JP2657879B2 - Liquid crystal element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device and a liquid crystal display.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal element used in an optical shutter or the like, particularly to 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 the alignment state of liquid crystal molecules.

[0002]

2. Description of the Related Art Clark and Lagerwall have proposed a display device of a type that controls transmitted light in combination with a polarizing element utilizing the refractive index anisotropy of ferroelectric liquid crystal molecules. (JP-A-56-107216, U.S. Pat.
No. 4 specification).

The 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 applied electric field in this state. Takes a first optical stable state or a second optical stable state, and maintains the state when no electric field is applied, that is, it has bistability. It has a quick response and is expected to be widely used as a high-speed and storage type display element. In particular, its function is expected to be applied to a large screen and high definition display.

In order for an optical modulator using a liquid crystal having bistability to exhibit predetermined driving characteristics, the liquid crystal disposed between a pair of parallel substrates needs to be driven by the liquid crystal regardless of the state of application of an electric field. It is necessary to be in a state of molecular alignment in which conversion between the two stable states effectively takes place.

In the case of a liquid crystal element utilizing birefringence of liquid crystal, the transmittance under crossed Nicols is

[0006]

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

[0007] The tilt angle θ in the above-described 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 equation, the tilt angle θ is 22.5 °
It is necessary that the tilt angle θ in the non-helical structure for realizing bistability be as close as possible to 22.5 ° when the angle is at the maximum.

As a method of aligning a ferroelectric liquid crystal, a liquid crystal molecular layer formed of a plurality of molecules forming a smectic liquid crystal is uniaxially aligned along a normal line over a large area. It is desirable that the manufacturing process can be realized by a simple rubbing process.

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

However, the alignment method used up to now, especially the alignment method using a rubbed polyimide film, is applied to the above-mentioned non-helical ferroelectric liquid crystal having a bistable structure disclosed by Clark and Ragawall. When the method was applied by using, the following problems were encountered.

That is, according to the experiments conducted by the present inventors, the tilt angle θ of a non-helical ferroelectric liquid crystal obtained by orienting a conventional rubbed polyimide film was used.
(Angle shown in FIG. 3 described later) Tilt angle in ferroelectric liquid crystal having a helical structure

[0012]

[Outside 1]

It has been found that the angle is smaller than (an angle shown in FIG. 2 described later). In particular, the tilt angle θ of a non-helical structure ferroelectric liquid crystal obtained by orienting with a conventional rubbed polyimide film is generally about 3 ° to 8 °, and the transmittance at that time is about 3% to 5% at most. Met.

As described above, according to Clark and Ragawall, the tilt angle of a ferroelectric liquid crystal having a non-helical structure for realizing bistability has the same angle as the tilt angle of a ferroelectric liquid crystal having a helical structure. In fact, the tilt angle θ in the non-helical structure is smaller than the tilt angle H in the helical structure. Moreover, it has been found that the cause of the tilt angle θ in the non-helical structure being smaller than the tilt angle H in the helical structure is due to the twisted arrangement of the liquid crystal molecules in the non-helical structure. In other words, in a ferroelectric liquid crystal having a non-helical structure, the liquid crystal molecules are continuous with respect to the normal of the substrate from the axis of the liquid crystal molecules adjacent to the upper substrate to the axis of the liquid crystal molecules adjacent to the lower substrate (the direction of twist arrangement). This is a twisted arrangement at 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 helical structure.

The alignment state of the chiral smectic liquid crystal produced by the conventional rubbed polyimide alignment film depends on the presence of the polyimide alignment film as an insulator layer between the electrode and the liquid crystal layer. When one polarity voltage for switching from (for example, a white display state) to a second optically 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 in a display. The above-mentioned reverse electric field generation phenomenon is clarified in, for example, "Switching Characteristics of SSFLC" by Akio Yoshida, October, 1987, "Transactions of Liquid Crystal Symposium", pp. 142-143.

Further, an alignment film of a simple substance of polyimide, which is generally used in the past, is formed by applying a polyamic acid solution as a precursor, coating and forming the film, and baking at a high temperature of at least about 300 ° C. to obtain an imidized film. And required a large amount of energy in the manufacturing process.

[0017]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a liquid crystal device which solves the above-mentioned problems.
In particular, it is an object of the present invention to provide a liquid crystal element which can generate a large tilt angle θ in a non-helical structure of a chiral smectic liquid crystal, and can achieve a display with high contrast and no afterimage.

Another object is to provide a liquid crystal device having an alignment film which can be formed by a manufacturing process which can be operated at a low temperature, is excellent in productivity, and can be selected from other constituent materials. Is to provide.

[0019]

That is, the present invention relates to a liquid crystal device having a chiral smectic liquid crystal sandwiched between a pair of substrates on which a transparent electrode is formed, and a polyamideimide alignment film on at least one of the substrates. At least a structural unit represented by the following general formula (I) and a structural unit represented by the following general formula (II) in the main chain of the imide
And a liquid crystal element having:

[0020]

Embedded image

(Wherein, R ₁ represents a divalent aliphatic or aromatic group, R ₂ and R ₃ represent a monovalent aliphatic or aromatic group, and x is an integer of x ≧ 1.) X, Y is -C _A H _{2A + 1}
Or - (CH ₂₎ shows the _{m C B F 2B + 1,} X, Y are identical
Or different. However, A, B ≧ 1, m
≧ 0. )

Hereinafter, the present invention will be described in detail. FIG. 1 is a schematic diagram showing an example of the ferroelectric liquid crystal device of the present invention. In FIG. 1, reference numerals 11a and 11b denote In ₂ O ₃ and IT
O (Indium tin oxide; Indium T
a substrate (glass substrate) covered with transparent electrodes 12a and 12b such as in Oxide, etc .;
1500 ° thick insulating films 13a and 13b (eg, SiO 2
₂ film, TiO ₂ film, Ta ₂ O ₅ film, etc.) and the above-mentioned polyamideimide, and an alignment film 1 having a thickness of 50 to 1000 mm.
4a and 14b are respectively laminated.

At this time, the alignment films 14a and 14b that have been rubbed (in the direction of the arrow) are arranged so as to be parallel and in the same direction (the direction A in FIG. 1). Substrates 11a and 11
b, a ferroelectric chiral smectic liquid crystal 15
Are arranged, and the distance between the substrates 11a and 11b is small enough to suppress the formation of the helical array structure of the ferroelectric chiral smectic liquid crystal 15 (for example, 0.1 mm).
(1 μm to 3 μm), and the ferroelectric chiral smectic liquid crystal 15 has a bistable alignment state. A sufficiently small ferroelectric chiral smectic liquid crystal 1 as described above
5 is arranged between the alignment films 14a and 14a.
b and a bead spacer 16 (for example,
(Silica beads, alumina beads, etc.). Reference numerals 17a and 17b denote 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 general formula (I) is used for incorporation into the main chain.

The polyamideimide used in the present invention can be obtained by heat-cyclizing a precursor synthesized by polymerizing a diamine and a tricarboxylic anhydride as described above and below.

The tricarboxylic anhydride used in the present invention includes, for example,

[0027]

Embedded image 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]

Embedded image

In the general formula (I), R ₁ is

[0031]

Embedded image

A divalent aliphatic group such as

[0033]

Embedded image

And a divalent aromatic group such as Also, R ₂ ,
R ₃

[0035]

Embedded image

A monovalent aliphatic group such as

[0037]

Embedded image

And the like. x is an integer of x ≧ 1.

Further, as the diamine, in addition to the diamine 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]

Embedded image

[0041] (wherein, X, Y is -C _A H _{2A + 1} or -
(CH ₂₎ shows the _{m C B F 2B + 1,} X, Y , even the same or
It may be different. However, A, B ≧ 1, m ≧ 0
You. )

When ordinary polyimide is used as an alignment film, it is difficult to align liquid crystals on an average molecular axis that generates a tilt angle close to the maximum tilt angle as described below. However,
Preferred properties can be obtained by having a specific polyamideimide chemical structure.

Furthermore, while polyimide requires a high temperature due to an imidization reaction during firing, polyamideimide can be fired at a low temperature because a part of it is an amide, thereby improving productivity. It is more advantageous.

In the present invention, as a method for complexing the polyamideimide, a method such as blending (mixing), copolymerization, or lamination at an arbitrary ratio can be used.

When the polyamide-imide alignment film used in the present invention is provided on a substrate, the polyamide acid, which is a precursor of the polyamide-imide, is converted into a solvent such as dimethylformamide, dimethylacetamide, dimethylsulfoxide, and N-methylpyrrolidone. To a 0.01 to 40% by weight solution, and the solution is applied to a substrate by a spinner coating method, a spray coating method, a roll coating method, or the like.
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 thickness of the polyamideimide film used in the present invention is set to about 30 to 1 μm, preferably 200 to 2000 μm. In this case, the insulating film 13 shown in FIG.
The use of a and 13b can be omitted. In the present invention, when a polyamideimide film is provided on the insulating films 13a and 13b, the thickness can be set to 500 ° or less, preferably 300 ° or less.

As the liquid crystal substance used in the present invention, a liquid crystal that generates a chiral smectic C phase through an isotropic phase, a cholesteric phase, and a smectic A phase in a temperature decreasing 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 central point in the temperature range of the cholesteric phase). As a specific liquid crystal material, for example, a liquid crystal material “LC-
1 "," 80B "and" 80SI ^* "are preferably used in a liquid crystal composition containing the following ratio.

[0047]

Embedded image

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 mixing ratios represent weight ratios, respectively.)

FIG. 2 schematically shows an example of a cell for explaining the operation of the ferroelectric liquid crystal. 21a and 2
Reference numeral 1b denotes a substrate (glass plate) coated with a transparent electrode made of a thin film of In ₂ O ₃ , SnO _2, ITO, or the like, between which a liquid crystal molecule 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 bold line 23 represents a liquid crystal molecule, and the liquid crystal molecule 23 has a dipole moment (P⊥) 24 in a direction perpendicular to the molecule. At this time, the angle forming the apex angle of the triangular pyramid represents the tilt angle H in the chiral smectic phase having the spiral structure. Substrate 2
When a voltage equal to or higher than 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 liquid crystal molecules 23 are oriented in such a manner that all dipole moments (P⊥) 24 are directed in the direction of the electric field. 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. Therefore, for example, if crossed Nicol polarizers are placed above and below the glass substrate surface, voltage It is easily understood that the liquid crystal optical modulation element whose optical characteristics change depending on the polarity.

The thickness of the surface stable ferroelectric liquid crystal cell in a bistable alignment state used in the liquid crystal element of the present invention can be made sufficiently thin (for example, 0.1 to 3 μm). As shown in FIG. 3, as the liquid crystal layer becomes thinner, the helical structure of the liquid crystal molecules is unwound 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 upward (34a). ) Or downward (34
Take either state of b).

When an electric field Ea or Eb having a different polarity or more than a certain threshold 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 upward 34a or downward 34b, and accordingly, the liquid crystal molecules are aligned in one of the first stable state 33a and the second stable state 33b. The first and second at this time
Is equivalent to the tilt angle θ.

The effects obtained by the ferroelectric liquid crystal cell are firstly that the response speed is extremely fast, and secondly that the orientation of liquid crystal molecules has bistability. The second point will be further described with reference to, for example, FIG.
When a is applied, the liquid crystal molecules are oriented to the first stable state 33a, which is stable even when the electric field is turned off. Also, when an electric field Eb in the opposite direction is applied, the liquid crystal molecules are oriented to the second stable state 33b and change the direction of the molecules, but remain in this state even after the electric field is turned off. As long as the applied electric field Ea does not exceed a certain threshold value, the respective alignment states are also maintained.

Next, FIG. 4 is a cross-sectional view schematically showing an alignment state of liquid crystal molecules aligned by an alignment method using a polyamideimide alignment film in the liquid crystal element of the present invention, and FIG. 5 is a view showing the C-director thereof. It 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
The liquid crystal molecules 52 are arranged by changing the position 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 onto a virtual plane perpendicular to the normal of the liquid crystal molecular layer 50 shown in FIG.

On the other hand, the orientation state caused by the conventional rubbed polyimide film is shown by a C-director diagram in FIG. The orientation state shown in FIG.
Since the torsion of the molecular axis is large from a to the lower substrate 51b, the tilt angle θ is small.

Next, FIG. 7A shows a C-director 81.
Is an explanatory diagram showing the tilt angle θ in the state of FIG. 5 (referred to as a uniform alignment state), and FIG. 7B shows the tilt angle θ in the state where the C-director 81 is in the state of FIG. 6 (referred to as a splay alignment state). FIG. In the figure, 60 denotes the rubbing axis was applied to polyamide-imide film of the present invention described above, 61a denotes an average molecular axis in the orientation state U _1, 61b denotes an average molecular axis in the orientation state U _2, 62a are aligned state The average molecular axis in S ₁ , 62b indicates the average molecular axis in the alignment state S ₂ . The average molecular axes 61a and 61b can be converted by applying opposite polarity voltages exceeding the threshold voltage to each other. The same occurs between the average molecular axes 62a and 62b.

Next, the usefulness of the uniform alignment 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,
Assuming that the capacity of the liquid crystal layer is C _LC and the spontaneous polarization of the liquid crystal is Ps, V _{rev which} causes an afterimage is expressed by the following equation.

[0060]

(Equation 2)

FIG. 8 is a cross-sectional view schematically showing the charge distribution in the liquid crystal cell, the direction of the spontaneous polarization Ps, and the direction of the reverse electric field V _rev . FIG. 8A shows a distribution state of + and-charges under the memory state before the application of the pulse electric field. At this time, the direction of the spontaneous polarization Ps is from + charges to-charges.
FIG. 8B shows that the direction of the spontaneous polarization Ps immediately after the release of the pulse electric field is opposite to the direction of FIG. 8A (therefore, the liquid crystal molecules change from one stable alignment state to the other stable alignment state). However, since the distribution of the + and-charges is the same as that in FIG. 8A, a reverse electric field V _rev is generated in the liquid crystal in the direction of arrow B. After a while, the reverse electric field V _rev disappears as shown in FIG. 8C, and the distribution of the + and-charges changes.

FIG. 9 is an explanatory view showing a change in the optical response in the splay alignment state caused by the conventional polyimide alignment film in place of a change in the tilt angle θ. As shown in FIG. 9, the pulse at the time of electric field application, the average molecular axis U under uniform alignment state of the maximum tilt angle around H average molecular axis S under splay alignment state along the direction of the arrow X ₁ (A) ₂ immediately after the release of the pulsed electric field, the action of the reverse electric field V _rev shown in FIG. 8B acts, so that the average molecular axis S (B) in the splay alignment state along the direction of arrow X _2. tilt angle θ is reduced to, and by the action of attenuation of the reverse electric field V _rev as shown in FIG. 8 (c), the tilt angle θ until the average molecular axis S (C) under the spray orientation state in the direction of arrow X ₃ Is obtained, thereby obtaining a stable alignment state in which is slightly increased. FIG. 10 is a graph showing the state of the optical response at this time.

According to the present invention, since the polyamide-imide film having the specific structure described above is used, in the orientation state obtained by the orientation treatment, the average molecular axis S (in the spray state shown in FIG. 9) is obtained. A), S (B) and S (C) do not occur, and therefore, they can be arranged on the average molecular axis that generates 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. According to FIG. 11, it is recognized that the optical response is not delayed due to the afterimage, and that high contrast is caused in the memory state.

[0064]

The present invention will be described more specifically with reference to the following examples.

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

[0066]

Embedded image

The coating film thus formed was subjected to a unidirectional rubbing treatment using a nylon blanket. Then, after spraying alumina beads having an average particle size of about 1.5 μm on one of the substrates, the two glass substrates are overlapped so that the respective rubbing axes are parallel to each other and in the same processing direction, and the cells are stacked. Was prepared.

In this cell, "CS-1014" (trade name) which is a ferroelectric smectic liquid crystal manufactured by Chisso Corporation
Is vacuum-injected under the isotropic phase, and then 0.5 ° C /
The alignment was achieved by slowly cooling to 30 ° C. for 30 hours. 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 above-mentioned liquid crystal cell is sandwiched between a pair of 90 ° crossed Nicol polarizers, a 30 V pulse of 50 μsec is applied, and then the 90 ° crossed Nicol is set to an 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. In addition, the delay of the optical response causing the afterimage was 0.2 seconds or less.

Further, when this liquid crystal cell was displayed by multiplexing driving using the driving waveform shown in FIG. 12, a high-contrast, high-quality display was obtained. Was erased to a white state, and the occurrence of an afterimage was not legible.
In FIG. 12, S _N , S _{N + 1} , and S _{N + 2} represent voltage waveforms applied to the scanning lines, and I represents a voltage waveform applied to typical information lines. (I−S _N ) is the information line I
7 is a composite waveform applied to the intersection between the scan line and the scan line _SN .
In this embodiment, V ₀ = 5 to 8 V and ΔT = 20 to 70
Performed in μsec.

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

[0073]

Embedded image

The same test as in Example 1 was performed, and the result was that the contrast ratio was 22: 1 and the optical response delay time was 0.3 seconds. When a display was performed by the multiplexing drive in the same manner as in the first embodiment, good results were obtained in both the contrast and the afterimage as in the first embodiment.

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]

Embedded image

The same test as in Example 1 was performed, and a result was obtained in which the contrast ratio was 12: 1 and the optical response delay time was 1.0 second. Further, when the display was performed by the multiplexing drive similar to that of the first embodiment, the contrast was smaller than that of the first embodiment, and an afterimage occurred.

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

[0079]

Embedded image

The same test as in Example 1 was performed, and a result was obtained in which the contrast ratio was 10: 1 and the optical response delay time was 2.0 seconds. When the display was performed by the multiplexing drive in the same manner as in Example 1, the contrast was smaller than that of 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 polyamide-imide alignment film represented by the following structural formula (VII) was used.

[0082]

Embedded image

The same test as in Example 1 was performed, and a result was obtained in which the contrast ratio was 5: 1 and the optical response delay time was 2.8 seconds. When the display was performed by the multiplexing drive in the same manner as in Example 1, the contrast was smaller than that of Example 1, and an afterimage was generated.

[0084]

As described above, according to the liquid crystal device of the present invention, the contrast in the bright state and the dark state is high, and particularly, the display contrast during multiplexing driving is very large, and high quality display can be obtained. In addition, an effect of not causing a noticeable afterimage phenomenon can be obtained. In addition, depending on the chemical structure, lower temperatures can be achieved due to the manufacturing process,
It is excellent in productivity and can be expanded to other constituent materials.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one 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 orientation 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.

FIG. 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.

FIG. 7A is an explanatory diagram showing a tilt angle θ in a uniform orientation state, and FIG. 7B is an explanatory diagram showing a tilt angle θ in a splay orientation 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 a change in a tilt angle θ at the time of applying an electric field and after the electric field is applied.

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

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 driving 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 angle in non-helical structure Ea, Eb electric field 50 liquid crystal molecular layer 51 a upper substrate 51 b lower substrate 52 liquid crystal molecules 53 cone 54 bottom surface 60 rubbing axis 61 a average molecular axis 61b in alignment state U ₁ average molecular axis 61 b in alignment state U ₂ the average molecular axes 81 C-director in the average molecular axis 62b oriented state S ₂ in the average molecular axis 62a oriented state S ₁

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takeshi Kadoba 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-64-78226 (JP, A)

Claims (1)

(57) [Claims] 1. A liquid crystal device having a chiral smectic liquid crystal sandwiched between a pair of substrates on which a transparent electrode is formed and a polyamideimide alignment film on at least one substrate, wherein at least one of the following general formulas is contained in the main chain of the polyamideimide. The structural unit represented by (I) and the following general formula (II)
And a structural unit represented by the formula: Embedded image (Wherein, R ₁ represents a divalent aliphatic or aromatic group, R ₂ and R ₃ represent a monovalent aliphatic or aromatic group, and x represents x
It is an integer of ≧ 1. X and Y are -C _A H _{2A + 1 or-} (C
H ₂₎ shows the _{m C B F 2B + 1,} X, Y , even or different identity
It may be. However, A, B ≧ 1, m ≧ 0
You. )