JPH05165031A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide a ferro-dielectric liquid crystal compound, which presents high contrast and quick response, and provide a liquid crystal display device of high performance in which the compound is incorporated. CONSTITUTION:The layer in the chiral smectic C phase is formed in the shevron structure as folded in a doglegged form, and the orientation zone produced from the relationship between the uniaxial orientation processing direction and the layer structure lies within the region surrounded by a lightening flaw generated in the uniaxial orientation processing direction and a hair-pin flaw generated behind the lightning flaw, or outside of the region surrounded by a hair-pin flaw generated in the orientation processing direction and a lightning flaw generated behind it. This is provided with an organic orientation film, whose orientation condition is uniform, which has a switching process involving inversion of liquid crystal molecule in the neighborhood of the base board, and wherein the pretilt angle of the smectic layer ranges 8-20 deg. This ferro- dielectric liquid crystal layer has a chevron structure containing one sort of compounds expressed by Eq. I. Using this, a liquid crystal display device is constructed which presents high contrast and quick response. For example, one which contains a formula II.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a matrix type large capacity display ferroelectric liquid crystal display device having a high contrast.

[0002]

2. Description of the Related Art At present, liquid crystal display devices are used in a wide range of fields such as timepieces, calculators, office automation equipment such as word processors and personal computers, and pocket televisions. Generally, the nematic phase is widely used. It was done.

However, in the twisted nematic liquid crystal display device, the driving margin rapidly narrows as the number of scanning lines increases, and a sufficient contrast cannot be obtained. It is difficult to make a high resolution display device such as 2000 lines.

On the other hand, the demand for higher resolution display devices is ever increasing. Especially WYSIWYG
(What you see is what you
get) -that is, to display on the display device the same one that is printed out-
(Desk Top Publishing) field and GUI (Graphical User Interface)
ACE) -based WINDOWS environment-an environment in which a screen for each of a plurality of independent operations and various information necessary for the operation are displayed on the screen of one display element-
S (Engineering Work Status)
n), BWS (Business Work Stat)
In the fields such as ion), display devices are required to have a large display capacity and high-speed response. Therefore, what is considered to be promising is a ferroelectric liquid crystal display device (Appl. Phys. Lett., 3 proposed by Clarke (NA Clark) and Lagerwall (Lagerwall)).
6 , 899 (1980); JP-A-56-107216; U.S. Pat. No. 4,367,924). This liquid crystal display element is different from the nematic liquid crystal display device of the field effect type that utilizes the dielectric anisotropy of liquid crystal molecules, and the molecules are arranged so that the polarities of the spontaneous polarization of the ferroelectric liquid crystal and the polarities of the electric field are matched. It is a switching liquid crystal display element.

This display method uses a chiral smectic C
Phase, a chiral smectic I phase, a chiral smectic F phase, and other ferroelectric liquid crystal phases are used. In this ferroelectric liquid crystal device, when the ferroelectric liquid crystal is injected into a cell with a thin cell gap, the helical structure of the chiral smectic phase of the ferroelectric liquid crystal is unraveled by the influence of the interface, and the liquid crystal molecules are smectic layer normal. Tilt angle θ
Bistability is shown in which a region that is stable by tilting only by and a region that is stable by tilting by −θ in the opposite direction are mixed. When a voltage is applied to the ferroelectric liquid crystal element in this state, the liquid crystal molecules become
The direction of spontaneous polarization of the liquid crystal molecules themselves can be aligned with the electric field direction. Therefore, by switching the polarity of the applied voltage, it is possible to switch the alignment of the liquid crystal molecules from a certain state to the other state.
With this switching, the polarization axis changes along with the alignment direction of the liquid crystal molecules. Since birefringent light changes in the ferroelectric liquid crystal in the cell, the transmitted light can be controlled by sandwiching the ferroelectric liquid crystal element between two polarizers.
Further, even if the voltage application is stopped, the alignment of the liquid crystal molecules is maintained in the state before the voltage application is stopped by the alignment regulating force of the interface, so that the memory effect can be obtained. In addition, the time required for switching drive is 1/1000 or less of that of the twisted nematic liquid crystal display device because the spontaneous polarization of the liquid crystal and the electric field strength directly act, and a high-speed response is possible, realizing a high-resolution display element. It is very promising in terms of conversion.

However, in such a ferroelectric liquid crystal display device, there are various problems in order to actually realize high speed response. For example, in order to perform high-contrast display without flicker with scanning lines of 1000 × 1000 lines or more, extremely high-speed response of, for example, 8.4 μsec is required. Therefore, it is proposed to add a chiral compound having a large spontaneous polarization to a low-viscosity non-chiral liquid crystal composition or to use a low-viscosity non-chiral liquid crystal such as a pyrimidine-based liquid crystal (for example, the 16th liquid crystal discussion meeting,
1K101, 1K102, 1K111, 1K112, 1
K114, 1K115, 1K116, 1K117, 1K
119, 3K106, Proceedings of 16th Liquid Crystal Symposium (19
90); Onishi et al., National Technic.
al Report, 33 , 35 (1987).

Further, not only the above-mentioned liquid crystal material has been developed, but also a new liquid crystal drive system for realizing high-speed response has been developed. Among them, a method called partial rewriting is known as an effective method (Kanbe, Proc. Of the Institute of Electronics, Information and Communication Engineers, "Optoelectronics" -Liquid Crystal Display and Related Materials-, January 1990, pp. 18-26). There is. This method is a method to access only where the screen needs to be rewritten. As a result, it becomes possible to provide a display element that can follow the movement of the mouse, which requires high speed in displaying graphics.

A so-called 1/3 bias driving method has been proposed as a specific driving method for obtaining a display without flicker by using the partial rewriting method (Japanese Patent Laid-Open No. 64-59389). Bulletin). The change in spontaneous polarization of this driving method is illustrated in FIG.

However, when the partial rewriting method based on the ⅓ bias driving method is applied, a high speed response can be realized to some extent, but a bias voltage of ⅓ of the rewriting voltage is applied to a pixel which is not rewritten. Therefore, there was a problem that the liquid crystal molecules fluctuate and the contrast is low. (Kanbe, The Institute of Electronics, Information and Communication Engineers Special Lecture Lecture Collection "Optoelectronics" -Liquid Crystal Display and Related Materials-, January 1990, p18- 26).

It is considered that such reduction in display contrast is mainly closely related to the layer structure of the ferroelectric liquid crystal used.

That is, in such a ferroelectric liquid crystal device, the layer structure of the ferroelectric liquid crystal layer is generally not an ideal bookshelf structure, but a chevron structure with a V-shape. It is known that Then, the bending direction of this layer occurs in two directions (17, 18) as shown in FIG. 4, and two different orientation states occur accordingly. At that time, an alignment defect called a zigzag defect occurs at a position where layers are bent in different directions. As shown in FIG.
For zigzag defects, there are 2 of <<>> and >><< in the bending direction of the layer.
The types of defects occur, the former is named as a lightning defect and the latter is named as a hairpin defect from the shape. By observing this shape, the bending direction of the layer can be defined.
[Jpn. J. Appl. Phys. , 28 , p. Fifty
(1988)].

These two orientations are called C1 orientation (chevron 1) and C2 orientation (chevron 2) in relation to the rubbing direction (Kanbe, Institute of Electronics, Information and Communication Engineers Special Lecture Lecture Collection "Optoelectronics". -Liquid crystal display and related materials-, January 1990, pp. 18-26, and JP-A-1-158415).

In any of the C1 orientation and the C2 orientation, the orientation in which the tilt angle of the liquid crystal molecules in one layer of the chevron is twisted and does not show a clear extinction position, and the orientation in which the tilt angle is uniform and shows a clear extinction position. The former can be classified into C1
T orientation and C2T orientation (T means twist), the latter being C
It is called 1U orientation and C2U orientation (U means uniform) (Fukuda, Takezoe, “Structure and Physical Properties of Ferroelectric Liquid Crystal”, Corona Co., 1990, p-327).

Further, it is difficult to obtain C1U and C2U orientations exhibiting the above-mentioned extinction position, zigzag defects and lightning defects, and C1U and C1T and C2U and C2T.
It is considered that the mixture of orientations is a cause of lowering the contrast of the display.

With respect to this point, it has been proposed to improve the contrast by applying a SiO ₂ oblique vapor deposition film as an alignment film formed on a liquid crystal substrate (Uemura,
Others, National Technical Repo
rt, 33 (1), 51 (1987). ). This is to impart a relatively high pretilt to the substrate interface by the obliquely vapor-deposited film to prevent the liquid crystal layer from bending and achieve an obliquely inclined layer structure. Also, a method of changing the layer structure to a bookshelf structure by applying an alternating electric field of high voltage to a cell having a bent structure has been proposed (Sato et al., 12th Liquid Crystal Conference (Nagoya),
1F16 (1986). ).

[0016]

Although the ferroelectric liquid crystal element has the advantages as described above, it is possible to obtain a high-contrast display without flicker in a large-capacity display element having 1000 × 1000 or more scanning lines. The following problems arise when trying to do so. That is, one method for displaying without flicker is 16.7 msec (60H
One screen is rewritten within z), but in this case, the ferroelectric liquid crystal material is required to have a very high response speed. For example, in the case of a display element with 1000 scanning lines, a high-speed response of 8.4 sec is required, as can be seen from the following formula. 16.7 (msec) ÷ 1000 ÷ 2 = 8.4
sec (divided by 2 here because at least 2 pulses are required for writing in the case of ferroelectric liquid crystal.)

However, it is not easy at present to realize the required response speed by improving the ferroelectric liquid crystal material. Moreover, it can be easily imagined that it is quite difficult to increase the capacity by increasing the speed of the liquid crystal material when a display element having a larger capacity is produced.

As a promising method for solving such a problem, a method called partial rewriting (Kanbe, Proc. Of the Institute of Electronics, Information and Communication Engineers, "Optoelectronics" -Liquid Crystal Display and Related Materials-, 1990) January, p
18-26) have been proposed. This method is a method of accelerating only where the screen needs to be rewritten.
As a result, it becomes possible to provide a display element that can follow the movement of the mouse, which requires high speed in displaying graphics.

However, the problem in using the 1/3 bias driving method is that even if the pixel is not rewritten,
3 Bias voltage is applied, and due to this bias voltage, the fluctuation of the molecule of the pixel which is not rewritten occurs, the memory state is impaired, and the contrast decreases due to the fluctuation of the molecule.

Further, in the method using the above-mentioned SiO ₂ oblique vapor deposition film, it is difficult to control the vapor deposition angle uniformly, and the display area is limited, and since the vacuum process is included, the manufacturing apparatus cost is increased. There is a big problem in terms of production. Further, in the method of applying an electric field described below, it is difficult to uniformly change the layer structure, and many of them gradually change to the original chevron structure with the passage of a long period of time, and have not yet been put to practical use.

With such a conventional method, it has not been realized yet to display a high contrast ratio in a wide temperature range.

The present invention has been made under the above circumstances, and in particular, it is intended to provide a ferroelectric liquid crystal display device capable of stably displaying a high contrast ratio in the 1/3 bias driving method in a wide temperature range. It is what

A practical ferroelectric liquid crystal composition is usually prepared by mixing a plurality of components. At times, a compound that does not exhibit a smectic C phase or a compound that does not exhibit a liquid crystal phase at all may be used as the component. The properties required for the ferroelectric liquid crystal composition include not only the high contrast achieved by combining with an appropriate device structure, but also the following properties. That is,
It is required that the response speed is fast, and from this point, low viscosity is required. Although it is effective to increase the spontaneous polarization in order to increase the response speed, in order to obtain good bistability of the ferroelectric liquid crystal device, the ferroelectric liquid crystal composition has a rather low spontaneous polarization. The value of (for example, 10 nC / cm) is often required. In order to obtain good orientation when applied to a ferroelectric element, the phase sequence of the ferroelectric liquid crystal composition is important, and in general, INAC (Isotropi) is used.
c-Nmatic-Smectic A-Smecti
The cC) phase series is most preferred. The long helical pitch in the nematic phase and the smectic C phase is also important for obtaining good orientation. It is also necessary to show a smectic C phase in a wide temperature range centering on room temperature,
Chemically stable, stable to light,
No coloring, not high viscosity, smectic C
It is also required to have an appropriate tilt angle in the phase.

The present invention has been made in such a situation, and an object of the present invention is to provide a liquid crystal composition and a liquid crystal element which are useful in producing a high contrast practical ferroelectric liquid crystal composition. To do.

[0025]

Thus, according to the present invention, a pair of substrates, on which electrodes are selectively formed on the surface, an insulating film and an alignment film are further formed thereon, and then uniaxial alignment treatment is applied, are provided. , The uniaxial alignment treatments are arranged to face each other on the upper and lower substrates so as to be substantially parallel to each other, and a liquid crystal having a chiral smectic C phase is interposed between these substrates to form a liquid crystal panel, and a voltage is selectively applied to the electrodes. In a ferroelectric liquid crystal display device having a driving means for switching the optical axis of the liquid crystal by applying a voltage and a means for optically discriminating the switching of the optical axis, a chiral smectic C
The layer structure in the phase is a chevron structure bent in a V shape, and the alignment region generated from the relationship between the uniaxial alignment treatment direction and the layer structure is a lightning defect generated in the uniaxial alignment treatment direction and behind the defect. The inside of the area surrounded by the hairpin defects that occur in the, or outside the area surrounded by the hairpin defects that occur in the alignment treatment direction and the lightning defects that occur behind, the alignment state is uniform. And a switching process involving inversion of liquid crystal molecules near the substrate, and an organic alignment film having a pretilt angle of the smectic layer with respect to the substrate of 8 ° or more and 20 ° or less. I) The following formula (I):

[Chemical 6] Or (ii) the following formula (II):

[Chemical 7] A compound (II) represented by the formula (II) and a compound (I) respectively, or iii) the following formula (III):

[Chemical 8] Compound (III), compound (II) and compound (I)
A liquid crystal display device comprising a ferroelectric liquid crystal composition having a chevron structure, each containing one of the above. Further, the compound (I) is particularly represented by the following formula (IV):

[Chemical 9] Or a compound (IV) represented by the following formula (V):

[Chemical 10] Compound (V) represented by is preferable.

According to the present invention, when a ferroelectric liquid crystal display device is constructed by combining the above-mentioned specific alignment film and a specific liquid crystal composition, the liquid crystal layer having a uniform C1U alignment and a chevron structure is spread over a wide temperature range. It is based on the discovery of the fact that a stable display with a high contrast ratio can be obtained without causing defects and non-uniformity of orientation.

The compounds (I), (II), (III) and (I
In the definitions of V) and (V), linear or branched alkyl groups include methyl, ethyl, propyl, i-propyl, butyl, i-butyl, pentyl, 1- or 2-methylbutyl, hexyl, 1 -Or 3-methylpentyl, heptyl, 1- or 4-methylhexyl, octyl, 1- or 5-methylheptyl, nonyl, 1- or 6-methyloctyl, decyl, 1-methylnonyl, undecyl, 1-
Included are methyldecyl, dodecyl, 1-methylundecyl and the like.

In these alkyl groups or alkoxy groups, the carbon chain may contain an asymmetric carbon. Further, one or more hydrogen atoms in these alkyl groups or alkoxy groups may be substituted with a fluorine atom, a chlorine atom, a bromine atom, a cyano group, a nitro group, a trifluoromethyl group, a methoxy group or the like.

Specific chemical structures of the compounds contained in the compounds (I), (IV) and (V) are as follows.

[Chemical 11]

[Chemical 12]

[Chemical 13]

[Chemical 14]

[Chemical 15]

[Chemical 16]

[Chemical 17]

[Chemical 18] Of these, preferred compounds include 11-2, 11-7, 11
-10, 12-1, 12-6, 12-7, 13-2, 13-9, 14-
1, 14-2, 15-4, 16-5, 16-11, 17-2, 18-
4, 18-12 and the like. In addition, specific chemical structures of those contained in the compound (II) include the following.

[Chemical 19]

[Chemical 20] Among them, preferred compounds include 19-4, 19-5, 20
-3, 20-6 and the like. Further, compound (III)
Specific chemical structures of those included in are as follows.

[Chemical 21]

[Chemical 22]

[Chemical 23] Of these, preferred compounds include 23-1, 23-2, and 23.
-3, 23-4, 21-6, 21-7, 22-7, 22-8 and the like.

The following is an example of the method for producing the compound represented by the compound (I). 2-fluoro-4
-(Trans-4-alkylcyclohexyl) benzoic acid (IV) was reacted with phosphorus pentachloride to form acid chloride (VII), and then reacted with alkyl 4-hydroxybenzoate (VIII) in a toluene solvent in the presence of pyridine. Can be obtained.

[Chemical 24]

The ferroelectric liquid crystal composition of the present invention is prepared by mixing the above compounds (I), (II), (III), (IV) and (V) with a known ferroelectric liquid crystal or composition. It can be prepared. In particular, it is suitable to prepare so that the phase sequence is INAC. Usually, the total content of the compounds (I), (IV), and (V) is 4 wt% or more, the above-mentioned compound (I),
It is preferable that the content of each single component contained in the groups (IV) and (V) is 25 wt% or less of the whole. If the total content of the compounds (I), (IV), and (V) is less than 4 wt%, the effect of improving the contrast by the 1/3 bias drive is insufficient, and the content per single component is 20 wt%.
If it exceeds the range, crystallization of the additive may occur, or the temperature range of the smectic C phase may not be compatible with the temperature range used as a display, which is not suitable.

The mixing ratio of the compound (II) to the compound (I) is preferably 5 to 20 wt%. 5 wt
If it is less than 1%, the effect of improving contrast by 1/3 bias driving is insufficient, and if it exceeds 20% by weight, crystallization of the additive occurs or the temperature range of the smectic C phase is not suitable for the temperature used as a display. Not suitable because it will disappear.

The mixing ratio of the compound (III) to the total of the compound (II) and the compound (I) is preferably 50 to 95 wt%. If it exceeds 95 wt%, the memory is insufficient or the contrast is not sufficiently improved by the 1/3 bias drive. If it is less than 20 wt%, an appropriate smectic C phase temperature range as a display cannot be maintained, which is not suitable. ..

The ferroelectric liquid crystal composition of the present invention comprises
Various additives may be incorporated as long as the effects intended by the present invention are not impaired. For example, from the viewpoint of improving the orientation, another liquid crystal compound having a fluoroalkyl group at the terminal or a liquid crystal compatible compound is compounded (usually 0.01 to 1 wt.
%), And examples thereof are disclosed in, for example, JP-A-3-4
No. 7,891, etc.

Next, as a preferred example thereof, the directions of the uniaxial alignment treatment of the pair of substrates are parallel to each other, the driven liquid crystal phase is a chiral smectic C phase, and the smectic layer structure is “ku” in the chiral smectic C phase. A liquid crystal element characterized by having a chevron structure bent in the shape of and having a uniform C1 orientation (C1U orientation) will be described.

In general, the layer structure in the chiral smectic C layer is generally "ku" as shown in FIG. 2 (a).
It is said to have a chevron structure that is folded in the shape of. There are two directions in which the layers are bent, as shown in the figure. At this time, an alignment defect called a zigzag defect occurs at a place where the bending direction of the layer changes. FIG. 2B is a schematic diagram when the zigzag defect is observed by a deflection microscope. The zigzag defect can be classified into a defect called a lightning defect and a defect called a hairpin defect. As a result of previous research, the layer structure is <<>>
It has been clarified that the portion marked with is corresponding to the lightning defect, and the portion having the layer structure >><< is corresponding to the hairpin defect (N. Hiji et al.
l. , Jpn. J. Appl. Phys. , 27 , L1
(1988). ). The relationship between the rubbing direction and the pretilt angle θ _P is as shown in FIG. 2 (a), and the above two orientations are called C1 orientation and C2 orientation from the relationship with the rubbing direction (Kanbe, Institute of Electronics, Information and Communication Engineers). Special Workshop Lecture Collection "Optoelectronics" -Liquid Crystal Display and Related Materials-, January 1990, pp. 18-26). The case where the rubbing axis and the bending direction of the layer are opposite is defined as C1 orientation (chevron 1), and the same case is defined as C2 orientation (chevron 2).

Now, when the pretilt angle θ _P is increased,
The difference in the alignment state of liquid crystal molecules between the C1 orientation and the C2 orientation becomes remarkable, and a large value of 8 ° or more (preferably
When using an alignment film exhibiting a high temperature side, a region showing a clear extinction position and a region not showing a quenching position are observed in the C1 alignment on the high temperature side, and a clear extinction position is observed in the C2 alignment on the low temperature side. Only the area showing is observed. It is generally accepted that uniform orientation and twist orientation are distinguished by the presence or absence of the extinction position (Fukuda, Takezoe, "Structure and Physical Properties of Ferroelectric Liquid Crystals", Corona Publishing Co., 1990, p-
327), where C is the extinction position in the C1 orientation.
The 1U (C1 uniform) orientation and the C1 orientation that does not show an extinction position are called C1T (C1 twist) orientation. Since only one type of C2 orientation was obtained, only the C2 orientation will be described. When a voltage waveform as shown in FIG. 3 is applied, good contrast is obtained in the C1U orientation, while contrast is significantly reduced in the C2 orientation, even though the extinction position is shown when no voltage is applied. Even lower contrast can be obtained with the C1T orientation. The researchers of the present invention have found that the contrast has the following tendency, and the C1U orientation is particularly preferable in terms of the contrast. C1U> C2 >> C1T

A specific example of such a ferroelectric liquid crystal display device of the present invention is shown in FIG. A transparent electrode 2a on the glass substrate 1a,
The substrate 9 is formed by forming the insulating film 3a and the alignment film 4a in this order. Here, the transparent electrode 2a is formed by arranging a plurality of transparent electrodes in a stripe shape so as to be parallel to each other, and the alignment film 4a has a structure subjected to a uniaxial alignment treatment by rubbing.

On the other hand, the substrate 10 is one in which the transparent electrode 2b, the insulating film 3b, and the alignment film 4b are formed in this order on the other glass substrate 1b under the same conditions. Similar to the substrate 9, the transparent electrode 2b and the alignment film 4b are formed by arranging a plurality of transparent electrodes in a stripe shape so as to be parallel to each other, and the alignment film 4b is subjected to a uniaxial alignment treatment by rubbing. It has a special structure.

Next, the alignment films 4a and 4b of the substrate 9 and the substrate 10 are opposed to each other, the transparent electrodes 2a and 2b thereof are orthogonal to each other, and the rubbing directions of the substrates 9 and 10 are substantially the same. The seal member 6 is spaced at intervals of about 1.5 to 3 μm, preferably 1.2 to 1.8 μm.
Stick together.

A liquid crystal cell 11 is formed by interposing a ferroelectric liquid crystal composition 7 between these substrates 9 and 10.

Further, polarizing plates 12a and 12b whose polarizing axes are substantially orthogonal to each other are arranged above and below the cell, and one polarizing axis of the polarizing plate is substantially aligned with one optical axis of the liquid crystal of the cell. Use as a display device.

Of course, the liquid crystal device which can use the liquid crystal composition containing at least one compound (I) is not limited to the above-mentioned ferroelectric liquid crystal device, but may be a ferroelectric liquid crystal device having another structure or a nematic liquid crystal device. It is needless to say that the present invention can be applied to a liquid crystal element using a phase (TN, STN, DSTN, etc.), a liquid crystal element using a smectic A phase (thermal writing, electroclinic, etc.), an antiferroelectric liquid crystal element, and the like.

[0044]

【Example】

 Synthesis Example 1 2-Fluoro-4- (trans-4-pentylcyclohexyl)
Synthesis of heptyl benzoyl (No. 101) 2-fluoro-4- (trans-4-pentylcyclohexyl)
Xyl) benzoic acid 0.7 g (0.0024 mol) in pentasalt
0.6g (0.0029mol) of phosphorus chloride was added, and the temperature was about 80 ° C.
It was heated to react. Generated POCl₃ And excess
The phosphorus pentachloride was removed under reduced pressure to give 2-fluoro-4- (tra
4-pentylcyclohexyl) benzoic acid chloride
Got This is dissolved in 10 ml of toluene and 4-hydro
With heptyl xyloxybenzoate 0.7 g (0.0030 mol)
1 ml of pyridine (dehydrochlorinating agent) was added. 10 at room temperature
After leaving it to stand for 3 hours, keep it at 70 ° C for 3 hours and then cool it to room temperature.
I rejected it. Then add ice and hydrochloric acid and extract with ether.
It was The ether layer is NaHCO ₃ Wash with aqueous solution, then water
I, Na₂SO_FourDried in. The ether was distilled off and the residue
High performance liquid chromatography (Waters Delta
Prep 3000 Liquid Chromatography; C-18
Rica gel column; solvent methanol + chloroform (8:
Purify in 2) and recrystallize from ethanol to obtain the desired product.
2-fluoro-4- (trans-4-pentylcyclohexyl
Xyl) heptyl benzoate was obtained. Infrared absorption of this compound
The absorption spectrum is shown in FIG. Also, the transition temperature of this compound
The degrees were as follows.Further, the compound (IX) used in the examples of the present invention is shown below.
You

[Chemical 25]

[Chemical 26]

[Chemical 27]

Example 1 A liquid crystal composition No. having the composition shown in Table 1 was prepared by using the compound (IX). 201 was produced. The transition temperature of this liquid crystal composition was as follows.

[Table 1] This liquid crystal composition showed a smectic C phase at room temperature,
No smectic A phase was shown.

Example 2 Liquid crystal composition No. 1 prepared in Example 1 201 is the compound No. of the compound (IX). 10% by weight of 101 is added,
Liquid crystal composition No. 202 was produced. This liquid crystal composition also showed a smectic C phase at room temperature. The composition of this liquid crystal composition is shown in Table 1. Compound No. By adding 101, the smectic A phase appeared, and the INAC phase series preferable for the orientation of the ferroelectric liquid crystal element was realized.

Example 3 The liquid crystal composition No. 1 prepared in Example 2 was used. 202, an optically active compound No. 202 shown in Compound (IX). 2% by weight of 124
Ferroelectric liquid crystal composition No. 203 was produced. The transition temperature of this liquid crystal composition was as follows. This liquid crystal composition also showed a smectic C phase at room temperature. The composition of this liquid crystal composition is shown in Table 2. This ferroelectric liquid crystal composition exhibits a chiral smectic C phase in a wide temperature range,
INA preferred for the orientation of ferroelectric liquid crystal elements
The C phase sequence is shown.

Example 4 I of 1000 Å thickness on each of two glass substrates
A TO film is formed, and a 500 Å SiO ₂ insulating film is formed on the TO film.
It was formed to a thickness of 0Å, and thereafter, uniaxial orientation treatment by rubbing was performed using a rayon cloth. These substrates,
A liquid crystal cell was produced by laminating with a thickness of 20 μm so that the rubbing directions were anti-parallel. A nematic liquid crystal E-8 manufactured by Merck & Co., Inc. was injected into this and the pretilt angle of the liquid crystal molecules from the substrate was measured by the magnetic field capacitance method. The results are shown in Table 2.

[Table 2]

Example 5 A ferroelectric liquid crystal device having the structure shown in FIG. 4 was produced. On a glass substrate 1a, a plurality of ITO transparent electrodes 2a having a thickness of 1000 Å are formed in stripes so as to be parallel to each other, and 500 Å SiO is formed as an insulating film 3a thereon.
And then PSI-A-200 as an alignment film 4a.
1 (polyimide manufactured by Chisso Petrochemical Co., Ltd.) was formed to a thickness of 400 Å by a spin coater, and then uniaxially oriented by rubbing using a rayon-based cloth to form a substrate 9
Formed. On the other hand, the glass substrate 1b on the other side was also treated under the same conditions to form the substrate 10.

Next, the substrate 9 and the other substrate 10
And the alignment films 4a and 4b are opposed to each other, the transparent electrodes 2a and 2b are orthogonal to each other, and the rubbing directions are substantially the same. The sealing member 6 was used for the pasting. Between the substrates 9 and 10, the ferroelectric liquid crystal composition No. 3 manufactured in Example 3 was injected from the injection port by a vacuum injection method. 20
After injecting 3, the injection port was cured with an acrylic UV curable resin to prepare a liquid crystal cell 11. Further, polarizing plates 12a and 12b whose polarization axes are substantially orthogonal to each other are provided above and below this cell.
Was arranged, and one polarization axis of the polarizing plate was made to substantially coincide with one of the optical axes of the liquid crystals of the cell to obtain a liquid crystal display device.

When the state of orientation of this ferroelectric liquid crystal element was examined, in the temperature range from the smectic C-smectic A transition point to room temperature, a region of small C2 orientation surrounded by minute zigzag defects was small. Except for, the entire surface was C1U oriented.

The tilt angle in the chiral smectic C phase of these ferroelectric liquid crystal devices was measured. The tilt angle was defined as 1/2 of the angle between the two extinction positions obtained by applying a rectangular wave of ± 10 V to the liquid crystal cell. The tilt angle was plotted against temperature (Fig. 6).

The voltage of the waveform shown in FIG. 3 (a) (V = ± 10
V) was applied and the memory pulse width was measured. Figure 7
Shown in. The memory pulse width is the minimum pulse width that allows bistable switching. When the pulse width was set to the memory pulse width and the waveform of FIG. 3A was applied, a contrast of 50 or more was obtained.

A voltage (V = ± 10 V) having a 1/3 bias waveform shown in FIG. 3B was applied and the memory pulse width was measured. The memory pulse width is the minimum pulse width that allows bistable switching. The results are shown in Fig. 7. In addition, the pulse width is set to the memory pulse width, and
When the waveform of (1) was applied, a high contrast of 10 was obtained. In this case, it can be concluded that a good black state can be maintained even when a bias is applied, and the fluctuation of molecules due to the bias voltage is suppressed.

Comparative Example 1 Liquid crystal composition No. 1 prepared in Example 3 Of the components contained in 203, compound No. No. 101 was removed for comparison as a ferroelectric liquid crystal composition No. 212 was produced. This liquid crystal composition also showed a smectic C phase at room temperature. This liquid crystal composition No. The composition of 212 is shown in Table 1.

Ferroelectric liquid crystal composition N in Example 5
o. 203 is a ferroelectric liquid crystal composition No. 203 for comparison. Two
A ferroelectric liquid crystal element was produced in the same manner as in Example 5 except that the liquid crystal element was replaced with 12. When the orientation was observed, it was C2 orientation, and a good extinction state was not observed.

Comparative Example 2 Ferroelectric liquid crystal composition No. 1 having the composition shown in Table 2 was prepared using the compound shown in Compound (IX). 206 to 211 were produced.

Ferroelectric liquid crystal composition N in Example 5
o. 203 is a ferroelectric liquid crystal composition No. 203 for comparison. Two
A ferroelectric liquid crystal element was produced in the same manner as in Example 5 except that the liquid crystal element was replaced with any of 06 to 211.

Further, the ferroelectric liquid crystal composition No. 3 in Example 5 was used. 203 for comparison with a ferroelectric liquid crystal composition N
o. 206 to 211 and replace PSI-A-2001 in the fifth embodiment with PSI-S-01.
A ferroelectric liquid crystal device was produced in the same manner as in Example 5 except that the liquid crystal element was replaced with 4 or PVA.

Table 3 shows the results of investigations on these ferroelectric liquid crystal elements. Neither of the ferroelectric liquid crystal elements provided the good results as obtained in Example 5.

[Table 3]

Example 6 Liquid crystal composition No. 6 prepared in Example 3 Of the components contained in 203, compound No. Compound N instead of 101
o. Ferroelectric liquid crystal composition No. 127 containing 15% of 127.
213 was produced. The transition temperature of this liquid crystal composition was as follows. This liquid crystal composition also showed a smectic C phase at room temperature. This liquid crystal composition No. Example 5 except replacing with 213
A ferroelectric liquid crystal element was produced in the same manner as in. Observation of the orientation revealed that in the temperature range from the smectic C-smectic A transition point to room temperature, except for the area of C2 orientation surrounded by minute zigzag defects, which is small in area,
The entire surface was C1U oriented.

The tilt angle in the chiral smectic C phase of these ferroelectric liquid crystal devices was measured. The tilt angle was defined as 1/2 of the angle between the two extinction positions obtained by applying a rectangular wave of ± 10 V to the liquid crystal cell. The tilt angle was plotted against temperature (Fig. 8).

The voltage of the waveform shown in FIG. 3A (V = ± 10
V) was applied and the memory pulse width was measured. The results are shown in Figure 9.
Shown in. The memory pulse width is the minimum pulse width that allows bistable switching. When the pulse width was set to the memory pulse width and the waveform of FIG. 3A was applied, a contrast of 50 or more was obtained.

A voltage (V = ± 10 V) having a 1/3 bias waveform shown in FIG. 3B was applied and the memory pulse width was measured. The memory pulse width is the minimum pulse width that allows bistable switching. The results are shown in Fig. 9. In addition, the pulse width is set to the memory pulse width, and
When the waveform of (1) was applied, a high contrast of 10 was obtained. In this case, it can be concluded that a good black state can be maintained even when a bias is applied, and the fluctuation of molecules due to the bias voltage is suppressed.

Example 7 Ferroelectric liquid crystal composition No. 1 having the composition shown in Table 1 was prepared using the compound shown in Compound (IX). 214 was produced. The transition temperature of this liquid crystal composition was as follows. This liquid crystal composition also showed a smectic C phase at room temperature. The ferroelectric liquid crystal composition No. 5 in Example 5 was used. No. 203 is a ferroelectric liquid crystal composition No. A ferroelectric liquid crystal element was produced in the same manner as in Example 5 except that the liquid crystal element was replaced with 214. When the orientation was observed, it was found to be C1U orientation over the entire surface in the temperature range from the smectic C-smectic A transition point to room temperature, except for the area of C2 orientation surrounded by minute zigzag defects and having a small area.

The tilt angle in the chiral smectic C phase of these ferroelectric liquid crystal devices was measured. The tilt angle was defined as 1/2 of the angle between the two extinction positions obtained by applying a rectangular wave of ± 10 V to the liquid crystal cell. The tilt angle was plotted against temperature (Fig. 10).

The voltage of the waveform shown in FIG. 3A (V = ± 10
V) was applied and the memory pulse width was measured. The results are shown in Figure 9.
Shown in. The memory pulse width is the minimum pulse width that allows bistable switching. When the pulse width was set to the memory pulse width and the waveform of FIG. 3A was applied, a contrast of 50 or more was obtained.

A voltage (V = ± 10 V) having a 1/3 bias waveform shown in FIG. 3B was applied and the memory pulse width was measured. The memory pulse width was set to the minimum pulse width that allows bistable switching. The results are shown in Fig. 11. In addition, the pulse width is set to the memory pulse width, and
A high contrast ratio of 10 was obtained by applying the waveform of. In this case, it can be concluded that a good black state can be maintained even when a bias is applied, and the fluctuation of molecules due to the bias voltage is suppressed.

Example 8 Ferroelectric liquid crystal composition No. 1 having the composition shown in Table 1 was prepared using the compound shown in Compound (IX). 215 was produced. The transition temperature of this liquid crystal composition was as follows. This liquid crystal composition also showed a smectic C phase at room temperature. The ferroelectric liquid crystal composition No. 3 in Example 5 was used. No. 203 is a ferroelectric liquid crystal composition No. A ferroelectric liquid crystal device was produced in the same manner as in Example 5 except that the liquid crystal element was replaced with 215. When the orientation was observed, it was found to be C1U orientation over the entire surface in the temperature range from the smectic C-smectic A transition point to room temperature, except for the area of C2 orientation surrounded by minute zigzag defects and having a small area.

The tilt angle in the chiral smectic C phase of these ferroelectric liquid crystal devices was measured. The tilt angle was defined as 1/2 of the angle between the two extinction positions obtained by applying a rectangular wave of ± 10 V to the liquid crystal cell. The tilt angle was plotted against temperature (Fig. 12).

The voltage (V = ± 10) of the waveform shown in FIG.
V) was applied and the memory pulse width was measured. The result is shown in Figure 1.
3 shows. The memory pulse width is the minimum pulse width that allows bistable switching. When the pulse width was set to the memory pulse width and the waveform of FIG. 3A was applied, a contrast of 50 or more was obtained.

A voltage (V = ± 10 V) having a 1/3 bias waveform shown in FIG. 3B was applied and the memory pulse width was measured. The memory pulse width is the minimum pulse width that allows bistable switching. The results are shown in Fig. 13. In addition, the pulse width is set to the memory pulse width, and
A high contrast ratio of 20 was obtained by applying the waveform of. In this case, it can be concluded that a good black state can be maintained even when a bias is applied, and the fluctuation of molecules due to the bias voltage is suppressed.

Example 9 Ferroelectric liquid crystal composition No. 1 having the composition shown in Table 1 was prepared using the compound shown in Compound (IX). 204, 205, 216,
217,218,219 was produced. This liquid crystal composition also showed a smectic C phase at room temperature.

Ferroelectric liquid crystal composition N in Example 5
o. No. 203 shown in Table 2 204, 205, 21
6,217,218,219 in the same manner as in Example 5 except that any one of the ferroelectric liquid crystal compositions is replaced.
A ferroelectric liquid crystal device was produced. When the orientation was observed in the temperature range from the smectic C-smectic A transition point to room temperature, the entire surface was C1U orientation except for the area of C2 orientation surrounded by minute zigzag defects and small in area.

A memory pulse width was measured by applying a voltage (V = ± 10 V) having a waveform shown in FIG. 3 (a) in a temperature region showing good C1U orientation. The memory pulse width is the minimum pulse width that allows bistable switching. Set the pulse width to the memory pulse width, and
When the waveform of (4) was applied, the contrast shown in Table 4 was obtained.

A memory pulse width was measured by applying a voltage (V = ± 10V) having a 1/3 bias waveform shown in FIG. 3 (b). The memory pulse width is the minimum pulse width that allows bistable switching. When the pulse width was set to the memory pulse width and the waveform of FIG. 3B was applied, the contrast shown in Table 4 was obtained.

[Table 4]

[0077]

According to the present invention, C1 can be used in a wide temperature range from the AC transition temperature to near room temperature.
A U orientation is obtained. The temperature range in which C1U switching can be performed during 1/3 bias driving is wide. A ferroelectric liquid crystal display device having the above feature can be obtained. Therefore, according to the present invention, it is possible to obtain a ferroelectric liquid crystal display device capable of stably displaying a high contrast ratio in a wide temperature range. And, of course, a driving method other than the 1/3 bias driving method can be applied.

[Brief description of drawings]

FIG. 1 is a diagram for explaining switching of a ferroelectric liquid crystal.

FIG. 2 is a diagram for explaining a chevron smectic C-phase chevron layer structure and C1 and C2 orientations.

FIG. 3A is a diagram showing an example of applied voltage waveforms of 0 bias and 3B of FIG. 3B.

FIG. 4 is a schematic cross-sectional view of a device for explaining a ferroelectric liquid crystal device of the present invention.

FIG. 5: Compound No. of the present invention FIG. 3 is a diagram showing an infrared absorption spectrum of 101.

FIG. 6 is a graph showing changes in tilt angle with temperature of a ferroelectric liquid crystal composition using the compound of the present invention.

FIG. 7 is a graph showing a temperature change of a memory pulse width of a ferroelectric liquid crystal composition using the compound of the present invention.

FIG. 8 is a graph showing a change in tilt angle with temperature of a ferroelectric liquid crystal composition using the compound of the present invention.

FIG. 9 is a diagram showing a temperature change of a memory pulse width of a ferroelectric liquid crystal composition using the compound of the present invention.

FIG. 10 is a graph showing a change in tilt angle with temperature of a ferroelectric liquid crystal composition using the compound of the present invention.

FIG. 11 is a graph showing changes in memory pulse width with temperature of a ferroelectric liquid crystal composition using the compound of the present invention.

FIG. 12 is a graph showing a change in tilt angle with temperature of a ferroelectric liquid crystal composition using the compound of the present invention.

FIG. 13 is a diagram showing changes in memory pulse width with temperature of a ferroelectric liquid crystal composition using the compound of the present invention.

[Explanation of symbols]

 1a, 1b Glass substrate 2a, 2b Transparent electrode 3a, 3b Insulating film 4a, 4b Alignment film 6 Sealing member 7 Ferroelectric liquid crystal composition 9, 10 Substrate 11 Liquid crystal cell 12a, 12b Polarizing plate 15 Lightning defect 16 Hairpin defect

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomoaki Kurata 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Co., Ltd. Inside the company

Claims (3)

[Claims] 1. A pair of substrates, on which electrodes are selectively formed on the surface, an insulating film and an alignment film are further formed on the electrodes, and then a uniaxial alignment treatment is performed on the upper and lower substrates. The liquid crystal panels are arranged so as to be substantially parallel to each other, and a liquid crystal having a chiral smectic C phase is interposed between these substrates to form a liquid crystal panel, and the optical axis of the liquid crystal is switched by selectively applying a voltage to the electrodes. In a ferroelectric liquid crystal display device having a driving means and a means for optically distinguishing the switching of the optical axis, the layer structure in the chiral smectic C phase is a chevron structure bent in a V shape. The alignment region resulting from the relationship between the alignment treatment direction and the layer structure is surrounded by the lightning defect generated in the uniaxial alignment treatment direction and the hairpin defect generated behind the defect. It is characterized by being inside the region or outside the region surrounded by the hairpin defect generated in the alignment treatment direction and the lightning defect generated in the rear direction, and the alignment state is uniform, and the vicinity of the substrate of liquid crystal molecules. And a ferroelectric liquid crystal layer having a pretilt angle of the smectic layer with respect to the substrate of 8 ° or more and 20 ° or less, and i) the following formula (I): [Chemical 1] Or a compound (I) represented by: ii) the following formula (II): A compound (II) and a compound (I) each represented by the following formula, or iii) the following formula (III): Compound (III), compound (II) and compound (I)
A liquid crystal display device comprising a ferroelectric liquid crystal composition having a chevron structure, each containing one of the above. 2. A compound (I) is particularly represented by the following formula (IV): Or a compound (IV) represented by the following formula (V): The device according to claim 1, which is a compound (V) represented by: 3. The tilt angle of the liquid crystal composition is 4 ° or more and 2
5 from the pretilt angle in the driving temperature range of 5 ° C or less
The device according to any one of claims 1 and 2, which is not larger than 0 ° or more.