JPH05155817A - Liquid crystal compound, composition and display device using the same - Google Patents

Abstract

PURPOSE:To obtain a new liquid crystal compound useful for manufacturing a practical ferroelectric liquid crystal composition having high contrast. CONSTITUTION:A new compound of formula I. The compound of formula I, for example, is obtained by reacting 2-fluoro-4-(trans-4-alkylcyclohexyl)benzoic acid with phosphorus tetrachloride to give an acid chloride and reacting the acid chloride with an alkyl 4-hydroxybenzoate in the presence of pyridine in toluene solvent. The compound of formula I is preferably combined with a compound of formula II (R5 and R6 are alkyl or alkyloxy; (m) and (n) are 0 or 1), etc., to manufacture a ferroelectric liquid crystal composition. When a ferroelectric liquid crystal display device utilizing CIU orientation is manufactured by using the ferroelectric liquid crystal composition containing the compound of formula I and an orientated film having a high pretilt angle, a high contrast can be obtained even in 1/3 bias drive.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a liquid crystal compound, a liquid crystal composition containing the same and a liquid crystal device.

[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, pocket televisions, etc., but generally used liquid crystal display devices utilize a nematic phase. It was done. As a liquid crystal display device using nematic liquid crystal, a twisted nematic type (Twisted Nemati
c TN type liquid crystal display device, Super twisted type (Supe
rtwistedBirefrengence Effect, SBE type) liquid crystal display device.

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. However, the display capacity of 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 device 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 decrease, and the manufacturing cost is very high. It has the drawback that In addition, 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, the demand for display devices in the world is becoming higher and higher,
In particular, DTP (D esk T op P ublishi
ng), EWS (E ngineering W ork
In fields such as Station, WYIWYG ( W ha
t y ou s ee i s w hat y ou g e
The concept of t) is vigorously emphasized. This is a concept of displaying the same as the one printed out on the display device. Since the resolution of the current laser printer is about 400 DPI (400 dot / inch), in order to realize the concept of WYSIWYG, a display device having at least A4 size or more and 2000 × 2000 or more resolution is required. ..

A ferroelectric liquid crystal display element (NA Clark ST Lager) is promising as a liquid crystal element capable of displaying a large capacity of 2000 × 2000 lines or more.
wall, Appl. Phys. Lett. , 36 , 899
(1980); JP-A-56-107216; U.S. Pat. No. 4367924)
Is. This liquid crystal display element is different from the field effect type nematic liquid crystal display device 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 polarity 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. 1, it is possible to realize a state in which a region in which liquid crystal molecules are inclined and stabilized by an angle θ with respect to the smectic layer normal and a region in which liquid crystal molecules are inclined and stabilized by θ in the opposite direction are mixed. Research has revealed. 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 performed. With this switching, the birefringent light changes in the ferroelectric liquid crystal in the cell, so that 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, 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, and high-speed response. Therefore, it is possible to construct 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, the manufacturing cost is reduced. It has the advantage of not increasing. In addition, the ferroelectric liquid crystal device has the advantage that it has a wide visual field, and it is highly promising as a large-capacity display-like device that realizes the concept of WYSIWYG.

[0009]

Ferroelectric liquid crystal devices have the advantages described above, but display high-contrast display without flicker in large-capacity display devices having 1000 × 1000 or more scanning lines. The following problems will arise. That is, one method for displaying without flicker is to rewrite one screen within 16.7 msec (60 Hz). In this case, the ferroelectric liquid crystal material is required to have a very high response speed. For example, 10 scan lines
In the case of 00 display elements, as can be seen from the following equation, 8.4 μ
A high-speed response of sec is required.

16.7 (msec) ÷ 1000 ÷ 2 = 8.4 μsec (Here, dividing by 2 means that in the case of a ferroelectric liquid crystal,
This is because at least 2 pulses are required for writing. However, it is not easy at present to realize the required response speed by improving the ferroelectric liquid crystal material. In addition, considering that the response speed must be further increased when producing a display device having a larger capacity, it is quite difficult to increase the capacity by increasing the speed of the liquid crystal material. You can easily imagine.

As a powerful technique for solving such a problem, a technique called partial rewriting (Kanbe, Proc. Of the Institute of Electronics, Information and Communication Engineers Special Workshop, "Optoelectronics" -Liquid Crystal Display and Related Materials-, 1990) January, p18-2
6) is 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 applied to the pixels which are not rewritten (hereinafter, this driving method will be used). Called 1/3 bias driving method). This driving method has been proposed in, for example, Japanese Patent Laid-Open No. 64-59389, but the biggest problem in using the 1/3 bias method is 1 / n
A bias voltage of 3 is applied, and this bias voltage causes fluctuations in the molecules of pixels that are not rewritten, resulting in a decrease in contrast. For example, the ferroelectric liquid crystal display prototyped using the partial rewriting method has not been obtained with a contrast of only 5: 1 (Kanbe, IEICE Technical Seminar, "Optoelectronics" -related to liquid crystal display. Materials-1990 1
Mon, p18-26). Further, the present inventors have produced a display device by combining various ferroelectric liquid crystal compositions with liquid crystal devices having various configurations, but it was obtained when a display was performed using the 1/3 bias driving method. The contrast value is 1.
It was about 5 to 8 and was a very unsatisfactory product.

In order to solve such a problem of contrast, it is necessary to apply an appropriate liquid crystal material to a ferroelectric liquid crystal device having an appropriate constitution. From such a viewpoint, a novel liquid crystal compound useful for improving 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. 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, the response speed is required to be high, and from this point, low viscosity is required. Increasing the spontaneous polarization is also useful for increasing the response speed, but in order to obtain good bistability of the ferroelectric liquid crystal device, it is possible to obtain good alignment when applied to the ferroelectric liquid crystal device. In order to obtain the property, the phase sequence of the ferroelectric liquid crystal composition is important, and in general, INAC (Isotrop)
ic-Nematic-Smectic A- Smec
The tic C ) phase series is most preferred. A long helical pitch in the nematic phase and smectic C phase is also necessary for obtaining good orientation. It is also required to be stable around room temperature, not colored, not to have a high viscosity, and to have an appropriate tilt angle in the smectic C phase.

The present invention has been made under such circumstances, and a novel liquid crystal compound, a liquid crystal composition, and a liquid crystal display useful for producing a practical high-contrast ferroelectric liquid crystal composition. The purpose is to provide a device.

[0015]

The present invention provides the following formula (I);

[0016]

[Chemical 2] A novel compound represented by, and a liquid crystal composition characterized by containing at least one compound thereof, and forming transparent electrodes respectively on the surfaces facing each other of the pair of translucent substrates, each transparent electrode is coated Forming an insulating film to
In a liquid crystal display device in which an organic alignment film that covers the alignment film is formed, and a liquid crystal is filled between a pair of translucent substrates, a pair of substrates having an alignment film subjected to an alignment process is formed by aligning the alignment process direction of the alignment film. Relates to a ferroelectric liquid crystal display device characterized in that they are arranged so as to be substantially parallel to each other and at least one liquid crystal composition is contained between the substrates.

The compound represented by the formula (I) is, for example, 2-
Fluoro-4- (trans-4-alkylcyclohexyl) benzoic acid (A) was reacted with phosphorus pentachloride to give an acid chloride (B), and then alkyl 4-hydroxybenzoate (C) was added in a toluene solvent in the presence of pyridine. ) And can be obtained. The compound represented by the formula (I) does not necessarily exhibit the smectic C phase, but it is likely to exhibit the smectic A phase and the nematic phase, and can be said to be a useful material for realizing the INAC phase series by mixing with other compounds. Moreover, the melting points are not high, and it is easy to mix with other compounds. It is stable both chemically and to light and is free of color.

Next, the conditions for using the compound of the present invention in the liquid crystal composition will be described. The compound represented by formula (I) can be applied to various liquid crystal compositions by combining with various compounds in an appropriate ratio. In particular, it is useful when producing a ferroelectric liquid crystal composition. Examples of the compound that may be combined with the ferroelectric liquid crystal composition when it is produced include compounds represented by the chemical formulas (III) and (IV).

[0019]

[Chemical 3]

[0020]

[Chemical 4] [In the formula, R5 and R6 are the same or different and each represents a linear or branched alkyl group or alkyloxy group having 1 to 15 carbon atoms, and m and n each represent an integer of 0 or 1. The ferroelectric liquid crystal composition of the present invention comprises the compound (I)
It can be prepared by mixing with the above-mentioned ferroelectric liquid crystal or composition. In particular, it is suitable to prepare so that the phase sequence is INAC. Usually, the content of the compound (I) is preferably 50 wt% or more as a whole, and 50 wt% or less of the whole one component contained in the compound (I) group.

When the total content of the compound (I) is less than 50 wt%, the effect of improving the contrast is insufficient by the 1/3 bias driving, and the content per single component is 50 w.
If it exceeds t%, the INAC phase series is not exhibited, and thus orientation failure occurs, which is not suitable. Various additives may be added to the ferroelectric liquid crystal composition of the present invention 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 may be blended (usually 0.01 to 1 wt%).

It is needless to say that the ferroelectric liquid crystal composition needs to exhibit a chiral smectic phase and needs to include an optically active compound having an appropriate structure, and it is appropriate to use a compound other than the compounds (III) and (IV). It goes without saying that various compounds may be added. Needless to say, the compound of the present invention can be applied to various liquid crystal compositions such as a nematic liquid crystal composition, a smectic A liquid crystal composition and an antiferroelectric liquid crystal composition.

The liquid crystal composition containing the compound of the present invention can be applied to various liquid crystal elements. Next, the ferroelectric liquid crystal composition containing the compound represented by the formula (I) is applied to the ferroelectric liquid crystal element. As an example of realizing a high contrast by using a pair of substrates in a liquid crystal device in which a ferroelectric liquid crystal is sandwiched between a pair of insulating precision substrates on which at least electrodes and an alignment film subjected to uniaxial alignment treatment are formed. The directions of the uniaxial alignment treatment are parallel, the driven liquid crystal phase is a chiral smectic C phase, and in the chiral smectic C phase, the smectic layer structure has a chevron structure bent in a V shape. In the temperature range, it occurs inside the area surrounded by the lightning defect that occurs in the uniaxial orientation treatment direction and the hairpin defect that occurs behind the defect, or in the uniaxial orientation treatment direction. The alignment state generated outside the region surrounded by the hairpin defect and the lightning defect generated behind the defect is a uniform state, and the ferroelectric liquid crystal is represented by the formula (I). A ferroelectric liquid crystal device characterized by containing at least one compound containing

Generally, it is said that the layer structure of the chiral smectic C layer has a febron structure which is generally in the shape of a dogleg as shown in FIG. 2 (a). There are two directions in which the layers bend, as shown in Fig. 2 (a). 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 observing the zigzag defect with a polarization 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
It has been clarified that the part with <<>> corresponds to the lightning defect and the part with the layer structure >><< corresponds to the hairpin defect (N. Hiji).
et al., Jpn. Appl. Phys., 27, L1.
(1988).). The relationship between the rubbing direction and the pretilt angle θ _P is shown in Fig. 2, and the above two orientations are called the C1 orientation and the C2 orientation because of the relationship with the rubbing direction (Kanbe, IEICE Technical Seminar Lecture Proceedings "Optoelectronics" -Liquid Crystal Display and Related Materials-, 1990
January 18th, p18-26). The case where the rubbing axis and the bending direction of the layer 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 alignment film showing a large value of 8 ° or more is used, a clear extinction position is obtained 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 the uniform orientation and the twist orientation are distinguished by the presence or absence of an extinction position (Fukuda, Takezoe, “Structure and Physical Properties of Ferroelectric Liquid Crystals”, Corona Publishing Co., Ltd., 1990, p327), now here. In the above, the one exhibiting the extinction position in the C1 orientation will be called C1U (C1 uniform) orientation, and the one not exhibiting the extinction position in the C1 orientation will be 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 of 1/3 bias as shown in FIG. 3B is applied, the obtained contrast is as follows, and only the C1U array can realize a practically high contrast. C1U> C2 >> C1T The ferroelectric liquid crystal composition containing the compound containing the compound (I) of the present invention, when combined with an alignment film having a large pretilt angle, tends to show C1U alignment, and is driven by 1/3 bias. Gives good contrast.

FIG. 4 is a sectional view showing an example of the liquid crystal element of the present invention. A plurality of transparent electrodes 2a are arranged in a stripe pattern on a glass substrate 1a so as to be parallel to each other, and an insulating film 3a and an alignment film 4a are formed on the transparent electrode 2a. The alignment film 4a is uniaxially aligned by rubbing. Processing is performed to form the substrate 9. On the other hand, on the other side of the glass substrate 1b, a plurality of transparent electrodes 2b are formed in stripes so as to be parallel to each other under the same conditions.
The insulating film 3b and the alignment film 4b are formed thereon, and the alignment film 4
The substrate 10 is formed by subjecting b to the rubbing orientation treatment.

Next, this substrate 10 is the other substrate 9
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, and the seal member 6 is spaced at an interval of about 1.5 to 3 μm.
Stick together. A liquid crystal cell 11 is created with a ferroelectric liquid crystal interposed between these substrates 9 and 10. Furthermore, 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 made to substantially coincide with one of the optical axes of the liquid crystals of the cell to form a liquid crystal display device. To do.

Of course, the liquid crystal element for which the liquid crystal composition containing at least one of the general formula (I) can be used is not limited to the above-mentioned ferroelectric liquid crystal element, but a ferroelectric liquid crystal element having another structure, or It is needless to say that the present invention can be applied to liquid crystal elements using nematic I (TN, STN, DSTN, etc.), liquid crystal elements using smectic A phase (thermal writing, electronic, etc.), and antiferroelectric liquid crystal elements.

【Example】

Example 1 0.7 g (0.0024 mol) of 2-fluoro-4- (trans-4-pentylcyclohexyl) benzoic acid was added to 0.6 g of phosphorus pentachloride.
g (0.0029 mol) was added, and the mixture was heated to about 80 ° C. and reacted. The produced POCl ₃ and excess phosphorus pentachloride were distilled off under reduced pressure to obtain 2-fluoro-4- (trans-4-pentylcyclohexyl) benzoic acid chloride. Dissolve this in 10 ml of toluene and heptyl 4-hydroxybenzoate.
0.7 g (0.0030 mol) and pyridine (demineralized water material) 1 m
1 was added. After leaving it for 10 hours at room temperature, it was kept at 70 ° C. for 3 hours and then cooled to room temperature. Then add ice and hydrochloric acid,
Extracted with etal. The ether layer was washed with aq. NaHCO ₃ , then water and dried over Na ₂ SO ₄ . The ether was distilled off, and the residue was purified by high performance liquid chromatography (Waters Deltaprep 3000 liquid chromatography; C-18 silica gel column; solvent methanol + chloroform (8: 2)) and recrystallized from ethanol. The desired 2-fluoro-4- (trans-4
-Pentylcyclohexyl) heptyl benzoate was obtained.
The infrared absorption spectrum of this compound is shown in FIG. Also,
The transition temperature of this compound was as follows.

[0031]

Comparative Example 1 A liquid crystal composition N having the composition shown in Table 3 was prepared using the compounds shown in Table 1.
Table 4 shows the transition temperatures of this liquid crystal composition of Example No. 201. This liquid crystal composition showed a smectic C phase at room temperature, but did not show a smectic A phase.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

Example 2 Liquid crystal composition No. 1 prepared in Comparative Example 1 201, compound No. 201 of the present invention synthesized in Example 1. Add 10% by weight of 101,
Further, the optically active substance Nos. 2% by weight of ferroelectric liquid crystal composition No. 124 was added. 202 was produced. This liquid crystal composition showed a smectic C phase at room temperature. The composition of this liquid crystal composition is shown in Table 3, and the transition temperature is shown in Table 4. This ferroelectric liquid crystal composition showed a chiral smectic C phase in a wide temperature range, and showed an INAC phase series preferable for the orientation of the ferroelectric liquid crystal device.

Example 3 1000 Å thick ITO on each of two glass substrates
A film is formed, and a 500 Å SiO ₂ insulating film is formed on top of this, and the alignment film shown in Table 5 is formed on this with a spin coater to a thickness of 400 Å, and then rubbed with rayon cloth. Uniaxial orientation treatment was performed. A liquid crystal cell was produced by laminating these substrates with a thickness of 20 μm so that the rubbing directions were anti-parallel. A nematic liquid crystal E-8 manufactured by Merck Ltd. was injected into this, and the pretilt angle was measured from the substrate of liquid crystal molecules by using the magnetic field capacitance method. The results are shown in Table 5.

[0039]

[Table 5]

Example 4 A ferroelectric liquid crystal display device having the structure shown in FIG. 4 was produced. On a glass substrate 1a, a plurality of ITO transparent electrodes 2a each having a thickness of 1000 Å are arranged in a stripe pattern so as to be parallel to each other, and 500 Å SiO ₂ is formed as an insulating film 3a on the ITO transparent electrodes 2a. , PSI-X-A-2001 as the alignment film 4a
(Polyimide manufactured by Chisso Petrochemical Co., Ltd.) was formed to a thickness of 400 Å by a spin coater, and then uniaxial orientation treatment by rubbing was performed using a rayon-based cloth to form a substrate 9. 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 are 1.5 μm thick so that the alignment films 4a and 4b face each other and the transparent electrodes 2a and 2b are orthogonal to each other and the rubbing directions are substantially the same. The silica spacers were separated by a distance of 1 and bonded with the sealing member 6 made of epoxy resin. Between the substrates 9 and 10, the ferroelectric liquid crystal composition No. 1 manufactured in Example 2 was injected from the injection port by the vacuum injection method. After injecting 202, 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 arranged above and below the cell, and one polarizing axis of the polarizing plates is made to substantially coincide with either optical axis of the liquid crystal 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 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 θ in the chiral smectic C phase of these ferroelectric liquid crystal devices was measured. The tilt angle θ 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.
θ was plotted against temperature (FIG. 6).

Voltage of the waveform shown in FIG. 3 (a) (V = ± 10V)
Was applied and the memory pulse width was measured. The results are shown in Fig. 7. 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. 3 (a) 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 1/3 bias waveform shown in FIG. 3 (b). The memory pulse width was set to the minimum pulse width capable of 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 (b) was applied, a high contrast of about 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 2 Liquid crystal composition No. 1 prepared in Example 2 Of the components contained in No. 202, compound No. 202 of the present invention. Compound No. 101 is used for comparison. Ferroelectric liquid crystal composition No. 117 20
3 was produced. This liquid crystal composition also has smectic C at room temperature.
Showed a phase. This liquid crystal composition No. The composition of 203 is shown in Table 3.
Table 4 shows the transition temperatures.

Ferroelectric liquid crystal composition N in Example 4
o. 202 is a ferroelectric liquid crystal composition No. 202 for comparison. 203
A ferroelectric liquid crystal display device was produced in the same manner as in Example 4 except that When the state of orientation of this ferroelectric liquid crystal element was examined, smectic C-smectic A
In the temperature range from the 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. The tilt angle θ was measured in the same manner as in Example 4 and plotted against temperature (FIG. 8).

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 pulse width was set to the memory pulse width and the waveform in Fig. 3 (b) was applied. Switching between C1U and C1U was 60 ° C.
C1U-C1U below 59 ° C
It became switching between.

Comparative Example 3 The liquid crystal composition No. 3 prepared in Example 2 was used. Of the components contained in No. 202, compound No. 202 of the present invention. 101 is the compound No. for comparison. 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 No. The composition of 204 is shown in Table 3
Table 4 shows the transition temperatures.

Ferroelectric liquid crystal composition N in Example 4
o. 202 is a ferroelectric liquid crystal composition No. 202 for comparison. 204
A ferroelectric liquid crystal display device was produced in the same manner as in Example 4 except that When the state of orientation of this ferroelectric liquid crystal element was examined, smectic C-smectic A
From the transition point to around 35 ° C, except for the area of C2 orientation surrounded by minute zigzag defects, which is small in area, the entire surface is C
The orientation was 1U, but at lower temperatures, it was C2 orientation.

A voltage (V = ± 10 V) having a 1/3 bias waveform shown in FIG. 3B was applied and the memory pulse width was measured.
When the pulse width was set to the memory pulse width and the waveform of FIG. 3 (b) was applied, switching between C1U and C1U was observed only in the range of 62 ° C. from the smectic C-smectic A transition point.

Comparative Example 4 Ferroelectric liquid crystal composition No. 3 having the composition shown in Table 3 was prepared using the compounds shown in Table 1. 205 to 210 were produced. Table 4 shows the transition temperatures of these liquid crystal compositions. The ferroelectric liquid crystal composition No. 1 in Example 4 was used. 202 is a ferroelectric liquid crystal composition No. 202 for comparison. A ferroelectric liquid crystal display device was produced in the same manner as in Example 4 except that any of 205 to 210 was substituted.

Further, the ferroelectric liquid crystal composition No. 1 in Example 4 was used. 202 is a ferroelectric liquid crystal composition No. 202 for comparison.
205-210, ZLI-4237 / 000 (Merck), ZL
Replace with any one of I-4655 / 000 (Merck)
In addition, the alignment film PSI-X-A-2001 in Example 4 is set to P
A ferroelectric liquid crystal was produced in the same manner as in Example 4 except that SI-XS-014 or PVA was used instead.

Table 6 shows the results of an examination of these ferroelectric liquid crystal elements. Neither of the ferroelectric liquid crystal elements provided the good results as obtained in Example 4.

[0053]

[Table 6]

[0054]

INDUSTRIAL APPLICABILITY The compound (I) of the present invention has a melting point not so high, is likely to show a smectic phase and a nematic phase, and is stable chemically and to light. Therefore, the compound (I) is useful as a component of a liquid crystal composition, and by combining it with other compounds,
Various liquid crystal compositions including various ferroelectric liquid crystal compositions can be prepared and can be applied to various liquid crystal devices.
In particular, when a ferroelectric liquid crystal display device utilizing C1U orientation is manufactured using a ferroelectric liquid crystal composition containing the compound (I) of the present invention and an orientation film having a high pretilt angle,
High contrast can be obtained even in the 3-bias drive.

[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 layer structure of a chiral smectic C phase, and a C1 orientation and a C2 orientation.

3A is a diagram showing an applied voltage waveform of 0 bias, FIG.
(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. FIG. 3 is a diagram showing an infrared absorption spectrum of 101.

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 tilt angle θ of 202.

FIG. 7: Ferroelectric liquid crystal composition N using the compound of the present invention
o. It is a figure which shows the temperature change of the memory pulse width of 202.

FIG. 8 shows a ferroelectric liquid crystal composition No. 3 for comparison. FIG. 6 is a diagram showing a change in tilt angle θ of 203 with temperature.

[Explanation of symbols]

 1a, 1b Glass substrate 2a, 2b Transparent electrode 3a, 3b Electrode protective film 4a, 4b Alignment film 6 Sealing member 7 Liquid crystal 9, 10 Substrate 11 Liquid crystal cell 12a, 12b Polarizing plate

Claims (3)

[Claims] 1. The following formula (I): A compound having: 2. A liquid crystal composition comprising at least one compound of formula (I) according to claim 1. 3. A transparent electrode is formed on each surface of a pair of translucent substrates facing each other, an insulating film is formed to cover each transparent electrode, and an organic alignment film is formed to cover the transparent electrode. In a liquid crystal display device in which liquid crystal is filled between translucent substrates, a pair of substrates having an alignment film subjected to alignment processing are arranged so as to face each other so that the alignment processing directions of the alignment films are substantially parallel to each other. A ferroelectric liquid crystal display device comprising at least one liquid crystal composition according to claim 2 in between.