JPH11279556A - Ferroelectric liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ferroelectric liq. crystal display which exhibits a high contrast and a unified alignment in all the pixels by using a ferroelectric liq. crystal contg. at least one kind of smectic liq. crystal and having a dielectric anisotropy lower than O. SOLUTION: The ferroelectric liq. crystal contains at least one kind of smectic liq. crystal represented by formula I or VI (wherein A is a group represented by one of formulas II to V; R and R' are each a 5-10C linear or branched alkyl or alkoxy; X and Y are each H or F provided at least one of them is F; and Z is a single bond or -OCO-. Pref., the pretilt angles of molecules of the ferroelectric liq. crystal are each 5-10 deg.. Pref., the ferroelectric liq. crystal has a dielectric anisotropy of -1 or lower and a spontaneous polarization of 10 nC/cm<2> or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 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 features such as memory properties, high-speed response, and a wide viewing angle, and can be applied to liquid crystal display devices with high definition and large display capacity. Actively studied. First, the operation principle of the ferroelectric liquid crystal display device will be described. FIG. 2A is a schematic diagram showing a movement path of ferroelectric liquid crystal molecules, and FIG.
It is a projection view from the arrow 8 direction of (a). Here, reference numeral 10 denotes a ferroelectric liquid crystal molecule.

[0003] Ferroelectric liquid crystal molecules are aligned parallel to the substrate,
A layer structure is formed perpendicular to the substrate. The molecules 10 are oriented at 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 perpendicular 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 a direction perpendicular to the long axis of the molecule. Double tilt angle 2 under force
It moves on the surface of a conical movement path 12 having a vertical angle of θ. Since the driving force of this movement is spontaneous polarization, it is 1/100 to 1/100 as compared with the conventional one using a nematic liquid crystal.
It has a high-speed response of 1000.

The molecule 10 has two stable states. When the molecule 10 is moved by the positive electric field E to the axis 13 shown in FIG. It has the property of being in a stable state 16 when it is moved to. This stable state is maintained as long as no electric field required for the movement of the molecules is applied. That is, it has a memory property.

If the absorption axis of the polarizing plate is made to coincide with one of the two stable states 14 and 16, for example, the molecular axis of the stable state 14, this state becomes a black state in which light does not pass, and the other state. At the time of the stable state 16, it is in a white state that transmits light. Then, the stable state of the molecule 10 is operated 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 state of the molecules fluctuates due to the bias voltage, causing a decrease in contrast.

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

As other orientation states, other C1 twist and C2 uniforms are known (Ferroelectri).
cs, 114, pp. 3 (1991), Proceedings of the Liquid Crystal Symposium (1991. Mukoden),
JP-A-2-165120), C1 twist, C
The contrast is low for both uniforms.

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 for reducing the force applied to liquid crystal molecules irrelevant to rewriting by utilizing the relationship has been proposed (JP-A-62-56933, JP-A-Hei.
24234). Hereinafter, this method will be described.

In addition to the spontaneous polarization Ps, the ferroelectric liquid crystal molecule has a difference Δε between the dielectric constant in the major axis direction and the minor axis direction of the molecule and the electric field E.
The force is proportional to the square of. That is, the force F acting on the ferroelectric liquid crystal molecules in the direction of the minor axis of the molecule is expressed as follows: F = K ₀ × Ps × E + K ₁ × Δε × E ² (1) _0, K ₁ is a 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 when Δε <0, as disclosed in Japanese Patent Application Laid-Open No. 1-234234.
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 and the effect is small up to around 30 V, K ₀ × Ps × E
Since the effect of the term is sufficiently larger than the effect of K ₁ × Δε × E ² , F increases as the voltage increases, and the response speed decreases. After 30 V, an area where the dielectric anisotropy acting on the ferroelectric liquid crystal molecules is less than 0 is a large effect.
The effect of ₁ × _Δε × E ² term is increased, F is small it becomes the response speed becomes larger as the voltage increases.

Utilizing such a relationship, Japanese Unexamined Patent Application Publication No.
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 scanning electrodes,
(1) is a selected waveform, and (2) is a non-selected waveform.
(3) and (4) are voltage waveforms applied to the signal electrodes,
(3) shows a black rewrite waveform, and (4) shows a white rewrite waveform. (5) to (8) show voltage waveforms applied to pixels when the above (1) and (2) are combined with (3) and (4).

The pixel A _{ij at} the intersection of the electrodes as shown in FIG.
The state of the liquid crystal of white to be configured rewritten into black state, when a voltage is applied waveform shown in FIG. 5 (1) to the scanning electrodes L _i, the voltage waveform shown to signal electrode S _j in FIG. 5 (3) To apply the voltage waveform shown in FIG. 5 (5) to the pixel _Aij . To rewrite the black state of the liquid crystal constituting the pixel A _ij to white state, when applying a voltage waveform shown in FIG. 5 (1) to the scanning electrodes L _i, to the signal electrodes S _j in FIG. 5 (4) The voltage waveform shown in FIG. 5 (6) is applied to the pixel A _ij by applying the voltage waveform shown in FIG.
Apply to The other pixels A _kj are applied to the scanning electrodes L _k in FIG.
The voltage waveform shown in (2) is applied to the signal electrode _Sj as shown in FIG.
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.

What is important in this driving method is that FIG.
Voltage shown in (6) and (5) -V _a, the absolute value of V _a is, at a voltage of 30V vicinity response speed is a voltage showing the minimum value in FIG. _{4, -V a -2V b ',} V a That is, the absolute value of + 2V _b ′ is a voltage sufficiently larger than 30V. 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 after 30 V, so that the display rewriting does not occur in the latter. Furthermore, the larger the latter voltage, which is not related to display rewriting, the smaller the force acting in the short axis direction of the liquid crystal molecules, the more the fluctuation of the liquid crystal molecules can be suppressed, and a higher contrast can be realized.

[0015] Also, FLW'91 Society of PWHSurguy
"The JOERS / ALVEY Ferroelectric Multiplexing S
8 proposes another method utilizing the above relationship. FIG. 8 is a diagram showing this drive voltage waveform. In this drive method, rewriting of one screen is performed over two fields, and the first field is rewritten. In FIG. 8A, the driving waveform shown in FIG.
In this field, 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) show the same voltage waveforms as in FIG.

[0016] The pixel A _ij to rewrite the white state to the black state, to the scanning electrodes L _i in the first field 8
When the selection voltage shown in (1) of (a) is applied, a black rewrite voltage shown in (3) of FIG. 8A is applied to the signal electrode _Sj , and (5) of FIG. Is applied to the liquid crystal molecules constituting the pixel to rewrite it into black information. Applying a selection voltage shown in (1) in FIG. 8 in the next second field to the scanning electrodes L _i (b), by applying a holding voltage indicating the signal electrode S _j to (4) shown in FIG. 8 (b) And (6) in FIG.
_Is applied to the liquid crystal molecules constituting the pixel _Aij to maintain a black state.

[0017] rewritten pixel A _ij from the black state to the white state, to the scanning electrodes L _i in the first field 8
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 _Sj, and shown in (6) of FIG. 8 (a). A voltage waveform is applied to the liquid crystal molecules constituting the pixel _Aij , and first, a black state is maintained. When applying a selection voltage shown in the following second field to the scanning voltage L _i (1) of FIG. 8 (b), the rewriting voltage of white indicated to the signal electrode S _j to (3) shown in FIG. 8 (b) To apply the voltage waveform shown in (5) of FIG. 8 (b) to the liquid crystal molecules constituting the pixel _Aij , and rewrite to the white state.

[0018] Other pixels A _ij (k ≠ i), the non-selection voltage shown in FIG. 8 to the scanning electrodes L _i in the first field in (a) (2) is applied, FIG to the signal 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 constituting the pixel _Aij .

In the second field, the scanning voltage _{Li is changed} to the level shown in FIG.
When the non-selection voltage shown in (b) of (b) is applied, the voltage waveform shown in (4) or (3) of FIG. 8B is applied to the signal voltage _Sj , and the signal waveform of FIG. The voltage waveform shown in (8) or (7) is applied to the liquid crystal molecules constituting the pixel _Aij .

At this time, the display state of A _ij does not change regardless of which voltage is applied. And become important in this driving method, the absolute value of the voltage -V _s + V _d or V _s -V _d shown in (5) (5) or FIG. 8 (b) of FIG. 8 (a), 6
It is around 40 V, which indicates the minimum value of the response speed in (a),
Figure 8 (a) (6) or the voltage of the voltage -V _s -V _d or V _s + V _d shown in (6) shown in FIG. 8 (b) is that the 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 a boundary of 40 V, so that display rewriting does not occur in the latter.

Further, the larger the latter voltage, which is not related to display rewriting, the smaller the force acting in the short axis direction of the liquid crystal molecules, the more the fluctuation of the liquid crystal molecules can be suppressed, and a higher 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 −V _s + V _d
Alternatively, 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-described driving method, the contrast is improved, and furthermore, If the C1 uniform is used, further improvement in contrast can be expected. However, when a ferroelectric liquid crystal display device as described above was actually manufactured, a contrast as high as expected could not be obtained.

Further, not only high contrast was not obtained, but also good switching was not obtained in some cases. Therefore, as a result of investigating such a cause, it was found that the C1 uniform is not suitable for the above-described driving method, and that a plurality of alignment states may be mixed in one pixel.

FIG. 9 is a polarization microscope observation view showing the alignment state when a liquid crystal material SCE-8 (manufactured by Merck) with Δε <0 is used for a parallel-rubbing ferroelectric liquid crystal element having a cell thickness of 2 μm. P. W. H. When driven by the driving method disclosed by Surguy et al., There are a portion a showing good contrast, a portion b showing only 5 or less contrast, and a portion c not switching.

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 as in the ferroelectric liquid crystal having a dielectric anisotropy of less than 0. Accordingly, an object of the present invention is 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, there is provided a first substrate in which a first electrode and a first alignment film having been subjected to a uniaxial alignment treatment are laminated in this order, A ferroelectric liquid crystal is interposed between a second electrode disposed so as to face the second substrate and a second substrate on which a second alignment film that has been uniaxially aligned is laminated in this order. In the liquid crystal, the direction of the pretilt angle of the molecule with respect to the first alignment film and the direction of the pretilt angle of the molecule with respect to the second alignment film are opposite to each other, the alignment state is a chevron structure, The liquid crystal includes at least one type of smectic liquid crystal represented by the general formula (I),

[0027]

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A ferroelectric liquid crystal display device having a dielectric anisotropy of less than 0 is provided. With this configuration, a high-contrast, high-speed driving ferroelectric liquid crystal display can be provided. That is, the material according to the present invention provides a stable C2U orientation,
The material was suitable for n driving.

According to a further aspect of the present invention, the first electrode and the first alignment film that has been subjected to the uniaxial alignment treatment are arranged in this order on the first substrate, and are arranged so as to face the first electrode. Second
A ferroelectric liquid crystal is interposed between the first electrode and a second substrate on which a uniaxially-aligned second alignment film is laminated in this order, and the ferroelectric liquid crystal corresponds to the first alignment film. The direction of the pretilt angle of the molecule and the direction of the pretilt angle of the molecule with respect to the second alignment film are opposite to each other, the alignment state is a chevron structure, and the ferroelectric liquid crystal is represented by the general formula (II). Including at least one type of smectic liquid crystal represented,

[0030]

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A ferroelectric liquid crystal display device having a dielectric anisotropy of less than 0 is provided. With this configuration, a high-contrast, high-speed driving ferroelectric liquid crystal display can be provided. That is, the material according to the present invention provides a stable C2U orientation,
The material was suitable for n driving.

In each of the above ferroelectric liquid crystals, the pretilt angle of the molecule with respect to the first alignment film and the pretilt angle of the molecule with respect to the second alignment film are both 5 ° to 5 °.
A ferroelectric liquid crystal display device characterized by 10 ° is provided.

The ferroelectric liquid crystal preferably has a dielectric anisotropy of -1 or less, and has a spontaneous polarization (hereinafter abbreviated as Ps) of 10 or less.
It is preferably nC / cm ² or less.

As the substrate of the present invention, a light-transmitting insulating inorganic substrate is used, and a glass substrate is usually used. On the first and second substrates, InO ₃ , SnO ₂ , I
First and second transparent electrodes made of a conductive thin film such as TO are provided. The first transparent electrode is used as a scanning electrode, and the second transparent electrode is used as 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 a direction perpendicular to the linear patterns.

An insulating film is arbitrarily formed thereon. This insulating film is made of, for example, tantalum oxide, niobium oxide, SiO
₂ , inorganic thin films such as SiNx and Al ₂ O _3, and organic thin films such as polyimide, photoresist resin, and polymer liquid crystal can be used. When the insulating film is an inorganic thin film, it can be formed by an anodic oxidation method, an evaporation method, a sputtering method, a CVD method, a solution coating method, or the like. When the insulating film is an organic thin film, using a solution in which an organic substance is dissolved or a precursor solution thereof, spinner coating, dipping coating, screen printing, roll coating, etc.
It may be formed by a method of forming by curing under predetermined curing conditions (heating, light irradiation, etc.), or by a vapor deposition method, a sputtering method, a CVD method, or the like, or by an LB (Langumuir-Blodgett) method.

The first and second liquid crystal alignment films are formed on the signal electrodes and the scanning electrodes or on the arbitrarily formed insulating film. As the liquid crystal alignment film, there are a case where an inorganic layer is used and a case where an organic layer is used. When an inorganic liquid crystal alignment film is used, oblique deposition of silicon oxide is favorable. Alternatively, a method such as rotary evaporation can be used. In the case of using an organic liquid crystal alignment film, nylon, polyvinyl alcohol, polyimide, or the like can be used. In addition, polymer liquid crystal, L
Orientation using a B film, orientation by a magnetic field, orientation treatment by a spacer edge method, and the like are also possible. In addition, Si
A method in which O ₂ , SiNx, or the like is deposited and rubbed thereon to perform an alignment treatment is also possible.

The pretilt angle is defined as an angle between a substrate surface and liquid crystal molecules for convenience. This is because the surface of the alignment film 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 determined by rubbing or obliquely depositing silicon oxide on a liquid crystal alignment film made of polyimide or the like, and then using the vertical alignment agent N, N-octadecyl-
3-aminopropyl trimesoxyl chloride (N, N-octadecyl-3-aminopro
pilltrimethyoxysilyl chromi
de: DMOAP). In 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, the conditions of the deposition process can be controlled by the deposition angle and the thickness of the silicon oxide.

The opposite directions of the pretilt angles are, for example, that the pretilt angles of the molecules 19 with respect to the first alignment film have 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 dielectric anisotropy of less than 0 according to the present invention is commercially available SCE-8, ZLI-3234B, ZLI.
In addition to -4851/000 and ZLI501014 / 000 (all manufactured by Merck), compounds (1) to (16) represented by the following formulas are appropriately mixed.

[0039]

Embedded image

[0040]

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After injecting the liquid crystal as described above, the injection port is sealed with, for example, an epoxy-based cured resin to form a liquid crystal cell. Further, if necessary, a polarizing plate whose polarization axes are substantially orthogonal to each other is arranged above and below the liquid crystal cell, and one of the polarization axes of the polarizing plate is substantially aligned with either one of the liquid crystals of the cell and the liquid crystal is strongly aligned. This is a dielectric liquid crystal display device.

Next, the C2U orientation will be described. Although it has been described above that the ferroelectric liquid crystal forms a layer structure perpendicular to the substrate, actually, it shows two types of layer structures (chevron layer structures) bent in a square shape. FIG. 10 is a sectional view of a ferroelectric liquid crystal device for explaining this structure. here,
4 'is the interface between the alignment films, 10 is the liquid crystal molecule, 12 is the movement path of the molecule, and 19 is the pretilt.

In Ferroelectrics, 114, pp. 3 (1991), Kanbe et al. Changed the bending direction of the chevron layer structure to pretilt 1
From the relationship with No. 9, the case where the bending direction and the pretilt 19 direction are opposite is referred to as C1 orientation, and the same case is referred to as C2 orientation. The other is uniform (U) and twist (T)
It is. The uniform is an orientation showing an extinction position, and the twist is an orientation showing no extinction position. Mukaiden et al., In a preliminary report of the 1991 Liquid Crystal Symposium, found that a parallel rubbing ferroelectric liquid crystal cell using an alignment film with a large pretilt angle had a C1
It reports that three orientations of U, C1T and C2 were obtained. As a result of further studies, the present inventors have found that the parallel rubbing ferroelectric liquid crystal device has C1U and C1U.
It was found that four orientation states of T, C2U and C2T exist. 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 and the direction of the pretilt 19 are opposite. (C) and (d) show the bending direction and the pretilt 19 of the chevron layer structure in C2 orientation.
The directions are the same. Among them, (a) and (c) are uniform alignment, and the directions of liquid crystal molecules at the interface between both alignment films are the same. On the other hand, (b) and (d) show twisted orientation, and a part of the chevron layer structure is twisted from the bent portion to the interface of the alignment film.

Further, the driving means of the present invention utilizes the fact that the response speed is minimized at a specific applied voltage and the response speed is increased at voltage values on both sides of the relationship between the applied voltage and the response speed. (Hereinafter, a specific applied voltage value at which the response speed becomes minimum 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. Therefore, it is necessary to use a non-rewriting waveform having a lower absolute value than the voltage used in the rewriting waveform. In the present invention,
By using a ferroelectric liquid crystal having a dielectric anisotropy of less than 0, the above-mentioned relationship appears, and a non-rewriting waveform can use a value having a larger absolute value than a voltage used in a rewriting waveform, and a bias voltage The contrast is prevented from lowering.

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 light leakage hardly occurs in the bias portion, so that the contrast is increased. Furthermore, as shown in Table 1, the response speed is faster than that of C1U.

[0047]

[Table 1]

Table 1 shows the values obtained by using a combination of the alignment film material and the liquid crystal material in the table and having the same structure as that of Example 1 shown below. Further, the C1U orientation in Table 5 was obtained by generating zigzag defects due to pressure impact or the like. The memory pulse width indicates the memory pulse width when the bipolar pulse shown in FIG. 7B is applied. The pulse voltage was set to 5 V / μm, and the minimum pulse width required to rewrite the entire pixel was obtained.

Further, the value of Vmin of C2U tends to be smaller than that of C1U, and the operating temperature range is wide. On the other hand, C
The 1T alignment has no extinction position, and the C2T alignment can improve the extinction by performing uniform transition by increasing the bias voltage applied to the pixel during the non-selection period in the matrix driving. Inferior to C2U orientation in point.

From the above, when driving by the method of the driving means of the present invention, the C2U orientation has the highest contrast and the highest response speed. Further, low voltage driving is also possible. Further, the configuration in which the pretilt angle is 5 ° or more and 10 ° or less is a structure for obtaining the above C2U orientation uniformly. When the pretilt angle is larger than 10 °, C2U
In addition to orientation, C1U orientation and the like are mixed, and the pretilt angle is 5 °
If it is less than 1, the C1T orientation and the like are mixed in addition to the C2U orientation, resulting in non-uniformity. Furthermore, C2U orientation cannot be obtained.

On the other hand, when the pretilt angle is 5 ° or more and 10 ° or more,
When it is less than or equal to °, uniform C2U alignment can be obtained for any liquid crystal material over all pixels. In addition, setting the spontaneous polarization to 10 nC / cm ² or less requires Vmin
Acts to reduce.

[0052]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be specifically described below with reference to examples. <Example 1> A ferroelectric liquid crystal device of the present invention will be exemplified.
FIG. 1 is a sectional view showing an example of the structure of a ferroelectric liquid crystal device. Two glass substrates (about 2 μm in thickness) 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. There plurality of arranged parallel to each other, a transparent insulating film thereon is made of SiO ₂ (thickness of about 2
00 nm).

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 with each other in a direction orthogonal to the signal electrode S, and a transparent scanning electrode L is formed thereon. ₂ is covered with a transparent insulating film 3b. On each of the insulating films 3a and 3b, alignment films 4a and 4b that have been subjected to a uniaxial alignment process by a rubbing process are formed. As the alignment film, a polyimide film or an organic polymer film of polyvinyl alcohol is used.

The two glass substrates 2a and 2b are bonded to each other with a sealant 5 except for a part of an injection port, and a ferroelectric liquid crystal 6 is inserted from the injection port into a space interposed between the alignment films 4a and 4b.
And the inlet is sealed with a sealant 5. The two glass substrates 2a and 2b thus bonded together
Is sandwiched between two polarizing plates 7a and 7b arranged so that the polarization axes are orthogonal to each other.

In this embodiment, PSI-A-
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 as to be the same in the first and second liquid crystal alignment films, that is, so that the pretilt angles were opposite to each other. The ferroelectric liquid crystal 6 has a Δ
SCE-8 with ε = −1.8, Ps = 3.2 nC / cm ²
(Merck) was injected to obtain a ferroelectric liquid crystal display device.

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

The relationship between the voltage and the response speed of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. The results are shown in FIG. In order to obtain good contrast at a driving voltage suitable for practical use by a driving method described later, it is necessary that a clear minimum value of the response speed and a voltage indicating the minimum value be small in this voltage-response speed relationship. is there. In this embodiment, as shown in FIG. 13A, a voltage (Vmi
n) was present.

FIG. 3 shows a schematic configuration diagram of a drive system of the ferroelectric liquid crystal display device. Each of the scanning electrodes L has a code L
Are distinguished by adding a subscript i (i = 0 to F) to the signal electrode S.
Are distinguished by adding a suffix j (j = 0 to F) to the code S. In the following description, any scan electrode _Li
And any signal electrode S _j is the pixel code A _ij of the intersection
It shall be represented by

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

[0060] The signal-side drive circuit 18 is a circuit for applying a voltage to the signal electrode S, is composed of a shift register and a latch and an analog switch (not shown), the signal electrodes S for the selected scanning electrodes L _i to display a black to _j applies a black writing voltage Vs _1, when displaying white applies white writing voltage Vs _0. Next, a driving method of this driving system will be described with reference to the drawings. Here, a description will be given of four pixels achieved by two scanning electrodes L ₁ and L ₂ and _two scanning electrodes S ₁ and S ₂ and signal electrodes.

Since Δε of the liquid crystal is less than 0, the voltage −
In a ferroelectric liquid crystal display device having a minimum response speed in response speed characteristics, when a voltage (V ₀ + V ₁ ) in a region where the effect of Δε <0, which is set by the following equation (2) is large, is applied. the force experienced by possible and the liquid crystal molecules receive the force when the [Delta] [epsilon] <0 effects a small area of the voltage set by the formula _{(3) (V 0/2} ) is applied is set to be substantially equal Becomes Here, Vmin is a voltage at which the response speed becomes minimum.

[0062] _{(V 0 + V 1)>} Vmin (2) V 0/2 <Vmin (3) Therefore, the pixels in the white or black or memory state, the voltage -V ₀ shown in (1) in FIG. 15 / FIG. 15 shows a voltage waveform that gives the same change in the amount of transmitted light as the change in the amount of transmitted light that occurs in the pixel when a voltage waveform in which voltage V _0/2 and voltage 0 continue after 2
The voltage waveforms of (2) to (6) exist. Further, the pixels in the white or black or memory state, resulting in a pixel when a voltage is applied to -V _0/2 and a voltage 0 is followed voltage waveform after the voltage V _0/2 as shown in (7) in FIG. 15 The voltage waveform that gives the same change in the amount of transmitted light as the change in the amount of transmitted light is shown in FIG.
The voltage waveforms (8) to (12) exist.

The dielectric anisotropy Δε <0 having such characteristics
The method of determining the drive waveform used for the ferroelectric liquid crystal display device in which the liquid crystal is injected is as follows. At this time, the change in the amount of transmitted light of the pixel that is not rewritten is made substantially equal to prevent crosstalk from occurring.

First, a voltage to be applied to a pixel at the time of non-selection is determined so that crosstalk does not occur at the time of non-selection. now,
It shall rewrite the pixel A _11. Selection voltage to the time L _1, the non-selection voltage is applied to the L _2, voltage, the holding voltage S ₂ is applied to rewrite the S _1. In Figure 15 the voltage waveforms applied to the configured pixel A ₂₂ a scanning voltage L ₂ and the holding voltage of the non-selected voltage is applied from the signal electrodes S ₂ was applied (1)
Then, a voltage waveform indicating a change in the amount of transmitted light that is substantially equal to a change in the amount of transmitted light of the pixel when this voltage waveform is applied is:
It is a voltage waveform of (2)-(6) of FIG. Such Of voltage waveform, and the voltage waveform applied from the signal electrodes S ₁ of applying a writing voltage to the scanning electrodes L ₁ of applying a non-selection voltage in FIG. 15 (2) to the configured pixel A _21.

Next, a pixel A comprising a scanning electrode L ₁ to which a selection voltage is applied and a signal electrode S ₂ to which a holding voltage is applied.
_The voltage waveform applied to ₁₂ is determined from the voltage waveforms (1) to (6) in FIG. In this case change in transmitted light amount of the A ₁₂ is set to be equal to A _12, and A ₂₂ of applying the non-selection waveform earlier. The voltages V ₂₂ , V ₂₁ , and V ₁₂ applied to the pixels A ₂₂ , A ₂₁ , and A ₁₂ are applied to the pixel A _{11 including} the scanning electrodes to which the selection voltage is applied and the signal electrodes to which the rewriting voltage is applied. between the voltage _{V 11, V 22 -V 21 =} V 12 -V 11 (4) i.e., V ₁₁ = V ₁₂ - since _{(V 22 -V 21) (5} ) becomes equation is satisfied, the pixel a _When the voltage waveform applied to the pixel A ₁₂ is determined so that the voltage applied to ₁₁ includes only 0 or a positive voltage, the voltage waveform shown in FIG. 15C is obtained.

The above calculations are performed using the waveform diagrams for the combinations of the voltage waveforms shown in FIG.
Shown in (5) of 6 (a) is a voltage waveform applied to the pixel A _11. Similarly, in addition to FIG.
The combination of the voltage waveforms of (d) can be made. 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.

The combination of the voltage waveforms applied to the scanning electrodes and the signal electrodes shown in FIG. 17B can be determined from the combination of the voltage waveforms shown in FIG. 16A. FIG.
The combination of the voltage waveforms applied to the scanning electrodes and the signal electrodes shown in FIG. 17A can be determined from the combination of the voltage waveforms shown in FIG.

FIG. 16 shows a voltage waveform applied to a pixel composed of the scanning electrode to which the non-selection voltage waveform shown in FIG. 17 (a) or (b) is applied and the signal electrode to which the holding voltage is applied. shed (c) or a voltage waveform of a combination of (1) a ₂₂ voltage waveform (a). As a voltage waveform applied to a pixel composed of the scanning electrode to which the non-selection voltage waveform shown in FIG. 17A or (b) is applied and the signal electrode to which the rewriting voltage waveform is applied, FIG. )
Or a combination of voltage waveforms in (a) (2) apply a voltage waveform of A _21.

The voltage waveform applied to the pixel composed of the scanning voltage applied with the selection voltage waveform shown in FIG. 17 (a) or (b) and the signal electrode applied with the holding voltage waveform shown in (6) of FIG. (c) or the combination of voltage waveforms of (a) (4) apply a voltage waveform of a _12. FIG. 16C shows a voltage waveform applied to a pixel composed of the scanning electrode to which the selection voltage waveform shown in FIG. 17A or (b) is applied and the signal electrode to which the rewriting voltage waveform is applied. Alternatively, the voltage waveform of ( ₁₁ ) A11 of the combination of the voltage waveforms of (a) is applied.

FIG. 17 shows the waveform of the selection voltage applied to the scanning electrodes.
If (1) in FIG. 17A or (1) in FIG. 17B is determined, the waveform of the rewriting voltage applied to the signal electrode is as shown in FIG.
17 (a) or (3) of FIG. 17 (b), the non-selection voltage waveform applied to the scanning electrode is (2) of FIG. 17 (a) or (2) of FIG. Are sequentially determined as shown in (4). This means that 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 to be applied to the pixel is determined as described above, Δε <6 shown in (6) of FIG.
When the voltage waveform in the region where the 0 effect is large is applied to the liquid crystal molecules constituting the pixel, the change in the amount of transmitted light of the pixel is as shown in FIG.
(7) or (8) in (a) or (7) in FIG. 17 (b)
The change in the amount of transmitted light of the pixel when the voltage waveform in the region where the Δε <0 effect is small as shown in (8) is applied to the liquid crystal molecules constituting the pixel, becomes almost equal to the ferroelectricity of the display quality without flicker. A liquid crystal display device can be obtained.

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

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

In the combination of the voltage waveforms shown in FIG.
The bias ratio is (5) in FIG. 17A or FIG.
(5) and the voltage ratio of (7) or (8) in FIG. 17A or (7) or (8) in FIG. 17B, B = V ₀ / 2ｂ (V ₁ + V _0/2 ) (9), and high contrast cannot be expected. However, FIG.
7 unit time axis of the combination of voltage waveforms of (a) from t ₀ and t _1, the combination of voltage waveforms in FIG. 17 (a),
When it is overlapped twice with a delay of 2t from itself,
FIG. 17A shows a combination of the voltage waveforms shown in FIG.
The time axis of the combination of the voltage waveforms in (b) is from t ₀ to t _1, and the combination of the voltage waveforms in FIG. It is a combination of waveforms. Bias ratio B in FIG. 18 _{B = V 0/2 ÷ (} 2V 1 + V 0) (10) , and the expected significant contrast.

By increasing the number of superpositions, higher contrast can be realized. FIG.
The combination of the voltage waveforms of FIG. 7 is superimposed any number of times is the region where the effect of Δε <0 is large, and the voltage waveform of (6) in FIG. 17A or FIG. The voltage waveforms of (7) and (8) in FIG. 17A or FIG. 17B, which are regions, were designed to give the same force in the short axis direction of the liquid crystal molecules. That is, the memory state of the liquid crystal molecules can be changed no matter how many times the voltage waveform of (6) in FIG. 17A or FIG. Because there is no. Further, the voltage instead of the voltage V _0/2 in FIG. 17 V _0/2 +
If α (α> 0) is used, higher contrast can be realized.

When this driving method is referred to as driving method 1,
Other than this, the driving method 2 shown in FIG. 8 (PWH Surguy et.
al., Ferroelectrics, 122, 63 (1991).) and FIG.
Driving method 3 (WO92 / 02925 (PCT)) or the like can be used.

The operation was performed by changing the voltage using the voltage waveform of FIG. Referring to equation (2), voltage V ₀ + V ₁ = 5
FIG. 18 (a) is a diagram showing characteristics obtained by applying the voltages (7) and (8) to pixels and measuring the optical response of the pixels to an electric signal by using a photodiode, with the voltage V ₀ being variable. 18
(A) applying the voltage of (6) to the pixel, comparing the characteristics of the optical response of the pixel measured with the photodiode to the electric signal,
V ₀ /2=10.5 V V ₁ = 29 V was obtained as a voltage giving substantially the same amount of transmitted light.

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

Further, the pixel was rewritten to one state even when the voltage of (5) of FIG. 18A was applied instead of the voltage of (6) of FIG. Further, when 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, a contrast of 30 was obtained.

<Comparative Examples 1 and 2> The ferroelectric liquid crystal display device manufactured in Example 1 was operated according to the voltage waveform of FIG. 22 which does not use a voltage in a region where the dielectric anisotropy is less than 0 and where the effect is large. However, since the switching speed is slow and light leakage due to a bias voltage is large, high contrast cannot be obtained. Note that this driving method is so-called 1/3 bias driving, and the τ-Vmi
It is not a driving method using n.

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

[0082]

[Table 2]

The pretilt angles were determined by applying nine types of alignment films shown in Table 2 on a pair of glass substrates, and rubbing.
The pair of substrates is attached to each other so as to have a thickness of 50 μm and the rubbing directions are antiparallel.
(Manufactured by Merck), and measured by the magnetic field capacity method.

This pretilt angle is considered to be the pretilt angle of the liquid crystal molecules of SCE-8 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 (1), the C2U orientation can be obtained uniformly over all the pixels. However, at 3 °, C2T and C2U coexist.
It can be seen that there is a case where C1T and C2U in °.

Example 1 uses PSI-A-2101 in Table 2, but the results obtained when PSI-A-2001 is used instead of PSI-A-2101 are shown below. The memory angle was defined as the memory angle at which no clear extinction position was obtained because the orientation was twisted in the absence of an electric field, as will be described later.

As shown in Table 2, this ferroelectric liquid crystal display device had a C1T orientation and a C1U orientation and a C2U orientation mixed with each other. The quenching property was poor and the display quality was uneven. The relationship between the voltage and the response speed in the C1T alignment of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. The results are shown in FIG. As shown in FIG. 13B, there was a voltage (Vmin) that minimized the response speed.

However, as in the first embodiment, V ₀ + V ₁
= 50V could not be switched. Furthermore, the ferroelectric liquid crystal display device whose initial alignment is C1T alignment is subjected to electric field application processing to obtain 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 a change with time.

Next, the results when PVA is used will be described. Since a clear extinction position could not be obtained due to twist alignment 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 lowest. As shown in Table 2, this ferroelectric liquid crystal display device had a C2T alignment on the entire surface and had poor extinction properties.

The relationship between the voltage and the response speed of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. The results are shown in FIG. As shown in FIG. 13B, there was a voltage (Vmin) at which the response speed became minimum around 60V. However, high-contrast switching could not be performed in the same manner as in Example 1.

Next, the results when RN-715 (manufactured by Nissan Chemical Industries, Ltd.) is used are shown. Since a clear extinction position could not be obtained due to twist alignment 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 lowest. As shown in Table 2, this ferroelectric liquid crystal display device has a C
The quenching property was poor in the orientation in which the C2U orientation was mixed in the 1T orientation.

Next, PSI-XSO12 and PSI-X
The results for the case where SO14 was used 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). Figure 1 shows the results
3 (a). 40V as shown in FIG.
A voltage (Vmin) at which the response speed was minimized was present in the vicinity. However, the extinction was poor because C2T and C2U were mixed as described above. Furthermore, it was often C2T.

<Examples 2 to 7> Instead of using SCE-8 as the ferroelectric liquid crystal in Example 1, the following compounds (1) to (9) were mixed at the ratios shown in Table 3 and Δε <
A ferroelectric liquid crystal display device was prepared using the No. 0 liquid crystal compositions 1 to 6. The value of each Δε is approximately -1.4 for composition 1, -2.0 for composition 2, -2.0 for composition 3,
Composition 5 is -1.7.

The relationship between the voltage and the response speed of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. The results are shown in FIG. As shown in FIGS. 14A and 14B, a voltage (Vmin) at which the response speed becomes minimum exists around 25 to 30V. The entire surface of these ferroelectric liquid crystal display devices was C2U alignment exhibiting good extinction.

[0094]

Embedded image

[0095]

Embedded image

[0096]

[Table 3]

[0097] These reference to voltage waveforms in FIG. 17, V _0/2
= 7.5 V, V ₁ = 15 V, and operated at a cycle of 10 Hz. At this time, (7) in FIGS. 17 (a) and (b),
No flicker was felt between when (8) was applied and when (6) was applied. FIGS. 17 (a) and (b)
By applying (5), the display could be rewritten.

<Examples 8 to 13> In Example 1, instead of using SCE-8 as the ferroelectric liquid crystal, compounds (8) to (16) were mixed in the ratio shown in Table 3 to obtain Δε <
The liquid crystal compositions 7 to 12 of P.I.
A ferroelectric liquid crystal display device was manufactured using AX007 (manufactured by Chisso Corporation).

The relationship between the voltage and the response speed of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. The results are shown in FIG. As shown in FIGS. 20A and 20B, a voltage (Vmin) at which the response speed becomes minimum exists around 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, switching was performed at a driving voltage of about 40 V with high speed and high contrast. In the above Examples 2 to 13, the pretilt angle was 7 °.
It can be seen that in the case of C2U, C2U can be obtained even if the material is changed.

<Examples 14 to 17> The liquid crystal compositions 1, 4 and 5 and ZLI-5014 / 000 (Δε: about −0.
Table 4 shows the results obtained by measuring the switching time and the driving voltage using the driving methods 1, 2, and 3, respectively. All had good results.

[0101]

[Table 4]

<Comparative Examples 9 and 10> In Example 2 using liquid crystal composition 2, PSI-A-21 was used as the alignment film.
01 (manufactured by Chisso) instead of pretilt angle 3
A ferroelectric liquid crystal display device was produced using PSI-XS014 of the present invention. This ferroelectric liquid crystal display is entirely C2T
The orientation was poor in quenching.

Further, the liquid crystal composition 3 was used to prepare PSI-X-
When S012 was used, C2T orientation was obtained. 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 different compositions (Δε: about -0.7)
And 5014/000 ([Delta] [epsilon]: about -0.9) (manufactured by Merck), instead of using PSI-A-2101 (manufactured by Chisso) for the alignment film, a PS having a pretilt angle of 5 [deg.] Was used.
A ferroelectric liquid crystal display device was manufactured using IA-X007 (manufactured by Chisso Corporation). A uniform C2U orientation was obtained over all pixels.

The relationship between the voltage and the response speed of the manufactured ferroelectric liquid crystal display device was measured using the voltage waveform shown in FIG. The results are shown in FIG. As shown in FIG. 21, the voltage (V
min) was present.

<Comparative Example 11> A pretilt angle of 2 ° was applied to the alignment film.
Of SCE-12 (manufactured by Merck) into a commercially available liquid crystal cell KSRO-02 (manufactured by EHC, cell gap: 2 μm, parallel rubbing) using LX-1400 (manufactured by Hitachi Chemical Co., Ltd.) This was a dielectric liquid crystal display device. This ferroelectric liquid crystal display device was an alignment in which C2T alignment was mixed in C1T alignment, had poor quenching properties, and had non-uniform display quality. In addition, as shown in Table 5, SCE-12 was used in Example 3.
Although the value of Δε is equal to that of SCE-8 used in
The value of the spontaneous polarization was a large ferroelectric liquid crystal composition.

[0107]

[Table 5]

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

[0109]

According to the present invention, a ferroelectric liquid crystal display device which can be driven at high speed with high contrast can be provided. That is, there was Vmin at which the C2U orientation could be obtained stably and the response speed was minimized in the low voltage region. Especially,
According to the present invention having a pretilt angle of 5 ° to 10 °, the ferroelectric liquid crystal display device having a uniform C2U orientation over all pixels can be provided.

Further, according to the present invention using a ferroelectric liquid crystal having a spontaneous polarization of 10 nC / cm ² or less, the above-described ferroelectric liquid crystal display device driven at a low voltage can be provided.

[Brief description of the drawings]

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

FIGS. 2A and 2B are schematic diagrams showing a movement path of ferroelectric liquid crystal molecules, and FIGS.

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

FIG. 4 is a characteristic diagram of a ferroelectric liquid crystal in which 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 satisfying Δε <0.

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

FIG. 9 is a view showing the orientation of a conventional ferroelectric liquid crystal display device.

FIG. 10 is a diagram illustrating 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 illustrating a direction of pretilt 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 one embodiment of the present invention.

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

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

FIG. 18 is a driving waveform diagram 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 diagram 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 Scan electrode S Signal electrode 4a, 4b Alignment film 6 Ferroelectric liquid crystal 19 Pretilt

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02F 1/1337 510 G02F 1/1337 510 G09F 9/35 335 G09F 9/35 335

Claims (4)

[Claims] 1. A first substrate having a first electrode and a first alignment film that has been subjected to a uniaxial alignment treatment laminated in this order, and a second electrode disposed so as to face the first electrode. A ferroelectric liquid crystal is interposed between a second alignment film subjected to uniaxial alignment processing and a second substrate laminated in this order, and pretilt of molecules in the ferroelectric liquid crystal with respect to the first alignment film is performed. The direction of the angle is opposite to the direction of the pretilt angle of the molecule with respect to the second alignment film, the alignment state is a chevron structure, and the ferroelectric liquid crystal is represented by the general formula (I). Including at least one type of smectic liquid crystal, A ferroelectric liquid crystal display device having a dielectric anisotropy of less than 0. 2. A first substrate on which a first electrode and a first alignment film subjected to a uniaxial alignment treatment are stacked in this order, and a second electrode disposed so as to face the first electrode. A ferroelectric liquid crystal is interposed between a second alignment film subjected to uniaxial alignment processing and a second substrate laminated in this order, and pretilt of molecules in the ferroelectric liquid crystal with respect to the first alignment film is performed. The direction of the angle and the direction of the pretilt angle of the molecule with respect to the second alignment film are opposite to each other, the alignment state is a chevron structure, and the ferroelectric liquid crystal is represented by the general formula (II) Including at least one type of smectic liquid crystal, A ferroelectric liquid crystal display device having a dielectric anisotropy of less than 0. 3. The ferroelectric liquid crystal according to claim 1, wherein a pretilt angle of the molecule with respect to the first alignment film and a pretilt angle of the molecule with respect to the second alignment film are both 5 ° to 10 °. A ferroelectric liquid crystal display device characterized by the above-mentioned. 4. The ferroelectric liquid crystal according to claim 2, wherein a pretilt angle of the molecule with respect to the first alignment film and a pretilt angle of the molecule with respect to the second alignment film are both 5 ° to 10 °. A ferroelectric liquid crystal display device characterized by the above-mentioned.