) independently from 1 to 10, and ta from 1 to 6
And pb is 0-4. ) 11. The liquid crystal device according to claim 7, wherein the fluorine-containing liquid crystal compound is represented by the following general formula (I). Embedded image Wherein A ¹ , A ² and A ³ are each independently: Represents ga, ha, and ia each independently represent an integer of 0 to 3 (provided that ga + ha + ia is at least 2). Each L ¹ and L ² is independently a single bond, —CO—O—,
-O-CO-, -COS-, -S-CO-, -CO-S
e-, -Se-CO-, -CO-Te-, -Te-CO
_{-, - CH 2 CH 2 -} , - CH = CH -, - C≡C -, -
CH = N -, - N = CH -, - CH 2 -O -, - O-C
Represents H ₂ —, —CO— or —O—. Each X ¹ ,
Y ¹ and Z ¹ are substituents of A ¹ , A ² and A ³ , and independently
H, -Cl, -F, -Br, -I, -OH, -OC
Represents H ₃ , —CH ₃ , —CN, or —NO ₂ , and each of ja, ma, and na independently represents an integer of 0 to 4. J ¹
_{Is, -CO-O- (CH 2)} ra -, - O- (CH 2)
_{ra -, - (CH 2)} ra -, - O-SO 2 -, - SO 2 -,
_{-SO 2 - (CH 2) ra} -, - O- (CH 2) ra -O-
(CH ₂ ) _rb -,-(CH ₂ ) _ra -N (C _pa H _{2pa + 1} )-
SO ₂ — or — (CH ₂ ) _ra —N (C _pa H _{2pa + 1} ) —C
Represents O-. ra and rb are independently 1-20, and pa is 0-4. R ¹ is _{-OC qa} H _2qa -O
-C _qb H _{2qb + 1} , -C _qa H _{2qa -OC qb} H _{2qb + 1} , -C
_qa H _2qa -R ³ , _{-OC qa} H _2qa -R ³ , -CO- _OC
qa H _2qa -R ^3, or represents _{-O-CO-C qa H 2qa} -R 3, linear, may be either branched (Here, R
_{^3, -O-CO-C qb H} 2qb + 1, -CO-O-C qb H
_{2qb + 1, -H, -Cl,} -F, -CF 3, -NO 2, -C
N, and qa and qb are independently 1-20).
R ² represents a C _xa F _2xa -X (X represents -H or -F, xa is an integer of 1 to 20). ] 12. The liquid crystal device according to claim 7, wherein the fluorine-containing liquid crystal compound is represented by the following general formula (II). Embedded image Wherein A ⁴ , A ⁵ , and A ⁶ are each independently: Represents gb, hb, and ib are each independently an integer of 0 to 3 (however, gb + hb + ib is at least 2)
Represents L ³ and L ⁴ are each independently a single bond, -CO-
O-, -O-CO-, -CO-S-, -S-CO-,-
CO-Se-, -Se-CO-, -CO-Te-, -T
e-CO -, - (CH 2 CH 2) ka - (ka is 1 to 4),
-CH = CH-, -C≡C-, -CH = N-, -N = C
_{H -, - CH 2 -O -} , - O-CH 2 -, - CO- or -
Represents O-. Each of X ² , Y ² , and Z ² is a substituent of A ⁴ , A ⁵ , and A ⁶ and independently represents —H, —Cl, —F, —Br, —
_{I, -OH, -OCH 3, -CH} 3, -CF 3, -OC
F ₃ , —CN, or —NO ₂ , and each jb, m
b and nb each independently represent an integer of 0 to 4; J ² is, -C
_{O-O-C rc H 2rc} -, - O-C rc H 2rc -, - C rc H
_{2rc -, - O- (C sa} H 2sa -O) ta -C rd H 2rd -, -
_{O-SO 2 -, - SO} 2 -, - SO 2 -C rc H 2rc -, - C
_rc H _2rc -N (C _pb H _{2pb + 1} ) -SO _2- , -C _rc H _2rc-
N (C _pb H _{2pb + 1} ) —CO—, rc and rd are independently 1 to 20, and sa is the respective (C _sa H _2sa −).
O) independently from 1 to 10, ta from 1 to 6, p
b is 0-4. R ⁴ _{is, -O- (C qc H 2qc -O} ) wa
_{-C qd H 2qd + 1, -} (C qc H 2qc -O) wa -C
_qd H _{2qd + 1} , -C _qc H _2qc -R ⁶ , _{-OC qc} H _2qc-
R ⁶ , -CO- _{OC qc} H _2qc -R ⁶ , or -O-CO-
_{C qc} H 2qc -R ⁶ represents a linear, it may be either branched (wherein, R ⁶ is _{-O-CO-C qd H 2qd} + 1, -
_{CO-O-C qd H 2qd} + 1, -Cl, -F, -CF 3, -N
Represents O ₂ , —CN, or —H, qc and qd are each independently an integer of 1 to 20, and wa is an integer of 1 to 10). R
^5, (C _xb F _2xb -O) represented by _za -C _ya F _{2ya + 1} (where the above formula xb is each (C _xb F _2xb -O)
Is independently 1 to 10, ya is 1 to 10, za
Is 1 to 10.) ] 13. The liquid crystal device according to claim 11, wherein the compound represented by the general formula (I) has a phenylpyrimidine core. 14. The liquid crystal device according to claim 12, wherein the compound represented by the general formula (II) has a phenylpyrimidine core. 15. The liquid crystal device according to claim 7, wherein the chiral smectic liquid crystal composition contains at least 50% by weight or more of a fluorine-containing liquid crystal compound containing ether oxygen in a chain in a terminal portion of the fluorocarbon. 16. A liquid crystal device comprising at least the liquid crystal element according to claim 1 and means for driving the liquid crystal element.