JPH0978067A - Liquid crystal element and liquid crystal apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal element excellent in high speed responsiveness and high brightness by using a specific liquid crystal composition and carrying the liquid crystal between a pair of substrates. SOLUTION: A liquid crystal composition contains a fluorocarbon terminal part and a hydrocarbon terminal part, both the terminal parts are linked with a central nucleus and contains a fluorine-containing liquid crystal compound having a (latent) smectic intermediate phase in an amount of >=70wt.%. The fluorine-containing liquid crystal compound contains at least one compounds of formula II, in an amount of >=10wt.%, expressed by formula I [B, D and E are each p-phenylene, etc.; (a), (b) and (c) are each 0-3; M and N are each COO, etc.; X, Y and Z are each a halogen, etc.; (l), (m) and (n) are each 0-4; G is COOCe H2e (e=1 to 20), etc.; A is O(Cf H2f O)u Cf 'H2f '+1 , etc.; R is (Cx F2x O)z Cy F2y+1 ] having one or more than one inner-chain ether oxygen in the fluorocarbon terminal chain and >=8 perfluorocarbons in the fluorocarbon terminal part, etc. The objective liquid crystal element is obtained by using the liquid crystal composition and carrying the liquid crystal between a pair of substrates each having at least an electric pole and an orientation controlling membrane.

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,
Due to the characteristics of the CRT, the visibility of a still image may be reduced due to flicker or scanning fringes due to insufficient resolution, or the phosphor may be deteriorated due to burn-in. In addition, recently, it has been found that the electromagnetic waves generated by the CRT adversely affect the human body, which may impair the health of the VDT worker.
Further, because of the large volume behind the screen in terms of structure, space saving in offices and homes may be hindered, and it may not be possible to fulfill the responsibility as a display in an advanced information society.

As a solution to such a disadvantage of the CRT, there is a liquid crystal display element. For example, M. Shut (M.
Schadt) and W. Helfrich (W. He)
Lfrich) "Applied Physics Letters"
s ") Volume 18, Issue 4 (issued February 15, 1971)
Twisted shown on pages 127-128
A liquid crystal device using a nematic (twisted nematic) liquid crystal is known. One is a simple matrix type liquid crystal element, which has a cost advantage. This liquid crystal element has a problem that crosstalk occurs in time-division driving using a matrix electrode structure with a high pixel density, so that the number of pixels is limited. Moreover, since the response speed is as slow as several tens of milliseconds or more, its use as a display is limited. In recent years, a liquid crystal element called TFT has been developed for such a simple matrix type. Since this type creates a transistor in each pixel, the problems of crosstalk and response speed are solved, but it is industrially very difficult to create a liquid crystal element without a defective pixel as the area increases. Difficult and, if possible, at great cost.

In order to improve the drawbacks of the conventional liquid crystal device, the use of a bistable liquid crystal device is clarified by Clark and Lagerw.
all) proposed. (JP-A-56-107
216, U.S. Pat. No. 4,367,924) As the liquid crystal having the bistability, a ferroelectric liquid crystal having 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, the ferroelectric liquid crystal has a very fast response speed and can exhibit a bistable state with memory properties. Further, since the viewing angle characteristics are also excellent, it is considered that they are suitable as a high-speed, high-definition, large-area display element or a light valve. Recently, Chandani and Takezoe have also proposed a chiral smectic antiferroelectric liquid crystal device having three stable states (Japanese Journal of Applied Physics).
of Applied Physics) 27, 198
8 years L729 page).

In such a chiral smectic liquid crystal element, as described in, for example, "Structure and Physical Properties of Ferroelectric Liquid Crystal" (Corona Publishing Co., Atsuo Fukuda, Hideo Takezoe, 1990), a zigzag alignment defect is formed. However, there is a problem that the contrast is significantly reduced. This defect is caused by the fact that the layered structure of the chiral smectic liquid crystal carried between the upper and lower substrates forms two types of chevron-like structures. Recently, there has been a movement to eliminate the chevron structure that causes the low contrast, and to reveal a layered structure called a bookshelf (hereinafter referred to as a bookshelf) or a structure close thereto to realize high contrast (for example, "Next-generation liquid crystal displays and liquid crystal materials" CMC Corporation, edited by Atsuo Fukuda, 1992). One method is to use a naphthalene-based liquid crystal material. In this case, the tilt angle is 10
22. It is about the degree and the ideal maximum transmittance is obtained.
There is a problem that the transmittance is very small as compared with 5 degrees and the transmittance is low, and there is also a problem that the bookshelf structure does not reversibly appear with respect to temperature. Another typical example is a method of inducing a bookshelf structure by applying a high electric field from the outside to a liquid crystal element having a chevron structure, but this method also has instability against external stimuli such as temperature. It's a problem. These bookshelf types have just been discovered, and there are various other problems for practical use.

Furthermore, a liquid crystal compound having a perfluoroether side chain as a liquid crystal having a structure of a bookshelf or a structure close to the bookshelf (US Pat. No. 5,262,082, International Patent Application WO 93/22396, 1993 4th Ferroelectric Liquid Crystal International Conference) P-46, Marc D. Radcliffe
Are disclosed. This liquid crystal can exhibit a bookshelf or a structure having a small layer inclination angle close to it without using an external field such as an electric field, and is suitable for a high-speed, high-definition, large-area liquid crystal element and a display device. However, further improvements are required in terms of speed, orientation, contrast, driving stability, etc. of liquid crystal elements. Moreover, in addition to improving each characteristic, a method and invention for improving a plurality of characteristics are required for higher performance.

[0007]

The present invention has been made in view of such a conventional technique. The present invention is intended to realize a chiral smectic liquid crystal device having a high speed, high contrast, large area, high definition, high brightness and high reliability, which has a bookshelf or a liquid crystal structure having a small layer tilt angle.

[0008]

As a result of intensive studies, the inventors of the present invention have found that a chiral smectic liquid crystal composition containing a liquid crystal compound having a perfluoroether side chain of a certain length or longer gives a very fast response. It has been found that it realizes a high-speed, high-contrast, large-area, high-definition, high-brightness chiral smectic liquid crystal device by realizing a high-performance, bookshelf or a structure with a small tilt angle close to it. Further, it was found that the composition exhibits good driving characteristics in an element having an asymmetric alignment film structure, particularly in a wide temperature range, and further has polyimide as an alignment film, and preferably has an asymmetric structure in the upper and lower substrates, that is, in the upper and lower substrates. It has been found that a device having different alignment characteristics with respect to liquid crystal molecules has high reliability and driving stability.

That is, the present invention provides a fluorine-containing liquid crystal compound group containing a fluorocarbon terminal portion and a hydrocarbon terminal portion, the both terminal portions being bound by a central nucleus, and having a smectic mesophase or a latent smectic mesophase. In a liquid crystal composition containing at least 10% by weight, in the fluorine-containing liquid crystal compound, at least one ether oxygen in the chain is contained in the fluorocarbon terminal chain, and perfluorocarbon is contained in the fluorocarbon terminal portion.
1 in the total amount of the composition containing at least one compound containing 1 or more compounds
A liquid crystal device using a liquid crystal composition characterized by containing 0% by weight or more, and a liquid crystal device using the liquid crystal device.

As used herein, a compound having a latent smectic mesophase means a compound having a smectic mesophase or a mixture with another compound having a latent smectic mesophase even if it does not show a smectic mesophase by itself. , A compound that develops a smectic mesophase under appropriate conditions. In the present invention, the ether oxygen in the chain refers to oxygen forming the main chain in the perfluoroether chain.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid crystal composition of the present invention comprises the fluorocarbon terminal portion and the hydrocarbon terminal portion, both terminal portions of which are bound by a central nucleus, and a smectic mesophase or a latent smectic mesophase is formed. Contains a fluorine-containing liquid crystal compound group as a main component. In the present invention, the compound group is contained in an amount of 70% by weight or more in the total amount of the composition in order to bring out a bookshelf structure or a structure having a small layer inclination angle close thereto.

The fluorocarbon terminal portion and the hydrocarbon terminal portion used in the liquid crystal composition of the present invention are contained, the both terminal portions being bound by a central nucleus, and having a smectic mesophase or a latent smectic mesophase. And a fluorine-containing liquid crystal compound (perfluoroether liquid crystal compound) containing at least one ether oxygen in the chain in the fluorocarbon terminal chain is disclosed in US Pat. No. 5,262,082 and International Patent Application WO93 / 2239.
6, 1993 4th International Conference on Ferroelectric Liquid Crystals P-46 (M
arc D. Radcliffe et al.), The perfluoroether liquid crystal compound is preferably contained in an amount of 30% by weight or more, and more preferably 50% by weight or more in order to reveal a structure having a small layer tilt angle close to a bookshelf. It Perfluoroether liquid crystal compound in the present invention is preferably the fluorocarbon terminal chains, -V is represented by _{(C x F 2x O) z} C y F 2y + 1, x is each (C _x F _2x O) Independently from 1 to 10
In, y is from 1 to 10, z is 10 1, V is a single _{bond, -COO-C r H 2r -} , - O-C r H 2r -, - O-
_{(C s H 2s O) t} -C r 'H 2r' -, - OSO 2 -, -
_{SO 2 -, - SO 2 -C} r H 2r -, - C r H 2r -, - C r H
_{2r -N (C p H 2p +} 1) -SO 2 -, - C r H 2r -N (C p H
_{2p + 1} ) -CO-, r and r ′ are each independently 1 to 20
_Where s is independently 1 to 10 for each (C _s H _2s O), t is 1 to 6 and p is 0 to 4.

The perfluoroether liquid crystal compound according to the present invention is preferably represented by the following general formula I, and is used from the viewpoint of having good liquid crystallinity.

[General Formula I]

[0015]

Embedded image And a, b and c are each independently 0 or 1 to 3
Represents the integer. However, a + b + c is at least 2.

M and N are independently -COO-,-
COS -, - COSe -, - COTe -, - (CH 2 C
H ₂ ) _d- (d represents an integer of 1 to 4), -C≡C-,
-CH = CH -, - CH = N -, - CH 2 -O -, - C
It represents O-, -O-, or a single bond, and its orientation may be any.

X, Y and Z are independently -H and -C.
l, -F, -Br, -I, -OH, -OCH 3, -C
H _3, represents -CF _3, -OCF _3, -CN, and -NO _2.
l, m and n each independently represent an integer of 0 to 4 (provided that when l, m and n are 2 or more, different substituents may be selected for each of X, Y and Z). .

G is --COO--C _e H _2e- , _--O --C _e H _{2e
-, - O (C e "} H 2e" O) t -C e 'H 2e' -, - C e H
_{2e -, - OSOO -, -} SOO -, - SOOC e H
_{2e -, - C e H 2e} -N (C p H 2p + 1) -SOO -, - C e
_{H 2e -N (C p H 2p} + 1) -CO- (e, e ' represents an integer of from 1 independently to 20, p is an integer from 0 to 4 .e "is respectively ( C _{e "} H _2e" O) independently represents an integer of 1 to 10, and t represents an integer of 1 to 6).

[0019] A is _{-O- (C f H 2f -O)} u -C f 'H
_{2f '+ 1, - (C} f H 2f -O) u -C f' H 2f '+ 1, -C f H 2f -
_{R ', - O-C f} H 2f -R', - COO-C f H 2f -
_{R ', - OCO-C f} H 2f -R' (R ' is -Cl, -
_{F, -CF 3, -NO 2,} -CN, -H, -COO-C f '
_{H 2f '+ 1, -OCO-} C f'' represents a _{+ 1, f, f' H} 2f each independently represents an integer of 1 to 20. u is 1 to 10
Is an integer. ), A may be linear or branched.

[0020] R is - (C _x F _2x O) a _z C _y F _{2y + 1,}
x is an integer of 1 to 10 independently for each (C _x F _2x O), y is an integer of 1 to 10, and z is an integer of 1 to 10. )

Further, specific structural examples of the perfluoroether liquid crystal compound include compounds having the following structures.

[0022]

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[0023]

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[0024]

[Chemical 6]

[0025]

[Chemical 7]

[0026]

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[0027]

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In the present invention, among the perfluoroether liquid crystal compounds, a compound containing eight or more perfluorocarbons in the fluorocarbon terminal portion is characteristically used. The compound characteristically accelerates the switching speed in the composition of the present invention, and this effect is particularly remarkable in the use of the perfluoroether liquid crystal compound. From the viewpoint of the effect on the switching speed, among the compounds containing 8 or more perfluorocarbons in the end portion of fluorocarbon, the compounds containing 10 or more perfluorocarbons in the end portion of fluorocarbon are preferably used.

Further, the ratio of the compound containing 8 or more perfluorocarbons in the fluorocarbon terminal portion, which is characteristic of the present invention, contained in the chiral smectic liquid crystal composition is 10 in view of the effect on the characteristics.
% By weight or more. It is preferably 30% by weight or more, more preferably 50% by weight or more. Further, it is preferable to add 10 perfluorocarbons in the fluorocarbon terminal portion.
A compound containing more than one compound can be contained in the chiral smectic liquid crystal composition of the present invention in an extremely small amount, and preferably 10% by weight or more.

The chiral smectic liquid crystal composition of the present invention essentially contains a compound having 8 or more or 10 or more perfluorocarbons in the fluorocarbon terminal portion, which is characteristic of the present invention. 8 perfluorocarbons in the part
A perfluoroether liquid crystal compound other than the compound containing one or more or 10 or more can be contained.

On the other hand, it may be difficult for such a compound having a long perfluorocarbon chain to obtain uniform orientation as compared with a compound having a short perfluorocarbon chain. In addition, it may be a factor that hinders obtaining good drive characteristics. As a result, it is preferable to mix these compounds in an appropriate amount according to various characteristics required for the liquid crystal composition, in particular, in consideration of the balance of switching speed, alignment property and driving characteristics.

Further, from the viewpoint of good compatibility with the perfluoroether liquid crystal compound, a perfluoroalkyl liquid crystal compound can be contained. Furthermore, a so-called hydrocarbon type liquid crystalline compound having no perfluorocarbon chain can be contained as another component. The chiral smectic liquid crystal composition of the present invention contains a chiral compound.

Specific examples of the perfluoroalkyl liquid crystal compounds described above include those described in JP-A-2-142753. Specific examples include those having the following structures.

[0034]

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[0035]

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[0036]

[Chemical 12]

[0037]

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[0038]

Embedded image

[0039]

[Chemical 15]

[0040]

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[0041]

Embedded image

[0042]

Embedded image

[0043]

Embedded image

[0044]

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Further, specific examples of so-called hydrocarbon type liquid crystalline compounds having no perfluorocarbon chain as other constituent components include those having the following structures.

[0046]

[Chemical 21]

[0047]

Embedded image

[0048]

Embedded image

[0049]

Embedded image

[0050]

Embedded image

[0051]

[Chemical formula 26]

[0052]

Embedded image

[0053]

Embedded image

[0054]

[Chemical 29]

[0055]

Embedded image

[0056]

[Chemical 31]

[0057]

Embedded image

[0058]

[Chemical 33]

[0059]

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[0060]

Embedded image

[0061]

Embedded image

[0062]

Embedded image

Further, specific examples of the chiral compound include those having the following structures, but the present invention is not limited thereto.

[0064]

[Table 1]

[0065]

[Table 2]

[0066]

[Table 3]

[0067]

[Table 4]

[0068]

[Table 5]

[0069]

Embedded image

[0070]

Embedded image

[0071]

[Table 6]

[0072]

[Table 7]

[0073]

[Table 8]

[0074]

[Table 9]

[0075]

[Table 10]

[0076]

[Chemical 40]

[0077]

Embedded image

[0078]

Embedded image

[0079]

Embedded image

[0080]

Embedded image

[0081]

Embedded image D-1: n = 6,2R, 5R D-2: n = 6,2S, 5R D-3: n = 4,2R, 5R D-4: n = 4,2S, 5R D-5: n = 3,2R, 5R D-6: n = 2,2S, 5R D-7: n = 2,2R, 5R D-8: n = 1,2S, 5R D-9: n = 1,2R, 5R

[0082]

Embedded image D-10: n = 1 D-11: n = 2 D-12: n = 3 D-13: n = 4 D-14: n = 6 D-15: n = 10

[0083]

Embedded image D-16: n = 8 D-17: n = 10

[0084]

Embedded image

[0085]

Embedded image

[0086]

Embedded image

[0087]

[Chemical 51]

[0088]

Embedded image

[0089]

Embedded image

In the chiral smectic liquid crystal composition used in the present invention, other compounds such as dyes,
Additives such as pigments, antioxidants and UV absorbers can also be included.

The liquid crystal element of the present invention usually has a structure in which a liquid crystal is sandwiched between a pair of electrode substrates, and a voltage is applied to the liquid crystal from the electrodes to control the alignment state.

FIG. 1 shows an example of the liquid crystal element of the present invention.
1 is a liquid crystal layer composed of a chiral smectic liquid crystal composition, and usually has a layer thickness of 5 μm in order to exhibit bistability.
m or less is preferable. 2 is a substrate, and glass, plastic, or the like is used. 3 is a transparent electrode such as ITO.
Reference numeral 4 denotes an orientation control layer, which requires a uniaxial orientation control layer on at least one substrate. As a forming method, 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, boron Inorganic substances such as nitrides, polyvinyl alcohol, polyimide, polyimide amide, polyester, polyamide, polyester imide, polyparaxylene, polycarbonate, polyvinyl acetal, polyvinyl chloride, polystyrene, polysiloxane, cellulose resin, melamine resin, urea resin, acrylic resin, etc. It is obtained by forming a film using the organic substance, and then rubbing the surface with a fibrous material such as velvet, cloth or paper. Further, an oblique vapor deposition method in which an oxide such as SiO or a nitride is vapor-deposited from the oblique direction of the substrate can also be used. The structure of the liquid crystal device of the present invention is not limited as long as it contains the chiral smectic liquid crystal composition as an essential component and controls the composition to impart a predetermined function.

In the present invention, an element having an asymmetric alignment film structure, that is, an element having different alignment characteristics for liquid crystal molecules on both substrates, preferably having alignment films having different alignment treatments on both substrates is preferably used. The liquid crystal composition of the present invention is very unlikely to have a cholesteric phase. In such a case, isotropic phase → smectic phase transition,
Alignment is formed while gradual generation of batnet, but the appearance of batton starting from one substrate and growing to the other substrate side, revealing good uniform alignment, and More preferably, an asymmetric element structure having an alignment film that has been uniaxially aligned on one substrate is preferable. Particularly preferably, a film obtained by uniaxially aligning a polyimide film is used as the alignment film. When the chiral smectic liquid crystal composition of the first invention is used in an element having an asymmetric alignment film structure, as compared with a device having a symmetric alignment film structure,
It is possible to obtain an element having good driving characteristics in a very wide temperature range. Also in this case, among the perfluoroether liquid crystal compounds, a compound containing 8 or more perfluorocarbons in the fluorocarbon terminal part is characteristically effective, and it is necessary that the compound is contained in an amount of 10% by weight or more in the total amount of the composition. It is preferably 30% by weight or more, more preferably 50% by weight or more. Further, among the compounds containing 8 or more perfluorocarbons in the fluorocarbon terminal portion, compounds containing 10 or more perfluorocarbons in the fluorocarbon terminal portion are preferably used.

Further, when polyimide is used as the uniaxially oriented film, better driving characteristics are obtained, and the stability of driving over time is also greatly improved. Particularly in the asymmetric structure, the effect of polyimide is remarkable. Also in this case, among the perfluoroether liquid crystal compounds, the compound containing 8 or more perfluorocarbons in the fluorocarbon terminal portion is characteristically effective, and the content is 10% by weight or more, preferably 30% by weight or more, It is preferably 50% by weight or more. Further, among the compounds containing 8 or more perfluorocarbons in the end portion of the fluorocarbon, compounds containing 10 or more perfluorocarbons in the end portion of the fluorocarbon are preferably used.

As a specific structure of the polyimide used as the alignment film, a repeating structure represented by the following general formula P is used as a concrete structure from the viewpoint of obtaining a better uniform alignment and a more uniform switching property. Polyimide consisting of units is preferred.

[0096] [Formula ^{P] (-K-P 1 -L} 1 -M 1 - (L 2) a -P 2 -)

[0097]

Embedded image Or an alkylene group having 1 to 20 carbon atoms, P ¹ ,
P ² represents an imide bond. M ¹ represents a single bond or —O—, and a represents 0, 1, 2. )

Specific structures of these polyimides include, for example, the following repeating unit structures.

[0099]

Embedded image

These polyimides can be preferably used on the side to which the uniaxial orientation treatment is applied in the asymmetric constitution.

In addition to the above orientation control layer, an insulating layer as another short-circuit preventing layer for the upper and lower substrates, or another organic material layer or inorganic material layer may be formed. Reference numeral 5 is a sealing material that bonds the substrates together. In addition to this, a gap control spacer (not shown) such as silica beads is provided between the substrates.
8 is a polarizing plate and 9 is a light source. Switching is performed in response to a switching signal from a signal power source (not shown), and it functions as a light valve for a display element or the like. Further, if the three transparent electrodes are arranged in a matrix in the upper and lower cross, pattern display and pattern exposure become possible, and they are used as, for example, displays for personal computers, word processors, etc., and light valves for printers.

The liquid crystal element of the present invention constitutes a liquid crystal device having various functions, and the data format and SY which are image information having scanning line address information shown in FIGS.
A liquid crystal display device is realized by using communication synchronization means using N signals. The reference numerals in the figure are as follows.

101 chiral smectic liquid crystal display device 102 graphic controller 103 display panel 104 scanning line driving device 105 information line driving device 106 decoder 107 scanning signal generating device 108 shift register 109 line memory 110 information signal generating device 111 driving control circuit 112 GCPU 113 Host CPU 114 VRAM

The image information is generated by the graphic controller 102 on the main body side and transferred to the display panel 103 according to the signal transfer means shown in FIGS. The graphic controller 102 is a CPU
(Central processing unit, abbreviated as GCPU) and 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 the good switching characteristics as described above, it exhibits excellent driving characteristics and reliability, high definition, high speed,
A large area display image can be obtained.

As a driving method of the liquid crystal element of the present invention, for example, JP-A-59-193426 and JP-A-59-19.
The driving method disclosed in Japanese Patent No. 3427, Japanese Patent Application Laid-Open No. 60-156046, Japanese Patent Application Laid-Open No. 60-156047 or the like can be applied.

FIG. 6 is an example of a waveform diagram of the driving method. Further, FIG. 5 is a plan view of an example of a chiral smectic liquid crystal panel in which matrix electrodes are arranged. FIG.
In the liquid crystal panel 51, the scanning lines of the scanning electrode group 52 and the data lines of the information electrode group 53 are wired so as to intersect with each other, and the chiral smectic liquid crystal is arranged between the scanning lines and the data lines at the intersections. Has been done.

In FIG. 6A, S _S is a selected scan waveform applied to the selected scan line, S _N is a non-selected scan waveform not selected, and I _S is applied to the selected data line. selection information waveform (black), I _N represents the non-selection information signal applied to the data line which is not selected (white). In the figure the _{(I S -S S) (I} N -S S) is the voltage waveforms applied to pixels on a selected scanning line, the voltage (I _S -S _S) is applied pixel black take the display state, the voltage (I _N -
The pixel to which S _S ) is applied takes a white display state.

FIG. 6B shows the drive 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 Δt of the single polarity voltage applied to the pixel on the selected scanning line.
Corresponds to the time of the write phase t _{2, and} the time of the 1-line clear t ₁ phase is set to 2Δt.

The values of the parameters V _S , V _I 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 change in the transmittance T when the drive voltage (V _S + V _I ) is changed while keeping the bias ratio, which will be described later, constant, that is, the VT characteristic. Where Δ
t = 50 μsec, bias ratio V _I / (V _I + V _S ) = 1
It is fixed at / 3. The positive side of FIG. 7 is shown in FIG. 6 (I
_N -S _S), the negative side waveform shown by (I _S -S _S) is applied.

Here, V ₁ and V ₃ are called the actual driving threshold voltage and the crosstalk voltage, respectively. Also, V ₂ <V ₁ <V ₃
At this time, ΔV = (V ₃ −V ₁ ) / (V ₃ + V ₁ ) is called a voltage margin, which is a parameter of the voltage width capable of matrix driving. It can be said that V ₃ is generally present in driving a chiral smectic liquid crystal display device. Specifically, FIG.
A voltage value causing switching by V _B in waveform _{(A) (I N -S S} ). Of course, it is possible to increase the value of V ₃ by increasing the bias ratio, increasing the bias ratio corresponds to a large amplitude of a data signal, an increase in flickering in image quality, contrast Is undesirably caused.

According to our study, the bias ratio is 1/3 to 1/4.
The degree was practical. 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, the above voltage is kept constant,
It is also possible to drive by changing the voltage application time Δt. The above voltage may be used as the voltage application time as it is, and at this time, the voltage application time threshold is Δt.
₁ , the voltage application time crosstalk value is Δt _2, and (Δ
t ₂ −Δt ₁ ) / (Δt ₂ + Δt ₁ ) = ΔT is called a voltage application time margin.

At such a certain temperature, it is possible to write two states of "black" and "white" to the selected pixel depending on the two directions of the information signal, and the non-selected pixel has the "black" or "white" state. The voltage margin or the voltage application time margin capable of maintaining the “white” state is unique because there is a difference depending on the liquid crystal material and the element configuration. Also,
Since the drive margin shifts even if the environmental temperature changes, in the case of an actual display device, it is necessary to set the optimal driving conditions for the liquid crystal material, the element configuration, and the environmental temperature.

[0117]

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

[Example 1] The compounds used are described below.

[0119]

Embedded image

[0120]

Embedded image

The liquid crystal cell used was a glass substrate with ITO, NMP / of polyimide precursor LP64 manufactured by Toray Industries, Inc.
The nBC = 2/1 solution was spin-coated and baked to form polyimide, which was then rubbed, and then the substrate and ITO.
A silane coupling agent (octadecyltriethoxysilane) was spin-coated on an attached glass substrate, and a silica bead spacer was sprinkled on the heat-treated substrate to form a gap, which was bonded to a substrate having a thickness of 1.8 μm.

The layer tilt angle δ was measured according to Jpn. J. Ap
pl. Phys. 27. It carried out based on the method described in L725 (1988).

As the drive waveform, the waveform shown in FIG. 6 was used. The bias ratio was ⅓, (V _I + V _S ) was fixed at 18 V, the voltage application time was variable, and the margin was measured.

A chiral smectic liquid crystal composition having the following composition (parts by weight) was prepared.

Composition α //////// (a) = 3/3/4
/ 50/20/0/10/0/5 Composition β //////// (a) = 33/4
/ 20/20/0/30/10/5 Composition γ //////// (a) = 3/3/4
/ 20/10/10/30/10/5 Composition ρ //////// (b) = 33/4
/ 20/35/5/20/0/5 Composition σ //////// (c) = 33/4
/ 20/35/5/20/0/10 Composition φ //////// (a) = 0/0/0
/ 20/45/5/20/20/5 Composition χ //////// (a) = 33/4
/ 20/35/5/20/0/5 Composition ω //////// (a) = 33/4
/ 20/40/0/15/5/5

The voltage application time threshold Δt ₁ and the voltage application time margin ΔT (μsec) immediately after the injection of each composition at 25 ° C.
The same shall apply hereinafter), and ΔT ₅₀ after 50 hours and ΔT (15) at 15 ° C. are shown in the table below.

[0127]

[Table 11]

The layer inclination angle at 25 ° C. of the composition is α
At 4.6 °, β at 5.5 °, γ at 6.6 °, ρ at 6.0
It was 6.1 ° in terms of ° and δ, and a layer state close to a bookshelf was formed almost stably.

Example 2 A 1.8 μm cell was prepared in the same manner as in Example 1 by using a polyimide having the following repeating units. Further, as in the first embodiment, ΔT (25), Δ
The result of measuring T (25) ₅₀ using the following composition is
It is shown in the table below.

[0130]

Embedded image

[0131]

[Table 12]

[Reference Example 1] A composition having the following composition was prepared.

Composition ζ //////// (a) = 3/3/4
/ 70/0/0/5/5/0/5

This composition was prepared in the same manner as in Example 1 at 25 ° C.
When evaluated by the same method, Δt₁(Μsec) is 45μ
sec, ΔT (25) is 7, ΔT (25 )₅₀Is 0, ΔT
(15) was 0.

[Reference Example 2] The polyimide of Example 1 was changed to polyvinyl alcohol (Aldrich) to prepare a cell (x) in the same manner. This gives the composition γ, χ of Example 1.
When evaluated in the same manner using, ΔT (2
5), there was no ΔT (25) ₅₀ .

Further, a cell (y) was prepared in which the polyimide used in Example 1 was placed on the upper and lower sides. Example 1
The evaluation results of the compositions α, φ, and χ of the above are shown in the following table.

[0137]

[Table 13]

[0138]

As described above, according to the liquid crystal element of the present invention, a very high-speed response is realized, and a bookshelf or a structure having a small layer inclination angle close to it is developed, and high speed and high speed are achieved. A chiral smectic liquid crystal device with high contrast, large area, high definition and high brightness has been realized. The liquid crystal element of the present invention exhibits good driving characteristics particularly in a wide temperature range, and further has high reliability and driving stability in an element having an asymmetric alignment film structure having polyimide as an alignment film.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross-sectional view of a liquid crystal element of the present invention.

FIG. 2 is a block diagram illustrating a display device including a liquid crystal element of the present invention and a graphics controller.

FIG. 3 is a diagram showing a timing chart of image information communication between a display device and a graphics 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 a liquid crystal panel in which matrix electrodes are arranged.

FIG. 6 is a diagram showing an example of drive waveforms used to drive the liquid crystal element of 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]

 1 Liquid Crystal Layer 2 Substrate 3 Transparent Electrode 4 Alignment Control Layer 5 Sealing Material 8 Polarizing Plate 9 Light Source 101 Chiral Smectic Liquid Crystal Display Device 102 Graphic Controller 103 Display Panel 104 Scanning Line Driving Device 105 Information Line Driving Device 106 Decoder 107 Scanning Signal Generating Device 108 Shift register 109 line memory 110 information signal generator 111 drive control circuit 112 GCPU 113 host CPU 114 VRAM

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Yamada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (12)

[Claims] 1. A fluorine-containing liquid crystal compound group comprising a fluorocarbon terminal portion and a hydrocarbon terminal portion, the both terminal portions being bound by a central nucleus, and having a smectic mesophase or a latent smectic mesophase as the liquid crystal. In a liquid crystal composition containing at least 10% by weight, in the fluorine-containing liquid crystal compound, at least one ether oxygen in the chain is contained in the fluorocarbon terminal chain, and perfluorocarbon is contained in the fluorocarbon terminal portion.
At least one compound containing 10 or more compounds in the total composition
A liquid crystal element comprising a liquid crystal composition containing at least wt% and carrying the liquid crystal between a pair of substrates having at least an electrode and an alignment control film. 2. The liquid crystal device according to claim 1, wherein a liquid crystal composition containing 30% by weight or more of at least one compound containing 8 or more perfluorocarbons in the end portion of the fluorocarbon is used. 3. A liquid crystal device according to claim 1, wherein a liquid crystal composition containing 50% by weight or more of at least one compound containing 8 or more perfluorocarbons in the end portion of the fluorocarbon is used. 4. A liquid crystal composition containing at least one compound of 10 or more perfluorocarbons among compounds containing 8 or more perfluorocarbons in the end portion of the fluorocarbon. The liquid crystal element described. 5. The liquid crystal device according to claim 4, wherein a liquid crystal composition containing 10% by weight or more of at least one compound containing 10 or more perfluorocarbons in the end portion of the fluorocarbon is used. 6. A fluorocarbon end portion and a hydrocarbon end portion, said both end portions being bound by a central nucleus, having a smectic mesophase or a latent smectic mesophase, and at least in said fluorocarbon end chain. The fluorocarbon terminal chain of the fluorine-containing liquid crystal compound containing ether oxygen in one chain has a -V
It is represented by _{(C x F 2x O) z} C y F 2y + 1, x is in each (C _x F _2x O) from 1 to independently 10, y is from 1 10
And z is 1 to 10, V is a single bond, -COO-C.
_{r H 2r -, - O-} C r H 2r -, - O- (C s H 2s O) t -C
_{r 'H 2r' -, -} OSO 2 -, - SO 2 -, - SO 2 -C r H
_{2r -, - C r H 2r} -, - C r H 2r -N (C p H 2p + 1) -S
_{O 2 -, - C r H} 2r -N (C p H 2p + 1) -CO-, independently from 1 r and r 'each independently is 20, s is the respective (C _s H _2s O) 6. The liquid crystal device according to claim 1, wherein the liquid crystal composition is 1 to 10, t is 1 to 6, and p is 0 to 4. 7. A fluorocarbon end portion and a hydrocarbon end portion, both end portions being bound by a central nucleus, having a smectic mesophase or a latent smectic mesophase, and at least in the fluorocarbon end chain. 7. The liquid crystal device according to claim 1, wherein the fluorine-containing liquid crystal compound containing ether oxygen in one chain is a compound represented by the following general formula I. [General Formula I] And a, b, and c each independently represent 0 or an integer of 1 to 3. However, a + b + c is at least 2. M, N
Are independently -COO-, -COS-, -COS
e -, - COTe -, - (CH 2 CH 2) d - (d is an integer of from 1 4), - C≡C -, - CH = CH -, -
_{CH = N -, - CH 2} -O -, - CO -, - O-, a single bond, its orientation may be either. X, Y and Z are each independently -H, -Cl, -F, -Br, -I, -O.
_{H, -OCH 3, -CH 3,} -CF 3, -OCF 3, -C
N, representing the -NO _2. l, m, and n are 0 independently.
Represents an integer of 4 (provided that l, m, and n are 2 or more,
Different substituents may be selected for each of X, Y and Z. ). G is _{-COO-C e H 2e -,} - O-C e
_{H 2e -, - O (C} e "H 2e" O) t -C e 'H 2e' -, - C e
_{H 2e -, - OSOO -,} - SOO -, - SOOC e H 2e
_{-, - C e H 2e -N} (C p H 2p + 1) -SOO -, - C e H
_{2e -N (C p H 2p +} 1) -CO- (e, e ' represents an integer of from independently 1 to 20, p is an integer from 0 to 4 .e "is each (C _e "H _2e" O) independently represents an integer of 1 to 10, t is an integer from 1 to 6.) represents .A is a _{-O- (C f H 2f -O)} u -C f ' H
_{2f '+ 1, - (C} f H 2f -O) u -C f' H 2f '+ 1, -C f H 2f
_{-R ', - O-C f} H 2f -R', - COO-C f H 2f -
_{R ', - OCO-C f} H 2f -R' (R ' is -Cl, -
_{F, -CF 3, -NO 2,} -CN, -H, -COO-C f '
_{H 2f '+ 1, -OCO-} C f'' represents a _{+ 1, f, f' H} 2f each independently represents an integer of 1 to 20. u is 1 to 10
Is an integer. ), A may be linear or branched. R is - (C _x F _2x O) a _{z C y F 2y + 1,} x is an integer from 1 independently of each (C _x F _2x O) to 10, and y is from 1 to 10 Is an integer and z is 1 to 1
It is an integer up to 0. ) 8. The liquid crystal device according to claim 7, wherein the compound represented by the general formula I is a compound having a phenylpyrimidine core in its structure. 9. The liquid crystal element according to claim 1, wherein the alignment control layer is subjected to different alignment treatments on both substrates. 10. The liquid crystal device according to claim 1, wherein at least one orientation control layer is made of polyimide. 11. The liquid crystal device according to claim 10, wherein the polyimide comprises a repeating unit represented by the following general formula P. [Formula ^{P] (-K-P 1 -L} 1 -M 1 - (L 2) a -P 2 -) ## STR2 ## Or an alkylene group having 1 to 20 carbon atoms, P ¹ ,
P ² represents an imide bond. M ¹ represents a single bond or —O—, and a represents 0, 1, 2. ) 12. A liquid crystal device using the liquid crystal element according to claim 1.