JPH063705A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain a high contrast by using a liquid crystal compsn. contg. a specific compd. and oriented films having a high pretilt angle. CONSTITUTION:The liquid crystal panel is constituted by disposing a pair of substrates, which are formed with electrodes on the surfaces and are formed with insulating films and the oriented films thereon and are then subjected to a uniaxial orientation treatment, in such a manner that the directions of the uniaxial orientation treatments face each other in parallel and interposing a liquid crystal having a chiral smectic C phase between these substrates. The laminar structure of the chiral smectic C phase is a chevron structure and the ferroelectric liquid crystal layer contains the compd. expressed by formula. The compd. expressed by the formula exhibits a m.p. which is not high. The compd. is liable to exhibit the smectic C phase and smectic A phase and is chemically stable to light as well. Then, the various liquid crystal compsns. are formable by combining the compd. with other compds.

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 high-contrast matrix-type large capacity display ferroelectric liquid crystal display device.

[0002]

2. Description of the Related Art At present, liquid crystal display elements are used in a wide range of fields such as timepieces, calculators, office automation equipment such as word processors and personal computers, pocket televisions, etc. However, generally widely used liquid crystal display elements have a nematic phase. It was used. A liquid crystal display device using a nematic liquid crystal includes a twisted nematic type (Twisted).
Nematic TN liquid crystal display device, Supertwisted Biref
There is a range effect (SBE type) liquid crystal display device and the like.

However, in the twisted nematic liquid crystal display element, there is a drawback that the driving margin becomes narrower as the number of scanning lines increases and a sufficient contrast cannot be obtained, so that it is difficult to make a large capacity display element. . In order to improve this TN type liquid crystal display element, a super twisted nematic (STN) type liquid crystal display element and a double layer super twisted nematic (DSTN) type liquid crystal display element have been developed. Therefore, the display capacity of about 800 × 1024 lines is currently the limit.

On the other hand, a thin film transistor (TF) is formed on the substrate.
An active matrix type liquid crystal display element in which T) is arranged has also been developed, and it has become possible to display a large capacity such as 1000 × 1000 lines, but the manufacturing process is long, the yield is likely to be lowered, and the manufacturing cost is very high. It has the drawback that Further, it is considered that this method is difficult to manufacture a large-capacity display element such as 2000 × 2000 lines due to restrictions such as semiconductor mobility.

However, there is a growing demand for display devices in the world toward higher resolutions, and in particular, DTP (Desk Top Publics) is being demanded.
ing), EWS (Engineering Wor)
k Station) and other fields such as WYSIWYG
(W hat y ou s ee i s w hat y ou
The concept of g et) has been actively emphasized. This is a concept of displaying on the display device the same one that is printed out. The resolution of current laser printers is 400 DPI (400 dot / inc)
h), so to realize the concept of WYSIWYG, at least A4 size or more, 2000 × 2
There is a demand for a display device having a resolution of 000 or more.

Ferroelectric liquid crystal display elements (NA. Clark and) are considered to be promising as liquid crystal elements capable of displaying a large capacity of 2000 × 2000 lines or more.
S. T. Lagerwall, Appl. Phys. L
ett. , 36,899 (1980); JP-A-56-1
07216; U.S. Pat. No. 4,367,924). This liquid crystal display element is different from the field effect type nematic liquid crystal display element 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.

Ferroelectric liquid crystal elements are chiral smectic C
Phase, chiral smectic F phase, chiral smectic I phase, and other ferroelectric liquid crystals are used. Although these ferroelectric liquid crystals have a helical structure, it is disclosed that when these ferroelectric liquid crystals are sandwiched between liquid crystal cells having a cell thickness smaller than the helical pitch, the helical structure is unraveled. Actually, as shown in FIG. 2, it is possible to realize a state in which a region in which liquid crystal molecules are inclined and stabilized with respect to the smectic layer normal by a tilt angle θ and a region in which liquid crystal molecules are inclined and stabilized in the opposite direction by θ are mixed. Subsequent studies have revealed it. By applying an electric field in the direction perpendicular to the paper surface in FIG. 1, the directions of the liquid crystal molecules and their spontaneous polarization can be made uniform, and switching between the two states can be performed by switching the polarity of the applied electric field. It can be carried out. With this switching, in the ferroelectric liquid crystal in the cell, the transmitted light can be controlled by sandwiching the ferroelectric liquid crystal element between two polarizers whose birefringent light changes. Furthermore, 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 a memory effect can be obtained. In addition, since the spontaneous polarization of the liquid crystal and the electric field directly act on the time required for the switching drive, a high-speed response on the order of μsec can be obtained.

As described above, the characteristics of this ferroelectric liquid crystal device include bistability, memory property, high speed response and the like. Therefore, it is possible to configure a high-resolution liquid crystal display device having a large number of scanning lines by a multiplex drive system by using this ferroelectric liquid crystal, and since an active element such as a thin film transistor is not required, It has an advantage that the manufacturing cost does not increase. In addition, the ferroelectric liquid crystal device also has the advantage of wide vision, and it is highly promising as a device for large-capacity display that realizes the concept of WYSIWYG.

[0009]

Although the ferroelectric liquid crystal device has the advantages as described above, in a large capacity display device having 1000 × 1000 or more scanning lines, a high-contrast display without flicker is obtained. However, the following problems arise. That is, one method for performing flicker-free display is 16.7 msec (60
One screen is rewritten within (Hz). 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,
As can be seen from the following formula, a high-speed response of 8.4 μsec is required.

16.7 (msec) ÷ 1000 ÷ 2 = 8.4 (μsec) (Here, dividing by 2 is for ferroelectric liquid crystal,
This is because writing requires at least 2 pulses. However, at present, it is not easy 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, IEICE Technical Seminar, "Optoelectronics" -Liquid Crystal Display and Related Materials-, 1990) January, p
18 ^- 26) has been proposed. 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.

However, in order to obtain a display without flicker by using this partial rewriting method, a bias voltage which is ⅓ of the writing voltage is also applied to the pixels which are not rewritten (hereinafter, this driving method is 1 / 3 bias drive method). This driving method is proposed in, for example, Japanese Patent Laid-Open No. 64-59389, but the problem of using the 1/3 bias driving method is that it is 1/3 even for a pixel which is not rewritten.
A bias voltage is applied, and this bias voltage causes fluctuations in the molecules of pixels that are not rewritten, which impairs the memory state and causes the decrease in contrast due to fluctuations in the molecules.

For example, in a ferroelectric display prototyped by Canon Inc. using the partial rewriting method, a contrast of only 5: 1 was obtained (Kanbe, The Institute of Electronics, Information and Communication Engineers Special Workshop Lecture Collection "Optoelectronics"-
Liquid Crystal Display and Related Materials-, January 1990, p18-2
6). Further, the present inventors have produced a display element by combining various ferroelectric liquid crystal display devices with various liquid crystal elements up to now, but it was obtained when the display was performed using the 1/3 bias driving method. The contrast value was about 1.5 to 8, which was unsatisfactory as a product.

In order to solve such a contrast problem, it is necessary to apply an appropriate liquid crystal material to a ferroelectric liquid crystal device having an appropriate structure. From such a viewpoint, a novel liquid crystal compound useful for improving the contrast, a liquid crystal composition using the same, and a liquid crystal element are required.
A practical ferroelectric liquid crystal composition is usually prepared by mixing a plurality of components. Sometimes, as the component, 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. The properties required for the ferroelectric liquid crystal composition include not only the high contrast achieved by combining with a suitable 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, the ferroelectric liquid crystal composition has rather low spontaneous polarization in order to obtain good bistability of the ferroelectric liquid crystal device. 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 generally INAC (Isotropic-Nmat) is used.
The ic-Slectic A-Sticc) phase sequence is most preferred.

A long helical pitch in the nematic phase and the smectic C phase is also necessary for obtaining good orientation. It is also necessary to show a smectic C phase in a wide temperature range around room temperature, and it is chemically stable, stable to light, has no coloring, does not have a high viscosity, and has a smectic C phase. It is also required to have an appropriate tilt angle.

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.

[0017]

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 resulting 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 region surrounded by the hairpin defects that occur in the, or outside the region surrounded by the hairpin defects that occur in the alignment treatment direction and the lightning defects that occur behind, the orientation state is uniform. And the ferroelectric liquid crystal layer is i) the following formula (I):

[0018]

[Chemical 5] Or at least one compound (I) represented by: ii) the following formula (II):

[0019]

[Chemical 6] Or at least one of compound (II) and compound (I) represented by: iii) the following formula (III):

[0020]

[Chemical 7] Or at least one compound (III) and compound (I) represented by: iv) the following formula (IV):

[0021]

[Chemical 8] A liquid crystal display device comprising a ferroelectric liquid crystal composition having a chevron structure, which comprises at least one of the compound (IV) and the compound (I) each represented by The present invention provides a uniform C1 when a ferroelectric liquid crystal display device is constructed by combining the above specific alignment film and a specific liquid crystal composition.
It is based on the discovery that a U-aligned chevron-structured liquid crystal layer can be obtained over a wide temperature range, and as a result, stable display with a high contrast ratio can be achieved without causing defects or non-uniformity of alignment. Is.

Compounds (I), (II), (III) and (I
In the definition of 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-methyloctyl , Decyl, 1-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 those contained in compound (I) include the following.

[0024]

[Chemical 9]

[0025]

[Chemical 10]

[0026]

[Chemical 11]

[0027]

[Chemical 12]

[0028]

[Chemical 13]

[0029]

[Chemical 14]

[0030]

[Chemical 15]

[0031]

[Chemical 16] Among these, preferred compounds include (1)-(4), (6), (1
1), (14), (26), (42), (45), (48), (49)-(51), (6
1), (65), (69) and the like. The compound (I) does not necessarily show the smectic C phase, but it is likely to show the smectic A phase, and when mixed with other compounds, the compound (I) or IAC or IN
It can be said that the material is useful for realizing the AC phase series.

Further, the melting point is not so high, and it is easy to mix with other compounds. It is chemically and light stable, and it is not colored. The compound (I) can be applied to various liquid crystal compositions by combining with various compounds at an appropriate ratio, and is particularly useful when preparing a ferroelectric liquid crystal composition. As an example of a compound that may be combined to form a ferroelectric liquid crystal composition, the compound (II),
(III) and (IV) can be mentioned.

Here, specific chemical structures of those contained in the compound (II) are as follows.

[0034]

[Chemical 17] Among these, preferred compounds include (75)-(84) and the like. Further, specific chemical structures of those contained in the compound (III) include the following.

[0035]

[Chemical 18]

[0036]

[Chemical 19]

[0037]

[Chemical 20]

[0038]

[Chemical 21]

[0039]

[Chemical formula 22]

[0040]

[Chemical formula 23] Of these, preferred compounds include (94), (96), (111)
, (112), (113), (122)-(131) and the like.
Further, specific chemical structures of those contained in the compound (IV) include the following.

[0041]

[Chemical formula 24]

[0042]

[Chemical 25]

[0043]

[Chemical formula 26]

[0044]

[Chemical 27]

[0045]

[Chemical 28]

[0046]

[Chemical 29] Among these, preferred compounds include (128)-(131) and (16
4), (184), (185), (196), etc. The ferroelectric liquid crystal composition of the present invention comprises the compounds (I) and (I
It can be prepared by mixing I), (III) and (IV) with a known ferroelectric liquid crystal or composition. Especially when the phase sequence is IN
It is suitably prepared to be AC.

Usually, the total content of compound (I) is 5
It is preferable that the content is at least wt% and not more than 20 wt% of the whole single component contained in the compound (I) group.
If the content of the entire compound (I) is less than 5 wt%, 1 /
The effect of improving the contrast is insufficient with 3 bias drive, and if the content per single component exceeds 20 wt%, crystallization of the additive may occur, or the temperature range of the smectic C phase becomes the temperature range used as a display. Not suitable because it will not fit.

The mixing ratio of the compound (II) to the compound (I) is preferably 20 to 95 wt%. 95 wt%
If the value exceeds 20%, the memory is insufficient, and the effect of improving the contrast by 1/3 bias driving is insufficient,
If it is less than%, the temperature range of the smectic C phase suitable for a display cannot be maintained, which is not suitable. Also,
The mixing ratio of the compound (III) to the compound (I) is 20 to 95w.
It is preferably t%. If it exceeds 95 wt%, the memory is insufficient or the contrast is not sufficiently improved by the 1/3 bias drive, and if it is less than 20 wt%, the suitable smectic C phase temperature range as a display cannot be maintained, which is not suitable. .

The mixing ratio of the compound (IV) to the compound (I) is preferably 20 to 95 wt%, particularly 10 to 95 wt%.
50 wt% is preferred. If it exceeds 50 wt%, the memory is insufficient or the contrast is not sufficiently improved by the 1/3 bias drive, and if it is less than 10 wt%, it is not suitable because the suitable temperature range of the smectic C phase as a display cannot be maintained. .

The ferroelectric liquid crystal composition of the present invention includes
Various additives may be incorporated as long as the effects intended by the present invention are not impaired. For example, in order to improve 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, for example.

Next, as a preferred example thereof, the directions of the uniaxial alignment treatment of the pair of substrates are parallel, 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 a square shape 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. In the bending direction of the layers, as shown in FIG. 2 (a),
There are two directions. 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 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 studies, the part with a layer structure <<>> corresponds to the lightning defect, and the part with a layer structure >><< corresponds to the hairpin defect. It has been clarified (N. Hiji
et al. , Jpn. J. Appl. Phys. , 2
7 , L1 (1988). ). The relationship between the rubbing direction and the pretilt angle θ _P is as shown in Fig. 2, and the above two orientations are called C1 orientation and C2 orientation because of the relationship with the rubbing direction (Kanbe, IEICE Special Workshop. Proceedings "Optoelectronics" -Liquid Crystal Display and Related Materials-, January 1990, p18-26). The case where the rubbing axis and the layer bending direction are the same is defined as C1 orientation (chevron 1), and the opposite case is defined as C2 orientation (chevron 2).

Now, when the pretilt angle θ _P is increased,
The difference in the alignment state of the liquid crystal molecules between the C1 orientation and the C2 orientation becomes remarkable, and when an orientation film showing a large value of 8 ° or more is used, a region showing a clear extinction position in the C1 orientation on the high temperature side. And a region showing no extinction position are observed, and in the C2 orientation on the low temperature side, only a region showing a clear extinction position is observed. It is generally accepted that uniform orientation and twist orientation are distinguished by the presence or absence of an extinction position (Fukuda, Takezoe, “Structure and Properties of Ferroelectric Liquid Crystals”, Corona Publishing Co., Ltd., 1990, p-327). Here, a C1 orientation shows an extinction position, a C1U (C1 uniform) orientation, and a C1 orientation shows no extinction position.
This is referred to as T (C1 twist) orientation. Since only one type of C2 orientation was obtained, only the C2 orientation will be described.

When a 1/3 bias voltage waveform as shown in FIG. 3B is applied, good contrast is obtained in the C1U orientation, whereas the extinction position is shown in the C2 orientation when no voltage is applied. Nevertheless, the contrast is significantly reduced, and even lower contrast is obtained for the C1T orientation. The researchers of the present invention have found that the contrast has the following tendency,
The C1U orientation is particularly preferable in terms of contrast.

Good contrast C1U> C2 >> C1T
Poor Contrast The ferroelectric liquid crystal composition containing the compound (I) easily exhibits CIU orientation when combined with an orientation film having a large pretilt angle, and gives good contrast at 1/3 bias driving. A specific example of such a ferroelectric liquid crystal display device of the present invention is shown in FIG.

The substrate 9 is formed by forming the transparent electrode 2a, the insulating film 3a, and the alignment film 4a in this order on the glass substrate 1a. 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, on the other side of the glass substrate 1b, under the same conditions, the transparent electrode 2b, the insulating film 3b,
The substrate 10 is one in which each layer is formed in the order of the alignment film 4b. Similar to the substrate 9, the transparent electrode 2b and the alignment film 4b are formed by arranging a plurality of transparent electrodes in stripes so that they are 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 of the substrates 9 and 10 are orthogonal to each other, and the rubbing directions of the substrates 9 and 10 are substantially the same. The seal member 6 is provided at intervals of about 1.0 to 3 μm, preferably 1.2 to 1.8 μm.
Stick together. A liquid crystal cell 11 is formed with a ferroelectric liquid crystal composition 7 interposed 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 of the optical axes of the liquid crystals 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, and a ferroelectric liquid crystal device having another structure or a nematic phase is used. It goes without saying that the present invention can be applied to such liquid crystal elements (TN, STN, DSTN, etc.), liquid crystal elements utilizing smectic A phase (thermal writing, electroclinic, etc.), antiferroelectric liquid crystal elements, and the like.

[0059]

【Example】

Example 1 The compounds used in the examples of the present invention are shown in Table 1. Liquid crystal composition No. 1 having the composition shown in Table 2 was prepared using the compounds shown in Table 1.
201 was produced. Table 3 shows the transition temperatures of this liquid crystal composition. This liquid crystal composition showed a smectic C phase at room temperature.

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

[Table 3]

[0063]

[Table 4]

[0064]

[Table 5]

Example 2 Liquid crystal composition No. 1 prepared in Example 1 Compound N in 201
o. Liquid crystal composition No. 119 was added by 10% by weight. Two
02 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 2.

Example 3 The liquid crystal composition No. prepared in Example 2 was used. 202 shows the optically active compound No. 2 shown in Table 1. 2% by weight of ferroelectric liquid crystal composition No. 130. 203 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 2, and the transition temperature is shown in Table 3.

[0067]

[Table 6]

Example 4 A ferroelectric liquid crystal device having the structure shown in FIG. 4 was produced. On the glass substrate 1a, a plurality of ITO transparent electrodes 2a having a thickness of 1000 Å are formed in stripes so as to be in equilibrium with each other, and 500 Å SiO is formed as an insulating film 3a.
₂ 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 Å by a spin coater, and then uniaxially oriented by rubbing with a rayon-based cloth to obtain a substrate 9
Was 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. Then,
The substrate 9 and the other substrate 10 are aligned with each other by the alignment film 4
1.5 μm so that a and 4 b face each other, the transparent electrodes 2 a and 2 b are orthogonal to each other, and the rubbing directions are substantially the same.
The seal members 6 made of epoxy resin were attached to each other with a space between them and a silica spacer. These substrates 9, 1
0 between the ferroelectric liquid crystal composition No. 1 manufactured in Example 3 from the injection port by the vacuum injection method. After injecting 203, the injection port is cured with an acrylic UV-curable resin to form a liquid crystal cell 1.
Created 1. Further, polarizing plates 12a and 12b whose polarization axes are substantially orthogonal to each other are arranged above and below the cell, and one polarization axis of the polarizing plates is substantially aligned with one of the optical axes of the liquid crystals of the cell to form a liquid crystal display device. did.

When the state of orientation of this ferroelectric liquid crystal element was examined, in the temperature region of the smectic C phase, the entire surface was C1U oriented except for the region of C2 orientation surrounded by minute zigzag defects and small in area. Met. The tilt angle θ in the chiral smectic C phase of these ferroelectric liquid crystal devices was measured. The tilt angle θ was defined as ½ of the angle between two extinction positions obtained by applying a rectangular wave of a liquid crystal cell ± 10V. θ was plotted against temperature (FIG. 5).

The voltage of the waveform shown in FIG. 3 (a) (V = ± 10
V) was applied and the memory pulse width was measured. The result is shown in Fig. 6.
Shown in. The memory pulse width was set to the minimum pulse width that enables bistable switching. When the pulse width was set to the memory pulse width and the waveform of FIG. 3 (a) was applied, a contrast of 30 or more was obtained. A voltage (V = ± 10V) having a 1/3 bias waveform shown in FIG. 3B is applied,
The memory pulse width was measured. The memory pulse width was set to the minimum pulse width that enables bistable switching.
The results are shown in Fig. 7. When the pulse width was set to the memory pulse width and the waveform of FIG. 3B was applied, a high contrast of 10 was obtained. In this case, it can be concluded that a good black state can be maintained when a bias is applied, and the fluctuation of molecules due to the bias voltage is suppressed.

Example 5 The liquid crystal composition No. prepared in Example 3 was used. Of the components contained in 203, compound No. Ferroelectric liquid crystal composition No. 204 was produced. This liquid crystal composition also showed a smectic C phase at room temperature. This liquid crystal composition N
o. The composition of 204 is shown in Table 2, and the transition temperature is shown in Table 3.

Ferroelectric liquid crystal composition N in Example 3
o. 203 is a ferroelectric liquid crystal composition No. A ferroelectric liquid crystal element was produced in the same manner as in Example 3 except that the liquid crystal element was replaced with 204. The tilt angle θ was measured and plotted against the temperature in the same manner as in Example 4 (FIG. 7). Furthermore, FIG.
The voltage of the 1/3 bias waveform shown in (b) (V = ± 10
V) was applied and the memory pulse width was measured. 204 did not have a memory property.

Example 6 The liquid crystal composition No. prepared in Example 3 was used. Of the components contained in 203, compound No. 119 as Compound No. 129
Ferroelectric liquid crystal composition No. 205 was produced. This liquid crystal composition also showed a smectic C phase at room temperature. This liquid crystal composition No. The composition of 205 is shown in Table 2, and the transition temperature is shown in Table 3.

Ferroelectric liquid crystal composition N in Example 3
o. 203 is a ferroelectric liquid crystal composition No. A ferroelectric liquid crystal element was produced in the same manner as in Example 3 except that 205 was substituted. Further, the tilt angle θ was measured and plotted against the temperature in the same manner as in Example 4 (FIG. 8). Figure 3
The voltage (V = ± 10V) of the 0 vice waveform shown in (a) and the voltage (V = ± 1) of the 1/3 bias waveform shown in FIG. 3B.
0 V) was applied and the memory pulse width was measured (FIG. 9).

The pulse width is set to the memory pulse width, and FIG.
When the waveform of (a) was applied, a contrast of 30 or more was obtained, and when the waveform of FIG. 3 (b) was applied, a high contrast of 10 was obtained.

Comparative Example For comparison, the compounds of Table 1 were used and the liquid crystal composition Nos. 206-No. 211 was created. These liquid crystal compositions exhibited a smectic C phase at room temperature. The ferroelectric liquid crystal composition No. 3 in Example 5 was used. 203 to these ferroelectric liquid crystal composition No. 206-No. A ferroelectric liquid crystal element was manufactured in the same manner as in Example 5 except that the liquid crystal element was replaced with 211.

The results are shown in Table 4. None of the ferroelectric liquid crystal compositions gave good results as obtained in Examples 5 and 6.

[0079]

[Table 7]

[0080]

The compound represented by the formula (I) has a melting point not so high, tends to show a smectic C phase and a smectic A phase, and is chemically and light-stable. Therefore, the compound represented by the formula (I) is useful as a component of a liquid crystal composition, and by combining with another compound, various liquid crystal compositions including various ferroelectric liquid crystal compositions are produced. It can be applied to various liquid crystal elements. In particular, when a ferroelectric liquid crystal device utilizing the C1U orientation was produced using a ferroelectric liquid crystal composition containing the compound represented by the formula (I) and an orientation film having a high pretilt angle, a 1/3 bias High contrast can be obtained even in driving.

[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 applied voltage waveform of 0 bias. (B) is a figure which shows an example of the applied voltage waveform of 1/3 bias.

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

FIG. 5: Ferroelectric liquid crystal composition N using the compound of the present invention
o. 6 is a diagram showing a change in tilt angle θ of 203 with temperature. FIG.

FIG. 6 is a ferroelectric liquid crystal composition N using the compound of the present invention.
o. FIG. 6 is a diagram showing a temperature change of a memory pulse width of 203.

FIG. 7: Ferroelectric liquid crystal composition N using the compound of the present invention
o. FIG. 6 is a diagram showing a change in tilt angle θ of 204 with temperature.

FIG. 8 shows a ferroelectric liquid crystal composition N using the compound of the present invention.
o. FIG. 6 is a diagram showing a temperature change of a tilt angle θ of 205.

FIG. 9: Ferroelectric liquid crystal composition N using the compound of the present invention
o. FIG. 5 is a diagram showing a temperature change of a memory pulse width of 205.

[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

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 a uniaxial alignment treatment is performed on the upper and lower substrates. The liquid crystal panel is 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 drive means and a means for optically distinguishing the switching of the optical axes, 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 a lightning defect that occurs in the uniaxial alignment treatment direction and a hairpin defect that occurs behind the defect. 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, the alignment state is uniform, and the ferroelectric liquid crystal layer I) The following formula (I): Or at least one compound (I) represented by: ii) the following formula (II): Or at least one of compound (II) and compound (I) represented by: iii) the following formula (III): Or at least one compound (III) and compound (I) represented by: iv) the following formula (IV): A liquid crystal display device comprising a ferroelectric liquid crystal composition having a chevron structure, which comprises at least one of the compound (IV) and the compound (I). 2. The device according to claim 1, wherein the pretilt angle of the liquid crystal molecules at the interface with the alignment film is 8 ° or more. 3. The device according to claim 2, wherein the tilt angle of the liquid crystal composition is not larger than the pretilt angle by 5 ° or more in the driving temperature range.