JPH0643433A - Ferroelectric liquid crystal display device - Google Patents

Abstract

PURPOSE:To improve a contrast by optimizing the combination of a driving method and orientation state utilizing such a relation between an impressed voltage and response speed as the relation that a ferroelectric liquid crystal having <0 dielectric anisotropy possesses. CONSTITUTION:Two sheets of glass substrates 2a, 2b are stuck to each other by a sealing material 5 exclusive a part of an injection port and the ferroelectric liquid crystal 6 is held from the injection port into the space held by oriented films 4a, 4a. The injection port is sealed by the sealing material 5. Two sheets of the glass substrates 2a, 2b stuck to each other in such a manner are held by two sheets of polarizing plates 7a, 7b disposed in such a manner that the axes of polarization intersect orthogonally with each other. The direction of the pretilt angle of the molecules of the ferroelectric liquid crystal 6 with the first oriented film and the direction of the pretilt angle of the molecules of the ferroelectric liquid crystal 6 with the second oriented film are opposite from each other and further, the orientation state of the ferroelectric liquid crystal 6 has a chevron structure and is uniform C2. The ferroelectric liquid crystal 6 has <0 dielectric anisotropy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric liquid crystal display device.

[0002]

2. Description of the Related Art Ferroelectric liquid crystals such as chiral smectic C-phase liquid crystals have excellent characteristics such as memory property, high-speed response and wide viewing angle, and can be applied to liquid crystal display devices with high definition and large display capacity. Has been actively studied. First, the operation principle of the ferroelectric liquid crystal display device will be described. 2 (a) is a schematic diagram showing the migration path of ferroelectric liquid crystal molecules, and FIG. 2 (b) is FIG.
It is a projection view from the arrow 8 direction of (a). Here, 10 represents a molecule of the ferroelectric liquid crystal.

Ferroelectric liquid crystal molecules are aligned parallel to the substrate,
A layer structure is formed perpendicular to the substrate. The molecules 10 are oriented with a tilt angle θ of 13 or 15 with respect to the normal direction 9 of this layer. The molecule 10 of the ferroelectric liquid crystal has a spontaneous polarization Ps in a direction orthogonal to its long axis, and when an external electric field is applied, it is proportional to the vector product of this electric field and the spontaneous polarization Ps in the direction perpendicular to the long axis of the molecule. Double the tilt angle 2 due to the force
It moves on the surface of a conical movement path 12 having an apex angle of θ. Since the driving force of this movement is spontaneous polarization, it is 1/100 to 1/100 of that of the conventional nematic liquid crystal.
It has a high-speed response of 1000.

The molecule 10 has two stable states, and when the molecule 10 is moved to the axis 13 shown in FIG. 2 (b) by the positive electric field E, the molecule 10 becomes the stable state 14, and the negative electric field E causes the molecule 10 to move to the axis 15. It has the property of reaching stable state 16 when moved to. This stable state is maintained unless an electric field necessary for the movement of molecules is applied. That is, it has a memory property.

If one of the two stable states 14 and 16, for example, the absorption axis of the polarizing plate is aligned with the molecular axis of the stable state 14, this state becomes a black state that does not transmit light and the other stable state. In the state 16, it is a white state that transmits light. Then, the stable state of the molecule 10 is manipulated for each pixel by matrix driving, and a predetermined display state is obtained.

However, when matrix driving is performed,
Since a bias voltage is applied to all the pixels, the bias voltage causes the state of the molecule to fluctuate, causing a reduction in contrast.

Therefore, conventionally, a C1 uniform, which is an alignment state in which light leakage due to application of a bias voltage is small and a reduction in contrast can be suppressed, has been used as the alignment state of the ferroelectric liquid crystal.

Other C1 twists and C2 uniforms are known as orientation states (Ferroelectri).
cs, 114, pp.3 (1991), Proceedings of Liquid Crystal Discussion Group (1991. Mukaiden),
JP-A-2-165120, etc.), C1 twist, C
Both 2 uniforms have low contrast.

On the other hand, in a ferroelectric liquid crystal having a dielectric anisotropy of less than 0, the relationship between the applied voltage and the response speed is such that the response speed becomes minimum at a specific applied voltage, and the response speed increases at voltage values on both sides thereof. A driving method has been proposed in which the force exerted on liquid crystal molecules unrelated to rewriting is reduced by utilizing the relationship (Japanese Patent Laid-Open No. 62-56933, Japanese Laid-Open Patent Application No.
24234). This method will be described below.

In the ferroelectric liquid crystal molecule, in addition to the spontaneous polarization Ps, the difference Δε in permittivity between the major axis direction and the minor axis direction of the molecule and the electric field E.
A force proportional to the square of works. That is, the force F acting in the direction of the minor axis of the ferroelectric liquid crystal molecule is F = K ₀ × Ps × E + K ₁ × Δε × E ² (1) (where K ₀ , K ₁ is a proportional constant). This force F is inversely proportional to the response speed.

FIG. 4 shows the relationship between the electric field E and the response speed of the liquid crystal of Δε <0, which is disclosed in Japanese Patent Laid-Open No. 1-24234.
As shown in FIG. 4, the response speed is minimum around 30V. In the region where the dielectric anisotropy acting on the ferroelectric liquid crystal molecules is less than 0 up to around 30 V, the effect of K ₀ × Ps × E term is sufficiently larger than the effect of K ₁ × Δε × E ² term. As the voltage increases, F increases and the response speed decreases. After 30V, it has a large effect that the dielectric anisotropy acting on the ferroelectric liquid crystal molecule is less than 0.
_Since the effect of ₁ × Δε × E ² term becomes large, F becomes small and the response speed becomes large as the voltage becomes large.

By utilizing such a relationship, Japanese Patent Laid-Open No. 1-22
Japanese Patent No. 4234 proposes the following driving method. FIG. 5 is a diagram showing this drive voltage waveform. Here, (1) and (2) are voltage waveforms applied to the scan electrodes,
(1) is a selected waveform and (2) is a non-selected waveform. (3),
(4) is a voltage waveform applied to the signal electrode, (3) is a black rewriting waveform, and (4) is a white rewriting waveform.
(5) to (8) are the above (1), (2) and (3),
The voltage waveform applied to a pixel when (4) is combined is shown.

The pixel A _{ij at} the intersection of the electrodes as shown in FIG.
In order to rewrite the white state of the liquid crystal constituting the above into the black state, when the voltage waveform shown in FIG. 5 (1) is applied to the scanning electrode L _i , the voltage waveform shown in FIG. 5 (3) is applied to the signal electrode S _j . _Is applied to apply the voltage waveform shown in FIG. 5 (5) to the pixel A _ij . To rewrite the black state of the liquid crystal forming the pixel A _ij to the white state, when the voltage waveform shown in FIG. 5 (1) is applied to the scanning electrode L _i , the signal electrode S _{j is changed} to the state shown in FIG. 5 (4). by applying a voltage waveform shown, FIG. 5 pixel voltage waveform shown in (6) a _ij
Apply to. The other pixel A _kj is connected to the scan electrode L _k as shown in FIG.
The voltage waveform shown in (2) is applied to the signal electrode S _j .
Since the voltage waveform shown in (3) or (4) is applied,
The voltage waveform shown in FIG. 5 (7) or (8) is applied to these pixels, and the display state of the pixels does not change.

The important point in this driving method is shown in FIG.
Voltage-V shown in (6) and (5)_a, V_aFigure 4 shows the absolute value of
Around 30V, which is the voltage at which the response speed shows the minimum value
So -V _a-2V_{b '}, V_a+ 2V_{b '}Absolute value of 30V
This means that the voltage is sufficiently large. Dielectric anisotropy Δ
Since ε <0, the liquid crystal is generated by the former voltage at the boundary of 30V.
The force acting on the molecule is more than the force acting on the liquid crystal molecule by the latter voltage.
Since it becomes large, display rewriting does not occur in the latter.
Yes. Furthermore, the latter voltage, which is unrelated to the rewriting of the display, is large.
The force acting on the minor axis of liquid crystal molecules becomes smaller,
The fluctuation of the molecule can be suppressed and high contrast can be obtained.
Can be realized.

At the FLC '91 Society, PWHSurg
uy et al. “The JOERS / ALVEY Ferroelectric Multiplexing
Scheme "proposes another method using the above relationship. Fig. 8 is a diagram showing this drive voltage waveform. This drive method is one field rewriting over two fields Then, the drive waveform shown in FIG.
8B, the drive waveform shown in FIG. 8B is applied. Here, (4) is a voltage waveform applied to the signal electrode S and shows a holding voltage waveform that does not contribute to rewriting. Others (1) to (8) represent voltage waveforms similar to those in FIG.

To rewrite the pixel A _ij from the white state to the black state, the scan electrode L _{i is changed} to the scan electrode L _i in the first field.
When the selection voltage shown in (1) of (a) is applied, the black rewriting voltage shown in (3) of FIG. 8 (a) is applied to the signal electrode S _j , and (5) of FIG. 8 (a) is applied. The voltage waveform shown in (1) is applied to the liquid crystal molecules constituting the pixel to rewrite black information. In the next second field, the selection voltage shown in (1) of FIG. 8B is applied to the scan electrode L _i, and the holding voltage shown in (4) of FIG. 8B is applied to the signal electrode S _j . Then, (6) in FIG.
The voltage waveform shown in is applied to the liquid crystal molecules forming the pixel A _ij to maintain the black state.

To rewrite the pixel A _ij from the black state to the white state, the scanning electrode L _{i is changed} to the scanning electrode L _i in the first field.
When the selection voltage shown in (1) of (a) is applied, the holding voltage shown in (4) of FIG. 8 (a) is applied to the signal electrode S _j and shown in (6) of FIG. 8 (a). The voltage waveform is applied to the liquid crystal molecules forming the pixel A _ij, and the black state is maintained first. When the selection voltage shown in (1) of FIG. 8B is applied to the scanning voltage L _{i in the} next second field, the white rewriting voltage shown in (3) of FIG. 8B is applied to the signal electrode S _j . Is applied to apply the voltage waveform shown in (5) of FIG. 8B to the liquid crystal molecules constituting the pixel A _ij , and rewrite to the white state.

In the other pixel A _ij (k ≠ i), the non-selection voltage shown in (2) of FIG. 8A is applied to the scan electrode L _i in the first field and the signal electrode S _j is applied to the pixel electrode S _j . 8 (a) (3)
Alternatively, the voltage waveform shown in (4) is applied, and the voltage waveform shown in (7) or (8) of FIG. 8A is applied to the liquid crystal molecules forming the pixel A _ij .

In the second field, the scanning voltage L _{i is changed} to FIG.
When the non-selection voltage shown in (2) of (b) is applied, the voltage waveform shown in (4) or (3) of FIG. 8 (b) is applied to the signal voltage S _j . The voltage waveform shown in (8) or (7) is applied to the liquid crystal molecules forming the pixel A _ij .

At this time, the display state of A _ij does not change regardless of which voltage is applied. What is important in this driving method is that the absolute value of the voltage −V _s + V _d or V _s −V _d shown in (5) of FIG. 8A or (5) of FIG.
It is around 40V which shows the minimum value of the response speed in (a),
This means that the voltage −V _s −V _d or V _s + V _d shown in (6) of FIG. 8A or (6) of FIG. 8B is sufficiently larger than 40V. Since the dielectric anisotropy Δε <0, the force acting on the liquid crystal molecules by the former voltage becomes larger than the force acting on the liquid crystal molecules by the latter voltage at the boundary of 40 V, so that rewriting of display does not occur in the latter.

Further, the larger the latter voltage irrelevant to the rewriting of the display, the smaller the force acting in the short axis direction of the liquid crystal molecules, the fluctuation of the liquid crystal molecules can be suppressed, and high contrast can be realized. Also, (5) the voltage -V _s + V _d or V _s -V advance the same polarity voltage -V _d or V _d of the front of _d for rewriting is applied, because the state easy rewriting the liquid crystal molecules, rewrite Is the voltage of -V _s +
V _d or V _s −V _d can be reduced.

[0022]

From the above, when a liquid crystal display device using a ferroelectric liquid crystal having a dielectric anisotropy (Δε) of less than 0 is driven by the above driving method, the contrast is improved, and further, , C1 uniform can be expected to further improve the contrast. However, when actually manufacturing the above-mentioned ferroelectric liquid crystal display device, the expected high contrast was not obtained.

In addition to high contrast, good switching may not be obtained in some cases. Then, as a result of investigating such a cause, it was found that the C1 unit foam was not suitable for the driving method as described above, and moreover, a plurality of alignment states may be mixed in one pixel.

FIG. 9 is a polarizing microscope observation view showing an alignment state when a liquid crystal material SCE-8 (manufactured by Merck) having Δε <0 is used for a parallel rubbing ferroelectric liquid crystal device having a cell thickness of 2 μm. P. W. H. There are a portion a which shows a good contrast when driven by the driving method published by Surguy et al., A portion b which shows a contrast of 5 or less, and a portion c which does not switch.

In view of the above, the present invention optimizes the combination of the driving method and the alignment state utilizing the relationship between the applied voltage and the response speed which the ferroelectric liquid crystal having the dielectric anisotropy of less than 0 has. By doing so, it is an object of the present invention to provide a high contrast ferroelectric liquid crystal display device. further,
An object of the present invention is to provide a ferroelectric liquid crystal display device capable of obtaining a single alignment state in all pixels.

[0026]

Thus, according to the present invention, the first electrode and the uniaxially oriented first alignment film are laminated in this order on the first substrate, and the first electrode. Ferroelectric liquid crystal is interposed between a second electrode arranged so as to face each other and a second substrate in which a uniaxially oriented second alignment film is laminated in this order. The electrodes are a plurality of scanning electrodes, the second electrode is a plurality of signal electrodes arranged so as to intersect with the scanning electrodes, and the intersections of the scanning electrodes and the signal electrodes are pixels. Is
A rewriting voltage of a voltage that can switch the liquid crystal molecules in a minimum time or a voltage close to it is applied to the pixel that rewrites the display on the selected scan electrode, and the display on the selected scan electrode is not rewritten. A driving unit for driving a pixel by applying a non-rewriting voltage higher than the rewriting voltage to the pixel, and a pretilt angle direction of molecules of the ferroelectric liquid crystal with respect to the first alignment film; The directions of the pretilt angles of the molecules of the ferroelectric liquid crystal with respect to the second alignment film are opposite to each other, and the alignment state of the ferroelectric liquid crystal has a chevron structure and a C2 uniform. Provided is a ferroelectric liquid crystal display device, wherein the dielectric liquid crystal has a dielectric anisotropy of less than 0.

Further, the pretilt angles are 5 ° to 5 °, respectively.
The above ferroelectric liquid crystal display device is provided which is 10 °. The dielectric anisotropy of the ferroelectric liquid crystal is -1.
The following is preferable, and the spontaneous polarization (hereinafter abbreviated as Ps) is 10 nC
/ Cm ² or less is preferable.

As the substrate of the present invention, a translucent insulating inorganic substrate is used, and a glass substrate is usually used. InO _3, SnO _{2 and} IT are formed on the first and second substrates, respectively.
First and second transparent electrodes made of a conductive thin film such as O are provided. The first transparent electrode is a scanning electrode,
The second transparent electrode is a signal electrode. The electrodes are composed of a plurality of transparent linear patterns, and the signal electrodes and the scanning electrodes are arranged in the directions in which the linear patterns are orthogonal to each other.

An insulating film is optionally formed on it. This insulating film is, for example, tantalum oxide, niobium oxide, SiO
_2, inorganic thin films such as SiNx and Al ₂ O ₃ , polyimide,
An organic thin film such as a photoresist resin or a polymer liquid crystal can be used. When the insulating film is an inorganic thin film, it can be formed by an anodic oxidation method, a vapor deposition method, a sputtering method, a CVD method, a solution coating method, or the like. When the insulating film is an organic thin film, a solution in which an organic substance is dissolved or a precursor solution thereof is used to apply a spinner coating method, a dip coating method, a screen printing method, a roll coating method, etc. It can also be formed by a method of curing and forming under conditions (heating, light irradiation, etc.), an evaporation method, a sputtering method, a CVD method, or an LB (Langumuir-Blodgett) method.

The first and second liquid crystal alignment films are formed on the signal electrodes and the scan electrodes or the insulating film formed arbitrarily. The liquid crystal alignment film may be an inorganic layer or an organic layer. When an inorganic liquid crystal alignment film is used, oblique deposition of silicon oxide is good. Alternatively, a method such as rotary evaporation can be used. When an organic liquid crystal alignment film is used, nylon, polyvinyl alcohol, polyimide, or the like can be used, and the alignment treatment is usually performed by rubbing the top. In addition, polymer liquid crystal, L
Alignment using the B film, alignment by a magnetic field, alignment treatment by a spacer edge method, and the like are also possible. Also, Si
A method of vapor-depositing O _2, SiNx or the like and rubbing the same to perform orientation treatment is also possible.

For the sake of convenience, the pretilt angle is defined as the angle between the substrate surface and the liquid crystal molecules. This is because the alignment film surface has fine irregularities. The size of the angle is defined by the size of the inclination from the in-plane direction of the substrate. The pretilt angle with respect to the liquid crystal alignment film according to the present invention is obtained by rubbing a liquid crystal alignment film of polyimide or the like or obliquely depositing silicon oxide, and then applying this to a vertical alignment agent N, N-octadecyl-.
3-aminopropyl trimesooxylyl chloride (N, N-octadedecyl-3-aminopro
pyltrimethyoxysilyl chlori
de: DMOAP). Under the rubbing treatment conditions, the pretilt angle can be changed by changing the type of cloth, the length of the fur and the number of rotations of the roller during the rubbing treatment. Further, under the vapor deposition processing conditions, it can be controlled by the vapor deposition angle of silicon oxide and the thick film.

The fact that the directions of the pretilt angles are opposite to each other means that the pretilt angle of the molecule 19 with respect to the first alignment film has a right angle with respect to the substrate 2, as shown in FIG. The pretilt angle of the molecule 19 with respect to the second alignment film has a left angle with respect to the substrate 2,
It means that they are opposite to each other. The smectic liquid crystal having a chevron structure having a dielectric anisotropy of less than 0 according to the present invention includes commercially available SCE-8, ZLI-3234B, and ZLI.
In addition to -4851/000, ZLI5014 / 000 and the like (all manufactured by Merck), compounds (1) to (16) and the like represented by the following formulas are appropriately mixed and prepared.

[0033]

[Chemical 1]

[0034]

[Chemical 2] After injecting the liquid crystal as described above, the injection port is sealed with, for example, an epoxy-based curing resin to form a liquid crystal cell. Further, if necessary, polarizing plates with polarization axes substantially orthogonal to each other are arranged above and below the liquid crystal cell, and one polarizing axis of the polarizing plate is substantially aligned with one of the optical axes of the liquid crystal of the cell to enhance the intensity. Dielectric liquid crystal display device.

Next, the C2U orientation will be described. Although it has been described above that the ferroelectric liquid crystal has a layered structure formed perpendicularly to the substrate, it actually shows two types of layered structures (chevron layered structures) bent in a V shape. FIG. 10 shows a sectional view of a ferroelectric liquid crystal device for explaining this structure. Where 4 '
Represents an interface of the alignment film, 10 represents a liquid crystal molecule, 12 represents a movement path of the molecule, and 19 represents a pretilt.

In Ferroelectrics, 114, pp.3 (1991), Kamibe et al. Pretilt the bending direction of chevron layer structure 1
From the relationship with 9, the case where the bending direction and the pretilt 19 direction are opposite is named C1 orientation, and the same case is named C2 orientation. The other is uniform (U) and twist (T)
Is. The uniform is an orientation showing the extinction position, and the twist is an orientation not showing the extinction position. Mukaiden et al., In the 1991 Liquid Crystal Symposium Proceedings, in a parallel rubbing ferroelectric liquid crystal cell using an alignment film with a large pretilt angle, C1
It is reported that three orientations of U, C1T and C2 were obtained. As a result of further detailed study by the inventors, in the parallel rubbing ferroelectric liquid crystal device, C1U, C1
It was found that there are four orientation states of T, C2U and C2T. FIG. 11 is a sectional view of a ferroelectric liquid crystal display device for explaining these alignment states. (A), (b)
In the C1 orientation, the bending direction of the chevron layer structure is opposite to the pretilt 19 direction. (C) and (d) show the C2 orientation and the bending direction of the chevron layer structure and the pretilt 19
The direction is the same. Of these, (a) and (c) are uniform alignments, and the directions of liquid crystal molecules at the interfaces of both alignment films are the same. On the other hand, (b) and (d) show twist orientation, and a part is twisted between the bent portion of the chevron layer structure and the alignment film interface.

[0037]

The driving means of the present invention utilizes the fact that in the relationship between the applied voltage and the response speed, the response speed becomes minimum at a specific applied voltage, and the response speed becomes large at voltage values on both sides of the applied voltage ( Hereinafter, a specific applied voltage value that minimizes the response speed is abbreviated as Vmin).

Therefore, in the conventional liquid crystal material having no Vmin, switching is performed at a higher speed when the voltage is increased, so that it is necessary to use a value lower than the voltage used in the rewriting waveform for the non-rewriting waveform. By using a ferroelectric liquid crystal having a dielectric anisotropy of less than 0, it is possible to make the above relationship appear and use a value larger than the voltage used in the rewriting waveform for the non-rewriting waveform.
This prevents the contrast from being lowered due to the bias voltage.

The C2U orientation used in the present invention is
Although the contrast is low in the conventional driving method, when the driving method using Vmin of the driving means of the present invention is used, the memory angle is widened, and the leakage of light in the bias portion hardly occurs, resulting in high contrast. Furthermore, Table 1
As shown in, the response speed is faster than that of CIU.

[0040]

[Table 1]

Table 1 shows values obtained by a display device having the same structure as in Example 1 shown below in which the alignment film material and the liquid crystal material in the table are combined. The CIU orientation in Table 5 is obtained by causing zigzag defects by pressure impact or the like. The memory pulse width is the memory pulse width when the bipolar pulse shown in FIG. 7B is applied, and the pulse voltage was 5 V / μm, and the minimum pulse width required to rewrite the entire surface of the pixel was obtained.

Further, C2U has a smaller value of Vmin than C1U, and the operating temperature range is wide. On the other hand, C
The IT orientation has no extinction position, and the C2T orientation can improve the extinction by performing uniform transition by increasing the bias voltage applied to the pixel in the non-selection period in matrix driving, but it does not affect the high speed / low voltage driving. It is inferior to the C2U orientation in the point.

From the above, when driven by the method by the driving means of the present invention, the C2U orientation has the highest contrast and the high response speed. Further, low voltage driving becomes possible. The pretilt angle of the second invention of the present application is 5 ° or more and 10 ° or more.
The structure described below is a structure for uniformly obtaining the C2U orientation. If the pretilt angle is greater than 10 °,
In addition to C2U orientation, CIU orientation and the like are mixed, and when the pretilt angle is less than 5 °, CIT orientation and the like are mixed in addition to C2U orientation, resulting in non-uniformity. Furthermore, the C2U orientation cannot be obtained.

On the other hand, the pretilt angle is 5 ° or more and 10
When it is less than or equal to 0, uniform C2U orientation can be obtained over all pixels for any liquid crystal material. Also, setting the spontaneous polarization to 10 nC / cm ² or less means that Vmi
Acts to reduce n.

[0045]

【Example】

Example 1 A ferroelectric liquid crystal device of the present invention is illustrated. FIG. 1 is a sectional view showing an example of the structure of a ferroelectric liquid crystal device. Two glass substrates (thickness about 2 μm) 2a and 2b are arranged to face each other, and a transparent signal electrode S made of indium tin oxide (hereinafter abbreviated as ITO) is provided on the surface of one glass substrate 2a. A plurality of them are arranged in parallel with each other, and Si is placed above them.
A transparent insulating film (thickness: about 200 nm) made of O ₂ is formed. On the surface of the other glass substrate 2b facing the signal electrode S, a plurality of transparent scanning electrodes L made of ITO are arranged in parallel to each other in a direction orthogonal to the signal electrode S, and SiO ₂ is formed thereon. It is covered with a transparent insulating film 3b. Alignment films 4a and 4b that have been uniaxially aligned by rubbing are formed on the insulating films 3a and 3b. A polyimide film or an organic polymer film of polyvinyl alcohol is used as the alignment film.

The two glass substrates 2a and 2b are bonded together with a sealant 5 leaving an injection port in part, and the ferroelectric liquid crystal 6 is inserted from the injection port into a space sandwiched between the alignment films 4a and 4b.
Are sandwiched, and the inlet is sealed with a sealant 5. Two glass substrates 2a and 2b bonded in this way
Is sandwiched between two polarizing plates 7a and 7b arranged such that their polarization axes are orthogonal to each other.

In this example, PSI-A- was used as the alignment film.
2101 (manufactured by Chisso) with a pretilt angle of about 7 °
Met. The thickness of this alignment film was about 50 nm. Then, the rubbing directions were arranged so that the first and second liquid crystal alignment films had the same direction, that is, the pretilt angles were opposite to each other. As the ferroelectric liquid crystal 6, Δ
SCE-8 with ε = -1.8 and Ps = 3.2 nC / cm ^2.
(Made by Merck) was injected to obtain a ferroelectric liquid crystal display device.

The orientation of this ferroelectric liquid crystal display device was observed and the tilt angle and memory angle were measured. The tilt angle is 21.
The angle was 4 ° and the memory angle was 13.9 °. Here, the tilt angle is 1/2 of the angle between extinction positions when an electric field is applied, and the memory angle is the angle between extinction positions when no electric field is applied. The entire surface of this ferroelectric liquid crystal display device was C2U orientation showing good extinction.

The voltage-response speed relationship of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. 7 (a). The results are shown in Fig. 13 (a). In order to obtain a good contrast at a driving voltage suitable for practical use by the driving method described later, it is necessary that the minimum value of the clear response speed and the voltage showing the minimum value are small in this voltage-response speed relationship. In this embodiment, as shown in FIG. 13A, there was a voltage (Vmin) at which the response speed became the minimum near 25V.

FIG. 3 shows a schematic diagram of the drive system of this ferroelectric liquid crystal display element. Each of the scan electrodes L is denoted by L
To the signal electrode S by adding a subscript i (i = 0 to F)
Each is distinguished by adding a subscript j (j = 0 to F) to the code S. Further, in the following description, an arbitrary scan electrode L _i
And a pixel at a portion where any signal electrode S _j intersects with each other is denoted by a symbol A _ij
Shall be represented by.

The scanning side drive circuit 17 is connected to the scanning electrode L of the ferroelectric liquid crystal element, and the signal side drive circuit 18 is connected to the signal electrode S.
Connect. The scan side drive circuit 17 is a circuit for applying a voltage to the scan electrode L, is composed of an address decoder (not shown), a latch, and an analog switch, and selects the scan electrode L _i corresponding to the designated pixel A _ij. Then, the voltage Vc ₁ is applied, and the non-selection voltage Vc ₀ is applied to the other scan electrodes L _k (k ≠ i).

The signal side drive circuit 18 is a circuit for applying a voltage to the signal electrode S, and is composed of a shift register, a latch, and an analog switch (not shown), and the signal electrode S for the selected scan electrode L _i . _When displaying black on _j , the black rewriting voltage Vs ₁ is applied, and when displaying white, the white rewriting voltage Vs ₀ is applied. Next, a driving method of this driving system will be described with reference to the drawings. Here, four pixels will be described, which are achieved by two scanning electrodes L ₁ and L ₂ and _two scanning electrodes S ₁ and S ₂ and a signal electrode.

In the ferroelectric liquid crystal display device having the minimum value of the response speed in the voltage-response speed characteristic because Δε of the liquid crystal is less than 0, a region where Δε <0 effect set by the following equation (2) is large liquid crystal molecules when a voltage (V ₀ + V ₁₎ and a force received by the liquid crystal molecules when applied, [Delta] [epsilon] <0 effects a small area of the voltage set by the formula _{(3) (V 0/2} ) is applied It is possible to set so that the force received by is almost equal. Here, Vmin is the voltage at which the response speed becomes the minimum. _{(V 0 + V 1)>} Vmin (2) V 0/2 <Vmin (3)

Therefore, a pixel in a white or black memory state
To the voltage −V shown in (1) of FIG. ₀Voltage after V / 2₀/
This occurs in a pixel when a voltage waveform of 2 and 0 is applied.
Voltage wave that gives the same change in transmitted light amount as the change in transmitted light amount
The shape is such that the voltage waveforms (2) to (6) in FIG. 15 exist.
Becomes Also, to the pixel in the memory state of white or black,
The voltage V shown in (7) of FIG.₀/ 2 after voltage -V₀/ 2
Transparency that occurs in a pixel when a voltage waveform with zero voltage is applied is applied.
Voltage waveform that gives the same change in transmitted light as the change in excess light
Indicates that the voltage waveforms (8) to (12) in FIG.
Becomes

Dielectric anisotropy Δε <0 having such characteristics
The method of determining the drive waveform used in the ferroelectric liquid crystal display device in which the liquid crystal is injected is as follows. At this time, changes in the amount of transmitted light of pixels that are not rewritten are made substantially equal to each other so that crosstalk does not occur.

First, the voltage applied to the pixel during non-selection is determined so that crosstalk does not occur during non-selection. now,
The pixel A ₁₁ is rewritten. At this time, a selection voltage is applied to L ₁ , a non-selection voltage is applied to L ₂ , a rewriting voltage is applied to S ₁ , and a holding voltage is applied to S ₂ . If the voltage waveform applied to the pixel A ₂₂ composed of the scanning voltage L ₂ to which the non-selection voltage is applied and the signal electrode S ₂ to which the holding voltage is applied is (1) in FIG. 15, when this voltage waveform is applied The voltage waveforms showing the change in the amount of transmitted light that is almost equal to the change in the amount of transmitted light of the pixel are the voltage waveforms of (2) to (6) in FIG. Among such voltage waveforms, (2) in FIG. 15 is a voltage waveform applied to the pixel A _{21 including} the scan electrode L ₁ to which the non-selection voltage is applied and the signal electrode S ₁ to which the rewriting voltage is applied.

Next, the scanning electrode L to which the selection voltage is applied₁When
Signal electrode S to which holding voltage is applied₂Pixel A composed of
₁₂The voltage waveform applied to the voltage of (1) to (6) in FIG.
Determine from the waveform. At this time A₁₂The change in the amount of transmitted light
A with non-selected waveform applied₁₂, And A_{twenty two}Will be equal to
I will Pixel A_{twenty two}, A_{twenty one}, A₁₂Voltage applied to
V _{twenty two}, V_{twenty one}, V₁₂And a scan electrode to which a selection voltage is applied.
Pixel A composed of signal electrodes to which replacement voltage is applied₁₁What
Applied voltage V₁₁Between V_{twenty two}-V_{twenty one}= V₁₂-V₁₁ (4) That is, V₁₁= V₁₂-(V_{twenty two}-V_{twenty one}) (5) Since the relational expression₁₁Voltage applied to
Pixel A so that contains only zero or positive voltage₁₂Voltage applied to
When the pressure waveform is determined, the voltage waveform of (3) in FIG. 15 is obtained.

The above calculation was performed using the waveform chart for the combination of voltage waveforms in FIG. 16 (a). For example, FIG.
(5) of (a) shows a voltage waveform applied to the pixel A ₁₁ . Similarly, in addition to this, FIG.
A combination of voltage waveforms in (d) can be created. Here (a), (b) to black because a positive voltage is applied to the pixel A ₁₁ is rewritten is, (c), since a negative voltage is applied to the pixel A ₁₁ is rewritten (d) In White Will be rewritten as

From the combination of voltage waveforms shown in FIG. 16A, the combination of voltage waveforms applied to the scan electrodes and signal electrodes shown in FIG. 17B can be determined. Also, FIG.
The combination of voltage waveforms shown in FIG. 17A can be determined from the combination of voltage waveforms of FIG. 6C.

Shown in (8) of FIG. 17A or 17B.
The scan electrode with the non-selective voltage waveform applied and the holding voltage with
The voltage waveform applied to the pixel composed of the signal electrodes
The combination of the voltage waveforms of FIG. 16 (c) or (a)
Seto (1) A_{twenty two}Apply the voltage waveform of. FIG. 17 (a)
Is a scan to which the non-selection voltage waveform shown in (7) of (b) is applied.
It consists of an electrode and a signal electrode to which a rewriting voltage waveform is applied.
The waveform of the voltage applied to the pixel shown in FIG.
Or (2) A of the combination of voltage waveforms in (a) _{twenty one}Voltage
Apply a waveform. As shown in (6) of FIG. 17 (a) or (b)
Scan the applied voltage waveform and the holding voltage waveform.
Voltage waveform applied to the pixel composed of the applied signal electrode
As a set of voltage waveforms in (c) or (a) of FIG.
Matching (4) A₁₂Apply the voltage waveform of. FIG. 17 (a)
Alternatively, when the selected voltage waveform shown in (5) of (b) is applied,
Consists of a scanning electrode and a signal electrode to which a rewriting voltage waveform is applied
16C shows a voltage waveform to be applied to the pixel to be generated.
Or (5) A of the combination of voltage waveforms of (a)₁₁Electric power
Apply a pressure waveform.

FIG. 17 shows the selection voltage waveform applied to the scan electrodes.
If (1) of (a) or (1) of FIG. 17B is determined, the rewriting voltage waveform applied to the signal electrode is as shown in FIG.
(3) in (a) or (3) in FIG. 17 (b), the waveform of the non-selection voltage applied to the scan electrode is (2) in FIG. 17 (a) or (2) in FIG. 17 (b), signal electrode The waveform of the holding voltage applied to is sequentially determined as (4). This is because the voltage of (1) in FIG. 17A is V ₁ , the voltage of (2) in FIG. 17A is V _2, and the voltage of (3) in FIG. 17A is V _3. ,
When the voltage V ₄ (4) in FIG. _{17 (a), V 3 =} V 1 -V 5 (6) V 4 = V 1 -V 6 (7) V 2 = V 3 + V 7 (8) Because there is a relationship.

When the voltage waveform applied to the pixel is determined in this way, Δε <shown in (6) of FIG. 17A or 17B.
FIG. 17 shows changes in the amount of transmitted light of a pixel when a voltage waveform in a region where the 0 effect is large is applied to liquid crystal molecules forming the pixel.
A pixel when a voltage waveform in a region where Δε <0 effect is small as shown in (7) or (8) of (a) or (7) or (8) of FIG. 17B is applied to liquid crystal molecules constituting the pixel. Therefore, it is possible to obtain a ferroelectric liquid crystal display device having a high display quality without causing flicker.

In both FIG. 17A and FIG. 17B, the voltage V
_If voltage V ₀ + α (α> 0) is used instead of ₀ ,
When the voltage waveform of (6) in (a) or (6) in FIG. 17 (b) is applied to the pixel, the change in the amount of transmitted light through the pixel is (7) or (8) in FIG. This is more preferable because it becomes smaller than the change in the transmitted light amount of the pixel when the voltage waveform of (7) or (8) in FIG. 17B is applied to the pixel.

Next, in this driving method, the bias ratio will be examined as a measure of contrast. The bias ratio is the ratio of the voltage applied to the pixel to be rewritten and the voltage applied to the non-selected pixel, and the larger this ratio, the greater the contrast.

In the combination of voltage waveforms shown in FIG. 17,
The bias ratio is (5) in FIG. 17A or FIG. 17B.
17 (a), (7) or (8) of FIG.
Is the voltage ratio B = V of (7) or (8) in FIG.₀/ 2 ÷ (V₁+ V₀/ 2) (9), so high contrast cannot be expected. However, FIG.
The unit time axis of the combination of the voltage waveforms in (a) is t₀From
t₁Then, the combination of the voltage waveforms in FIG.
Figure 18 (a) when it is overlapped twice by shifting the time from itself by 2t
The combination of the voltage waveforms of
The time axis of the combination of pressure waveforms is t₀To t ₁And, Figure 1
The combination of the voltage waveforms of 7 (b) is calculated by itself and time 2
When t is shifted and overlapped twice, the set of voltage waveforms in FIG.
It will be a combination. The bias ratio B in FIG. 18 is B = V₀/ 2 ÷ (2V₁+ V₀) (10), and a considerable contrast can be expected.

Higher contrast can be realized by increasing the number of overlays. Figure 1
The combination of the voltage waveforms of 7 is overlapped any number of times in a region where the effect of Δε <0 is large, and the voltage waveform of (6) in FIG. 17A or 17B and the effect of Δε <0 are small. The voltage waveforms of (7) and (8) in the region of FIG. 17A or 17B are designed so that the same force is applied in the short axis direction of the liquid crystal molecules. This is similar to the case where the memory state of liquid crystal molecules does not change when not selected, as shown in FIG.
This is because the memory state of liquid crystal molecules cannot be changed no matter how many times the voltage waveforms of (6) are overlapped. Furthermore, FIG.
Voltage at 7 V _0/2 instead to the voltage _{V 0/2 + α (α} >
By using 0), higher contrast can be realized.

When this driving method is called driving method 1,
Other than this, the driving method 2 (PWH Surguy et.
al., Ferroelectrics, 122, 63 (1991).) and FIG. 23.
The driving method 3 (WO92 / 02925 (PCT)) represented by the above can be used.

The operation was performed by changing the voltage using the voltage waveform of FIG. With reference to the equation (2), the voltage V ₀ + V ₁ = 5
The figure shows a characteristic in which the voltage is fixed at ₀ V, the voltage V ₀ is variable, the voltages (7) and (8) in FIG. 18A are applied to the pixel, and the optical response thereof is measured as an electric signal with a photodiode. 18
The voltage of (6) of (a) is applied to the pixel, and the optical response of the pixel is compared with the characteristics measured by a photodiode to compare the characteristics.
V ₀ /2=10.5V V ₁ = 29V was obtained as a voltage giving almost equal amounts of transmitted light.

The voltages of (7) and (8) of FIG. 18A are used as the bias voltage, and the voltage of (6) of FIG.
It is applied at a frequency of 0 Hz, and then (7) and (8) in FIG.
18B was used as the bias voltage, the voltage of (6) in FIG. 18B was applied at a cycle of 10 Hz, and these were repeated, but no flicker was felt.

Further, even if the voltage of (5) of FIG. 18A was applied instead of the voltage of (6) of FIG. 18A, the pixel was rewritten to one state. Further, even if the voltage of (5) of FIG. 18B was applied instead of the voltage of (6) of FIG. 18B, the pixel was rewritten to the other state.
At this time, contrast 30 was obtained.

Comparative Examples 1 and 2 When the ferroelectric liquid crystal display device manufactured in Example 1 was operated by the voltage waveform of FIG. 22 in which the voltage in the region where the dielectric anisotropy was less than 0 and where the effect was large was not used, switching was performed. Due to the slow speed and large light leakage due to the bias voltage, high contrast could not be obtained. In addition, this driving method is
This is so-called 1/3 bias driving, and is not the driving method using τVmin according to the present invention.

Comparative Examples 3 to 6 Table 2 shows the measurement results of the liquid crystal alignment state, tilt angle and memory angle in the ferroelectric liquid crystal display device of Example 1 when the type of alignment film was changed.

[0073]

[Table 2] The pretilt angle is obtained by applying nine kinds of alignment films shown in Table 2 on a pair of glass substrates and rubbing them, and adhering the pair of substrates with a thickness of 50 μm so that the rubbing directions are antiparallel. Nematic liquid crystal E-8 (manufactured by Merck) was injected, and measurement was performed by a magnetic field capacitance method.

This pretilt angle is considered to be the pretilt angle of the SCE-8 liquid crystal molecules with respect to the alignment film. From Table 2, the pretilt angles are 5 ° and 7 ° with respect to SCE-8.
In the case of, C2U orientation can be obtained uniformly over all pixels, but at 3 °, C2T and C2U coexist.
It can be seen that at °, there are cases where it becomes CIT and cases where it becomes C2U.

The case of using PSI-A-2101 in Table 2 is Example 1, but the result of using PSI-A-2001 instead of PSI-A-2101 is shown below. Since a clear extinction position could not be obtained because the orientation was a twist orientation as described later when no electric field was applied, the angle between the two positions where the amount of transmitted light was the lowest was defined as the memory angle.

As shown in Table 2, in this ferroelectric liquid crystal display device, the C1T orientation and the C2U orientation were mixed, and the extinction was poor and the display quality was uneven. The voltage-response speed relationship in the C1T orientation of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. The results are shown in Fig. 13 (b). Figure 1
As shown in 3 (b), the voltage (V
min) existed.

However, as in Example 1, V ₀ + V ₁
Switching was not possible under the condition of = 50V. Further, a ferroelectric liquid crystal display device having an initial orientation of C1T orientation is subjected to an electric field application treatment to produce C1U or C2U.
The orientation could be changed. At this time, the C1U orientation was not only slower in switching speed than the C2U orientation, but also inferior in stability and returned to the C1T orientation due to aging.

Next, the results of using PVA will be shown. Since a clear extinction position could not be obtained due to the twist orientation in the absence of an electric field, the memory angle was set to an angle between two positions where the amount of transmitted light was the lowest. As shown in Table 2, this ferroelectric liquid crystal display device had C2T orientation on the entire surface and had poor extinction property.

The voltage-response speed relationship of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. 7 (a). The results are shown in Fig. 13 (b). As shown in FIG. 13B, a voltage (Vmin) that minimizes the response speed was present near 60V. However, switching with high contrast could not be performed in the same manner as in Example 1.

Next, the results in the case of using RN-715 (manufactured by Nissan Chemical Co., Ltd.) will be shown. Since the memory angle did not have a clear extinction position due to the twist orientation when there was no electric field,
The angle was defined as the angle between the two positions where the amount of transmitted light was the lowest.
As shown in Table 2, this ferroelectric liquid crystal display device has a C1T
The extinction was poor in the orientation in which the C2U orientation was mixed in the orientation.

Next, PSI-XSO12 and PSI-XS
The results of using O14 are shown. FIG. 7 shows the relationship between the voltage and the response speed of the manufactured ferroelectric liquid crystal display device.
It measured using the voltage waveform shown to (a). The result is shown in Figure 1.
3 (a). 40V as shown in FIG.
There was a voltage (Vmin) near which the response speed was minimized.
However, since C2T and C2V are mixed as described above, the extinction property is poor. Furthermore, it was often C2T.

Examples 2 to 7 In place of using SCE-8 as the ferroelectric liquid crystal in Example 1, Δε <0 liquid crystal compositions 1 to 6 in which the following compounds 1 to 9 were mixed in the ratios shown in Table 3 A ferroelectric liquid crystal display device was prepared by using. The respective values of Δε are approximately -1.4 for composition 1 and -2.0 for composition 2 and composition 3.
Is -2.0, and Composition 5 is -1.7.

The voltage-response speed relationship of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. 7 (a). The results are shown in Fig. 14. As shown in FIGS. 14 (a) and 14 (b), a voltage (Vmin) at which the response speed became the minimum was present around 25 to 30V. The entire surface of these ferroelectric liquid crystal display devices had a C2U orientation showing good extinction.

[0084]

[Chemical 3]

[0085]

[Chemical 4]

[0086]

[Table 3] Using these voltage waveforms in FIG. 17, V ₀ /2=7.5
V, V ₁ = 15 V was set and operated at 10 Hz cycle. At this time, no flicker was felt between the time of applying (7) and (8) in FIGS. 17A and 17B and the time of applying (6). Further, the display could be rewritten by applying (5) in FIGS. 17A and 17B.

Examples 8 to 13 Liquid crystal composition 7 of Δε <0 in which compounds (8) to (16) were mixed in the ratio shown in Table 3 instead of using SCE-8 as the ferroelectric liquid crystal in Example 1. 12 to 12, PSI-A-X007 (manufactured by Chisso Corporation) was used for the alignment film to manufacture a ferroelectric liquid crystal display device.

The voltage-response speed relationship of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. 7 (a). The results are shown in Fig. 20. As shown in FIGS. 20 (a) and 20 (b), a voltage (Vmin) at which the response speed became the minimum was present in the vicinity of 30 to 40V. Incidentally, these ferroelectric liquid crystal display devices showed C2U orientation. When these were operated using the voltage waveform of the driving method 3, the driving voltage of 4
Switching was performed at high speed and high contrast at about 0V. In the above Examples 2 to 13, the pretilt angle was 7 °.
In the case of, C2U can be obtained even if the material is changed.

Examples 14 to 17 Liquid Crystal Compositions 1, 4 and 5 and ZLI-5014 / 000
Table 4 shows the results of measuring the switching time and the driving voltage using (Δε: about −0.9) and the above driving methods 1, 2, and 3. All were good results.

[0090]

[Table 4]

Comparative Examples 9 and 10 PSI-XS014 having a pretilt angle of 3 ° was used in place of PSI-A-2101 (manufactured by Chisso Corporation) as the alignment film in Example 2 using the liquid crystal composition 2. A dielectric liquid crystal display device was created. This ferroelectric liquid crystal display device had C2T orientation on the entire surface and had poor extinction.

Further, using the liquid crystal composition 3, PSI-X-
Also when S012 was used, the orientation was C2T. Thus, when the pretilt angle was 3 °, C2U was not obtained at all with materials other than SCE8.

Examples 18 and 19 Instead of using SCE-8 as the ferroelectric liquid crystal in Example 1, ZLI-4851 / 000 having a different composition was used.
(Δε: about −0.7) and 5014/000 (Δε:
Approximately -0.9) (manufactured by Merck) is used for the alignment film with PS.
A ferroelectric liquid crystal display device was produced by using PSI-A-X007 (manufactured by Chisso Corporation) having a pretilt angle of 5 ° instead of using IA-2101 (manufactured by Chisso Corporation). A uniform C2U orientation was obtained over all pixels.

The voltage-response speed relationship of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. 7 (a). The results are shown in Fig. 21. As shown in FIG. 21, the voltage (Vmin) at which the response speed becomes minimum around 40 to 50V.
Existed.

Comparative Example 11 Liquid crystal cell KSRO-02 (commercially available) using an LX-1400 (manufactured by Hitachi Chemical Co., Ltd.) having a pretilt angle of 2 ° as an alignment film.
H. C. A ferroelectric liquid crystal display device in which SCE-12 (manufactured by Merck Ltd.) was injected into a cell gap of 2 μm, parallel rubbing manufactured by the same company. This ferroelectric liquid crystal display device is C1
In the orientation in which the C2T orientation is mixed in the T orientation, the extinction was poor and the display quality was non-uniform. As shown in Table 5, SCE-12 was a ferroelectric liquid crystal composition having a larger Δε value but a larger spontaneous polarization value than SCE-8 used in Example 3.

[0096]

[Table 5] The voltage-response speed relationship of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. 7 (b). The results are shown in Fig. 19. As shown in FIG. 19, there was no voltage (Vmin) that minimized the response speed within the measurement range up to 60V.

[0097]

According to the present invention, it is possible to provide a ferroelectric liquid crystal display device which can be driven at high speed with high contrast. Further, according to the present invention in which the pretilt angle is 5 ° to 10 °, the C value that is uniform over all pixels regardless of the liquid crystal material is used.
It was possible to provide the ferroelectric liquid crystal display device having a 2U orientation.

Further, according to the present invention which uses the ferroelectric liquid crystal having the spontaneous polarization of 10 nC / cm ² or less, it is possible to provide the above-mentioned ferroelectric liquid crystal display device driven at a low voltage.

[Brief description of drawings]

FIG. 1 is a sectional view of a ferroelectric liquid crystal display device showing an embodiment of the present invention.

2A and 2B are schematic diagrams (a) and (b) of FIG. 2 showing a moving path of ferroelectric liquid crystal molecules.

FIG. 3 is a configuration diagram of a drive system of a ferroelectric liquid crystal display device.

FIG. 4 is a characteristic diagram of a ferroelectric liquid crystal with Δε <0.

FIG. 5 is a diagram showing a drive voltage waveform of a conventional ferroelectric liquid crystal with Δε <0.

FIG. 6 is a characteristic diagram of another ferroelectric liquid crystal with Δε <0.

FIG. 7 is a voltage waveform diagram applied to measure the characteristics of a ferroelectric liquid crystal with Δε <0.

FIG. 8 is a diagram showing another drive voltage waveform of a conventional ferroelectric liquid crystal with Δε <0.

FIG. 9 is a diagram in which the orientation of a conventional ferroelectric liquid crystal display device is observed.

FIG. 10 is a diagram for explaining a layer structure of a ferroelectric liquid crystal.

FIG. 11 is a diagram for explaining an alignment state of a ferroelectric liquid crystal.

FIG. 12 is a diagram showing a pretilt direction at an interface of an alignment film of a ferroelectric liquid crystal.

FIG. 13 is a characteristic diagram of a ferroelectric liquid crystal with Δε <0 used in one example of the present invention.

FIG. 14 is a characteristic diagram of a ferroelectric liquid crystal with Δε <0 used in another example of the present invention.

FIG. 15 is a diagram for explaining a drive voltage waveform used in an example of the present invention.

FIG. 16 is a diagram for explaining a drive voltage waveform used in an example of the present invention.

FIG. 17 is a drive voltage waveform diagram used in one example of the present invention.

FIG. 18 is a drive waveform chart used in another embodiment of the present invention.

FIG. 19 is a characteristic diagram of a ferroelectric liquid crystal with Δε <0 used in another comparative example of the present invention.

FIG. 20 is a characteristic diagram of a ferroelectric liquid crystal with Δε <0 used in another example of the present invention.

FIG. 21 is a characteristic diagram of a ferroelectric liquid crystal with Δε <0 used in another example of the present invention.

FIG. 22 is a drive voltage waveform chart used in another embodiment of the present invention.

FIG. 23 is a drive voltage waveform diagram used in another embodiment of the present invention.

[Explanation of symbols]

 2a, 2b substrate L scanning electrode S signal electrode 4a, 4b alignment film 6 ferroelectric liquid crystal 19 pretilt

Claims (3)

[Claims] 1. A first substrate having a first electrode and a uniaxially oriented first alignment film laminated in this order, and a second electrode arranged so as to face the first electrode. Ferroelectric liquid crystal is interposed between a second alignment film that has been uniaxially aligned and a second substrate that is laminated in this order, and the first electrode is a plurality of scanning electrodes Is a plurality of signal electrodes arranged so as to intersect with the scanning electrodes, and the intersections of the scanning electrodes and the signal electrodes are configured as pixels, and the display on the selected scanning electrode is rewritten. A rewriting voltage of a voltage that can switch the liquid crystal molecules in a minimum time or a voltage close to the voltage is applied to the pixel, and the rewriting voltage is higher than the rewriting voltage in the pixel that does not rewrite the display on the selected scan electrode. Driving for driving pixels by applying non-change voltage The direction of the pretilt angle of the molecules of the ferroelectric liquid crystal with respect to the first alignment film and the direction of the pretilt angle of the molecules of the ferroelectric liquid crystal with respect to the second alignment film are opposite to each other. The ferroelectric liquid crystal has an orientation state of a chevron structure and a C2 uniform, and the ferroelectric liquid crystal has a dielectric anisotropy of less than 0. Liquid crystal display device. 2. The ferroelectric liquid crystal display device according to claim 1, wherein the pretilt angles are both 5 ° to 10 °. 3. The ferroelectric liquid crystal display device according to claim 1, wherein the ferroelectric liquid crystal has spontaneous polarization of 10 nC / cm ² or less.