JPH05273558A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To obtain the high-grade display which obviates the generation of after-images by the degradation in the surface energy of orientation control films and the increase in tilt angle by using monomolecular film or cumulative monomolecular films consisting of polyamide acid and two kinds of alkyl amines as the orientation control films. CONSTITUTION:The orientation control films of the liquid crystal element constituted by filling a ferroelectric liquid crystal forming plural molecular arrangement layers perpendicular to a pair of parallel substrates or approximately perpendicularly thereto between these substrates are formed of the polyamide acid and the first alkyl amine expressed by any of formulas (I) to (III) (X, Y are H, CH3, C2H5; (p), (q), (w) are an integer of >=26; 12<=p<=26, 15<=p+q<=52, 17<=p+q+w<=60) and the second alkyl amine expressed by any of formulas (IV) to (VI) (X, Y are H CH3, C2H5; (p), (q), (w) are an integer of <=16; 1<=p<=16, 4<=p+q<=16, 4<=p+q+w<=16).

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A display element of the type in which transmitted light rays are controlled by combining it with a polarizing element by utilizing the refractive index anisotropy of ferroelectric liquid crystal molecules has been proposed by Clarke and Lagerwall. 56-107216, U.S. Pat. No. 4,367,924, etc.). This ferroelectric liquid crystal generally has a chiral smectic C phase (SmC ^* ) or H phase (SmH ^* ) in a specific temperature range, and in response to an electric field applied in this state, it has a first optical stability. Has either a state or a second optically stable state, and has the property of maintaining that state when no electric field is applied, that is, a bistable state, and has a quick response to changes in the electric field. Wide use as a high-speed and memory type display element is expected.

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 electric field application state. It is necessary that the molecular arrangement is such that conversion between the two stable states occurs effectively.

By the way, as a method of aligning a ferroelectric liquid crystal, a method of using an alignment control film subjected to a uniaxial alignment treatment such as a rubbing treatment or an oblique vapor deposition treatment is generally known. In most of the conventional alignment methods, the alignment is controlled by a polyimide film obtained by rubbing a ferroelectric liquid crystal under the state of a helical structure that does not show bistability.

However, when the above-mentioned conventional alignment control film is applied to the alignment control for the ferroelectric liquid crystal having the non-helical structure exhibiting the bistability announced by Clark and Lagerwall, the following problems occur. Had a point.
That is, the tilt angle θ in the non-helical ferroelectric liquid crystal obtained by aligning with the conventional alignment control film (see FIG.
Is smaller than the tilt angle H (corresponding to 1/2 of the apex angle of the triangular cone shown in FIG. 2 described later) in the ferroelectric liquid crystal having the spiral structure. In particular, the tilt angle θ of a non-helical ferroelectric liquid crystal obtained by aligning with a conventional alignment control film is generally about 10 °, and the transmittance at that time is about 3 to 5% at most.

As described above, according to Clark and Ragga Wall, the tilt angle θ in the ferroelectric liquid crystal having the non-helical structure for realizing the bistability is smaller than the tilt angle H in the helical structure. Moreover, the reason why the tilt angle θ in the non-helical structure is smaller than the tilt angle H in the spiral structure is
It was found to be due to the twisted arrangement of 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 aligned with the axis (direction of twist alignment) of the liquid crystal molecules adjacent to the lower substrate relative to the axis of the liquid crystal molecules adjacent to the upper substrate. The twist angle is continuously arranged at the 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.

By the way, in the case of a liquid crystal element utilizing the birefringence of liquid crystal, the transmittance under a crossed Nicols is

[0008]

[Equation 1] (Wherein I ₀ : incident light intensity, I: transmitted light intensity, θ: tilt angle, Δn: refractive index anisotropy, d: liquid crystal layer thickness, λ: incident light wavelength). To be done.

Tilt angle θ in the above-mentioned non-helical structure
Will appear as the 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 maximum transmittance is obtained when the tilt angle θ is 22.5 °, but the tilt angle θ in the non-helical structure that realizes the bistability is as large as about 10 °. Yes,
Therefore, when considering the application as a display device,
There is a problem that the transmittance is not sufficient if it is about 3 to 5%.

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 is generated in the ferroelectric liquid crystal layer,
This reverse electric field V _rev caused an afterimage on the display. The reverse electric field generation phenomenon described above is described in, for example, Akio Yoshida, October 1987 [Liquid Crystal Conference Proceedings] P. 142
~ P. 143 [SSFLC switching characteristics].

As a method for solving such a problem, a polymer compound such as a polypeptide derivative or a maleic anhydride derivative or a polymerizable substance is used for the alignment film, or a fluoride or an alkyl chain is introduced into the polyimide molecule. There is an example in which the orientation is enhanced by making the substrate or the orientation film itself uneven.

[0012]

The alignment film described in the above prior art is effective in solving the problems of optical response speed and bistability, but considers a high-definition display device in a large area. In that case, there was an insufficient point regarding the uniformity within and between pixels. When a polymer material is used, it is difficult to control the orientation of all the polymer main chains when trying to widen the display area. Even if rubbing treatment is performed, weak rubbing treatment is performed over a large area. Was unreasonable.

When a polymerizable substance is used, the alignment film is first formed and then the polymerization is performed. Therefore, the degree of polymerization in the alignment film is locally varied, which causes a large area. It was difficult to obtain uniform orientation. Also,
Materials available are limited to those with polymerizable moieties,
The selection range is narrowed. Furthermore, it is practically extremely difficult to reduce the volume change (expansion or contraction) of the membrane during polymerization to zero, and with such a volume change,
Defects such as cracks may occur in the film, leading to a decrease in the orientation.

Further, there is a method of introducing a fluoride or an alkyl chain into a polyimide molecule in order to lower the surface energy and increase the tilt angle. However, by introducing such a fluoride or an alkyl chain, a monomolecular film or a monomolecular film is formed. When a molecular cumulative film is produced, it is not always easy to increase the molecular density in the film while maintaining homogeneity, because the fluorides or alkyl chains repel each other.

In general, the Langmuir-Blodgett (LB) method is a simple method for preparing the above-mentioned monomolecular film or monomolecular accumulating film. In particular, the polyimide molecule having the above-mentioned fluoride or alkyl chain is used. LB
In order to form a film by the method, the film forming material and film forming conditions such as introducing a special metal ion are very limited in order to successfully alleviate the repulsion of the above-mentioned molecules, and thus the versatility is improved. poor.

In addition, the method of forming irregularities on the substrate or the alignment film itself has a problem that the production process becomes complicated because it has a step for forming irregularities in the production of the liquid crystal element.

An object of the present invention is to provide a liquid crystal device which solves the above-mentioned problems of the prior art, and is a ferroelectric liquid crystal having a non-helical structure which realizes at least two stable states, particularly bistability. It is an object of the present invention to provide a high-definition liquid crystal element capable of achieving a display in which a high-contrast image is displayed and a residual image does not occur by increasing the tilt angle of the pixel shutter, thereby improving the transmittance when the pixel shutter is opened.

[0018]

That is, the present invention has a strong array having a pair of parallel substrates and an array of molecules forming a plurality of layers perpendicular or substantially perpendicular to the planes of the pair of parallel substrates. In a liquid crystal element having a dielectric liquid crystal, at least one substrate of the pair of parallel substrates has an alignment control film that preferentially aligns the plurality of layers in one direction, and the alignment control film is a polyamic acid. And a first alkylamine represented by any one of the following general formulas (1) to (3) and a second alkylamine represented by any one of the following general formulas (4) to (6). A liquid crystal element characterized by being a molecular film or a cumulative film thereof.

[0019]

[Chemical 3]

(In the formula, X and Y are --H, --CH ₃ , --C ₂
Represents any one of H ₅ , p, q, w are integers of 26 or less, 12 ≦ p ≦ 26, 15 ≦ p + q ≦ 52, 17 ≦ p +
q + w ≦ 60. )

[0021]

[Chemical 4]

(In the formula, X and Y are --H, --CH ₃ , --C ₂
Represents any one of H ₅ , p ′, q ′ and w ′ are integers of 16 or less, 1 ≦ p ′ ≦ 16, 4 ≦ p ′ + q ′ ≦ 16,4
≦ p ′ + q ′ + w ′ ≦ 16. )

According to the present invention, a polyamic acid alkylamine salt prepared by mixing a polyamic acid and a first alkylamine is used as a matrix material, and a second alkylamine is added to the matrix material to obtain an alkyl group. By filling the space between the amine molecules with the second alkylamine, it becomes possible to improve the orientation, uniformity, and in-plane density of the monomolecular film or monomolecular cumulative film, and when used as an alignment control film. In addition, the surface energy is reduced and the tilt angle can be increased, as well as high-definition display is possible.

The present invention will be described in detail below. Figure 1
FIG. 3 is a cross-sectional view showing an embodiment of the liquid crystal element 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) and the like, which is a substrate (glass substrate) covered with transparent electrodes 12a and 12b, on which an insulating film 13 is formed.
a and 13b (eg, SiO ₂ film, TiO ₂ film, Ta ₂ film
(O ₅ film or the like) and the orientation control films 14a and 14b are laminated respectively.

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
b is a ferroelectric liquid crystal, preferably at least 2
Ferroelectric liquid crystal 13 having a non-helical structure showing two stable states is arranged. The transparent electrodes 12a and 12b described above are
In order to drive the ferroelectric liquid crystal 13 by multiplexing, it is preferable that the stripe-shaped wirings are arranged and the stripes intersect each other. The inter-liquid crystal distance in which the ferroelectric liquid crystal 15 is arranged is held by the bead spacers 16 (for example, silica beads, alumina beads, etc.) arranged between the alignment control films 14a and 14b. Further, 17a and 17b represent polarizing plates.

In the present invention, the above polyamic acid is obtained by subjecting a carboxylic acid anhydride and a diamine to a condensation reaction. Examples of the carboxylic acid anhydride include pyromellitic acid anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid anhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid anhydride, 2, and the like. 2-bis (3,4
-Dicarboxyphenyl) -1,1,1,3,3,3-
Hexafluoropropanoic anhydride and the like can be mentioned.

As the diamine, phenylenediamine,
4,4'-oxydianiline, 4,4'-dioxyphenylenedianiline, 4,4'-phenylenedianiline, 4,4'-thiodianiline, 4,4'-sulfonyldianiline, 4,4 ′ -Methylenedianiline, 2,2
-Bis (4-aminophenyl) -1,1,1,3,3,3
Examples thereof include 3-hexafluoropropane and 1,3-bis (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane.

Since the polyamic acid used in the present invention may partially contain the above-mentioned structural unit in the polymer main chain, two or more kinds of carboxylic acid anhydrides and / or two or more kinds of diamines are used. It is also possible to use the copolymer polyamic acid used.

In the present invention, the alkylamine includes the first alkylamine represented by any one of the general formulas (1) to (3) and the one represented by the general formulas (4) to (6). Secondary alkylamine of the second alkylamine represented, primary or secondary alkylamine, further partially or wholly substituted with an alkyl group, partially substituted with a hydroxyl group, branched alkyl It is possible to use a group having a cyclic structure such as a benzene ring.

In order to further lower the surface energy of the monomolecular film or the monomolecular accumulative film, in particular, not only the second alkylamine but also one or both of the molecules of the polyamic acid and the first alkylamine. It is effective to have at least one or more or all fluorine groups in part or all of the molecule.

Specific examples of the first alkylamine represented by any of the above general formulas (1) to (3) include N,
N-dimethyloctadecylamine, N-methyl-di-n
-Octadecylamine, tri-n-hexylamine and the like.

Specific examples of the second alkylamine represented by any one of the general formulas (4) to (6) are 2,2,3,3,4,4,4-heptafluorobutylamine, Heptafluorobutylamine, perfluorotrihexylamine and the like can be mentioned.

Further, in the present invention, the monomolecular film forming the orientation control film or a cumulative film thereof is made of polyamic acid
It is formed by mixing the second alkylamine and the second alkylamine, and the mixing ratio of these molecules is preferably such that all the carboxyl groups of the polyamic acid are amine salified. That is, there are usually two carboxyl groups per repeating unit of the polyamic acid. In this case, relaxation of the number of repeating units of the polyamic acid: moles of the first alkylamine = 1: 1 to 1:
It is desirable that the ratio is 3, and more preferably 1: 2 to 1: 2.5.

The number of moles of the second alkylamine is such that the number of repeating units of the polyamic acid is relaxed: the number of moles of the second alkylamine = 1: 2 to 1: 10000, and more preferably 1:10 to 1: 1000. It is desirable to do.

As the solvent at this time, any solvent such as N, N-dimethylacetamide (DMAC), in which polyamic acid and amine are sufficiently dissolved and which can develop such a solution on the water surface, can be used. May also be used,
A mixed solvent may be used. Also, the concentration is not particularly limited,
From the standpoint of developability, the range of 1 × 10 ⁻⁵ to 1 × 10 ⁻³ repeating units / l is preferable.

The solution of the polyamic acid-mixed amine salt prepared as described above is gently spread on the water surface. At this time,
As the aqueous phase, pure water g of 2 to 25 ° C. is generally used, but the pH is adjusted by adding various metal ions or adding acid or alkali.
The adjustment of may be performed. Next, the polyamic acid amine salt mixed solvent developed on the water surface is compressed to form a monomolecular film of the polyamic acid mixed amine salt on the water surface.

It is possible to accumulate two layers of the Y-type monolayer on the support by immersing the monolayer in a direction across the monolayer on the water surface while keeping the surface pressure constant, and then withdrawing the monolayer. It will be possible. In order to transfer the polyamic acid amine salt monomolecular film onto the substrate, a method such as the horizontal dipping method or the rotating cylinder method can be used in addition to the above-mentioned vertical dipping method.

Ferroelectric liquid crystals that can be used in the liquid crystal device of the present invention include, for example, p-decyloxybenzylidene-p'-amino-2-methylbutyl cinnamate (DOBAMBC), p-hexyloxybenzylidene-
p'-amino-2-chloropropyl cinnamate (HO
BACPC), p-decyloxybenzylidene-p'-amino-2-methylbutyl-α-cyanocinnamate (D
OBAMBCC), p-tetradecyloxybenzylidene-p′-amino-2-methylbutyl-α-cyanocinnamate (TDOBAMBCC), p-octyloxybenzylidene-p′-amino-2-methylbutyl-α-chlorocinnamate (OOBAMBCC) ), P-octyloxybenzylidene-p′-amino-2-methylbutyl-α-methylcinnamate, 4,4′-azoxycinnamic acid-bis (2-methylbutyl) ester,
4-o- (2-methyl) butyl resorcylidene-4'-octylaniline, 4- (2'-methylbutyl) phenyl-4'-octyloxybiphenyl-4-carboxylate, 4-hexyloxyphenyl-4- (2 ″ -methylbutyl) biphenyl-4′-carboxylate, 4-
Octyloxyphenyl-4- (2 ″ -methylbutyl)
Biphenyl-4'-carboxylate, 4-heptylphenyl-4- (4 "-methylhexyl) biphenyl-
4'-Carbochelate, 4- (2 "-methylbutyl) phenyl-4- (4" -methylhexyl) biphenyl-
4 ″ -carboxylate and the like can be mentioned, and these can be used alone or in combination of two or more kinds. Further, other cholesteric liquid crystals and smectic liquid crystals can be contained within a range showing ferroelectricity. , Ferroelectric liquid crystal as chiral smectic C phase (SmC ^* ), H phase (SmH ^* ), I phase (SmI)
^* ), K phase (SmK ^* ) and G phase (SmG ^* ) can be used.

FIG. 2 schematically shows an example of a ferroelectric liquid crystal cell using a spiral structure. 21a and 21b
Is In ₂ O ₃ , SnO ₂ or ITO (Indium T
inOxide) is a substrate (glass plate) coated with a transparent electrode, and Sm oriented so that a plurality of liquid crystal molecular layers 22 or layers perpendicular to the glass substrate surface are provided therebetween.
A liquid crystal of C ^* (Calrus smectic C 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, the tilt angle H in the chiral smectic phase of the helical structure, which takes the angle forming the apex angle of the triangular pyramid, is shown. Board 21a
When a voltage of a certain threshold value or more is applied between the electrodes on the electrodes 21b 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. You can change direction.

In a preferred embodiment of the present invention, the ferroelectric liquid crystal device shown in FIG. 3 having at least two stable states, particularly a bistable state, can be used. That is, when the thickness of the liquid crystal cell is sufficiently thin (1 μm), as shown in FIG. 3, the helical structure of the liquid crystal molecules is unwound and becomes a non-helical structure even when an electric field is not applied, and its dipole moment is increased. Pa or Pb is upward (34a) or downward (3
The bistable state is formed by taking either of the states 4b).

In such a cell, as shown in FIG. 3, an electric field Ea or Eb having a polarity equal to or more than a certain threshold changes its direction from the electric field vector to the upward direction 34a or the downward direction 34b, and the liquid crystal molecule is accordingly changed to the first direction. It is oriented in either the first stable state 33a or the second stable state 33b. 1/2 of the angle formed by the first and second stable states at this time
Corresponds to the tilt angle θ.

There are two advantages of using such a ferroelectric liquid crystal as an optical modulator. Firstly, the response speed is extremely fast, and secondly, the alignment of the liquid crystal molecules has bistability. In order to effectively realize such a high response speed and a memory effect due to bistability, it is preferable that the cell be as thin as possible, and in general, it is 0.
5 μm to 20 μm, particularly 1 μm to 5 μm are suitable.

Next, FIG. 4 is a sectional view schematically showing an alignment state of liquid crystal molecules aligned by the alignment method of the present invention, and FIG. 5 is a view showing its C-director. 51a shown in FIG.
Reference numerals 51b and 51b respectively represent an upper substrate and a lower substrate. Reference numeral 50 denotes a liquid crystal molecule layer organized by liquid crystal molecules 52, in which the liquid crystal molecules 52 are arranged at different positions along a bottom surface 54 (circle) of a 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 polyimide or polyamide film is shown by the C-director diagram of FIG. In the orientation state shown in FIG. 6, the tilt angle θ is small because the twist of the molecular axis is large from the upper substrate 51a to the lower substrate 51b.

Next, FIG. 7A shows a C-director 81.
Is an explanatory view showing the tilt angle θ in the state of FIG. 5 (referred to as a uniform orientation state), and FIG. 7B shows the tilt angle θ when the C-director 81 is in the state of FIG. 6 (referred to as a splay orientation state). FIG. In the figure, 60 represents a rubbing treatment axis applied to the above-described specific polyimide or polyamide film of the present invention, 61a is an average molecular axis in an alignment state U ₁ , 61b is an average molecular axis in an alignment state U ₂ , 62a Is the average molecular axis in the oriented state S ₁ , and 62b is the average molecular axis in the oriented state S ₂ . The average molecular axes 61a and 61b are
It is possible to perform conversion by applying voltages of opposite polarities which exceed each other's threshold voltage. The same applies to the average molecular axes 62a and 6
It also occurs with 2b.

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,
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 represented by the following equation.

[0049]

[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.
FIG. 8B shows that the direction of the spontaneous polarization Ps immediately after the release of the pulse electric field is opposite to that in the case of FIG. 8A (therefore, 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 or polyamide alignment film in place of a change in tilt angle θ. As shown in FIG. 9, when the pulse electric field is applied, the arrow X ₁
Along the direction of the mean molecular axis S under splay orientation
From (A) to the average molecular axis U _{2 in} the uniform orientation state near the maximum tilt angle H, the reverse electric field V _rev shown in FIG.
And the tilt angle θ decreases along the direction of arrow X ₂ to the average molecular axis S (B) in the splay alignment state,
Then, due to the action of the attenuation of the reverse electric field V _rev shown in FIG. 8C, a stable alignment state in which the tilt angle θ is slightly increased along the direction of the arrow X ₃ to the average molecular axis S (C) under the splay alignment state is obtained. can get. FIG. 10 is a graph showing the state of optical response at this time.

According to the present invention, the above-mentioned polyamic acid, a first alkylamine and a second alkylamine of 2 are used.
In the orientation state obtained by the orientation method using a monomolecular film or a monomolecular accumulating film using one kind of alkylamine, the average molecular axes S (A), S under the spray state shown in FIG.
(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. According to FIG. 11, it can be seen that the optical response is not delayed due to the afterimage and that the high contrast in the memory state is caused.

[0053]

EXAMPLES The present invention will be specifically described 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 subjected to a hydrophobic treatment. Next, first, the polyamic acid represented by the following formula (7) is DMAC.
Dissolved in. (Converted monomer concentration 1 × 10 ^-3 M)

[0055]

[Chemical 5]

[0056] Subsequently, N prepared separately, N-1 × by the same solvent of dimethyl octadecylamine 10 ^-3 M solution and a 1 × 10 ^-3 M solution according same solvent hept fluoroalkyl tributylamine 1: 2: 2 (V / V) to prepare a polyamic acid-mixed amine salt solution.

The solution was spread on a water phase made of pure water having a water temperature of 20 ° C. to form a monomolecular film on the water surface. After evaporation of the solvent, the surface pressure was increased to 25 mN / m. While keeping the surface pressure constant, the above ITO substrate was gently immersed in a direction crossing the water surface at a speed of 5 mm / min, and then 5 m
It was gently pulled up at m / min to form a two-layer Y-type monomolecular cumulative film. By repeating this operation, 6 layers (film thickness = 8)
A monomolecular cumulative film of a polyamic acid mixed amine salt of 0Å) was formed.

After that, alumina beads having an average particle diameter of 1.5 μm are dispersed on one of the substrates, and then the two substrates are superposed so that the respective substrates may be pulled up in parallel and in the same direction to form a liquid crystal cell. Created.

Into this cell, a ferroelectric smectic liquid crystal product name [CS-1014] manufactured by Chisso Corporation was vacuum-injected under an isotropic phase, and then 0.5 ° C./h from the isotropic phase. It was possible to orient by slowly cooling to 30 ° C. The phase change in the cell of this example using this [CS-1014] was as follows.

[0060]

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

A liquid crystal cell having the 6-layer LB film formed as described above as an alignment film was sandwiched between a pair of 90 ° crossed Nicol polarizers, and after applying a 30 V pulse of 50 μsec, 90 ° crossed. Nicole was set to the extinction position (darkest state), and the transmittance at this time was measured with a photomultimeter. The tilt angle θ was 16 °, and the transmittance in the darkest state was 0.9%. The transmittance in the bright state was 50%, so the contrast ratio was 55: 1. Also,
The delay of the optical response that causes the afterimage was 0.2 seconds or less.

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 the entire screen was displayed in a white state after image display by character input. After erasing, the occurrence of afterimage was not readable. Incidentally, S in FIG.
_N , S _{N + 1} , and S _{N + 2} represent voltage waveforms applied to the scanning lines, and I represents voltage waveforms applied to typical information lines. (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 8 V and ΔT = 20 to 70 μsec. Further, the uniformity of pixels including the contrast ratio and the optical response was good.

Example 2 As in the case of Example 1, two 1.1 mm thick glass plates provided with an ITO film of 1000 Å thickness were prepared and subjected to a hydrophobic treatment. Next, the polyamic acid represented by the following formula (8) was dissolved in DMAC.

[0064]

[Chemical 6]

Subsequently, separately prepared N-methyl-di-n
- 1 × by the same solvent of octadecylamine 10 ^-3 M solution and 1 × by the same solvent hept fluoroalkyl tributylamine ^10-3
The M solution was mixed at 1: 2: 10 (V / V) to prepare a polyamic acid mixed amine salt solution.

The solution was spread on a water phase made of pure water having a water temperature of 20 ° C. to form a monomolecular film on the water surface. After evaporation of the solvent, the surface pressure was increased to 25 mN / m. While keeping the surface pressure constant, the above ITO substrate was gently immersed in a direction crossing the water surface at a speed of 10 mm / min, and then 1
It was gently pulled up at 0 mm / min to form a two-layer Y-type monomolecular cumulative film. By repeating this operation, four layers (film thickness = 60 Å) of a monomolecular accumulating film of a polyamic acid mixed amine salt were formed and used as an orientation control film.

Next, a liquid crystal element was prepared in the same manner as in Example 1, and the liquid crystal element was evaluated. The contrast ratio when the orientation control film in this embodiment is used is 5
The ratio of 3: 1, the optical response was 0.2 sec or less. Further, when the display was performed by the multiplexing drive, the same results as in Example 1 were obtained for the contrast and the afterimage, and the uniformity of the pixels was good.

Example 3 Two glass plates each having an ITO film of 1000 Å and provided with a thickness of 1.1 mm were prepared in the same manner as in Example 1 and subjected to a hydrophobic treatment.

Next, the same polyamic acid as in Example 1 was added to D
Was dissolved in MAC, prepared separately, N, N-dimethyl octadecyl 1 × 10 ^-3 M solution according same solvent 1 × 10 ^-3 M solution and hepta fluoroalkyl butyl amines by the same solvent of the amine 1: 2: 10 (V / V) to prepare a polyamic acid-mixed amine salt solution. The solution was spread on a water phase made of pure water having a water temperature of 20 ° C. to form a monomolecular film on the water surface. After evaporation of the solvent, the surface pressure was increased to 25 mN / m. While keeping the surface pressure constant, the above ITO substrate plate is gently immersed in a direction crossing the water surface at a speed of 50 mm / min, and then gently pulled up at 50 mm / min to form a two-layer (thickness = 30 Å) Y-type A monomolecular cumulative film was prepared and used as an orientation control film.

Next, a liquid crystal element was prepared in the same manner as in Example 1, and the liquid crystal element was evaluated. The contrast ratio when the orientation control film in this embodiment is used is 5
3: 1, the optical response was 0.4 sec. When the display was performed by the multiplexing drive, the same results as in Example 1 were obtained for the contrast and the afterimage, and the uniformity of the pixels was good.

Example 4 In the same manner as in Example 1, two 1.1 mm-thick glass plates provided with an ITO film having a thickness of 1000 Å were prepared and subjected to a hydrophobic treatment. Next, the polyamic acid represented by the following formula (9) was dissolved in DMAC.

[0072]

[Chemical 7]

[0073] Subsequently, N prepared separately, N-1 × by the same solvent of dimethyl octadecylamine 10 ^-3 M solution and a 1 × 10 ^-3 M solution according same solvent hept fluoroalkyl tributylamine 1: 2: 10 (V / V) to prepare a polyamic acid-mixed amine salt solution. Water temperature of this solution 20 ℃
It was spread on the water phase consisting of pure water, and a monomolecular film was formed on the water surface. After evaporation of the solvent, the surface pressure was increased to 25 mN / m. While keeping the surface pressure constant, the above-mentioned ITO substrate was gently immersed in a direction transverse to the water surface at a speed of 10 mm / min, and then gently pulled up at 10 mm / min to form a two-layer Y-type monomolecular cumulative film. .. By repeating this operation, four layers (film thickness = 60 Å) of a monomolecular accumulating film of a polyamic acid mixed amine salt were formed and used as an orientation control film.

Next, a liquid crystal element was prepared in the same manner as in Example 1, and the liquid crystal element was evaluated. The contrast ratio when the orientation control film in this embodiment is used is 5
The optical response of 8: 1 was 0.2 sec or less. When the display was performed by the multiplexing drive, the same results as in Example 1 were obtained for the contrast and the afterimage, and the uniformity of the pixels was good.

Example 5 As in Example 1, two 1.1 mm thick glass plates provided with an ITO film of 1000 Å were prepared and subjected to a hydrophobic treatment. Next, the same polyamic acid as in Example 4 was DMA-treated.
It was dissolved in C.

Subsequently, separately prepared N-methyl-di-n
- 1 × by the same solvent of octadecylamine 10 ^-3 M solution and 1 × by the same solvent hept fluoroalkyl tributylamine ^10-3
The M solution was mixed at 1: 2: 10 (V / V) to prepare a polyamic acid mixed amine salt solution. Water temperature 2
It was spread on a water phase consisting of pure water at 0 ° C. to form a monomolecular film on the water surface. After evaporation of the solvent, the surface thickness was increased to 25 mN / m. While keeping the surface pressure constant, the above-mentioned ITO substrate was gently immersed in a direction transverse to the water surface at a speed of 10 mm / min, and then gently pulled up at 10 mm / min to form a two-layer Y-type monomolecular cumulative film. .. By repeating this operation, two layers (thickness = 30Å) of a monomolecular accumulating film of a polyamic acid mixed amine salt were formed and used as an orientation control film.

Next, a liquid crystal element was prepared in the same manner as in Example 1, and the liquid crystal element was evaluated. The contrast ratio when the orientation control film in this embodiment is used is 5
The optical response of 8: 1 was 0.2 sec or less. When the display was performed by the multiplexing drive, the same results as in Example 1 were obtained for the contrast and the afterimage, and the uniformity of the pixels was good.

Example 6 An alignment control film was formed in the same manner as in Example 5. Subsequently, the orientation control film was unidirectionally rubbed with a nylon touch cloth. Next, a liquid crystal element was prepared in the same manner as in Example 1, and the contrast ratio and the delay of the optical reaction were measured. As a result, the contrast ratio was 51: 1 and the delay of the optical response was 0.2 sec or less. It has been found that the same excellent element characteristics are obtained when the rubbing treatment is applied to the orientation control film in the invention. When the display was performed by the multiplexing driving, the same results as in Example 1 were obtained for the contrast and the afterimage, and the uniformity of the pixels was good.

Example 7 As in Example 1, two 1.1 mm thick glass plates provided with an ITO film having a thickness of 1000 Å were prepared.

Next, the same polyamic acid as in Example 1 was added to D
Dissolved in MAC and separately prepared N-methyl-di-n-
1 × 10 ⁻³ M solution of octadecylamine in the same solvent and 1 × 10 ³ of heptafluorobutylamine in the same solvent.
^{The -3} M solution was mixed at 1: 2: 10 (V / V) to prepare a polyamic acid-mixed amine salt solution.

Here, the above ITO substrate was gently immersed in a direction across the water surface on a water phase made of pure water having a water temperature of 20 ° C., and then the solution was spread on the water phase to form a single molecule on the water surface. A film was formed. After removing the solvent by evaporation, the surface pressure is 25mN /
I raised it to m. 10mm while keeping the surface pressure constant
The film was gently pulled up at a speed of / min to form one layer (film thickness = 15Å) of a polyamic acid-mixed amine salt monomolecular film, which was used as an orientation control film.

Next, when the alignment control film of this example was used, the contrast ratio was 53: 1 and the optical response was 0.2 sec or less. When the display was performed by the multiplexing drive, the same results as in Example 1 were obtained for the contrast and the afterimage, and the uniformity of the pixels was good.

[0083]

According to the present invention, by using a monomolecular film or a monomolecular cumulative film composed of polyamic acid and two kinds of alkylamines as an alignment control film, the surface energy of the alignment control film is lowered and tilt Since the angle is increased, 1) the contrast in the bright state and the dark state is high, and particularly the display contrast at the time of multiplexing driving is very large, and a high quality display is obtained. 2) An unpleasant afterimage phenomenon does not occur. 3) Further, the in-plane density was improved and the uniformity of pixels was improved. The effect such as was 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 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.

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 control film 15 Ferroelectric 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 Substrate lifting direction or rubbing treatment axis 61a Average molecular axis in orientation state U ₁ 61b Average molecular axis in orientation state U ₂ 62a In orientation state S ₁ in the average molecular axis 62b oriented state S ₂ The average molecular axes 81 C-director

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshihiro Yanagisawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Haruki Kawata 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (4)

[Claims] 1. A liquid crystal device comprising a pair of parallel substrates and a ferroelectric liquid crystal having an array of molecules forming a plurality of layers perpendicular or substantially perpendicular to the surfaces of the pair of parallel substrates, At least one of the pair of parallel substrates has an orientation control film for orienting the plurality of layers preferentially in one direction, and the orientation control film comprises polyamic acid and the following general formulas (1) to ( 3) A first alkylamine represented by any one of 3) and a second alkylamine represented by any one of the following general formulas (4) to (6) is a monomolecular film or a cumulative film thereof. Characteristic liquid crystal element. [Chemical 1] (Wherein, X, Y is -H, -CH _3, represents one of _{-C 2 H 5, p, q} , w is 26 an integer, 12 ≦ p
≦ 26, 15 ≦ p + q ≦ 52, 17 ≦ p + q + w ≦ 60
Is. ) [Chemical 2] (Wherein, X, Y is -H, -CH _3, represents one of _{-C 2 H 5, p ',} q', w ' at 16 an integer, 1
≦ p ′ ≦ 16, 4 ≦ p ′ + q ′ ≦ 16, 4 ≦ p ′ + q ′
+ W ′ ≦ 16. ) 2. The liquid crystal element according to claim 1, wherein the alignment control film is formed by a Langmuir-Blodgett method. 3. The liquid crystal device according to claim 1, wherein the polyamic acid has a fluorine group in the molecule. 4. The liquid crystal device according to claim 1, wherein the first alkylamine has a fluorine group in the molecule.