JP2763220B2 - Liquid crystal display - Google Patents

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 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 clock processors, calculators, OA equipment such as word processors and personal computers, and pocket televisions, but the most widely used one is a nematic phase. It was done.

However, the twisted nematic type liquid crystal display device has a drawback that the drive margin is rapidly narrowed with the increase in the number of scanning lines, and a sufficient contrast cannot be obtained. It is difficult to make a high-resolution display element such as 2000 lines.

On the other hand, a higher resolution display device is required.
Requirements are increasing. Especially WYSIWYG
(What you see is what you
 get)-that is, the same one that is printed out
Display on a display device-DTP required
(Desk Top Publishing)
GUI (Graphical User Interf)
ace) based WINDOWS environment-multiple independent
One screen for each work and various information necessary for the operation
EW required for the environment to display in the screen of the display element
S (Engineering Work Status)
n), BWS (Business Work Stat)
(ion), etc., the display element has a large display capacity
And high-speed response is required. So promising
Are Clark and Ragbal
Ferroelectricity proposed by (Lagerwall)
Liquid crystal display device (Appl. Phys. Lett.,3
6, 899 (1980); JP-A-56-107216.
Gazette; U.S. Pat. No. 4,367,924). This liquid crystal
The display element uses an electric field effect that utilizes the dielectric anisotropy of liquid crystal molecules.
Unlike the nematic liquid crystal display device of the type, ferroelectric
The polarity of the spontaneous polarization of the liquid crystal matches the polarity of the electric field
It is a liquid crystal display element in which molecules switch.

[0005] This display method is chiral smectic C
Phase, a chiral smectic I phase, a ferroelectric liquid crystal phase such as a chiral smectic F phase. In this ferroelectric liquid crystal device, when the ferroelectric liquid crystal is injected into a cell having a small cell gap, the spiral structure of the chiral smectic phase of the ferroelectric liquid crystal is loosened due to the influence of the interface, and the liquid crystal molecules are separated from the smectic layer normal. Angle of inclination θ
This shows bistability in which a region that is stable by only tilting and a region that is stable by tilting in the opposite direction by −θ are mixed. When a voltage is applied to the ferroelectric liquid crystal element in this state, the liquid crystal molecules
The direction of spontaneous polarization of the liquid crystal molecules themselves can be aligned with the direction of the electric field. Therefore, by switching the polarity of the applied voltage, switching for switching the orientation of the liquid crystal molecules from a certain state to another state becomes possible.
With this switching, the polarization axis changes along with the orientation direction of the liquid crystal molecules. Since the birefringent light changes in the ferroelectric liquid crystal in the cell, the transmitted light can be controlled by interposing the ferroelectric liquid crystal element between two polarizers.
Further, even if the application of the voltage is stopped, the alignment of the liquid crystal molecules is maintained in the state before the stop of the application of the voltage by the alignment regulating force at the interface, so that a memory effect can be obtained. In addition, the time required for the switching drive is as fast as 1/1000 of that of a twisted nematic liquid crystal display device because the spontaneous polarization of the liquid crystal and the electric field strength directly act, 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 actually realizing high-speed response. For example, in order to perform high-contrast display without flicker on scanning lines of 1000 × 1000 lines or more, an extremely high-speed response of, for example, 8.4 μsec is required. Therefore, a proposal is made 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,
1K101, 1K102, 1K111, 1K112, 1
K114, 1K115, 1K116, 1K117, 1K
119, 3K106, Proceedings of the 16th Liquid Crystal Symposium (19
90); Onishi, et al., National Technic.
al Report, 33 , 35 (1987).

Further, in addition to the development of the above-mentioned liquid crystal material, a new liquid crystal driving method for realizing high-speed response has been developed. Among them, a technique called partial rewriting (Kanbe, Proceedings of the IEICE Technical Seminar “Optoelectronics—Liquid Crystal Display and Related Materials,” Jan. 1990, pp. 18-26) is known as an effective technique. I have. This method is a method of accessing only a place where the screen needs to be rewritten. As a result, a display element that can follow the movement of a mouse that requires high speed in displaying graphics can be provided.

A so-called 1/3 bias driving method has been proposed as a specific driving method for obtaining a flicker-free display by using the partial rewriting method (Japanese Patent Laid-Open No. 64-59389). Gazette). FIG. 1 illustrates a change in spontaneous polarization in this driving method.

However, when the partial rewriting method based on the 1/3 bias driving method is applied, a high-speed response can be realized to some extent, but a bias voltage of 1/3 of the rewriting voltage is applied to a pixel which is not rewritten. Therefore, there was a problem that fluctuation of liquid crystal molecules occurred and the contrast was low (Kanbe, Proc. Of the IEICE Technical Seminar, "Optoelectronics-Liquid Crystal Display and Related Materials-," January 1990, p18- 26).

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

In other words, in such a ferroelectric liquid crystal element, the layer structure of the ferroelectric liquid crystal layer is generally not an ideal bookshelf structure, but a chevron structure in a shape of a "<". It is known that Then, as shown in FIG. 4, the direction in which this layer is bent occurs in two directions (17, 18), and two different orientation states are generated accordingly. At that time, an orientation defect called a zigzag defect occurs in a place where the bending direction of the layer is different from that of the layer. As shown in FIG.
In the zigzag defect, in the direction in which the layer bends, << and >>
<< The two types of defects occur, and the former is named a lightning defect, and the latter is named a hairpin defect, and by observing this shape, the bending direction of the layer can be defined. [Jpn. J. Appl. Phys. , 2
8 , p. 50 (1988)].

Such two orientations are called C1 orientation (chevron 1) and C2 orientation (chevron 2) because of the relationship with the rubbing direction. (Kanbe, Proc. -Liquid Crystal Display and Related Materials-, January 1990, pp. 18-26, and JP-A-1-158415).

In each of the C1 alignment and the C2 alignment, 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 alignment angle is uniform and the tilt angle shows a clear extinction position. And the former is C1
T orientation and C2T orientation (T means twist), the latter being C
It is called 1U orientation and C2U orientation (U is a uniform) (Fukuda, Takezoe, "Structure and Physical Properties of Ferroelectric Liquid Crystal", Corona, 1990, p-327).

It is difficult to obtain the C1U and C2U orientations exhibiting the above-mentioned extinction positions, zigzag defects and lightning defects, C1U and C1T, C2U and C2T.
It is considered that the mixture of the orientations causes the display to have a low contrast.

In this regard, a proposal has been made to improve the contrast by applying an obliquely deposited SiO ₂ film as the alignment film formed on the 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 deposited film, thereby preventing the liquid crystal layer from being bent and achieving an obliquely inclined layer structure. In addition, a method has been proposed in which a layer structure is changed to a bookshelf structure by applying a high voltage alternating electric field to a cell having a bent structure (Sato et al., The 12th Liquid Crystal Symposium (Nagoya),
1F16 (1986). ).

[0016]

Although the ferroelectric liquid crystal device has the above advantages, a high-contrast display without flicker can be realized in a large-capacity display device having 1000 × 1000 or more scanning lines. Attempting to do so raises the following issues: That is, one method for performing flicker-free display is 16.7 msec (60H
One screen is rewritten within z). In this case, a very fast response speed is required for the ferroelectric liquid crystal material. For example, in the case of a display element having 1000 scanning lines, a high-speed response of 8.4 sec is required as can be understood from the following equation. 16.7 (msec) ÷ 1000 ÷ 2 = 8.4
sec (Here, dividing by 2 is because at least two pulses are required for writing in the case of a ferroelectric liquid crystal.)

However, at present, it is not easy to achieve the required response speed by improving the ferroelectric liquid crystal material. In addition, when a display device having a larger capacity is produced, it is easily imagined that it is quite difficult to increase the capacity by increasing the speed of the liquid crystal material.

As an effective method for solving such a problem, a method called partial rewriting (Kanbe, Proc. Of the IEICE Technical Seminar, "Optoelectronics-Liquid Crystal Display and Related Materials-," 1990 January, p
18-26) have been proposed. This method is a method of accelerating only the area where the screen needs to be rewritten.
As a result, a display element that can follow the movement of a mouse that requires high speed in displaying graphics can be provided.

However, the problem when the 1/3 bias driving method is used is that 1 /
When a bias voltage of 3 is applied, the bias voltage causes fluctuations in the molecules of the pixels that are not rewritten, so that the memory state is impaired or the contrast is lowered due to the fluctuations in the molecules.

Further, in the method using the obliquely deposited SiO ₂ film, it is difficult to uniformly control the deposition angle, which limits the display area. In addition, the use of a vacuum process increases the cost of the manufacturing apparatus. There is a big problem in production. In addition, it is difficult to uniformly change the layer structure in the method of applying an electric field described later, and many of the methods gradually change to the original chevron structure over a long period of time, and have not yet been put to practical use.

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

The present invention has been made under such circumstances, and in particular, will provide a ferroelectric liquid crystal display device capable of stably displaying a high contrast ratio in a wide temperature range in a に お い て bias driving method. It is assumed that.

A practical ferroelectric liquid crystal composition is usually prepared by mixing a plurality of components. In some cases, a compound that does not exhibit a smectic C phase or a compound that does not exhibit a liquid crystal phase at all is used as the component. The properties required for the ferroelectric liquid crystal composition include not only high contrast in combination with an appropriate device structure but also the following properties. That is,
A high response speed is required, and from this point, a low viscosity is required. Increasing spontaneous polarization is effective for increasing the response speed, but in order to obtain good bistability of a ferroelectric liquid crystal device, a ferroelectric liquid crystal composition has a rather low spontaneous polarization. (For example, 10 nC / cm) is often required. In order to obtain good orientation when applied to a ferroelectric element, a phase series of a ferroelectric liquid crystal composition is important. In general, an INAC (Isotropi) is used.
c-Nmatic-Smectic A-Smecti
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 over a wide temperature range around room temperature,
Chemical stability, light stability,
No coloring, no high viscosity, smectic C
It is also required that the phase has an appropriate tilt angle.

The present invention has been made under such circumstances, and it is an object of the present invention to provide a liquid crystal composition and a liquid crystal element useful for producing a practical high-contrast ferroelectric liquid crystal composition. I do.

[0025]

According to the present invention, an electrode is selectively formed on the surface, an insulating film and an alignment film are formed thereon, and then a pair of substrates which are subjected to a uniaxial alignment treatment are formed. A liquid crystal panel having a chiral smectic C phase is interposed between the substrates so that the directions of the uniaxial alignment treatment are substantially parallel to the upper and lower substrates, and a liquid crystal panel is interposed between these substrates. 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 identifying the switching of the optical axis, a chiral smectic C
The layer structure in the phase is a chevron structure bent in the shape of a "ku", and the alignment region generated from the relationship between the uniaxial alignment processing direction and the layer structure is a lightning defect generated in the uniaxial alignment processing direction and the back of the defect. It is characterized by being inside a region surrounded by hairpin defects occurring at the same time, or outside a region surrounded by hairpin defects occurring in the alignment processing direction and lightning defects occurring behind, and its alignment state is uniform And having a switching process involving inversion of liquid crystal molecules near the substrate;
Chi Tsu pretilt angle against the substrate of the click layer 8 ° or more 2
The ferroelectric liquid crystal layer is composed of an organic alignment film of 0 ° or less, and i) the following formula (IV) :

Embedded image In either a compound represented by (IV), ii) the following formula (III):

Embedded image To provide a liquid crystal display device comprising a compound represented by (III) and of compound (IV) is from each ferroelectric liquid crystal composition of the chevron structure containing one or. Further, the following formula (V):

Embedded image It is preferable to include the compound (V) represented by

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

In the definitions of the above compounds ( III), (IV) and (V), straight-chain or branched-chain 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-hexyloctyl, decyl, -Methylnonyl, undecyl, 1-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 ( IV) and (V) include the following.

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Embedded image Among them, preferred compounds include 11-2, 11-7, 11
-10, 12-1, 12-6, 12-7, 13-2, 13-9, 14-
1 , 14-2 , 18-4 and the like. The above compound
Of the products, 14-3 to 17-7 are compounds (IV) and (V)
However, these are not included in the ferroelectric liquid crystal layer.
Is a compound which may be Further , specific chemical structures of those contained in compound (III) include the following.

Embedded image

Embedded image

Embedded image Among these, preferred compounds are 23-1, 23-2, 23
-3, 23-4, 21-6, 21-7, 22-7, 22-8 and the like.

An example of a method for producing the compound represented by the compound (IV) is as follows. 2-fluoro-
4- (trans-4-alkylcyclohexyl) benzoic acid ( (VI) is reacted with phosphorus pentachloride to give acid chloride (VII)
After that, it can be obtained by reacting with a 4-hydroxyalkyl (VIII) in a toluene solvent in the presence of pyridine.

Embedded image

The ferroelectric liquid crystal composition of the present invention comprises the above compound
Compounds ( III), (IV) and (V) can be adjusted by mixing with known ferroelectric liquid crystals and compositions. In particular, it is suitable to adjust the phase sequence so as to be INAC. Usually, the content of the compounds ( IV) and (V) is 4 wt% in total.
As described above, it is preferable that the content of each component contained in the compounds ( IV) and (V) is 25 wt% or less. When the total content of the compounds ( IV) and (V) is less than 4 wt%, the effect of improving the contrast by 1/3 bias driving is insufficient, and the content per component of the single product is 20 wt%.
% Is not suitable because crystallization of the additive occurs and the temperature range of the smectic C phase does not match the temperature range used as a display.

[0032]

Further, the mixing ratio of the sum of the compound (III) of the reduction compound (IV) is preferably set to 50~95wt%. If it exceeds 95 wt%, the memory may be insufficient,
1/3 bias driving is not contrast sufficiently improved, when less than 20 wt%, is not suitable because it can not maintain the temperature range suitable <br/> Sumeku Ji click C phase as a display.

The ferroelectric liquid crystal composition of the present invention includes:
Various additives may be blended as long as the intended effects of the present invention are not impaired. For example, from the viewpoint of improving the orientation, another liquid crystal compound having a fluoroalkyl group at a terminal or a liquid crystal compatible compound is blended (usually 0.01 to 1 wt.
%), Examples of which are described in, for example,
7, 891 and the like.

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

In general, the layer structure in the chiral smectic C layer generally has a “ku” as shown in FIG.
It is said to have a chevron structure folded in the shape of a letter. As shown in the figure, there are two directions in which the layers bend. At this time, an alignment defect called a zigzag defect occurs where the bending direction of the layer changes. FIG. 2B is a schematic diagram when the zigzag defect is observed with 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 was changed to <<
It is clear that the portion with >>> corresponds to the lightning defect, and the portion with the layer structure >>>> corresponds to the hairpin defect (N. Hij).
i et al. , Jpn. J. Appl. Phys. ,
27 , L1 (1988). ). The relationship between the rubbing direction and the pretilt angle θ _P is as shown in FIG. 2A, and the above two orientations are C1 orientation and C1 orientation based on the relationship with the rubbing direction.
It is called two orientations (Kanbe, Proceedings of the IEICE Technical Seminar, "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 case where they are the same is defined as C2 orientation (chevron 2).

By increasing the pretilt angle θ _P ,
The difference between the alignment states of the liquid crystal molecules in the C1 alignment and the C2 alignment becomes remarkable, and a large value of 8 ° or more (preferably
When the alignment film showing (〜 °) is used, in the C1 orientation on the high temperature side, a region showing a clear extinction position and a region not showing a quenching position are observed, and in the C2 orientation on the low temperature side, a clear extinction position is observed. Are observed only. It is generally accepted that the uniform alignment and the twist alignment are distinguished by the presence or absence of an extinction position (Fukuda, Takezoe, "Structure and Physical Properties of Ferroelectric Liquid Crystal", Corona, 1990, p-
327) Here, what shows the extinction position in the C1 orientation is C
A 1U (C1 uniform) orientation and a C1 orientation that does not show an extinction position are referred to as a 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, whereas in the C2 orientation, the contrast is significantly reduced despite the fact that the extinction position is shown when no voltage is applied, Even lower contrast can be obtained for the C1T orientation. Researchers of the present invention have found that the contrast has the following tendency, and the C1U orientation is particularly preferable in terms of contrast. C1U> C2 >> C1T

FIG. 4 shows a specific example of such a ferroelectric liquid crystal display device of the present invention. A transparent electrode 2a,
The substrate 9 is obtained by forming each layer in the order of the insulating film 3a and the alignment film 4a. 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 in which uniaxial alignment processing by rubbing is performed.

On the other hand, the substrate 10 is obtained by forming the respective layers on the other glass substrate 1b in the order of the transparent electrode 2b, the insulating film 3b and the alignment film 4b under the same conditions. Like 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 uniaxial alignment treatment by rubbing. The structure has been.

Next, the substrates 9 and 10 are arranged such that the alignment films 4a and 4b face each other, the transparent electrodes 2a and 2b are orthogonal to each other, and the rubbing directions of the substrates 9 and 10 are substantially the same. And the sealing member 6 is spaced at an interval of about 1.5 to 3 μm, preferably 1.2 to 1.8 μm.
Paste in.

A liquid crystal cell 11 is formed between the substrates 9 and 10 with the ferroelectric liquid crystal composition 7 interposed therebetween.

Further, polarizing plates 12a and 12b whose polarizing axes are substantially orthogonal to each other are arranged above and below the cell, and one of the polarizing axes of the polarizing plate is made to substantially coincide with one of the liquid crystal axes of the cell. Display device.

Needless to say, the liquid crystal element in which the liquid crystal composition containing at least one compound (IV) can be used is not limited to the above-mentioned ferroelectric liquid crystal element, but a ferroelectric liquid crystal element having another structure or a nematic liquid crystal element. Needless to say, 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-pentylcyclohexene
Synthesis of hexyl) heptyl benzoate (No. 101) 2-Fluoro-4- (trans-4-pentylcyclohexyl)
0.7 g (0.0024 mol) of benzoic acid
0.6 g (0.0029 mol) of phosphorus hydride is added,
To heat the reaction. POCl generated_Three And excess
Of phosphorus pentachloride was distilled off under reduced pressure to give 2-fluoro-4- (toluene).
4-pentylcyclohexyl) benzoic acid chloride
I got This was dissolved in 10 ml of toluene, and
0.7 g (0.0030 mol) of heptyl xylbenzoate
1 ml of pyridine (dehydrochlorinating agent) was added. 10 at room temperature
After leaving for 3 hours, keep at 70 ° C for 3 hours, then cool to room temperature
Rejected. Then add ice and hydrochloric acid, extract with ether
Was. The ether layer was washed with NaHCO _Three Wash with aqueous solution and then with water
Na_TwoSO_FourAnd dried. Distill ether off and leave residue
To high performance liquid chromatography (Deltas made by Waters)
Prep 3000 liquid chromatography; C-18
Ricagel column; solvent methanol + chloroform (8:
Purify in 2) and recrystallize from ethanol
2-fluoro-4- (trans-4-pentylcyclohexane
Xyl) heptyl benzoate was obtained. Infrared absorption of this compound
The yield spectrum is shown in FIG. Also, the transition temperature of this compound
The degrees were as follows:Further, Compound (IX) used in Examples of the present invention is shown below.
You.

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Reference Example 1 Using the compound of the compound (IX), the liquid crystal composition No. 1 having the composition shown in Table 1 was prepared. 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.

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

The liquid crystal composition prepared in Example 2 Example 1 No. No. 202 shows the optically active compound No. shown in the compound (IX). 124 was added in an amount of 2% by weight, and the ferroelectric liquid crystal composition No. 124 was added. 203 were 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. Table 1 shows the composition of the liquid crystal composition. This ferroelectric liquid crystal composition shows a chiral smectic C phase in a temperature range of pickup,
INA which is preferable for the orientation of a ferroelectric liquid crystal device
The C phase series was shown.

Example 3 1000 mm thick I on each of two glass substrates
A TO film was formed, and a 500 ° SiO ₂ insulating film was formed thereon.
These substrates were formed to a thickness of 0 ° and then subjected to a uniaxial orientation treatment by rubbing using a rayon-based cloth.
A liquid crystal cell was fabricated by bonding the substrates at a thickness of 20 μm so that the rubbing directions were antiparallel. The nematic liquid crystal E-8 manufactured by Merck was injected into this, and the pretilt angle of the liquid crystal molecules from the substrate was measured using a magnetic field capacity method. Table 2 shows the results.

Example 4 A ferroelectric liquid crystal device having the structure shown in FIG. 4 was manufactured. On a glass substrate 1a, a plurality of ITO transparent electrodes 2a each having a thickness of 1000 ° are arranged in a stripe shape so as to be parallel to each other, and a 500 ° SiO 2 is formed thereon as an insulating film 3a.
Is formed, and then PSI-A-200 is formed as the alignment film 4a.
1 (polyimide manufactured by Chisso Petrochemical Co., Ltd.) was formed to a thickness of 400 ° by a spin coater, and then subjected to a uniaxial orientation treatment by rubbing using a rayon-based cloth to obtain a substrate 9.
Was formed. On the other hand, the same process was performed on the other glass substrate 1b to form a substrate 10.

Next, the substrate 9 and the other substrate 10
In order that 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 almost coincident with each other, the resin is made of an epoxy resin through a silica spacer at a 1.5 μm interval. The sealing member 6 was used for bonding. Between these substrates 9 and 10, the ferroelectric liquid crystal composition No. prepared in Example 3 from the injection port by a vacuum injection method. 20
After injecting No. 3, the injection port was cured with an acrylic UV-curable resin to form a liquid crystal cell 11. Further, polarizing plates 12a and 12b whose polarization axes are substantially perpendicular to the upper and lower sides of the cell.
Was arranged, and one polarization axis of the polarizing plate was made substantially coincident with one of the optical axes of the liquid crystal of the cell to obtain a liquid crystal display device.

Examination of the orientation of the ferroelectric liquid crystal device revealed that, in the temperature region from the smectic C-smectic A transition point to room temperature, a small C2 orientation region surrounded by minute zigzag defects was observed. Except for, the entire surface was in C1U orientation.

The tilt angles of these ferroelectric liquid crystal devices in the chiral smectic C phase were measured. The tilt angle was defined as 角度 of the angle between the two extinction positions obtained when a rectangular wave of ± 10 V was applied to the liquid crystal cell. The tilt angle was plotted against temperature (FIG. 6).

The voltage (V = ± 10) having the waveform shown in FIG.
V) was applied and the memory pulse width was measured. Fig. 7 shows the results.
Shown in The memory pulse width was set to 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 memory pulse width was measured by applying a voltage (V = ± 10 V) having a ｂ bias waveform shown in FIG. 3B. The memory pulse width was set to the minimum pulse width that allows bistable switching. FIG. 7 shows the results. Also, the pulse width is set to the memory pulse width, and FIG.
As a result, a high contrast of 10 was obtained. In this case, it can be concluded that a favorable black state can be maintained even when the bias is applied, and that the fluctuation of molecules due to the bias voltage is suppressed.

[0055] The liquid crystal composition was prepared in Comparative Example 1 Example 2 No. Among the components contained in Compound No. 203 Ferroelectric liquid crystal composition was divided <br/> taken for comparison 101 No. 212 was produced. This liquid crystal composition also showed a smectic C phase at room temperature. This liquid crystal composition No. Table 1 shows the composition of 212.

The ferroelectric liquid crystal composition N in Example 4
o. No. 203 is a ferroelectric liquid crystal composition No. 203 for comparison. 2
A ferroelectric liquid crystal device was manufactured in the same manner as in Example 4 except that the ferroelectric liquid crystal device was replaced with No. 12. When the orientation was observed, it was C2 orientation, and no favorable quenching state was observed.

Comparative Example 2 Using the compound shown in Compound (IX), a ferroelectric liquid crystal composition having the composition shown in Table 2 was prepared. 206 to 211 were produced.

The ferroelectric liquid crystal composition N in Example 4
o. No. 203 is a ferroelectric liquid crystal composition No. 203 for comparison. 2
A ferroelectric liquid crystal element was manufactured in the same manner as in Example 4 , except that the ferroelectric liquid crystal element was replaced with any one of 06 to 211.

[0059] Further, the strength in Example 4 ferroelectric liquid crystal composition No. 203 is a ferroelectric liquid crystal composition N for comparison.
o. 206 to 211, and PSI-A-2001 in the fourth embodiment is replaced with PSI-S-01.
A ferroelectric liquid crystal device was manufactured in the same manner as in Example 4 except that the ferroelectric liquid crystal device was replaced with PVA or PVA.

Table 3 shows the results of an examination of these ferroelectric liquid crystal devices. None of the ferroelectric liquid crystal devices obtained good results as obtained in Example 4 .

[Table 3]

Reference Example 2 The liquid crystal composition No. 2 prepared in Example 2 Among the components contained in Compound No. 203 Compound N instead of 101
o. No. 127 containing 15% of ferroelectric liquid crystal composition No. 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 device was produced in the same manner as in the above. When the orientation was observed, in the temperature range from the smectic C-smectic A transition point to room temperature, except for the area of small C2 orientation surrounded by small zigzag defects,
The entire surface was in the C1U orientation.

The tilt angles of these ferroelectric liquid crystal devices in the chiral smectic C phase were measured. The tilt angle was defined as 角度 of the angle between the two extinction positions obtained when a rectangular wave of ± 10 V was applied to the liquid crystal cell. The tilt angle was plotted against temperature (FIG. 8).

The voltage (V = ± 10) having the waveform shown in FIG.
V) was applied and the memory pulse width was measured. FIG. 9 shows the results.
Shown in The memory pulse width was set to 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 1/3 bias waveform voltage (V = ± 10 V) 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. FIG. 9 shows the results. Also, the pulse width is set to the memory pulse width, and FIG.
As a result, a high contrast of 10 was obtained. In this case, it can be concluded that a favorable black state can be maintained even when the bias is applied, and that the fluctuation of molecules due to the bias voltage is suppressed.

Reference Example 3 Using the compound shown in Compound (IX), the ferroelectric liquid crystal composition No. 1 having the composition shown in Table 1 was prepared. 214 were 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. In the ferroelectric liquid crystal composition No. 5 in Example 5, 203 is a ferroelectric liquid crystal composition No. 203. Example with the exception of replacing with 214
In the same manner as in No. 4 , a ferroelectric liquid crystal element was produced. Observation of the orientation revealed that the entire surface was in the C1U orientation in the temperature region from the smectic C-smectic A transition point to room temperature, except for a small C2 orientation region surrounded by minute zigzag defects.

The tilt angles of these ferroelectric liquid crystal devices in the chiral smectic C phase were measured. The tilt angle was defined as 角度 of the angle between the two extinction positions obtained when a rectangular wave of ± 10 V was applied to the liquid crystal cell. The tilt angle was plotted against temperature (FIG. 10).

The voltage (V = ± 10) having the waveform shown in FIG.
V) was applied and the memory pulse width was measured. FIG. 9 shows the results.
Shown in The memory pulse width was set to 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 1/3 bias waveform voltage (V = ± 10 V) 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. Also, the pulse width is set to the memory pulse width, and FIG.
As a result, a high contrast ratio of 10 was obtained. In this case, it can be concluded that a favorable black state can be maintained even when the bias is applied, and that the fluctuation of molecules due to the bias voltage is suppressed.

Reference Example 4 Using the compound shown in Compound (IX), the ferroelectric liquid crystal composition No. 1 having the composition shown in Table 1 was prepared. 215 were 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. In the ferroelectric liquid crystal composition No. in Example 4, 203 is a ferroelectric liquid crystal composition No. 203. Example except for replacing with 215
In the same manner as in No. 4 , a ferroelectric liquid crystal element was produced. Observation of the orientation revealed that the entire surface was in the C1U orientation in the temperature region from the smectic C-smectic A transition point to room temperature, except for a small C2 orientation region surrounded by minute zigzag defects.

The tilt angles of these ferroelectric liquid crystal devices in the chiral smectic C phase were measured. The tilt angle was defined as 角度 of the angle between the two extinction positions obtained when a rectangular wave of ± 10 V was applied to the liquid crystal cell. The tilt angle was plotted against temperature (FIG. 12).

The voltage (V = ± 10) having the waveform shown in FIG.
V) was applied and the memory pulse width was measured. Figure 1 shows the results
3 is shown. The memory pulse width was set to 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 memory pulse width was measured by applying a voltage (V = ± 10 V) having a バ イ ア ス bias waveform shown in FIG. 3B. The memory pulse width was set to the minimum pulse width that allows bistable switching. FIG. 13 shows the results. Also, the pulse width is set to the memory pulse width, and FIG.
As a result, a high contrast ratio of 20 was obtained. In this case, it can be concluded that a favorable black state can be maintained even when the bias is applied, and that the fluctuation of molecules due to the bias voltage is suppressed.

Reference Example 5 Using the compound shown in Compound (IX), the ferroelectric liquid crystal composition No. 1 having the composition shown in Table 1 was obtained. 204, 205, 216, 2
17, 218 and 219 were produced. This liquid crystal composition also showed a smectic C phase at room temperature.

The ferroelectric liquid crystal composition N in Example 4
o. No. 203 shown in Table 1 204, 205, 21
6, 217, 218, and 219 in the same manner as in Example 4 except that the ferroelectric liquid crystal composition was replaced with any one of the following:
A ferroelectric liquid crystal device was manufactured. Observation of the orientation in the temperature region from the smectic C-smectic A transition point to room temperature showed that the entire surface was in C1U orientation except for a small C2 orientation region surrounded by minute zigzag defects.

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

A voltage having a 1/3 bias waveform (V = ± 10 V) 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. 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 obtained in a wide temperature range from the AC transition temperature to around room temperature.
A U orientation is obtained. The temperature range in which C1U switching can be performed during the ３ bias driving is wide. Is 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 ３ bias driving method can be applied.

[Brief description of the drawings]

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

FIG. 2 is a diagram for explaining a chevron layer structure of a chiral smectic C phase, and C1 orientation and C2 orientation.

3A is a diagram illustrating an example of an applied voltage waveform with 0 bias, and FIG. 3B is a diagram illustrating an example of an applied voltage waveform with 1/3 bias.

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

FIG. 5: Compound No. of the present invention FIG. 2 is a view showing an infrared absorption spectrum of the infrared sensor 101.

FIG. 6 is a diagram showing a temperature change of a tilt angle of a ferroelectric liquid crystal composition using the compound of the present invention.

FIG. 7 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. 8 is a diagram showing a temperature change of a tilt angle of a ferroelectric liquid crystal composition using the compound of the present invention.

FIG. 9 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. 10 is a diagram showing a temperature change of a tilt angle of a ferroelectric liquid crystal composition using the compound of the present invention.

FIG. 11 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. 12 is a diagram showing a temperature change of a tilt angle of a ferroelectric liquid crystal composition using the compound of the present invention.

FIG. 13 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.

[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

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomoaki Kurate 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor: Veiko Taniguchi 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka In-house (56) References JP-A-3-252624 (JP, A) JP-A-3-31392 (JP, A) JP-A-2-110189 (JP, A) (58) Fields studied (Int. . ^6, DB name) C09K 19/42 CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] An electrode is selectively formed on the surface, an insulating film and an alignment film are formed thereon, and then a pair of substrates subjected to a uniaxial alignment process is applied to a pair of upper and lower substrates. A liquid crystal panel having a chiral smectic C phase is interposed between these substrates so as to be substantially parallel to each other, and a liquid crystal panel is formed. 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 discriminating switching of an optical axis, a layer structure in a chiral smectic C phase is a chevron structure bent in a “<” shape. The alignment region generated from the relationship between the alignment processing direction and the layer structure is surrounded by lightning defects generated in the uniaxial alignment processing direction and hairpin defects generated behind the defects. It is characterized by being inside the region or outside the region surrounded by hairpin defects occurring in the alignment processing direction and lightning defects occurring behind, the alignment state is uniform, and near the substrate of the liquid crystal molecules and having a switching process with a reversal in, consists of Sumeku Ji click layer organic alignment film substrate against pretilt angle of 8 ° or more than 20 ° of, and the ferroelectric liquid crystal layer is i) the following formula ( IV) : Or is a compound represented by (IV), ii) the following formula (III): ## STR3 ## Compound represented by (III) and of compound (IV) liquid crystal display device comprising a from each ferroelectric liquid crystal composition of the chevron structure containing one or. 2. The method according to claim 1, further comprising the following formula (V): The device according to claim 1 , comprising a compound (V) represented by the following formula: 3. The tilt angle of the liquid crystal composition is not less than 4 ° and not more than 2 °.
In the driving temperature range of 5 ° C or less, 5
Apparatus according to any of claims 1 to 2, characterized in that it is not greater than 0 °.