JP2000290653A - Liquid crystal element and liquid crystal device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal device designed to resolve such problems as afterimage due to liquid crystal hysteresis, liquid crystal aligning deterioration and image sticking, and to provide a liquid crystal apparatus mounting the liquid crystal device. SOLUTION: This liquid crystal device is such one as to use a chiral smectic liquid crystal 21 held by a pair of substrates 41, 42 and having monostability, namely, a fluorine-contg. chiral liquid crystal compound having smectic or potentially smectic phase, along with such a chiral smectic liquid crystal composition composed exclusively of a group of compounds made up of (a) fluorochemical terminal segment having at least one methylene group and optionally having at least one in-chain ether oxygen, (b) chiral or achiral saturated hydrocarbon terminal segment, and (c) a central core segment binding the above segments thereto, and have the function to alternately apply pole-reversing drive voltage to the liquid crystal 21 by electrodes 43 provided on the substrates 41, 42 to conduct light modulation.

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 flat panel display, a projection display, a printer and the like, and a liquid crystal device having the same, and more particularly to a liquid crystal device using a monostable liquid crystal.

[0002]

2. Description of the Related Art Conventionally, a CRT has been most widely used as a display, and this CRT has been widely used as a video output for televisions and VTRs, or as a monitor for personal computers. However, due to the characteristics of this CRT, flicker or scanning stripes due to insufficient resolution lowers the visibility of a still image, or the phosphor deteriorates due to burn-in.

In addition, recently, it has been found that electromagnetic waves generated by a CRT adversely affect a human body, and there is a concern that the health of a VDT worker may be impaired. Furthermore, since the CRT is required to have a large volume behind the screen due to its structure, the convenience of information equipment is significantly impaired, and the space saving of offices and homes is impeded.

There is a liquid crystal element which solves such a drawback of the CRT. As an example of this liquid crystal element, for example, Applied Physics Letters by M. Schadt and W. Helfrich
A liquid crystal using a twisted nematic liquid crystal disclosed in Vol. 18, No. 4 (published on Feb. 15, 1971), pp. 127 to 128 is known.

Further, in recent years, liquid crystal elements called TFTs using this type of liquid crystal have been developed and commercialized. Here, this type of liquid crystal element is one in which a transistor is formed for each pixel, there is no problem of crosstalk, and a 10-12 inch class display is preferable due to rapid progress of production technology in recent years. It is being made with productivity. However, there are still problems in productivity, liquid crystal response speed, and viewing angle with respect to a frame frequency of 60 Hz or more, which is a point that a larger size or a moving image can be reproduced without any problem.

On the other hand, as a liquid crystal element using spontaneous polarization as a switching torque, for example, a chiral smectic liquid crystal element is disclosed in Clark and Lagerwall.
(JP-A-56-107216, U.S. Pat. No. 4,367,924).

Here, as the liquid crystal, a ferroelectric liquid crystal composed of 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, Since it has a very fast response speed and excellent viewing angle characteristics, it is considered to be suitable as a high-speed, high-definition, large-area simple matrix display element or light valve.

Recently, chiral smectic antiferroelectric liquid crystal devices have also been proposed by Chandani, Takezoe et al. (Japanese Journal of Applied Physics).
ics) 27, 1988, L729). In addition, recently, among the antiferroelectric liquid crystal materials, a V-shaped response characteristic having a thresholdless value, a small hysteresis, and advantageous characteristics for gradation display has been discovered (for example, Japanese Journal of Applied Physics (Japanese Journal)
of Applied Physics) Vol. 36, 3586, 1997
page).

A V-shaped switching liquid crystal having a spontaneous polarization as a switching torque includes a monostable surface-stabilized F
LC (for example, Journal of Applied Physics 61, 1987, p. 2400), Deformed Helix FLC (for example, Ferroelectrics 85, 19
1988, p. 173), Twisted smectic FLC (for example, Applied Physics Letter 60, 1992, 28)
0), a threshold-less antiferroelectric LC, a polymer liquid crystal-stabilized FLC (for example, SID '96 digest, 1996, p. 699).

An active matrix liquid crystal element using these liquid crystals has been actively developed to realize a high-speed display sufficient for expressing moving images (for example, Japanese Patent Application Laid-Open No. 9-50049).

[0011]

However, such a conventional liquid crystal device using the above-mentioned chiral smectic liquid crystal has a serious problem in terms of reliability such as afterimages due to hysteresis, deterioration of alignment over time, and image sticking. There is a strong need for improvement in this regard.

Accordingly, the present invention has been made in view of such circumstances, and a liquid crystal element capable of improving afterimage, deterioration of alignment over time and image sticking due to hysteresis of liquid crystal, and a liquid crystal having the same are provided. It is intended to provide a device.

[0013]

According to the present invention, there is provided a chiral smectic liquid crystal having a monostable property, and a pair of substrates having an electrode for sandwiching the liquid crystal and applying a driving voltage to the liquid crystal. The liquid crystal is a fluorine-containing chiral liquid crystal compound having a smectic phase or a potential smectic phase, and (a) a fluorochemical terminal having at least one methylene group and optionally having at least one ether oxygen in a chain. Part and
A chiral smectic liquid crystal composition consisting of only a compound group consisting of (b) a chiral or achiral saturated hydrocarbon terminal portion and (c) a central core portion connecting the terminal portions, and performing light modulation. A drive voltage whose polarity is inverted is alternately applied to the liquid crystal by the electrodes.

Further, the present invention is characterized in that the monostable state of the liquid crystal is changed to a black display state.

Further, according to the present invention, the liquid crystal may include at least one liquid crystal.
An achiral compound in which a fluorocarbon terminal portion having an ether oxygen in one chain and a hydrocarbon terminal portion are connected by a central core, and containing a compound having a smectic phase or a potential smectic phase as a component. Things.

Further, according to the present invention, the spontaneous polarization of the liquid crystal is 10
nC / cm ² or less.

Further, the present invention is characterized in that alignment films for aligning the liquid crystal are formed on the substrates so as to have different alignment configurations.

Further, the present invention is characterized in that an active element is connected to the electrode, and the driving voltage whose polarity is inverted is alternately applied to the liquid crystal through the electrode and the active element.

Further, the present invention is characterized in that a transistor is used as the active element.

According to the present invention, there is provided a liquid crystal device having a liquid crystal element, wherein the liquid crystal element is the liquid crystal element according to any one of claims 1 to 7.

Further, the present invention is characterized in that gradation display is possible according to the magnitude of the driving voltage.

Further, the present invention is characterized in that a light source is arranged behind the liquid crystal element.

Further, as in the present invention, the monostable chiral smectic liquid crystal sandwiched between a pair of substrates is a fluorine-containing chiral liquid crystal compound having a smectic phase or a latent smectic phase,
(A) a fluorochemical terminal moiety having at least one methylene group and optionally having at least one ether oxygen in the chain; (b) a chiral or achiral saturated hydrocarbon terminal moiety; By using a chiral smectic liquid crystal composition consisting of only a compound group consisting of a central core portion connecting the terminal portions, and a compound group consisting of only a compound group, and by using an electrode provided on the substrate, alternately applying a drive voltage having a polarity inversion to the liquid crystal. Light modulation is performed.

[0024]

Embodiments of the present invention will be described below.

FIG. 1 is a cross-sectional view showing the structure of a liquid crystal device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a liquid crystal layer composed of a liquid crystal (composition), and a chiral smectic liquid crystal is used as the liquid crystal. In this case, usually, the thickness of the liquid crystal layer 1 is preferably 5 μm or less in order to realize the stability of the ferroelectric phase. Also, 2a and 2b are substrates, glass,
Plastic or the like is used. 3a and 3b are transparent electrodes such as ITO, 5 is a sealing material, 8a and 8b are polarizing plates, and 9 is a light source.

Reference numerals 4a and 4b denote orientation control films, and at least one of the orientation control films is a uniaxial orientation control film. Incidentally, as a method of forming the uniaxial orientation control film, for example, by solution coating or evaporation or sputtering on the substrate,
Inorganic substances such as silicon monoxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, boron nitride, polyvinyl alcohol, polyimide, polyimide amide, polyester, polyamide, After forming a film using an organic material such as polyesterimide, polyparaxylene, polycarbonate, polyvinyl acetal, polyvinyl chloride, polystyrene, polysiloxane, cellulose resin, melamine resin, urea resin, and acrylic resin, the surface is velvet, cloth or paper. It is obtained by rubbing with a fibrous material such as

Further, an oblique vapor deposition method in which an oxide or a nitride such as SiO is vapor-deposited from an oblique direction of the substrate may be used. Further, it is also possible to provide a short prevention layer in addition to the above.

In particular, it is preferable to use a polyimide rubbing film as a uniaxial orientation control film in order to obtain better uniaxial orientation. Here, the polyimide is usually obtained by coating and baking in the form of a polyamic acid. In addition, polyamic acid is excellent in productivity because it is easily soluble in a solvent. Further, recently, a polyimide soluble in a solvent has also been produced, and from the viewpoint of such technological advances, polyimide is preferably used because it can obtain better uniaxial orientation and has high productivity.

As a more preferred specific example, a polyimide alignment film having a repeating unit represented by the following general formula (I) is provided in order to improve the uniaxial orientation.

[0030]

Embedded image In the formula, A: a tetravalent group having an aromatic ring, an aromatic polycyclic ring, a heterocyclic ring, or a condensed polycyclic structure; B: a fatty group, an aromatic ring group including an alicyclic group, or-(Ph)
_a − (O) _c − (CH ₂ ) _x − (D) _e − (CH ₂ ) _y − (O) _d − (Ph) _b −
(Ph is a phenyl group) R ₁ R ₂ a = b: 0 or 1 c = d: 0 when a = b = 0, 0 when a = b = 1
Or 1 x, y: each independently an integer of 1 or more, provided that x + y + e is 2 or more and 10 or less.

On the other hand, the two substrates 2a and 2b face each other via a spacer (not shown). The spacer determines the distance (cell gap) between the substrates, and silica beads or the like are used. . Here, the optimum range and upper limit of the cell gap determined by the spacer are different depending on the liquid crystal material, but the uniform uniaxial alignment and the average molecular axis of the liquid crystal molecules when no electric field is applied are almost aligned with the alignment processing axis. Is preferably set in the range of 0.3 to 10 μm in order to express an alignment state substantially the same as the axis in the average direction of the above. The polyimide films formed on both substrates are usually rubbed to impart uniaxial orientation.

In the present invention, a liquid crystal having a monostable state as described later is used. Here, this monostable state can be expressed by, for example, an orientation configuration. As a typical method, there is a method in which the configuration of the upper and lower alignment films is asymmetric. In this case, a monostable state cannot be developed simply by asymmetry,
For example, by using the upper and lower alignment films having a large difference in charging characteristics, it is possible to perform mono-stabilization in one surface stable direction without an external electric field.

As an example of such an alignment film,
There is a combination of the above-described uniaxial orientation control film and a film having no (or no) uniaxial orientation. Examples of the film not provided with the uniaxial orientation include a uniaxial orientation using a material used for the uniaxial orientation control film. Examples include those that have not been subjected to a control treatment, various polymer materials, and films that have conductivity in the sense of suppressing the influence of an anti-electric field.

Further, as a film having conductivity, a film in which conductive fine particles are dispersed in a binder material may be mentioned, and is preferably used in that charging characteristics can be differentiated from polyimide which is preferably used as a uniaxial alignment control film. .
There is also a method of using a monostable state by using a driving method. For example, there is a method in which a DC signal offset is always superimposed on a driving signal and used. Furthermore, it is also possible to create a state in which the one-sided stable state is excessively burned by processing with a DC voltage for a certain period of time.

On the other hand, the liquid crystal used in the present invention includes:
There is a monostable surface-stabilized FLC having monostability, and since this liquid crystal uses spontaneous polarization as a switching torque, a high-speed liquid crystal element can be realized. Although the switching speed of the liquid crystal depends on the driving voltage,
It is also possible to set it to s or less, 500 μs or less, or 100 μs or less.

Further, such a liquid crystal is a fluorine-containing chiral liquid crystal compound having a smectic phase or a potential smectic phase, which compound has (a) at least one methylene group and at least one ether in a chain. It consists only of a compound group consisting of a fluorochemical terminal portion which may have oxygen, (b) a chiral or achiral saturated hydrocarbon terminal portion, and (c) a central core portion connecting the terminal portions. A chiral smectic liquid crystal composition is used.

By alternately applying a drive voltage having an inverted polarity to such a liquid crystal as will be described later, an afterimage based on hysteresis, deterioration of alignment over time, burn-in, etc. The problem can be greatly improved.

The specific structure of the fluorine-containing compound is represented by the following general formulas (I), (II) and (II).
There are the compounds represented by I), and furthermore, a synthesis method and specific examples of these compounds are described in JP-A-6-329592.
(Especially the compounds described in Tables 1 to 15), JP-A-7-316
555 (especially the compounds described in Tables 1-1 to 18). Compounds having a perfluoro terminal moiety are described in JP-A-63-27451 (especially compounds described in Table 1), JP-A-2-142755 (especially compounds described in Table 1), and WO 96/3325 (especially Table 1).
Compounds described in (1) to (1) to (1) to (I-180), and compounds described in JP-A-6-118178 (in particular, compounds described in (I-1) to (I-180)). -256231 (especially (I-1) to (I-223)
Described compounds).

[0039]

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).

Each of L ¹ and L ² is independently a single bond, -C
O-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 ¹ , A ² , A
³ , independently of -H, -Cl, -F, -B
r, -I, represent _{-OH, -OCH 3, -CH 3,} -CN, or -NO _2, each of ja, ma, na are independently 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-
(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 rb
Is independently 1 to 20, and pa is 0 to 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 represents _{-O-CO-C qa H 2qa} -R 3, linear, may be either branched (wherein, R ³ is, -O-CO-C _qb H _{2qb + 1} , -CO-O-
_{C qb H 2qb + 1, -H} , -Cl, -F, -CF 3, -NO
₂ , -CN, and qa and qb are independently 1-20).

R ² represents C _xa F _2xa -X (X is -H
Or -F, and xa is an integer of 1 to 20).

[0046]

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 1~4), - CH = CH - , - C≡C -, - CH = N
-, - N = CH -, - CH 2 -O -, - O-CH 2 -,
Represents -CO- or -O-.

X ² , Y ² and Z ² are A ⁴ , A ⁵ and A
⁶ is independently -H, -Cl, -F, -B
_{r, -I, -OH, -OCH 3} , -CH 3, -CF 3,
Represents —O—CF ₃ , —CN, or —NO ₂ , and each of jb, mb, and nb represents 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-, wherein rc and rd are independently 1-2.
0, sa is independently 1 to 10 for each (C _sa H _2sa -O), ta is 1 to 6, pb is 0 to 4
It is.

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, -O}} -C qc H 2qc -R 6, -CO
^{_{-O-C qc H 2qc -R 6}} , or _{-O-CO-C qc} H 2qc
Represents —R ^{6 and} may be linear or branched (provided that R ⁶ is —O—CO—C _qd H _{2qd + 1} , —CO—
_{O-C qd H 2qd + 1} , -Cl, -F, -CF 3, -NO
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 is (C _xb F _2xb -O) _za -C _ya F
_{2ya + 1} is represented by (wherein, the formula xb is 1 to 10 independently of each _{(C xb F 2xb -O),} ya is 1
And za is 1-10).

[0053]

## STR4 ## Formula (III) Wherein M, N and P are each independently:

[0054]

Embedded image

[0055]

Embedded image Represents

A, b and c are such that a + b + c is at least 1
And preferably an integer of 0 to 3 independently, provided that it is not larger than 2.

Each of A and B may independently be in any direction, ie, -C (= O) -O-, -C (= O) -S
-, -C (= O) -Se-, -C (= O) -Te-,-
_{(CH 2 CH 2) k -} ( where, k is 1 to 4) -CH = C
H -, - C≡C -, - CH = N -, - CH 2 -O -, -
Represents C (= O)-, -O-.

Each of X, Y and Z is independently -H,
-Cl, -F, -Br, -I, -OH, -OCH 3, -
CH ₃ , —CF ₃ , —OCF ₃ , —CN, and —NO ₂ , where 1, m and n each independently represent an integer of 0 to 4.

D may be in any direction.

[0060]

Embedded image Represents

[0061] r and r 'are independently an integer of 0 to 20, s is from 1 to 10 independently of each (C _s H _2s O)
And t is an integer of 1 to 6, and p is an integer of 0 to 4.

R is

[0063]

Embedded image Represents

R 'is independently -Cl, -F, -CF
_{3, -NO 2, -CN, -H} , -C q H 2q + 1, -O-
(O =) CC _q H _{2q + 1} , -C (= O) -OC _q H
_{2q + 1, -Br, -OH,} -OC q H 2q + 1 ( preferably,
-H, -F), and q 'is the respective ( _Cq'H
2q'- O) is independently 1 to 20, q is an integer of 1 to 20, w is an integer of 1 to 10, v is an integer of 0 to 6, and v 'is each independently Is an integer of 0 to 6, q is an integer of 1 to 3, each D is the structure shown above, and the direction may be either independently, and the ring structure containing D has 3 to 10 atoms. It consists of. W is each independently N, CR ', or SiR', and R 'may be chiral or achiral.

Rf ′ is -R ^* -D- (O) _x -CH ₂
Represents -D'- _Rf . Here, R ^* may be a cyclic chiral or an acyclic chiral. D and D ′ each have the same structure as that described above, and may each independently have any direction, x is 0 or 1, and R _f is fluoroalkyl, perfluoroalkyl, fluoroether, or perfluoroether. is there. Preferably R _f is fluoroalkyl, fluoroether or perfluoroether.

Specific examples of the compound represented by formula (I) are listed below.

[0067]

Embedded image

[0068]

Embedded image

[0069]

Embedded image

[0070]

Embedded image

[0071]

Embedded image

[0072]

Embedded image

[0073]

Embedded image

[0074]

Embedded image

[0075]

Embedded image

[0076]

Embedded image

[0077]

Embedded image

[0078]

Embedded image Specific examples of the compound represented by the general formula (II) are listed below.

[0079]

Embedded image

[0080]

Embedded image

[0081]

Embedded image

[0082]

Embedded image

[0083]

Embedded image Specific examples of the compound represented by the general formula (III) are listed in the following table.

[0084]

[Table 1]

[0085]

[Table 2]

[0086]

[Table 3]

[0087]

[Table 4]

[0088]

[Table 5] Incidentally, the liquid crystal element of the present invention is an active element, and FIG.
FIG. 1 shows an example in which the configuration shown in FIG. 1 described above is used as one pixel as an example of such an active element. In the figure, reference numerals 41 and 42 denote a pair of transparent substrates (for example, glass substrates). Of the transparent substrates 41 and 42, a lower substrate 41 has a transparent pixel electrode 43 and an active electrode connected to the pixel electrode 43. The elements 44 are formed in a matrix.

Incidentally, as the active element 44,
It is composed of a thin film transistor called a TFT using a semiconductor such as an amorphous silicon base, a polysilicon type, a μ crystal base, and single crystal silicon. The active element 44 includes a gate electrode (not shown) formed on the substrate 41, a gate insulating film (not shown) covering the gate electrode, a semiconductor layer (not shown) formed on the gate insulating film, and a semiconductor layer (not shown). And a source electrode and a drain electrode (not shown) formed thereon.

On the other hand, as shown in FIG. 3, a gate line (scanning line) 4 is provided between the rows of the pixel electrodes 43 on the lower substrate 41.
5, and information signal lines 46 are arranged between the columns of the pixel electrodes 43, respectively. The gate electrode of each TFT 44 is connected to the corresponding gate line 45, and the drain electrode is connected to the corresponding information signal line 46.

Further, each gate line 45 has an end 45a.
Are connected to a row driver 31 for applying a gate signal to scan a gate line 45, and each information signal line 46 applies a signal corresponding to display data to the information signal line 46 via an end 46a. 32.

The gate line 45 is covered with the gate insulating film of the TFT 44 except for the end 45a, and the information signal line 46 is formed on the gate insulating film. The pixel electrode 43 is formed on the gate insulating film, and is connected at one end to the source electrode of the TFT 44.

On the other hand, on the upper substrate 42 of FIG. 2, a transparent electrode 47 facing each pixel electrode 43 of the lower substrate 41 is formed. Here, the counter electrode 47 is formed of one electrode having an area covering the entire display area, and a reference voltage is applied. Then, the transmittance changes in accordance with the information signal voltage applied to the pixel electrode 43, and gradation expression can be performed. In addition, a capacitor serving as an auxiliary capacitance is often arranged for each pixel.

In the figure, reference numerals 18 and 19 denote alignment control films, reference numeral 20 denotes a sealing member, reference numeral 21 denotes a liquid crystal, and reference numeral 22 denotes a spacer. Reference numerals 23 and 24 denote polarizing plates arranged in crossed Nicols.

In the active element described above, when the gate is turned on, charges are injected into the liquid crystal cell as a pixel, the gate is turned off in a short time, and information is written to the pixel on the next scanning line. Here, since the liquid crystal 21 has spontaneous polarization, it becomes a voltage drop factor when the gate is turned off with the reversal of the spontaneous polarization except when the switching is completed within the gate-on time. Therefore, the spontaneous polarization is preferably not too large, specifically, 10 nC
/ Cm ² or less. This is preferable in order to suppress the alignment deterioration due to the incorporation of polar impurities and the like.

In the present invention, when focusing on one pixel, it is preferable that a voltage signal having an inverted polarity is alternately input from the information signal line 46. By performing such a driving, the burn-in is greatly reduced. be able to. In the present invention, when such polarity inversion driving is performed, the method described below is preferably used.

First, a voltage signal having a code for switching in a direction other than the monostable direction is supplied, and the liquid crystal 21 is switched to be converted into a light modulation signal. This can, of course, be expressed in gradation.

Next, signals having different polarities are given to the liquid crystal 21.
In the monostable direction. Here, the state of switching in the monostable direction corresponds to the orthogonal polarization plates 23 and 24.
When one of the optical axes is used as a normally black element that is used in alignment with a monostable optical axis, a black state or a state very close to the black state is expressed.

In this case, when this element is viewed as a display element, it becomes a non-hold type display, and since the liquid crystal element of the present invention performs high-speed switching, it is very preferable in that the image quality of moving image display is excellent.

The time ratio between the period in which the switching is performed in the monostable direction and the period in which the switching is performed in the non-monostable direction is not particularly limited, but the seizure is suppressed by minimizing the bias of the DC component. In the sense, the ratio is preferably in the range of 1: 9 to 9: 1, and more preferably in the range of 3: 7 to 7: 3.

Further, with respect to the information signal voltage value to be switched in the monostable direction, it is also preferable to minimize the bias of the DC component in total in accordance with the time ratio. Typically, there is a method in which a time ratio is set to 1: 1 and a signal having a different polarity gives a signal having an absolute value equivalent to that of the immediately preceding or succeeding light modulation signal.

Such a matrix element is used in a transmission type or a reflection type. If it is transparent,
Usually a light source is used. In the case of reflection, a reflection layer is formed in the element. Further, the present invention is applied to both a direct view type and a projection type. It can also be used as a light valve for a printer or the like.

On the other hand, FIG. 4 is a block diagram of a liquid crystal display device which is an example of a liquid crystal device having such a liquid crystal element. This liquid crystal display device uses a liquid crystal element for a display panel.

In the figure, 101 is a liquid crystal display device, 102 is a graphic controller, 103 is a display panel, 104 is a scanning line driving circuit, 105 is an information line driving circuit, 106 is a decoder, 107 is a scanning signal generation circuit,
108 is a shift register, 109 is a line memory, 11
0 is an information signal generation circuit, 111 is a drive control circuit, 112
Is a GCPU (Central Processing Unit), 113 is a host CP
U and 114 are VRAMs (memory for storing image information). Note that a light source is disposed on the back surface of the display panel 103 (see FIG. 1).

Here, the graphic controller 102
Is the host C with the GCPU 112 and VRAM 114 at the core.
The graphic controller 10 manages and communicates image information between the PU 113 and the liquid crystal display device 101.
The image information from 2 is transferred as display information to the information line drive circuit 105 via the drive control circuit 111 in accordance with the transfer clock, and as scan line address information to the scan line drive circuit 104.

Thereafter, in the information line drive circuit 105, based on the transferred display information, FIG.
Are transferred to the display panel 103 via the information signal generating circuit 110.

In the liquid crystal display device having such a configuration, since the liquid crystal element has good switching characteristics as described above, excellent driving characteristics and reliability are exhibited, and high-definition, high-speed, large-area display is performed. Images can be obtained.

Next, an example of this embodiment will be described. Note that the present embodiment (the present invention) is not limited to these examples.

[0109]

Example 1 In this example, the following compounds were mixed at A / B / C / D = 47/32/16/5 (% by weight) to prepare a liquid crystal composition α.

[0110]

Embedded image The phase transition temperature of this liquid crystal composition α was 7 for Tiso.
5 ° C., AC transition temperature was 49 ° C. The tilt angle was 29 ° and the spontaneous polarization was 6.2 nC / cm ² (each of which was 3 nC / cm ² ).
0 ° C).

Next, a cell was manufactured by the following method.

First, an ITO film having a thickness of about 70 nm was formed as a transparent electrode on two glass substrates having a thickness of 1.1 mm. Next, a 0.7 wt% solution of a polyamic acid precursor of a polyimide having a repeating unit shown below is applied to a pair of substrates on which such an ITO film is formed for 5 times.
Spin coating was performed at 00 rpm for 5 seconds and the second time at 1500 rpm for 30 seconds.

[0113]

Embedded image Next, after pre-drying was performed at 80 ° C. for 5 minutes, heating and baking were performed at 230 ° C. for 1 hour, and thereafter, a rubbing process using a nylon cloth was performed on the alignment films on both substrates as a uniaxial alignment process. .

Next, a ladder type polysiloxane base material and antimony-doped SnOx oxide ultrafine particles (particle diameter: about 100 °) were dispersed on one of the substrates at a solid content concentration of 10 watts.
A solution in which a methanol / isopropanol / toluene = 44/43/3 (% by weight) solution was added to a t% ethanol solution at a ratio of 3% was applied at 1500 rpm for 10 seconds by spin coating. After this, 80
After pre-drying at 5 ° C. for 5 minutes, the substrate was dried by heating at 200 ° C. for 1 hour to prepare another substrate.

Next, IPA (isopropyl alcohol) / ethanol / toluene = 60/30/10 (% by weight) in which silica beads having an average particle size of 2.4 μm are dispersed at 0.01% by weight on the surface of a polyimide substrate. 1500r solution
pm, spin coating under the condition of 10 sec.
A bead spacer of about 0 / mm ² was sprayed. Thereafter, a thermosetting liquid adhesive was applied on the substrate by a printing method.

Then, the two substrates thus obtained are bonded together facing each other, heated and cured in an oven at 150 ° C. for 90 minutes to form a cell, and then the above liquid crystal is injected into the cell. did.

Next, as shown in FIG. 5, an active element is formed using the liquid crystal cell (area 0.9 cm ² ) S, a silicon single crystal transistor (ON resistance 50 Ω) T, and a 2 nF ceramic capacitor C. Created. And
A gate signal having a selection period of 30 μS was given to this active element, and the waveform shown in FIG. 6 was given from the information signal line. In FIG. 6, switching to a white or gray state is performed by a positive voltage, and resetting to an initial (black) state is performed by a negative voltage signal. One frame is 16 ms, 8 ms is displayed, and 8 ms is not displayed.

(Optical Response) Next, the electro-optical response of this liquid crystal element was measured. The measurement was performed using a polarizing microscope equipped with a photomultiplier tube, and the change in transmittance was measured under crossed Nicols. At this time, the cell was set so that the cell was darkest in the state where no electric field was applied.

The transmittance for each frame when the transmittance for white 1 is 100% is shown below.

White 2 100% White 3 102% White 4 101% Gray 1 32% Gray 2 33% Gray 3 32% Gray 4 33% Black 1 <1% Black 2 <1% Black 3 <1% Black 4 <1 As described above, light modulation was performed with good reproducibility regardless of the previous state, and there was almost no hysteresis. The switching speed to white state (time until 90% switching) was measured to be 340 μs.

<Embodiment 2> In this embodiment, the waveform represented by the white waveform in FIG. 6 was continuously applied for 100 hours using the liquid crystal element used in Embodiment 1. Thereafter, the transmittances of the white, gray, and black waveforms were measured in the same manner as in Example 1 using the waveforms shown in FIG.
Was measured in each frame, and it was found that in the case of the liquid crystal element of the present invention, image sticking was extremely suppressed.

<Embodiment 3> In this embodiment, the liquid crystal used in the embodiment 1 was converted to A / D = 97/3 (% by weight) (the spontaneous polarization of this liquid crystal at 30 ° C. was 3.6 nC / cm ^2). The same measurement as in Example 1 was performed. And the result was as shown below.

White 2 101% White 3 100% White 4 101% Gray 1 24% Gray 2 25% Gray 3 25% Gray 4 25% Black 1 <1% Black 2 <1% Black 3 <1% Black 4 <1 As described above, light modulation was performed with good reproducibility regardless of the previous state, and there was almost no hysteresis. Further, when the image sticking durability measurement was performed on this device in the same manner as in Example 2, there was almost no change from the transmittance shown above as in Example 2.

<Example 4> In this example, the same measurement as in Examples 1 and 2 was performed by changing the non-uniaxially oriented film of Example 1 to nylon. Seizure was very suppressed.

<Embodiment 5> In this embodiment, the liquid crystal used in Embodiment 1 is changed to A / C / D = 50/43/7.
When the same measurement as in Examples 1 and 2 was performed,
Hysteresis and image sticking were very suppressed as in the case of the above. The spontaneous polarization of this liquid crystal at 30 ° C. was 8.9 nC
/ Cm ² .

Next, a comparative example will be described.

The liquid crystal used in Example 1 was A / E = 94/6
(% By weight) (the liquid crystal E was a chiral compound having the structure shown below), and the transmittance was measured in the same manner as in Example 1. As a result, the difference between the transmittances of Gray 1 and Gray 4 was 20% or more. Was found to have large hysteresis. The spontaneous polarization of this liquid crystal at 30 ° C. was 25.3 nC /
cm ² .

Further, when the liquid crystal was changed to C / E = 96/4 (% by weight) and B / E = 98/2 (% by weight) and the same measurement was performed, it was found that in each case, large hysteresis was observed. all right. The temperature of each liquid crystal was 30 ° C.
At 17.6 nC / cm ² and 8.9 nC
/ Cm ² .

Further, the same measurement as in Example 1 was performed using the liquid crystal α of Example 1 and the waveform shown in FIG. 6 except for the signal on the minus side.
Gray and black were indistinguishable in transmittance.

[0130]

Embedded image

[0131]

As described above, as in the present invention, as the monostable chiral smectic liquid crystal sandwiched between a pair of substrates, a chiral smectic liquid crystal composition comprising the above-described compound is used. The optical modulation is performed by alternately applying a drive voltage whose polarity is inverted to the above, it is possible to improve afterimages due to hysteresis, deterioration of alignment over time, and image sticking. In addition, by improving the afterimage based on the hysteresis, the deterioration of the alignment over time, and the burn-in, a liquid crystal device with high-speed response and high image quality and a liquid crystal device having the same can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a liquid crystal element according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a configuration of an active element using the configuration shown in FIG. 1 as one pixel.

FIG. 3 is a top view of one substrate of the active element.

FIG. 4 is a block diagram of a liquid crystal device including the liquid crystal element.

FIG. 5 is a circuit diagram of an active element manufactured in Example 1 of the present embodiment.

FIG. 6 is a diagram showing a waveform applied to the active element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal layer 2a, 2b Substrate 3a, 3b Transparent electrode 9 Light source 21 Liquid crystal 41, 42 Transparent substrate 44 Active element 101 Liquid crystal display device 103 Display panel

Continued on the front page (72) Inventor Koji Noguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Masahiro Terada 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Sho Makoto Mori 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H093 NA11 NA16 NA34 NA53 NC34 ND12 NE06 NF17 NF20 NG02 NG12 NH02 4H027 BA06 BD08 BD19 BD22 BD24 DE03 DE09 5C094 AA02 AA12 AA13 AA31 BA03 BA49 CA19 CA25 EA04 EA05 EB02 ED20 FB01 GA10 JA02

Claims (10)

[Claims] 1. A liquid crystal device comprising: a chiral smectic liquid crystal having a monostable property; and a pair of substrates having an electrode for sandwiching the liquid crystal and applying a driving voltage to the liquid crystal. A fluorine-containing chiral liquid crystal compound having a smectic phase, (a) a fluorochemical terminal portion having at least one methylene group and optionally having at least one ether oxygen in the chain, and (b) a chiral or A chiral smectic liquid crystal composition comprising only a group of compounds consisting of: an achiral saturated hydrocarbon terminal portion; and (c) a central core portion connecting the terminal portions; A liquid crystal device characterized by alternately applying a drive voltage whose polarity is inverted to the drive voltage. 2. The liquid crystal device according to claim 1, wherein the monostable state of the liquid crystal is set to a black display state. 3. The liquid crystal is an achiral compound in which at least one fluorocarbon terminal portion having ether oxygen in the chain and a hydrocarbon terminal portion are connected by a central core, and has a smectic phase or a potential smectic phase. The liquid crystal device according to claim 1, comprising a compound as a component. 4. The liquid crystal has a spontaneous polarization of 10 nC / cm ^2.
4. The liquid crystal device according to claim 1, wherein: 5. The liquid crystal device according to claim 1, wherein alignment films for aligning the liquid crystal are formed on the substrates so as to have different alignment configurations. 6. The liquid crystal device according to claim 1, wherein an active element is connected to the electrode, and the driving voltage whose polarity is inverted is alternately applied to the liquid crystal through the electrode and the active element. . 7. The liquid crystal device according to claim 6, wherein a transistor is used as the active device. 8. A liquid crystal device provided with a liquid crystal element, wherein the liquid crystal element is the liquid crystal element according to any one of claims 1 to 7. 9. The liquid crystal device according to claim 8, wherein gradation display is possible according to the magnitude of the driving voltage. 10. The liquid crystal device according to claim 8, wherein a light source is disposed behind the liquid crystal element.