JPH06102515A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To stably provide a display which generates a large tilt angle theta and with which high-contrast images are displayed uniformly with a wide area without generating after-images. CONSTITUTION:This liquid crystal element is constituted by having oriented films 14a, 14b on at least one of a pair of substrates 11a, 11b provided with transparent electrodes 12, 12b and clamping a ferroelectric liquid crystal 15 between the substrates. These oriented films 14a, 14b are the composite consisting of >=2 kinds of polymer components and the polyamide expressed by formula is incorporated into one of these polymer components. (In the formula, R1, R2: 1 to 10C alkyl group or 1 to 10C fluoroalkyl group, where R1, R2 may be the same or different).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a liquid crystal display device and a liquid crystal display.
The present invention relates to a liquid crystal element used in an optical shutter or the like, particularly to a liquid crystal element having a chiral smectic phase, and more specifically to a liquid crystal element having improved display characteristics by improving the alignment state of liquid crystal molecules.

[0002]

2. Description of the Related Art Conventionally, a display device of a type in which transmitted light rays are controlled by using a refractive index anisotropy of ferroelectric liquid crystal molecules in combination with a polarizing device has been proposed by Clark and Lagerwall. (JP-A-56-107216, U.S. Pat. No. 4,3)
67,924, etc.).

This ferroelectric liquid crystal generally has a non-helical chiral smectic C phase (SmC ^* ) or H phase (SmH ^* ) in a specific temperature range, and responds to an electric field applied in this state. Has either a first optical stable state or a second optical stable state, and has the property of maintaining that state when no electric field is applied, that is, bistability, and is resistant to changes in the electric field. It has a quick response and is expected to be widely used as a high-speed and memory type display element, and in particular, due to its function, it is expected to be applied as a large-screen, high-definition display.

In order for the optical modulation element using the liquid crystal having the bistability to exhibit a predetermined driving characteristic, the liquid crystal arranged between the pair of parallel substrates is irrespective of the applied state of the electric field. It is necessary for the molecular alignment to be such that conversion between the two stable states occurs effectively.

Further, in the case of a liquid crystal element utilizing the birefringence of liquid crystal, the transmittance under the crossed Nicols is expressed by the following formula.

[0006]

[Equation 1] (In the formula, I ₀ is the incident light intensity, I is the transmitted light intensity, θ is the tilt angle, Δn is the refractive index anisotropy, d is the thickness of the liquid crystal layer, and λ is the wavelength of the incident light.)

The tilt angle θ in the above-mentioned non-helical structure appears as an angle in the average molecular axis direction of the twisted liquid crystal molecules in the first and second alignment states. According to the above formula, the maximum transmittance is obtained when the tilt angle θ is 22.5 °, and the tilt angle θ in the non-helical structure that realizes bistability is as close as possible to 22.5 °. is necessary.

By the way, as a method of aligning a ferroelectric liquid crystal, a liquid crystal molecular layer composed of a plurality of molecules forming a smectic liquid crystal is uniaxially aligned along its normal line over a large area. What can be realized and the manufacturing process can be realized by a simple rubbing treatment is desirable.

For example, US Pat. No. 4,561,726 is known as an alignment method for a ferroelectric liquid crystal, especially a chiral smectic liquid crystal having a non-helical structure.

[0010]

However, the alignment method that has been used so far, in particular, the alignment method using a rubbing-treated polyimide film, is applied to the non-helical structure exhibiting the bistability disclosed by Clark and Lagerwall. When applied to a ferroelectric liquid crystal, it had the following problems.

That is, according to the experiments conducted by the present inventors, the tilt angle θ in the non-helical ferroelectric liquid crystal obtained by aligning with the conventional rubbing-treated polyimide film.
(Angle shown in FIG. 3 to be described later) is smaller than a tilt angle H in the ferroelectric liquid crystal having a helical structure (angle of half apex angle of triangular pyramid shown in FIG. 2 to be described later). There was found. In particular, the tilt angle θ of a ferroelectric liquid crystal having a non-helical structure obtained by aligning with a conventional rubbing-treated polyimide film is generally about 3 ° to 8 °, and the transmittance at that time is about 3% to 5%. Met.

As described above, according to Clarke and Lagerwall, the tilt angle of the ferroelectric liquid crystal having a non-helical structure which realizes the bistability has the same angle as the tilt angle of the ferroelectric liquid crystal having the helical structure. As expected, the tilt angle θ in the non-helical structure is actually smaller than the tilt angle H in the spiral structure. Moreover, it has been found that the reason why the tilt angle θ in the non-helical structure is smaller than the tilt angle H in the helical structure is due to the twist alignment of the liquid crystal molecules in the non-helical structure.

The orientation state of the chiral smectic liquid crystal produced by the conventional rubbing-treated polyimide orientation film is the first optically stable state due to the presence of the polyimide orientation film as an insulating layer between the electrode and the liquid crystal layer. When a one-polarity voltage for switching from (for example, a white display state) to a second optical stable state (for example, a black display state) is applied, after the application of the one-polarity voltage is canceled,
A reverse electric field V _rev of the other polarity was generated in the ferroelectric liquid crystal layer, and this reverse electric field V _rev caused an afterimage at the time of display. The reverse electric field generation phenomenon described above is described in, for example, Akio Yoshida, "SS Proceedings of Liquid Crystal Symposium", October, 1987, "SS", pages 142-143.
Switching characteristics of FLC ”.

To solve such a problem, the present applicants have already proposed to use a new alignment film such as polyimide. However, even in this alignment state, there are a high-contrast state (uniform arrangement) and a low-contrast state (twisted arrangement). When multiplexing driving is performed in this state, a twisted array appears at the upper and lower limits of the writable driving range in the high contrast state. This tendency becomes remarkable when the display area becomes large, due to uneven rubbing, rounding of the waveform, and the like. As a result, the range of the state of uniform orientation is narrowed.

Therefore, an object of the present invention is to provide a liquid crystal device that solves the above-mentioned problems, and even in a large display area, a large tilt angle θ is generated by using a chiral smectic liquid crystal having a non-helical structure. Another object of the present invention is to provide a liquid crystal element that can stably achieve a display that has two states of high contrast and that does not cause an afterimage.

[0016]

The present inventors have found through experiments that the above problems can be solved by using a liquid crystal device having the following characteristics.

That is, according to the present invention, in a liquid crystal device having an alignment film on at least one of a pair of substrates provided with transparent electrodes and sandwiching a ferroelectric liquid crystal between the substrates, the alignment film is 2 A composite consisting of at least one polymer component,
In addition, the liquid crystal device is characterized in that one of its polymer components contains a polyamide represented by the following structural unit (1).

[0018]

[Chemical 2]

(In the formula, R ₁ and R ₂ have 1 to 10 carbon atoms.
Represents an alkyl group or a fluoroalkyl group having 1 to 10 carbon atoms. However, R ₁ and R ₂ may be the same or different. )

The present invention will be described in detail below. FIG. 1 is a schematic view showing an example of the liquid crystal element of the present invention. In FIG. 1, 11a and 11b are In ₂ O ₃ and ITO (Indium Tin Oxide; Indium Tin O).
a substrate (glass substrate) covered with transparent electrodes 12a and 12b such as xide), and 200Å to 1000 on it.
Å thick insulating films 13a and 13b (eg, SiO ₂ film, T
(iO ₂ film, Ta ₂ O ₅ film, etc.) and alignment films 14 a and 14 b each made of a polymer composite and having a thickness of 50 Å to 1000 Å are laminated.

At this time, the alignment films 14a and 14b, which have been rubbed (in the arrow direction) so as to be parallel and in the same direction (direction A in FIG. 1), are arranged. Substrates 11a and 11
A ferroelectric smectic liquid crystal 15 is arranged between the substrate b and the substrate b, and the distance between the substrates 11a and 11b is sufficiently small to suppress the formation of the helical alignment structure of the ferroelectric smectic liquid crystal 15 ( (For example, 0.1 μm to 3 μm)
, The ferroelectric smectic liquid crystal 15 has a bistable orientation state. Ferroelectric smectic liquid crystal 15
The sufficiently small inter-liquid crystal distance where
It is held by a bead spacer 16 (for example, silica beads, alumina beads, etc.) arranged between the substrates 11a and 11b. Reference numerals 17a and 17b denote polarizing plates.

According to the experiments conducted by the present inventors, as will be apparent from the examples described below, by using an alignment method using a specific polymer composite alignment film subjected to rubbing treatment,
Shows a large optical contrast between bright and dark states,
In particular, an optical response at the time of switching (at the time of multiplexing driving) which causes a large contrast to non-selected pixels at the time of multiplexing driving disclosed in U.S. Pat. No. 4,655,561 and the like and further causes an afterimage at the time of display An alignment state was achieved that did not cause burr.

The alignment film used in the present invention is a composite composed of two or more polymer components containing the polyamide represented by the structural unit (1). As the polymer component of the composite used in the present invention, polyamide, polyimide and polyamideimide are preferable.

As the dicarboxylic acid component of the polyamide used in the present invention, the dicarboxylic acid usually used in the production of polyamide is used. Among them, more preferable specific examples are terephthalic acid, isophthalic acid, 4,
4'-biphenyldicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 1,8
Examples thereof include naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 4,4 ″ -terphenyldicarboxylic acid.

As the tetracarboxylic acid component of the polyimide used in the present invention, a tetracarboxylic dianhydride usually used in the production of polyimide is used. Among these, more preferred specific examples are pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic acid. Dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride, 3,3 ", 4,4" -terphenyl tetracarboxylic dianhydride, 1,4,5,8-
Naphthalenetetracarboxylic dianhydride, 2,3,6,7
-Naphthalene tetracarboxylic dianhydride and the like can be mentioned.

As the acid component of the polyamide-imide used in the present invention, trimellitic acid anhydride can be used.

Further, as the diamine component of the polyimide, polyamide and polyimideamide used in the present invention,
It can be commonly used in such polyimide, polyamide, and polyimideamide.

Specific examples of the diamine component include 2,2-
Bis (4-amino-phenoxyphenyl) propane,
3,3-bis (4-amino-phenoxyphenyl) pentane, 4,4-bis (4-amino-phenoxyphenyl) heptane, 5,5-bis (4-amino-phenoxyphenyl) nonane, 2,2-bis (4-amino-phenoxyphenyl) butane, 2,2-bis (4-amino-phenoxyphenyl) pentane, 2,2-bis (4-amino-phenoxyphenyl) hexane, 3,3-bis (4
-Amino-phenoxyphenyl) hexane, 3,3-bis (4-amino-phenoxyphenyl) heptane, 4,
4-bis (4-amino-phenoxyphenyl) octane, 2,2-bis (4-amino-phenoxyphenyl)
-3-Methyl-butane, 2,2-bis (4-amino-phenoxyphenyl) -4-methyl-pentane, 2,2-
Bis (4-amino-phenoxyphenyl) -5-methyl-hexane, 3,3-bis (4-amino-phenoxyphenyl) -2-methyl-pentane, 2,2-bis (4-
Amino-phenoxyphenyl) -hexafluoropropane, 2,2-bis (4-amino-phenoxyphenyl)
-Decyl fluoropentane etc. can be mentioned.

When the acid component and the diamine component are reacted with each other, the ratio of both used is preferably 1 mol of the acid component to 1 mol of the diamine component.

The number average molecular weight of the polymer forming the alignment film in the present invention is, for example, 5,000 to 100,000, preferably 2
Those of 10,000 to 80,000 are desirable. Further, the alignment film in the present invention may be a mixture or a copolymer of the same polymer. The amount of the polyamide component of the structural unit (1) used in the present invention is 80% by weight or less, preferably 10 to 50% by weight or less based on the whole composite. If it is contained in a large amount exceeding 80% by weight, on the contrary, the orientation is deteriorated, which is not preferable.

When the alignment film used in the present invention is provided on a substrate, the polymer is dissolved in a solvent such as dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolide, etc., and 0.01 to 40% by weight is added. As a solution, the solution is applied to the substrate by a spinner coating method, a spray coating method, a roll coating method, or the like, and then 100 to 35
Drying at a temperature of 0 ° C, preferably 180 ° C to 300 ° C,
Form a polymer film. In some cases, the alignment film can be formed by dehydration ring closure. This polymer film is then rubbed with a cloth or the like.

The polymer film used in the present invention is 30 Å
The film thickness is set to about 1 μm, preferably 200Å to 2000Å. At this time, the insulating film 13a shown in FIG.
And the use of 13b can be omitted. Further, in the present invention, when the polymer film is provided on the insulating films 13a and 13b, the thickness of the polymer film can be set to 200 Å or less, preferably 100 Å or less.

The liquid crystal substance used in the present invention is preferably a liquid crystal which produces a chiral smectic C phase through an isotropic phase, a cholesteric phase and a smectic A phase in the temperature lowering process. In particular, the pitch in the cholesteric phase is preferably 0.8 μm or more (however, the pitch in the cholesteric phase is measured at the center point in the temperature range of the cholesteric phase). Specific liquid crystal substances include, for example, the following liquid crystal substances “A”, “B” and “C”.
A liquid crystal composition containing the following ratio is preferably used.

[0034]

[Chemical 3]

Liquid crystal (1) [A] ₉₀ / [B] ₁₀ (2) [A] ₈₀ / [B] ₂₀ (3) [A] ₇₀ / [B] ₃₀ (4) [A] ₆₀ / [ B] ₄₀ (5) [C] (The above compounding ratios represent weight ratios.)

FIG. 2 schematically shows an example of a cell for explaining the operation of the ferroelectric liquid crystal. 21a and 2
1b is a substrate (glass plate) covered with a transparent electrode composed of a thin film of In ₂ O ₃ , SnO ₂ or ITO, and SmC ^{* in} which the liquid crystal molecular layer 22 is oriented so as to be perpendicular to the glass substrate surface ^. Liquid crystal of (chiral smectic C) phase or SmH ^* (chiral smectic H) phase is enclosed. A thick line 23 represents a liquid crystal molecule, and the liquid crystal molecule 23 has a dipole moment (P⊥) 24 in a direction orthogonal to the molecule. At this time, 1/2 of the angle forming the apex angle of the triangular pyramid represents the tilt angle H in the chiral smectic phase having such a spiral structure.

When a voltage above a certain threshold is applied between the electrodes on the substrates 21a and 21b, the helical structure of the liquid crystal molecules 23 is unraveled, and all the dipole moments (P⊥) 24 are oriented in the direction of the electric field. Can change the orientation direction. The liquid crystal molecule 23 has an elongated shape,
It exhibits refractive index anisotropy in the major axis direction and the minor axis direction. Therefore, for example, if crossed Nicol polarizers are placed above and below the glass substrate surface, it becomes a liquid crystal optical modulation element whose optical characteristics change depending on the polarity of voltage application. Is easily understood.

The surface-stabilized ferroelectric liquid crystal cell in the bistable orientation state used in the liquid crystal device of the present invention can be made sufficiently thin (for example, 0.1 to 3 μm). As the liquid crystal layer becomes thinner in this way, as shown in FIG. 3, the helical structure of the liquid crystal molecules unwinds and becomes a non-helical structure even when no electric field is applied, and the dipole moment Pa or Pb of the liquid crystal molecule is directed upward (34a ) Or downward (34
Take either of the states of b).

When an electric field Ea or Eb having a polarity different from a certain threshold value is applied to such a cell by the voltage applying means 31a and 31b as shown in FIG. 3, the dipole moment becomes the electric field vector of the electric field Ea or Eb. Correspondingly, the direction is changed to the upward direction 34a or the downward direction 34b, and the liquid crystal molecules are aligned in either the first stable state 33a or the second stable state 33b accordingly. First and second at this time
The half of the angle formed by the stable state of 1 corresponds to the tilt angle θ.

The effects obtained by this ferroelectric liquid crystal cell are, firstly, that the response speed is extremely fast, and secondly that the orientation of the liquid crystal molecules is bistable. The second point will be further explained with reference to FIG. 3, for example.
When a is applied, the liquid crystal molecules are aligned in the first stable state 33a, but this state is stable even when the electric field is cut off. When a reverse electric field Eb is applied, the liquid crystal molecules are oriented in the second stable state 33b and change their orientation, but they remain in this state even when the electric field is cut off. Further, unless the applied electric field Ea exceeds a certain threshold value, the respective alignment states are also maintained.

Next, FIG. 4 is a sectional view schematically showing an alignment state of liquid crystal molecules aligned by an alignment method using an alignment film in a liquid crystal element of the present invention, and FIG. 5 is a view showing its C-director. .

Reference numerals 51a and 51b shown in FIG. 4 represent an upper substrate and a lower substrate, respectively. 50 is a liquid crystal molecule 52
In the liquid crystal molecule layer organized by, the liquid crystal molecules 52 are arranged at different positions along the bottom surface 54 (circle) of the cone 53.

FIG. 5 is a diagram showing a C-director.
In FIG. 5, U ₁ is the C-director 81 in one stable orientation state, and U ₂ is the C-director 81 in the other stable orientation state. The C-director 81 is a projection of the molecular long axis on a virtual plane perpendicular to the normal line of the liquid crystal molecular layer 50 shown in FIG.

On the other hand, the alignment state produced by the conventional rubbing-treated polymer film is shown by the C-director diagram of FIG. The alignment state shown in FIG. 6 corresponds to the upper substrate 51a.
Since the twist of the molecular axis is large from the bottom to the lower substrate 51b, the tilt angle θ is small.

Next, FIG. 7A shows a C-director 81.
5 is an explanatory view showing the tilt angle θ in the state of FIG. 5 (referred to as uniform orientation state), and FIG. 7B shows the tilt angle θ in the state of the C-director 81 shown in FIG. 6 (referred to as splay orientation state). FIG. In the figure, 60 indicates a rubbing treatment axis applied to the above-mentioned specific polymer film of the present invention,
61a is the average molecular axis in the orientation state U ₁ (one stable orientation state in the uniform), 61b is the average molecular axis in the orientation state U ₂ (the other stable orientation state in the uniform), 6
2a represents the average molecular axis in the alignment state S ₁ (one stable alignment state in the spray), and 62b represents the average molecular axis in the alignment state S ₂ (the other stable alignment state in the spray). The average molecular axes 61a and 61b can be converted by applying opposite polarity voltages that exceed each other's threshold voltage. The same thing occurs between the average molecular axes 62a and 62b.

Next, the usefulness of the uniform orientation state with respect to the delay (afterimage) of the optical response due to the reverse electric field V _rev will be described.

The capacitance C _i of the insulating layer (alignment film) of the liquid crystal cell,
When the capacitance of the liquid crystal layer is C _LC and the spontaneous polarization of the liquid crystal is _{P s} , V _{rev which} causes an afterimage is expressed by the following equation.

[0048]

[Equation 2]

FIG. 8 is a sectional view schematically showing the distribution of charges in the liquid crystal cell, the direction of spontaneous polarization Ps, and the direction of the reverse electric field V _rev . FIG. 8A shows the distribution state of + and-charges under the memory state before the application of the pulse electric field, and the direction of the spontaneous polarization Ps at this time is from the + charge to the-charge.

In FIG. 8B, the direction of the spontaneous polarization Ps immediately after the release of the pulsed electric field is opposite to that in the case of FIG. 8A (therefore, the liquid crystal molecules are stable from one stable alignment state to the other stable alignment state). However, since the distribution state of the + and-charges is the same as that in the case of FIG. 8A, the reverse electric field V _rev is generated in the liquid crystal in the direction of the arrow B. . This reverse electric field V _rev disappears after a while and the distribution state of + and − charges changes as shown in FIG. 8C.

FIG. 9 is an explanatory view showing a change in optical response in a splay alignment state caused by a conventional polymer alignment film in place of a change in tilt angle θ. As shown in FIG. 9, when a pulsed electric field is applied, the average molecular axis S (A) in the splay alignment state to the average molecular axis U in the uniform alignment state near the maximum tilt angle H along the direction of arrow X _{1 After} overshooting to ₂ and immediately after releasing the pulsed electric field,
Working action of the reverse electric field V _rev as shown in FIG. 8 (b), the arrow X ₂
Along the direction of the average molecular axis S under splay orientation
The tilt angle θ decreases to (B), and due to the action of the attenuation of the reverse electric field V _rev shown in FIG. 8C, the average molecular axis S (C) in the splay alignment state is reached along the direction of the arrow X _3. A stable alignment state in which the tilt angle θ is slightly increased can be obtained. Figure 1
0 is a graph showing the state of optical response at this time.

According to the present invention, since the alignment film made of the polymer film having the above-mentioned specific chemical structure is used, in the alignment state, the average molecular axis S ( A), S (B), and S (C) do not occur, and therefore, they can be arranged on the average molecular axis that produces a tilt angle θ close to the maximum tilt angle H. FIG. 11 is a graph showing the state of the optical response of the present invention at this time. That is, it can be said that the uniform alignment state described above can be obtained by using the alignment film of the present invention.

[0053]

EXAMPLES The present invention will be described more specifically below with reference to examples.

Example 1 An ITO film having a thickness of 1000 Å was provided, 1.1 mm
Two glass plates having a thickness of 200 mm in length and 200 mm in width are prepared, and 25 parts by weight of polyamide represented by the following structural formula (3) and 75 parts by weight of polyamide represented by the following structural formula (2) are provided on each glass plate. 2.0% by weight of N-methylpyrrolidone / n-butylcellosolve = 1/1 mixed with
The solution was applied for 30 seconds by a spinner rotating at 3000 rpm.

After the film formation, heat drying was performed at 250 ° C. for about 1 hour. The number average molecular weight of the polyamide used was 5000 for the structural formula (3) and 40,000 for the structural formula (2). The number average molecular weight is a value measured by gel permeation chromatography (GPC). The film thickness at this time was 250Å. The coated film was unidirectionally rubbed with a nylon flocked cloth.

After that, alumina beads having an average particle diameter of about 1.5 μm were dispersed on one glass plate, and then two glass plates were stacked so that the rubbing treatment axes were parallel to each other and were in the same treatment direction. A cell was created together.

[0057]

[Chemical 4]

"CS-1014" (trade name), which is a ferroelectric smectic liquid crystal manufactured by Chisso Corporation, was vacuum-injected into this cell under an isotropic phase, and then 0.5 from the isotropic phase.
Orientation could be achieved by slow cooling to 30 ° C at a rate of ° C / min. The phase change in the cell of this example using this ferroelectric liquid crystal "CS-1014" was as follows.

[0059]

[Equation 3] (Iso. = Isotropic phase, Ch = cholesteric phase, SmA
= Smectic A phase, SmC ^* = Chiral smectic C phase)

The above-mentioned liquid crystal cell is sandwiched between a pair of 90 ° crossed Nicols polarizers, a 30 V pulse of 50 μsec is applied, and then the 90 ° crossed Nicols are set to the extinction position (darkest state). Was measured by a photomultiplier. Subsequently, when a -30 V pulse of 50 μsec was applied and the transmittance (bright state) at this time was measured by the same method, the tilt angle θ was 12.0 °, and the transmittance in the darkest state was At 1.2%, the light transmittance is 3
It was 2.0%. Therefore, the contrast ratio is 2
It was 7: 1. The optical response that caused the afterimage was less than 0.2 seconds.

When this liquid crystal cell was displayed by multiplexing drive using the drive waveform shown in FIG. 12, a high-contrast and high-quality display was obtained, and after the image was displayed by inputting a predetermined character, the entire white state was obtained. After erasing, the afterimage was illegible.

Note that S _N , S _{N + 1} , and S _{N + 2} in FIG. 12 represent voltage waveforms applied to the scanning lines, and (I−S _N ).
Is a composite waveform applied to the intersection of the information line I and the scanning line S _N. Further, in this embodiment, V ₀ = 5 to 8V, ΔT
= 20 to 70 μsec.

Examples 2 to 7 Cells were obtained in the same manner as in Example 1 except that the alignment control film and the liquid crystal material obtained from the polymer components shown in Tables 1 and 2 were used. The number average molecular weight of the polyamide of the structural unit (1) used in the present invention was about 5,000, and other polymers were about 50,000.

The same test as in Example 1 was carried out for each. Table 3 shows the uniformity of alignment in the liquid crystal element as a result of the contrast ratio and the optical response time. Further, when the display was performed by the same multiplexing driving as in Example 1, the same results as in Example 1 were obtained for the contrast and the afterimage.

[0065]

[Table 1]

[0066]

[Table 2]

[0067]

[Table 3]

(Note) Evaluation of uniformity in liquid crystal element ⊚: Good orientation even by multiplexing driving. ◯: Alignment unevenness partially occurred even by multiplexing driving. X: Alignment unevenness occurred due to multiplexing driving.

Comparative Examples 1 to 6 A cell was prepared in exactly the same manner as in Example 1 except that the orientation control film, polymer component and liquid crystal material shown in Tables 4 and 5 were used. Table 6 shows the results for the contrast ratio and the optical response of each cell, and for Comparative Examples 1 and 2, the uniformity of alignment in the liquid crystal element.

Further, when the display was performed by the same multiplexing driving as in Example 1, the contrasts of Comparative Examples 3 to 6 were smaller than those of this Example, and the afterimage was generated. Regarding the uniformity of the alignment and the contrast due to the multiplexing driving of Comparative Examples 1 and 2, the unevenness was slightly generated compared to the present example in the case of a large area.

[0071]

[Table 4] Table 4

[0072]

[Table 5]

[0073]

[Table 6]

[0074]

As described above, according to the liquid crystal element of the present invention, the contrast in the bright state and the dark state is high, and even in a large display area, a chiral smectic liquid crystal having a non-helical structure is used to obtain a large tilt angle. θ was generated, and a high-quality display stably having two states with high contrast was obtained. In addition, an effect that a noticeable afterimage phenomenon does not occur can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a liquid crystal element of the present invention.

FIG. 2 is a perspective view showing an alignment state of a chiral smectic liquid crystal having a helical structure.

FIG. 3 is a perspective view showing an alignment state of a chiral smectic liquid crystal having a non-helical molecular arrangement.

FIG. 4 is a cross-sectional view showing an alignment state of a chiral smectic liquid crystal aligned by an alignment method using an alignment film according to the present invention.

5 is a C-director diagram of the chiral smectic liquid crystal of FIG. 4 in a uniform alignment state.

FIG. 6 is a C-director diagram in a splay alignment state.

7A is an explanatory diagram showing a tilt angle θ in a uniform alignment state, and FIG. 7B is an explanatory diagram showing a tilt angle θ in a splay alignment state.

FIG. 8 is a cross-sectional view showing a charge distribution in a ferroelectric liquid crystal, a direction of spontaneous polarization P _s , and a direction of a reverse electric field V _rev .

FIG. 9 is an explanatory diagram showing changes in tilt angle θ during and after application of an electric field.

FIG. 10 is a graph showing optical response characteristics of a liquid crystal element of a conventional example.

FIG. 11 is a graph showing optical response characteristics of the liquid crystal element of the present invention.

FIG. 12 is a waveform diagram of a drive voltage used in an example of the present invention.

[Explanation of symbols]

11a, 11b Glass substrate 12a, 12b Transparent electrode 13a, 13b Insulating film 14a, 14b Alignment film 15 Ferroelectric smectic liquid crystal 16 Bead spacer 17a, 17b Polarizing plate 21a, 21b Substrate 22 Liquid crystal molecular layer 23 Liquid crystal molecule 24 Dipole moment 31a , 31b Voltage application means 32 Vertical layer 33a First stable state 33b Second stable state 34a Upward dipole moment 34b Downward dipole moment H Tilt angle in helical structure θ Tilt angle in non-helical structure Ea, Eb Electric field 50 Liquid crystal molecule layer 51a Upper substrate 51b Lower substrate 52 Liquid crystal molecules 53 Cones 54 Bottom surface 60 Rubbing treatment axis 61a Average molecular axis in orientation state U ₁ 61b Average molecular axis in orientation state U ₂ 62a Average molecular axis in orientation state S ₁ the average molecular axis 8 at 62b orientation state S ₂ C- director

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Goji Kadono 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. A liquid crystal device comprising an alignment film on at least one of a pair of substrates provided with transparent electrodes, and a ferroelectric liquid crystal sandwiched between the substrates, wherein the alignment film comprises two or more polymers. A liquid crystal element, which is a composite of components and which contains a polyamide represented by the following structural unit (1) in one of its polymer components. [Chemical 1] (In the formula, R ₁ and R ₂ represent an alkyl group having 1 to 10 carbon atoms or a fluoroalkyl group having 1 to 10 carbon atoms. However, R ₁ and R ₂ may be the same or different. ) 2. The liquid crystal device according to claim 1, wherein the content of the polyamide represented by the structural unit (1) is 80% by weight or less based on the whole composite.