JP3091091B2 - Liquid crystal display device - 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. More specifically, the present invention relates to a liquid crystal device using a ferroelectric liquid crystal.

[0002]

2. Description of the Related Art A conventional liquid crystal display device uses a nematic liquid crystal. As a liquid crystal display device using a nematic liquid crystal, a twisted nematic type (Twisted Nematic) is used.
matic, TN type) liquid crystal device, super twisted type (Su
pertwisted Birefringence Effect (SBE type) liquid crystal display devices. The TN type liquid crystal display device has a drawback that the drive margin becomes narrower as the drive system becomes more multiplexed, and a sufficient contrast cannot be obtained. Further, the SBE type liquid crystal display device which is an improved type of the TN type liquid crystal display device and uses a large twist angle has a drawback that when used for large-capacity display, the contrast is lowered and the response speed is reduced. Therefore, in 1980, Clark (NAC)
Lack and STLagerwall have proposed a liquid crystal display device using a chiral smectic C liquid crystal, that is, a ferroelectric liquid crystal (US Pat. No. 4,368,924).
No. JP-A-56-107216).

This liquid crystal display device is different from a conventional nematic liquid crystal display device using an electro-incline effect utilizing the dielectric anisotropy of liquid crystal molecules, in which the polarity of the spontaneous polarization of the ferroelectric liquid crystal and the polarity of the electric field are different. This is a liquid crystal display element using a rotational force for matching the two. Characteristics of this liquid crystal display element include bistability, memory properties, high-speed response, a wide viewing angle, and the like. That is, as shown in FIG. 2, when the liquid crystal is injected into a cell in which the gap of the ferroelectric liquid crystal is thinned, the helical structure of the ferroelectric liquid crystal is released under the influence of the substrate interface, and the liquid crystal molecules 11 are formed by the smectic layer method. Angle of inclination + θ with respect to line 12
A region that is stable by tilting by 17 and a region that is stable by tilting by −θ18 in the opposite direction are mixed, and have bistability. By applying an electric field 16 to the ferroelectric liquid crystal in this cell, the directions of the liquid crystal molecules 11 and the spontaneous polarization 15 can be made uniform, and by switching the polarity of the applied electric field 16, Switching that switches the orientation of 11 from one state to another is possible.

[0004] With the switching operation, the birefringent light of the ferroelectric liquid crystal in the cell changes, so that the transmitted light can be controlled by interposing a polarizing cell between one polarizer. Further, even when the application of the electric field 16 is stopped, the alignment of the liquid crystal molecules 11 is maintained in the state before the stop of the electric field application due to the alignment regulating force at the interface, so that a memory effect can be obtained. In addition, the time required for switching has a high-speed response of 1/1000 or less of that of the nematic liquid crystal display element because the spontaneous polarization of the liquid crystal and the electric field directly act on it.
Thereby, high-speed display is possible.

[0005] Therefore, application of the excellent characteristics of the ferroelectric liquid crystal to a liquid crystal display device having a high definition and a large display capacity and a spatial modulation device capable of storing light at high speed and with high speed has been actively studied. ing.

[0006]

However, the Clark and Lagabar type liquid crystal display devices also have many problems. First, the liquid crystal of the chiral smectic C phase exhibiting ferroelectricity has low molecular symmetry as compared with a normal nematic liquid crystal, and further has a strong crystallinity, which makes it difficult to uniformly align the liquid crystal. There was a disadvantage that it was difficult to obtain.

In the initial model of ferroelectric liquid crystal,
It has been considered that the layer structure of the smectic C phase takes a structure perpendicular to the substrate called a bookshelf type as shown in FIG. Here, 9 and 10 are substrates, 13 is a smectic layer, and 12 is a smectic layer normal line.

However, when a cell is formed by using a conventional alignment method based on rubbing or the like, the expected switching phenomenon and optical characteristics are largely different from each other, and the switching is completely different from the proposed model. As one of the factors, it was analyzed by the small angle scattering method of X-ray that the layer structure has a structure that bends in the shape of a “ku” called a chevron as shown in FIG. 4 [TPRieker , N.
A. Clark et al .: Phys. Rev. Lett. 59, p2658 (198
7)]. However, reference numeral 14 denotes a connecting portion of the chevron structure, which is a place called a chevron interface. Another difference from the original model is that not only do spontaneous polarization and uniform alignment of liquid crystal molecules be uniform, but also twist alignment in which molecules are twisted between the upper and lower substrates. [Y. Ouchi,
H. Takezoe and A. Fukada: Jpn. J. Appl. Phys. 26,
p1 (1987)]. In particular, it has been found that a ferroelectric liquid crystal aligned by rubbing has a twisted alignment in many cases because a regulating force at the interface acts strongly. When such an orientation is taken, a difference in optical molecular axis in switching between two states generally does not appear effectively, and high contrast characteristics cannot be obtained.

In order to solve these drawbacks, there have been proposed a number of methods for achieving the model proposed by Clark et al. One of them is that a method using a SiO oblique deposition method has a relatively high pretilt. There is a report that the layer is prevented from being bent by imparting to the substrate, and an obliquely inclined layer structure is achieved. As a second method, a method of changing the layer structure to a bookshelf structure by applying a high voltage alternating electric field to a cell having a bent structure has been proposed [Sato et al., The 12th Liquid Crystal Discussion ( Nagoya), 1F16 (1986)], all reported that high contrast characteristics were obtained.

[0010] However, the oblique vapor deposition method has a serious problem in terms of production because it is difficult to make the vapor deposition angle uniform and requires a vacuum process. In addition, it is difficult to uniformly change the layer structure of the method of applying an electric field, and in many cases, the original chevron structure gradually changes with the passage of a long period of time, and has not yet been put to practical use. The present invention has been made to solve such a problem, and an object of the present invention is to provide a liquid crystal display element and a liquid crystal display device which can exhibit high contrast characteristics despite a chevron structure.

[0011]

According to the present invention, a ferroelectric liquid crystal is interposed between substrates having an alignment film on the surface of a pair of transparent electrodes, and the surface of the alignment film is subjected to a uniaxial alignment treatment. In the liquid crystal display device, the liquid crystal has a smectic layer structure, the direction of the bending is the same as the direction of the uniaxial alignment treatment, and the alignment film is 2,2-bis [4- (4-aminophenoxy) phenyl. ] Propane, 1,2,4,
Provided is a liquid crystal display device comprising a polyimide containing 5-benzenetetracarboxylic dianhydride as a main component.

In the present invention, the alignment film is formed from a specific polyimide. This polyimide contains, as main components, an amine component represented by 2,2-bis [4- (4-aminophenoxy) phenyl] propane and a carboxylic acid component which is 1,2,4,5-benzenetetracarboxylic dianhydride. And polymerized.

The polymerization is usually carried out using 2,2-bis [4-
An amine represented by (4-aminophenoxy) phenyl] propane and a carboxylic acid component represented by 1,2,4,5-benzenetetracarboxylic dianhydride are mixed in a solvent and heated. This is performed by forming a polyamic acid solution, applying it to a substrate constituting a liquid crystal cell, and then heating the substrate to a predetermined temperature. The polymerization is
In addition to the above main component, a small amount of, for example, 1-amino-4-trimethoxysilylbenzene or the like can be further added as an auxiliary component. At this time, 2,2-bis [4- (4-
Aminophenoxy) phenyl] propane and 1,2,4
The molar ratio with 5-benzenetetracarboxylic dianhydride is
The ratio is preferably from 1: 1 to 1: 2. When 1-amino-4-trimethoxysilylbenzene is used as a sub-component, it is preferable to polymerize each component in a molar ratio satisfying the following formula.

[0014]

(Equation 1) (Where A, B and C are 1,2,4,5-benzenetetracarboxylic dianhydride and 2,2-bis [4-
(4-aminophenoxy) phenyl] propane and 1-
Shows amino-4-trimethoxysilylbenzene. ).
More preferably,

[0015]

(Equation 2) It is.

The solvent used for mixing the amine component and the carboxylic acid component is, for example, N-methylpyrrolidone (NM
P), dimethylacetamide (DMAC), diethylformamide (DMF) and the like can be used. It is preferable that the heating is usually performed at 50 ° C. or lower. More preferably, the temperature is between 5 and 50C. In the polyamic acid solution, the concentration of the polyamic acid is set so as to have a viscosity suitable for coating, and is usually 0.1 to 30% by weight.

As the substrate constituting the liquid crystal display element of the present invention, for example, a light-transmitting insulating substrate made of glass, plastic (polymethyl methacrylate or the like) or the like can be used.
An electrode in which an electrode is selectively formed on the surface and an insulating film is further formed thereon can be used. The heating is preferably performed under conditions that can convert the applied polyamic acid into a polyimide film by polymerization.
Performed for 240 minutes. The polyimide film can be used as an alignment film by performing a uniaxial alignment treatment. The uniaxial orientation treatment is preferably performed by a rubbing method.

In the present invention, a liquid crystal cell is formed using a substrate having the above-mentioned alignment film formed on at least one of a pair of substrates, and a ferroelectric liquid crystal is interposed in the liquid crystal cell to constitute a liquid crystal display element. Is done.

The details of the present invention will be described below. As shown in FIG. 12, the method of aligning the ferroelectric liquid crystal cell is such that the direction of the uniaxial alignment treatment between the substrates is the same (a), the alignment is the opposite (b), or only one substrate is uniaxially aligned. (C). The liquid crystal molecules at the liquid crystal-substrate interface can be raised from the substrate surface by appropriate uniaxial alignment treatment,
It is known that so-called pretilt can be generated. It is also known that the direction in which the pretilt occurs can be controlled by the direction of the uniaxial orientation treatment. For example, in the case of the rubbing method, it is known that the rubbing direction is the direction of the pretilt. Of these three orientations, those having the same uniaxial orientation direction are preferred. In the opposite case, many linear defects are generated, and it is difficult to obtain a uniform orientation. Next, a case where a uniaxial orientation treatment is applied to only one substrate will be described. Usually, ferroelectric liquid crystal material is INAC (Isotropic-Nematic-Smectic A-Smectic
C) Although having a phase series, it is important to obtain good orientation in the nematic phase in order to obtain good orientation in the smectic C phase. The nematic phase of the ferroelectric liquid crystal material is spirally wound, and if uniaxial alignment treatment is performed on both substrates, uniform nematic phase alignment can be easily obtained, but if uniaxial alignment treatment is eliminated on one substrate, When the liquid crystal is twisted in the nematic phase and the temperature is lowered to the smectic C phase, it is difficult to obtain a good orientation. In addition, if a liquid crystal having no nematic phase is used, this problem can be solved. However, the smectic A phase tends to have a non-uniform orientation in which fine domains are mixed.

On the other hand, an orientation in which the directions of the uniaxial orientation processing of the substrates on both sides are the same can be obtained by a processing such as applying rubbing in the same direction (parallel rubbing).
Good alignment can be obtained relatively easily by combining a ferroelectric liquid crystal having a NAC phase series. However, it is difficult to make the entire surface uniform with this alone. This can be difficult for two reasons. One is related to the bending of the smectic layer. It is well known that a ferroelectric liquid crystal cell has a bent layer structure (chevron layer structure), but two regions can exist as shown in FIG. Kobe et al. Name these as C1 and C2 in relation to pretilt [Ferroelectrics 114, p3 (1991)], but if no pretilt exists, it is related to the direction of uniaxial orientation processing such as rubbing. The other is a uniform (U) and a twist (T) as shown in FIGS. The uniform is an orientation showing an extinction position, and the twist is an orientation showing no extinction position. In FIGS. 6 and 7, reference numeral 19 denotes a C-director of liquid crystal molecules. Mukaidon et al., In a parallel rubbing ferroelectric liquid crystal cell using a high pretilt alignment film, C1U (C1-uniform), C1T
(C-1 twist) and three orientations of C2 were reported [Jpn. J. Appl. Phys. 30, pL1823 (199).
1)]. Furthermore, in the parallel rubbing ferroelectric liquid crystal cell, C1U, C1T,
It has been reported that there are four orientation states, C2U (C2-uniform) and C2T (C-2 twist) [Proc. Japan Display '92 Hiroshima, p519 (199)
2)]. FIG. 8 shows the molecular orientation in these states. C1T and C2T do not have an extinction position and are not suitable for display with essentially high contrast, and C1U and C2U have an extinction position, so there is a possibility of high contrast display. Furthermore, as described by Mukaiden et al., C1U has a wider memory angle (the angle between the extinction position without applying an electric field and the normal of the smectic layer) than C2U, so that higher contrast can be obtained. It has the potential to be realized. However,
According to Tagawa et al., C2U has a shorter pulse width than C1U,
Faster switching has been reported. C1U and C2 capable of achieving high contrast display in this way
U also has different characteristics, and a display mode, a device configuration, and a driving method utilizing the characteristics are reported.

A device utilizing the wide memory angle characteristic of C1U is reported by Mukaiden et al. In a mode driven by the method of Japanese Patent Laid-Open No. 1-59389 or Numao [Sharp Technical Report No. 50, p45 (1991)]. [Proc. Japan Disp
lay '92 Hiroshima, p579 (1992)]. A mode for driving a device has been reported as one that takes advantage of the ease of switching by a pulse, which is a feature of C2U.
This mode will be described in more detail. The FLC molecule 11 has a spontaneous polarization Ps15 in a direction perpendicular to the long axis direction of the molecule as shown in FIG.
E16 and spontaneous polarization P created from the voltage applied to
2 which receives a force proportional to the vector product of s15 and tilt angle θ
It moves on the surface of a conical trajectory 20 having a double apex angle 21.

In addition, a force proportional to the difference Δε between the permittivity in the major axis direction and the minor axis direction of the molecule and the square of the electric field E16 acts on the FLC molecule 11. That is, the force F acting on the FLC molecule 11 is given by F = K ₁ × Ps × E + K ₂ × Δε × E ² (1) Therefore, if a FLC material having a negative dielectric anisotropy Δε is sealed in a panel, the force acting on the FLC molecules is smaller than a certain electric field due to the spontaneous polarization P due to the effect of the dielectric anisotropy Δε <0.
Although the force due to the effect of s15 is remarkably large, the force due to both effects is substantially the same above a certain electric field.

It is known that the effect of the negative dielectric anisotropy shows a minimum voltage in a voltage-response speed characteristic as shown in FIG. As a method of driving an FLC panel utilizing this phenomenon, for example, Japanese Patent Application Laid-Open Nos. Sho 62-56933 and
2-280824, JP-A-1-24234, or T
he "Joers / Alvey" Ferroelectric Multiplexing Scheme:
[Ferroelectric 122, p63 (1991)]. Using these FLC materials with negative dielectric anisotropy and the driving method,
High contrast is obtained, which is very effective as a display device.

However, for example, The "Joers / Alvey"
According to the Ferroelectric Multiplexing Scheme, it is reported that high contrast was obtained. However, when a ferroelectric liquid crystal cell was actually manufactured, high contrast was not easily obtained, and sometimes good switching was not obtained. The biggest cause is that the orientation of the ferroelectric liquid crystal cell affects switching behavior and contrast. For example, FIG. 11 is a polarization microscope observation showing the alignment state of a cell obtained by injecting a liquid crystal material SCE-8 (manufactured by Merck) having a negative dielectric anisotropy into a parallel-rubbing ferroelectric liquid crystal cell having a cell thickness of 1.5 μm. The figure shows the "J
When driven by the oers / Alvey "Ferroelectric Multiplexing Scheme, there are a part a showing good contrast, a part b showing only 5 or less contrast, and a part c not switching.

Comparing the four alignment states of a ferroelectric liquid crystal cell having a negative dielectric anisotropy, C1T and C2T have no extinction position and the dark state is not black, so that good contrast cannot be obtained. Further, the C1U orientation has a disadvantage that it is difficult to switch, and even if the switching is performed, the orientation changes to a mixture of C2 states during driving. In contrast, the present inventors have found that the C2U state provides good contrast.

In the case where the dielectric anisotropy is not negative, the display device uses the mode reported by Mukaiden et al. [Proc. Japan Display '92 Hiroshima, p579 (1992)].
Is valid and in this case C1U is required, but C2U
Since the extinction position exists even for U, the signal threshold value is clear for a storage element such as a spatial modulation element, which is effective. Here, a clear signal threshold means that the difference in optical level between the stored optical states is clear.

As described above, the present invention is intended to achieve high contrast characteristics especially when a ferroelectric liquid crystal having a negative dielectric anisotropy is used as a display device. Irrespective of the extinction position, it provides uniform alignment without extinction and defects, and the direction of the bending of the smectic layer structure is the same as the direction of the uniaxial alignment treatment applied to the alignment film. Is provided.

[0028]

The present invention will be described below with reference to examples. FIG.
FIG. 1 is a schematic sectional view showing an example of the structure of a ferroelectric liquid crystal cell 1 according to the present invention. Two glass substrates 2a and 2b are arranged to face each other, and a plurality of transparent signal electrodes S made of indium tin oxide (hereinafter abbreviated as ITO) or the like are arranged in parallel on the surface of one glass substrate 2a. Placed,
A transparent insulating film 3a made of SiO ₂ or the like is formed thereon. On the surface of the other glass substrate 2b facing the signal electrode S, a plurality of transparent scanning electrodes L made of ITO or the like are arranged in parallel with each other in a direction orthogonal to the signal electrodes S, and a SiO ₂ or the like is placed thereon. Transparent insulating film 3b made of
It is covered with. An alignment film 4 of the present invention on which a uniaxial alignment process such as a rubbing process is performed on each of the insulating films 3a and 3b.
a, 4b are formed. These two glass substrates 2a, 2
b is bonded with a sealing agent 5 via a spacer 8 for controlling the cell thickness, leaving a part of the injection port, and a ferroelectric liquid crystal (FL) is inserted from the injection port into a space sandwiched between the alignment films 4a and 4b.
C) 6 is sandwiched, and the injection port is sealed with a sealant 5. The two substrates 9 and 10 thus bonded together
Is sandwiched between two polarizing plates 7a and 7b arranged such that their polarization axes are orthogonal to each other.

Example 1 As shown in FIG. 1, 300 to 500
A plurality of transparent electrodes S having a thickness of 0 angstroms, preferably 1000 to 3000 angstroms, are arranged in stripes so as to be parallel to each other, and 300 to 5000 angstroms, preferably 5 to 50 angstroms, are formed thereon.
An electrode protective film 3a of SiO ₂ having a thickness of 00 to 2000 Å is formed by sputtering, and a carboxylic acid component which is 1,2,4,5-benzenetetracarboxylic dianhydride;
An amine component having a structure represented by 2,2-bis [4- (4-aminophenoxy) phenyl] propane and 1-amino-4-trimethoxysilylbenzene were added in a ratio of 8: 7: 1.
The mixture was mixed with NMP at a molar ratio of 8 and polymerized at 15 ° C. for 5 hours to obtain an NMP solution containing 10% of polyamic acid. This solution was applied onto the electrode protection film 3a by spin coating, and calcined at 100 ° C. for 5 minutes, and then calcined at 200 ° C. for 1 hour to form a polyimide film of about 500 Å. The structural formula in the polyimide at this time is shown below.
The compounds of the formulas (1) and (2) and the precursor of the formula (3) are in a mixed state, and the imidation ratio is about 80 to 85%.
It is.

[0030]

Embedded image Thereafter, the surface of the polyimide film is rubbed with a rayon-based cloth to perform a uniaxial alignment treatment, and the polyimide alignment film 4a is formed.
Was formed to obtain a substrate 9.

On the other hand, on the other glass substrate 2b, a plurality of transparent electrodes L are formed in the form of stripes so as to be parallel to each other under the same conditions, and an electrode protection film is formed thereon under the same conditions. 3b, a polyimide film is formed via
The surface of the polyimide film was subjected to a uniaxial alignment treatment by rubbing to form an alignment film 4b, which was used as a substrate 10. Then, the substrates 9 and 10 are arranged such that the alignment films 4a and 4b are opposed to each other, and the rubbing directions are substantially the same.
L is arranged at right angles, and 1.5
At intervals of μm, portions other than the injection port were bonded with a sealing material 5 made of epoxy resin.

Next, the ferroelectric liquid crystal 6 (manufactured by Merck; SCE-8) is injected between the substrates 9 and 10 by a vacuum injection method, and the injection port is sealed with a sealing material 5 to form a liquid crystal cell. Was prepared. Further, the polarizing plates 7a and 7b 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 substantially coincident with one of the optical axes of the liquid crystal cell, and the liquid crystal display device 1 is turned on. And

In this liquid crystal display device, uniform C2U alignment without defects was obtained over the entire surface. In addition, The "Joers / Alv
When driven by the method shown in ey "Ferroelectric Multiplexing Scheme, a high contrast display could be obtained.

Example 2 An experiment was carried out in the same manner as in Example 1 except that the firing temperature of the alignment film was changed to 300 ° C. At this time, the structural formula in the polyimide is mainly that of the above formula (2), and the imidization ratio is 9
5% or more. This liquid crystal display device also had a uniform C2U alignment without defects over the entire surface. In addition, The "Joers
/ Alvey "Ferroelectric Multiplexing Scheme Driving with the method shown in the table, high contrast display was obtained.

Example 3 In Examples 1 and 2, the carboxylic acid component which is 1,2,4,5-benzenetetracarboxylic dianhydride and 2,2-bis [4- (4-aminophenoxy) phenyl The weight ratio of the amine component having the structure represented by propane to 1-amino-4-trimethoxysilylbenzene is 5: 4: 1.8,
The same experiment was performed while changing the ratios to 4: 3: 0.9, 60: 59: 1.8, and 1: 1: 0. In each of the liquid crystal display devices, uniform C2U alignment without defects was obtained over the entire surface.
Furthermore, The "Joers / Alvey" Ferroelectric Multiplexing
When driven by the method shown in Scheme, a high contrast display could be obtained.

Example 4 The ferroelectric liquid crystal materials of Examples 1 to 3
Example 1 except that the material was replaced with a material having the composition shown in re1-6.
In the same manner as in Nos. 1 to 3, ferroelectric liquid crystal cells were produced.

[0037]

[Table 1]

[0038]

Embedded image In each of the liquid crystal display devices, uniform C2U alignment without defects was obtained over the entire surface. Furthermore, The "Joers / Alvey" Ferr
When driven by the method shown in the oelectric Multiplexing Scheme, a high contrast display could be obtained.

Example 5 The ferroelectric liquid crystal material in Examples 1 to 3 was obtained from CS manufactured by Chisso.
A ferroelectric liquid crystal cell was fabricated in the same manner as in Examples 1 to 3, except that the cell was replaced with -1014. In each of the liquid crystal displays, uniform C2U alignment without defects was obtained over the entire surface, but the "Joers / Alvey" Ferroelectric Multiplexing
It could not be driven in the way shown in Scheme. C
S-1014 is because the dielectric anisotropy is not negative,
A clear signal threshold could be obtained simply as an on-off optical storage element.

Example 6 The liquid crystal cells of Examples 1 to 5 were heated to an isotropic phase, allowed to stand at room temperature, and naturally cooled to a ferroelectric phase. All cells show C2U stably, except for CS-1014 The "Joers / A
lvey "Ferroelectric Multiplexing Scheme.
CS-1014 was able to obtain a clear signal threshold simply as an on-off optical storage element.

Example 7 As a comparative example, an alignment film was formed of polyvinyl alcohol (PV).
A) and the experiments of Examples 1 to 6 were performed. These liquid crystal cells had many defects, and the four alignment states were mixed. Despite using the same liquid crystal material as in Examples 1 to 6 not only as a display device but also as a simple optical storage element, compared with Examples 1 to 6, very high performance, particularly in terms of contrast and uniformity Was low.

[0042]

According to the present invention, a high-contrast, large-capacity display ferroelectric liquid crystal display can be obtained. Further, an optical storage element having a clear optical level can be obtained. Further, in the present invention, by adding a small amount of 1-amino-4-trimethoxysilylbenzene, the wettability of the alignment film on the substrate is improved, so that the coating is facilitated, and thus a uniform film is formed. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a ferroelectric liquid crystal cell.

FIG. 2 is a diagram showing the operation principle of a ferroelectric liquid crystal.

FIG. 3 is a diagram showing a bookshelf layer structure of a ferroelectric liquid crystal cell.

FIG. 4 is a diagram showing a chevron layer structure of a ferroelectric liquid crystal cell.

FIG. 5 is a schematic diagram of a C1 orientation and a C2 orientation in a chiral smectic C phase chevron layer structure.

FIG. 6 is a diagram showing twist alignment in a chevron layer structure of a ferroelectric liquid crystal cell.

FIG. 7 is a diagram showing uniform alignment in a chevron layer structure of a ferroelectric liquid crystal cell.

FIG. 8 is a diagram illustrating four orientation states of C1U, C1T, C2U, and C2T.

FIG. 9 is a diagram showing a state of ferroelectric liquid crystal molecules in a smectic C phase.

FIG. 10 shows Δε <0 cited from JP-A-1-24234.
4 is a graph showing a voltage-memory pulse width characteristic of the FLC material of FIG.

11A and 11B are diagrams illustrating an alignment state of a ferroelectric liquid crystal cell, wherein FIG. 11A shows a C2 uniform, FIG. 11B shows a C1 twist, and FIG. 11C shows a C1 uniform.

FIG. 12 is a view showing a method of aligning a ferroelectric liquid crystal;
(A) shows an orientation in which the direction of the uniaxial orientation treatment is the same between the substrates, (b) shows an orientation in which the directions are opposite, and (c) shows an orientation in which only one substrate undergoes the uniaxial orientation treatment.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Norio Murata 3-6-32 Nakanoshima, Kita-ku, Osaka-shi, Osaka Chisso Corporation (72) Inventor Yukino Abe 3-6-32 Nakanoshima, Kita-ku, Osaka, Osaka No. Chisso Corporation (56) References JP-A-63-14126 (JP, A) JP-A-4-194822 (JP, A) JP-A-4-107529 (JP, A) JP-A-5-88186 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/1337

Claims (2)

(57) [Claims] 1. A liquid crystal display device in which a ferroelectric liquid crystal is interposed between substrates having an alignment film on the surface of a pair of transparent electrodes, and the surface of the alignment film is subjected to a uniaxial alignment treatment. And the direction of the bending and the direction of the uniaxial alignment treatment of the alignment film are in the same direction, and the alignment film has 2,2-bis [4- (4) as an amine component.
-Aminophenoxy) phenyl] propane and a polyimide film formed by condensation using 1,2,4,5-benzenetetracarboxylic dianhydride as a carboxylic acid component as main raw materials, respectively. . 2. The liquid crystal display element according to claim 1, wherein the polyimide film is formed by condensation by adding a small amount of 1-amino-4-trimethoxysilylbenzene as an amino component.