JPH06180451A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To provide a liquid crystal device showing high contrast between a bright state and a dark state and especially very high display contrast for multiplexing driving and giving high-quality display and an effect to prevent vissually offensive afterimages. CONSTITUTION:This liquid crystal device consists of a chiral smectic liquid crystal inserted between a pair of parallel substrates having electrodes and a polyamide-imide oriented film on at least one substrate. The polyamide-imide has a structural unit expressed by formula in the main chain. In formula, R1 is a bivalent aliphatic group or aromatic group, R2 and R3 are univalent aliphatic groups or aromatic groups, and (x) is an integer >=1.

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 a ferroelectric liquid crystal element, and more particularly to a liquid crystal element which is advantageous in a manufacturing process and has improved display characteristics by improving an alignment state of liquid crystal molecules.

[0002]

2. Description of the Related Art 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. (Unexamined-Japanese-Patent No. 56-107216, US Patent No. 436792.
No. 4, 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 orthogonal Nicols is

[0006]

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

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

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

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.

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 ferroelectric liquid crystal having a non-helical structure and exhibiting bistability, which was announced by Clark and Lagerwall. However, the following problems were encountered.

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.
Tilt angle in ferroelectric liquid crystal having a helical structure (angle shown in FIG. 3 described later)

[0012]

[Outer 1]

It has been found that it is smaller than (the angle shown in FIG. 2 described later). 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 Clark and Ragawall, the tilt angle of the ferroelectric liquid crystal having a non-helical structure for realizing the bistability has the same angle as the tilt angle of the ferroelectric liquid crystal having the spiral 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. In other words, in a ferroelectric liquid crystal with a non-helical structure, the liquid crystal molecules are continuous with respect to the normal line of the substrate in the axis of the liquid crystal molecules adjacent to the lower substrate (direction of twist alignment) than the axis of the liquid crystal molecules adjacent to the upper substrate. Are arranged with a twist angle δ, which causes the tilt angle θ in the non-helical structure to be smaller than the tilt angle H in the spiral 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 above-mentioned reverse electric field generation phenomenon has been clarified, for example, by Akio Yoshida, “Switching Characteristics of SSFLC” on pages 142-143 of “Liquid Crystal Conference Proceedings”, October 1987.

Further, a generally used alignment film of a simple substance of polyimide is conventionally formed by applying a film of a polyamic acid solution which is a precursor thereof to form a film and then baking the film at a high temperature of at least 300 ° C. for imidization. However, a large amount of energy was required in the manufacturing process.

[0017]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a liquid crystal device which solves the above problems.
In particular, it is an object of the present invention to provide a liquid crystal element capable of achieving a display which produces a large tilt angle θ in a non-helical structure of chiral smectic liquid crystal, has a high contrast image, and does not cause an afterimage.

Further, another object is a liquid crystal device having an alignment film which can be formed by a manufacturing process capable of lowering the temperature and is excellent in productivity and which can be selected in other constituent materials. To provide.

[0019]

Means for Solving the Problems That is, the present invention provides a liquid crystal device having a chiral smectic liquid crystal sandwiched between a pair of parallel substrates on which transparent electrodes are formed and having a polyamideimide alignment film on at least one of the substrates. A liquid crystal device comprising a polyamideimide having at least a structural unit represented by the following general formula (I) in the main chain.

[0020]

[Chemical 2]

(In the formula, R ₁ is a divalent aliphatic group or aromatic group, R ₂ and R ₃ are monovalent aliphatic groups or aromatic groups, and x is an integer of x ≧ 1. )

The present invention will be described in detail below. FIG. 1 is a schematic view showing an example of a ferroelectric liquid crystal device of the present invention. In FIG. 1, 11a and 11b are In ₂ O ₃ and IT, respectively.
O (Indium tin oxide; Indium T
in Oxide) is a substrate (glass substrate) covered with transparent electrodes 12a and 12b such as 200 Å or more.
1500 Å thick insulating films 13a and 13b (for example, SiO
₂ film, TiO ₂ film, Ta ₂ O ₅ film, etc.) and the alignment film 1 having a thickness of 50 Å to 1000 Å formed by the above-mentioned polyamide-imide.
4a and 14b are laminated respectively.

At this time, the alignment films 14a and 14b which are 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
Ferroelectric chiral smectic liquid crystal 15
Are arranged, and the distance between the substrates 11a and 11b is sufficiently small to suppress the formation of the helical alignment structure of the ferroelectric chiral smectic liquid crystal 15 (for example, 0.
1 μm to 3 μm), and the ferroelectric chiral smectic liquid crystal 15 has a bistable alignment state. The sufficiently small ferroelectric chiral smectic liquid crystal 1 described above
The distance between the liquid crystals in which No. 5 is arranged is determined by the alignment films 14a and 14
bead spacer 16 (for example,
Silica beads, alumina beads, etc.). Further, 17a and 17b indicate polarizing plates.

The polyamide-imide alignment film used in the present invention has at least the above-mentioned general formula (I) in its main chain.
The diamine compound having the structural unit represented by the formula (1) but having the structural unit represented by the general formula (I) is used for incorporation into the main chain.

The polyamide-imide used in the present invention can be obtained by heating and ring-closing a precursor synthesized by polymerizing a diamine and a tricarboxylic acid anhydride as described above and below.

The tricarboxylic acid anhydride used in the present invention is, for example,

[0027]

[Chemical 3] Etc. are mentioned as an example.

As the diamine, a diamine having a structural unit represented by the following general formula (I) is used.

[0029]

[Chemical 4]

In the general formula (I), R ₁ is

[0031]

[Chemical 5]

A divalent aliphatic group such as

[0033]

[Chemical 6]

And other divalent aromatic groups. Also, R ₂ ,
R ₃ is

[0035]

[Chemical 7]

A monovalent aliphatic group such as

[0037]

[Chemical 8]

An aromatic group such as x is an integer of x ≧ 1.

Further, as the diamine, in addition to the diamine body having the structural unit represented by the general formula (I),
2,2-bis [4-, represented by the following general formula (II)
(Aminophenoxy) phenyl] alkyl compounds and the like can be used.

[0040]

[Chemical 9]

(Where X and Y are -C _x H _{2x + 1 or-}
(CH ₂ ) _m C _y F _{2 y + 1} , X and Y may be the same or different. However, x, y ≧ 1 and m ≧ 0. )

When ordinary polyimide is used as the alignment film, it is difficult to align the liquid crystal on the average molecular axis that produces a tilt angle close to the maximum tilt angle as described below. However,
The preferred properties can be obtained by having a specific polyamide-imide chemical structure.

Further, polyimide requires a high temperature because it is accompanied by an imidization reaction during firing, whereas polyamideimide can be fired at a low temperature because a part of polyamideimide is an amide. This is advantageous.

As the method for compounding the polyamide-imide in the present invention, a method such as blending (mixing), copolymerization, or laminated constitution at an arbitrary ratio can be used.

When the polyamide-imide alignment film used in the present invention is provided on a substrate, polyamic acid which is a precursor of polyamide-imide is mixed with a solvent such as dimethylformamide, dimethylacetamide, dimethylsulfoxide and N-methylpyrrolidone. To a 0.01 to 40 wt% solution, and the solution is applied onto the substrate by a spinner coating method, a spray coating method, a roll coating method, or the like, and then 10
The polyamideimide film can be formed by heating at a temperature of 0 to 350 ° C, preferably 150 to 300 ° C. This polyamide-imide film is then rubbed with a cloth or the like. The polyamide-imide film used in the present invention is set to a thickness of about 30Å to 1 µ, preferably 200Å to 2000Å. At this time, the insulating film 13 shown in FIG.
The use of a and 13b can be omitted. Further, in the present invention, when the polyamide-imide film is provided on the insulating films 13a and 13b, this film thickness can be set to 500 Å or less, preferably 300 Å or less.

As the liquid crystal substance used in the present invention, 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 is preferable. 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). As a concrete liquid crystal substance, for example, a liquid crystal substance “LC-
A liquid crystal composition containing 1 "," 80B "and" 80SI ^* "in the following ratios is preferably used.

[0047]

[Chemical 10]

Liquid crystal (1) (LC-1) ₉₀ / (80B) ₁₀ (2) (LC-1) ₈₀ / (80B) ₂₀ (3) (LC-1) ₇₀ / (80B) ₃₀ (4) (LC-1) ₆₀ / (80B) ₄₀ (5) 80SI ^* (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. The 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, the tilt angle H in the chiral smectic phase of the helical structure that the angle forming the apex angle of the triangular pyramid is applied is shown. Board 2
When a voltage above a certain threshold is applied between the electrodes on 1a and 21b, the helical structure of the liquid crystal molecules 23 is unwound, and the dipole moment (P⊥) 24 is oriented in the electric field direction. Can be changed. The liquid crystal molecules 23 have an elongated shape and exhibit refractive index anisotropy in the major axis direction and the minor axis direction thereof. Therefore, for example, if crossed Nicol polarizers are placed above and below the glass substrate surface, a voltage is applied. It is easy to understand that the liquid crystal optical modulator has optical characteristics that change depending on the polarity.

The surface-stabilized ferroelectric liquid crystal cell in the bistable alignment 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, as long as the applied electric field Ea does not exceed a certain threshold value, the respective alignment states are still maintained.

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

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 orientation state produced by the conventional rubbing-treated polyimide film is shown by the C-director diagram of FIG. The alignment state shown in FIG.
Since the twist of the molecular axis is large from a toward 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 represents a rubbing treatment axis applied to the above-described polyamide-imide film of the present invention, 61a is an average molecular axis in the alignment state U ₁ , 61b is an average molecular axis in the alignment state U ₂ , and 62a is an alignment state. The average molecular axis in S ₁ and 62b represent the average molecular axis in the oriented state S ₂ . 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 optical response delay (afterimage) 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 Ps, V _rev that causes an afterimage is expressed by the following equation.

[0060]

[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.
8 (b) shows that the direction of the spontaneous polarization Ps immediately after the release of the pulse electric field is opposite to the direction shown in FIG. 8 (a) (the liquid crystal molecules are changed from one stable alignment state to the other stable alignment state). However, since the distribution state of + 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 arrow B direction. 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 polyimide 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 overshoot to _2, the pulse immediately after the electric field is canceled, at work action in a reverse electric field V _rev as shown in FIG. 8 (b), the arrow X ₂ in the average molecular axis under splay alignment state along the direction S (B) The tilt angle θ decreases to the average molecular axis S (C) in the splay alignment state along the direction of the arrow X ₃ due to the action of the attenuation of the reverse electric field V _rev shown in FIG. 8C. A stable orientation state with a slight increase is obtained. FIG. 10 is a graph showing the state of optical response at this time.

According to the present invention, since the polyamideimide film having the above-mentioned specific structure is used, in the alignment state obtained by the alignment treatment, 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. It can be seen from FIG. 11 that the optical response is not delayed due to the afterimage and that the high contrast is caused in the memory state.

[0064]

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

Example 1 Two 1.1 mm-thick glass plates provided with a 1000-Å-thick ITO film were prepared, and a polyamideimide precursor represented by the following structural formula (III) was formed on each of the glass plates. Of N-methyl-2-pyrrolidone / n-butylcellosolve = 5 / 1,3.0 wt% solution was spin-coated to form a film, and heated and baked at 250 ° C. for about 1 hour. The film thickness at this time was 250Å.

[0066]

[Chemical 11]

The coating film thus formed was unidirectionally rubbed with a nylon blanket. After that, alumina beads having an average particle diameter of about 1.5 μm are dispersed on one of the substrates, and then two glass substrates are stacked so that the rubbing treatment axes are parallel to each other and are in the same treatment direction. Was produced.

In this cell, "CS-1014" (trade name), which is a ferroelectric smectic liquid crystal manufactured by Chisso Corporation
After vacuum injection under isotropic phase, 0.5 ° C /
Orientation could be achieved by slow cooling to 30 ° C. for h. The phase change in the cell of this example using this ferroelectric liquid crystal "CS-1014" was as follows.

[0069]

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

The liquid crystal cell described above was sandwiched between a pair of 90 ° crossed Nicols polarizers, a 30 V pulse of 50 μsec was applied, and then the 90 ° crossed Nicols were set to the extinction position (darkest state). The transmittance at this time was measured by a photomultiplier, and then 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 15 °. , The transmittance in the darkest state is 1%, the transmittance in the bright state is 25%,
Therefore, the contrast ratio was 25: 1. Further, the delay of the optical response that causes the afterimage was 0.2 seconds or less.

Further, 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 full-screen display after image display by predetermined character input. When the image was erased to a white state, the afterimage could not be read.
Note that S _N , S _{N + 1} , and S _{N + 2} in FIG. 12 represent voltage waveforms applied to the scanning lines, and I represents voltage waveforms applied to typical information lines. (I-S _N ) is the information line I
Is a composite waveform applied to the intersection of the scanning line S _N and the scanning line S _N.
Further, in this embodiment, V ₀ = 5 to 8 V, ΔT = 20 to 70
It was performed in μsec.

Example 2 A cell was prepared in the same manner as in Example 1 except that the polyamideimide alignment film represented by the following structural formula (IV) was used.

[0073]

[Chemical 12]

The same test as in Example 1 was conducted, and the results were that the contrast ratio was 22: 1 and the optical response time was 0.3 seconds. Further, when the display was performed by the same multiplexing driving as in Example 1, good results were obtained in terms of contrast and afterimage as in Example 1.

Comparative Example 1 A cell was prepared in the same manner as in Example 1 except that the polyamideimide alignment film represented by the following structural formula (V) was used.

[0076]

[Chemical 13]

The same test as in Example 1 was carried out, and the results were that the contrast ratio was 12: 1 and the optical response time was 1.0 second. Further, when the display was performed by the same multiplexing driving as in Example 1, the contrast was smaller than that in Example 1 and an afterimage was generated.

Comparative Example 2 A cell was prepared in the same manner as in Example 1 except that the polyamideimide alignment film represented by the following structural formula (VI) was used.

[0079]

[Chemical 14]

The same test as in Example 1 was conducted, and the result was that the contrast ratio was 10: 1 and the optical response time was 2.0 seconds. Further, when a display was performed by the same multiplexing driving as in Example 1, the contrast was smaller than that in Example 1 and an afterimage was generated.

Comparative Example 3 A cell was produced in the same manner as in Example 1 except that the polyamideimide alignment film represented by the following structural formula (VII) was used.

[0082]

[Chemical 15]

The same test as in Example 1 was conducted, and the results were that the contrast ratio was 5: 1 and the optical response time was 2.8 seconds. Further, when a display was performed by the same multiplexing driving as in Example 1, the contrast was smaller than that in Example 1 and an afterimage was generated.

[0084]

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 particularly the display contrast during the multiplexing driving is very large and a high quality display can be obtained. In addition, an effect that a noticeable afterimage phenomenon does not occur can be obtained. Furthermore, depending on the chemical structure, it is possible to lower the temperature than before due to the manufacturing process,
It has excellent productivity, and the range of choice can be expanded to other constituent materials.

[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 Ps, 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 chiral 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

[Outside 2] θ Tilt angles in non-helical structure Ea, Eb Electric field 50 Liquid crystal molecular layer 51a Upper substrate 51b Lower substrate 52 Liquid crystal molecule 53 Cone 54 Bottom 60 Rubbing treatment axis 61a Average molecular axis in orientation state U ₁ 61b In orientation state U ₂ Average molecular axis 62a Average molecular axis in oriented state S ₁ 62b Average molecular axis in oriented state S ₂ 81 C-Director

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

Claims (1)

[Claims] 1. A liquid crystal device having a chiral smectic liquid crystal sandwiched between a pair of parallel substrates on which transparent electrodes are formed and having a polyamideimide alignment film on at least one substrate, wherein at least one of the following general structures is present in the main chain of the polyamideimide. A liquid crystal device having a structural unit represented by formula (I). [Chemical 1] (In the formula, R ₁ is a divalent aliphatic group or an aromatic group, R ₂ ,
R ₃ represents a monovalent aliphatic group or aromatic group, and x is x ≧
It is an integer of 1. )