JPS62291620A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To improve the transmittivitity when a picture element shutter is open by forming the film of one substrate of a monomolecular film or cumulative monomercular film of a high-polymer compd. having a hydrophilic part and hydrophobic part in combination within the same molecule and orienting the films preferentially in one direction on the substrate surface. CONSTITUTION:This liquid crystal element is provided with a pair of the upper substrate 11a and lower substrate 11b which are disposed in parallel with each other and have fine ruggedness on the surface and transparent electrodes 12a and 12b wired to the respective substrates. A ferroelectric liquid crystal 13 having the non-spiral structure to exhibit two stable states is disposed between the upper substrate 11a and the lower substrate 11b. Orientation control films 14a and 14b formed of the monomolecular films or cumulative monomercular films of the high-polymer compd. are respectively disposed on the substrates 11a and 11b and the high-polymer compds. has the hydrophilic part and hydrophobic part in combination within the molecule. An external factor is given to the monomolecular film developed on a liquid surface at the time of transferring said film to the substrate, by which the arrangement or orientation of the film constituting element after the accumulation is additionally improved in the case of forming the cumulative monomolecular film. The uniaxial orientation control function is thereby improved.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a liquid crystal element used in a liquid crystal display element, a liquid crystal-optical shutter, etc., particularly a liquid crystal element using ferroelectric liquid crystal. ,
More specifically, the present invention relates to a liquid crystal element with improved display characteristics by improving the initial alignment state of liquid crystal molecules.

[Prior Art] Clark and Lager Wall display devices utilize the refractive index anisotropy of ferroelectric liquid crystal molecules to control transmitted light in combination with a polarizing element.
wal l) (Japanese Unexamined Patent Publication No. 56-10
No. 7216, US Pat. No. 4,367,924, etc.). This ferroelectric liquid crystal generally has a chiral smectic C phase (Sac") or an H phase (Sac") in a specific temperature range.
mH"), and in this state, it assumes either the first optically stable state or the second optically stable state in response to an applied electric field, and maintains that state when no electric field is applied. It has the property of maintaining its stability, that is, bistability, and also has a quick response to changes in electric field, and is expected to be widely used as a high-speed and memory-type display element.

In order for an optical modulation element using this bistable liquid crystal to exhibit predetermined driving characteristics, the liquid crystal disposed between a pair of parallel substrates must be
It is necessary that the molecules be in such a state that conversion between two stable states can effectively occur. For example, for ferroelectric liquid crystals with Sac" or SsH" phase, 5t
It is necessary to form a region (monodomain) in which the liquid crystal molecular phase having the aC" or SmH" phase is perpendicular to the substrate surface, and therefore the liquid crystal molecular axes are arranged substantially parallel to the substrate surface.

By the way, as a method for aligning ferroelectric liquid crystals, a method using an alignment control film that has been subjected to a uniaxial alignment treatment such as a rubbing treatment or a lateral evaporation treatment is generally known.

This conventional alignment method has mostly been applied to ferroelectric liquid crystals with a helical structure that exhibits no bistability. For example, the alignment method disclosed in Japanese Patent Application Laid-Open No. 60-230635 involves controlling the alignment of a ferroelectric liquid crystal using a polyimide film subjected to rubbing treatment in a state of a helical structure that does not exhibit bistability.

However, when the conventional alignment control film as described above is applied to control the alignment of a ferroelectric liquid crystal with a non-helical structure that exhibits bistability as announced by Clark and Lagauer, it has the following problems. was.

[Problems to be Solved by the Invention] According to experiments conducted by the present inventors, the tilt angle of a ferroelectric liquid crystal with a non-helical structure obtained by alignment using a conventional alignment control film (see below) The angle shown in Figure 3) is smaller than the tilt angle (corresponding to 1/2 of the apex angle of the triangular pyramid shown in Figure 2 below) in a ferroelectric liquid crystal with a helical structure. found. In particular, the tilt angle 0 of a ferroelectric liquid crystal with a non-helical structure obtained by alignment using a conventional alignment control film is generally about 10°, and the transmittance at that time is about 3 to 5% at most.

Thus, according to Clark and Lagauer, the tilt angle of a ferroelectric liquid crystal with a non-helical structure that achieves bistability should be the same as the tilt angle of a ferroelectric liquid crystal with a helical structure. However, in reality, the tilt angle θ in the non-helical structure is smaller than the tilt angle ■ in the helical structure. Furthermore, it has been found that the reason why the tilt angle θ in the non-helical structure becomes smaller than the tilt angle 2 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 with a non-helical structure,
As shown in FIG. 4, the liquid crystal molecules are continuous from the axis 42 of the liquid crystal molecules adjacent to the upper substrate to the axis 43 (twisted direction 44) of the liquid crystal molecules adjacent to the lower substrate with respect to the normal to the substrates. They are arranged in a twisted manner with a twist angle δ, and this causes the tilt angle 0 of the non-helical structure to be smaller than the tilt angle 2 of the helical structure.

Note that 41 in the figure represents a uniaxial alignment axis obtained by rubbing treatment or oblique vapor deposition treatment formed on the upper and lower substrates.

By the way, in the case of a liquid crystal element that utilizes the birefringence of liquid crystal, the transmittance under crossed Nicols is expressed as follows. Tilt angle θ in the non-helical structure mentioned above
appears as an angle between the average molecular axes of the twisted liquid crystal molecules in the first and second alignment states. According to the above equation, the maximum transmittance occurs when the tilt angle θ is 22.5°, but in a non-helical structure that achieves bistability, the tilt angle θ is as large as about 10°. Therefore, when considering application as a display device, there is a problem that the transmittance is about 3 to 5%, which is not sufficient.

It is therefore an object of the present invention to solve the aforementioned problems, namely to increase the tilt angle in a ferroelectric liquid crystal with a non-helical structure that achieves at least two stable states, in particular bistability, and thereby An object of the present invention is to provide a liquid crystal element with improved transmittance when the shutter is opened.

Another object of the present invention is to provide a liquid crystal element using an alignment control g1 film suitable for forming monodomains of ferroelectric liquid crystal.

[Means for Solving the Problem] and [Operation] That is, the present invention comprises a pair of parallel substrates and 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 ferroelectric liquid crystal having an alignment, at least one of the pair of parallel substrates has a coating of a polymeric substance that preferentially orients the plurality of layers in one direction, and in particular, The coating of the polymeric substance is formed of a monomolecular film or a monomolecular cumulative film of a polymeric compound having both a linophilic part and a hydrophobic part in the same molecule, and the film is further coated on the surface of the substrate. This liquid crystal element is characterized by being subjected to an alignment treatment for preferentially aligning a molecular accumulation film in one direction.

In particular, in the liquid crystal element of the present invention, the substrate surface is subjected to an alignment treatment, and specifically, fine irregularities are formed on the substrate surface in order to preferentially orient a monomolecular film or a monomolecular cumulative film in one direction. or a liquid crystal element in which the surface of the substrate is rubbed in a certain direction.

The present invention will be explained in detail below.

FIG. 1 is a sectional view showing one implementation of the liquid crystal element of the present invention. The liquid crystal element shown in FIG. 1 includes a pair of upper and lower substrates 11a and ttb, which are arranged in parallel and have fine irregularities on their surfaces, and transparent electrodes 12a and 12b wired to each substrate. A ferroelectric liquid crystal, preferably a non-helical ferroelectric liquid crystal 13 exhibiting at least two stable states, is arranged between the upper substrate 11a and the lower substrate 11b.

The transparent electrodes 12a and 12b described above are made of ferroelectric liquid crystal 13.
In order to perform multiplexing driving, it is preferable that the wiring be arranged in a stripe shape, and that the stripe shapes be arranged to intersect with each other.

In the liquid crystal element of the present invention, alignment control films 14a and 14b formed of a monomolecular film or a monomolecular cumulative film of a polymer compound are arranged on substrates 11a and llb, respectively.

The polymer compound constituting the monomolecular film or monomolecular cumulative film in the present invention has both a hydrophobic part and a woody part in its molecule, and these are arranged in a well-balanced manner in terms of higher order structure. Any molecular compound can be used. In general, typical constituent elements of the hydrophobic moiety are alkyl groups and unsaturated hydrocarbon groups, and both linear and branched groups can be used. Further examples include hydrophobic groups such as fused polycyclic phenyl groups such as phenyl, naphthyl, and anthranyl, and chain polycyclic phenyl groups such as biphenyl and terphenyl. Each of these may be used alone or in combination to form the hydrophobic portion of the molecule.

On the other hand, the most typical constituent elements of the hydrophilic part are 3, such as carboxyl groups and their metal salts and amine salts, sulfonic acid groups and their metal salts and amine salts, sulfonamide groups, amide groups, amino groups, imino group, hydroxyl group, quaternary amino group, oxyamino group, oximino group, diazonium group, guanidine group, hydrazine group,
Examples include hydrophilic groups such as phosphoric acid groups, silicic acid groups, and aluminic acid groups. These also constitute the tree-like part of the above molecule either singly or in combination.

Here, having a woody group and a hydrophobic group in a molecule means, for example, that a molecule has both one woody group and a hydrophobic group as described above in the molecule, or one in the molecule. When it has the above woody group and hydrophobic group, in the structure of the entire molecule, one part is woody in relation to other parts, while the latter part is hydrophobic in relation to the former part. It means having a relationship of

In polymer compounds, hydrophobic groups and lignophilic groups have not only one-dimensional arrays but also secondary structures such as α-hesox and β-sheet structures, and even higher-order structures such as three-dimensional structures. Therefore, it is necessary that the hydrophobic group and the woody group are distributed in a well-balanced higher-order structure. By arranging and orienting molecules having these higher-order structures in a highly ordered manner, it is expected that an orientation control function not found in conventional orientation control films will be exhibited.

Specific examples of the above-mentioned polymer compounds constituting the monomolecular film or monomolecular cumulative film in the present invention include the following polymers.

■ Polypeptide derivatives For example, as a synthetic polypeptide, ■ Poly γ-methyl-L-glutamate (PMLG) ■
Polyγ-benzyloxycarbonyl-lysine (PBLG) Polyε-benzyloxycarbonyl-lysine (
A polypeptide having a molecular weight of 10,000 to 1 million, preferably a molecular weight of 100,000 to 700,000, obtained by dehydration polymerization of amino acids such as PBCL) and their derivatives.

Furthermore, as natural proteins, for example, ■Bacteriorhodopsin ■Cytochrome C ■Kymotrypsin ■Bovine serum albumin ■Trypsin Particulate proteins such as

(1) Areic anhydride polymer derivatives Examples include (1) Poly n-octadecyl vinyl ether-maleic anhydride (Co., Ltd.) Polyoctadecene-1-maleic anhydride (2) Polystyrene-maleic anhydride. Preferably, the number of molecules z t, ooo to 100,000.

■, polyamic acid derivative 3.3', 4.4'-diphenyltetracarboxylic acid O
or an acid anhydride such as pyrometic acid O, p-phenylenediamine [Co.], 4,4'-diaminodiphenyl and 4.
4'-diaminoterphenyl [phase], and also 4.4'
- Long chain alkylamine salts of polyamic acids obtained by 1:1 dehydration condensation with diamino compounds such as diaminodiphenyl ether O (e.g. N(Cl13)2+CH2q
CI+3.10≦n≦25).

These polyamic acid monomolecular films are turned into polyimide monomolecular films by acid and heat treatment, and this polyimide film is used as an alignment control film.

4 of the method for creating a monomolecular film or a monomolecular film in the present invention! ! The main point is that Kuhn, who is widely known to the general public,
An example of using a Langmuir-Prodgett method film forming apparatus devised by the research group of HM) will be described. In this example, the liquid for developing the monomolecular film is water.

First, the above-mentioned film-forming molecules are prepared and dissolved in a volatile solvent such as benzene or chloroform.

Drop this solution into the tank (trough) using a dropper,
A monomolecular film of the film-forming molecules is developed on the aqueous phase. Next, the float (or partition plate) provided to prevent the monomolecular film from spreading freely on the aqueous phase and spreading too much is moved to reduce the spread area of the monomolecular film and to prevent the monomolecular film from spreading too much. Surface pressure is applied to the monolayer until it becomes a two-dimensional solid film. While maintaining this surface pressure, the monomolecular film is transferred onto the substrate by gently moving the substrate up and down perpendicular to and across the water surface. A monomolecular film is produced as described above, and a monomolecular cumulative film having a desired degree of accumulation is formed by repeating the above-mentioned up and down operations.

Although the case where a monomolecular film or a monomolecular cumulative film is created using Kuhm's film forming apparatus has been described above, the apparatus for creating a monomolecular film or a monomolecular cumulative film in the present invention is limited to the above example. However, it is possible to widely use other film forming apparatuses based on the principles of the Langmuir-Prodgett method, such as the horizontal deposition method and the cylindrical rotation method.

It is known that in a monomolecular film or a monomolecular cumulative film of a polymer compound formed on a substrate in this manner, the molecules constituting the film exhibit a constant orientation characteristic with respect to the direction in which the substrate is pulled up.

That is, the monomolecular film or monomolecular cumulative film of the polymer compound is
It is thought that it has a uniaxial orientation control effect in the dipping direction. These alignment films can also have a function as an insulating film, and are usually formed with a thickness in the range of about 50A to IJL, preferably 100A to 100OA.

By applying an external factor when transferring the monomolecular film developed on the liquid surface to the substrate, the arrangement or orientation of the film constituent molecules after accumulation can be further enhanced. - It becomes possible to improve the axial orientation control function. What is an external factor?
Specifically, it is the substrate surface shape (unevenness), and in the present invention,
A substrate having grooves, specifically about 0.1 pm to 1 pm, preferably 0.1 pm to 1 pm. This can be obtained by using a substrate having grooves (hereinafter referred to as groups) with a pitch of about 1 to 1 μm or a substrate rubbed in a certain direction.

Alignment film m film 14a which has undergone -axial orientation treatment by significantly enhancing the arrangement and orientation of constituent molecules of a monomolecular film or a monomolecular cumulative film.
and 14b can be obtained. In the present invention, the groups can be formed by dry etching the surface of the glass substrate using a known lithography technique. Then, an ITO electrode is sputtered onto the croup to form a transparent electrode substrate. However, on a glass substrate,
It is also possible to first form an ITO electrode and then form an organic resist or 5 in 2 groups on the surface of the electrode substrate and use this as the transparent electrode substrate. The shape of the group is about 20A to 100OA, preferably 10A to 100OA.
Sharp edges with a groove depth of 0.8 to 500 A are preferred.

Next, a ferroelectric liquid crystal having molecular alignment forming a plurality of layers perpendicular to the planes of a pair of parallel substrates used in the liquid crystal element of the present invention will be described.

FIG. 2 schematically depicts an example of a ferroelectric liquid crystal cell using a helical structure. 21a and 21b are In,
Q, , 5n02 and ITO (Indium Tin)
It is a substrate (glass plate) coated with a transparent electrode such as 0xide), between which a plurality of liquid crystal molecular layers 22 are oriented to form a layer perpendicular to the surface of the glass substrate.
(chiral smectic C phase) liquid crystal is sealed. The bold line a23 represents a liquid crystal molecule, and this 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 ■ in the chiral smectic phase of the helical structure. Substrates 21a and 2
When a voltage above a certain threshold is applied between the electrodes on 1b,
The orientation direction of the liquid crystal molecules 23 can be changed so that the helical structure of the liquid crystal molecules 23 is unwound and the dipole moment (PA) 24 is all oriented in the direction of the electric field.

However, a ferroelectric liquid crystal using this helical structure returns to its original helical structure when no electric field is applied, and does not show any decline in bistability.

In a preferred embodiment of the invention, a ferroelectric liquid crystal element as shown in FIG. 3 may be used which has at least two stable states, especially a bistable state. In other words, when the thickness of the liquid crystal cell is made sufficiently thin (for example, Ig), the helical structure of the liquid crystal molecules unravels even in the absence of an applied electric field and becomes a non-helical structure, as shown in Figure 3. The child moment Pa or pb is directed upward (34a) or downward (34
If either of b) is bad, a bistable state is formed. When such a cell is given an electric field Ea or Eb of different polarity above a certain threshold as shown in FIG. 3, the dipole moment electric field Ea or Eb will be directed upward 34a or downward 34b in accordance with the electric field vector. Accordingly, the liquid crystal molecules are oriented in either the first stable state 7f, 33a or the second stable state 7g3:+b. At this time, 1/2 of the angle formed by the first and second stable states corresponds to the tilt angle θ.

There are two advantages to using such a ferroelectric liquid crystal as an optical modulation element. Firstly, the response speed is extremely fast, and secondly, the alignment of liquid crystal molecules has bistability. To explain the second point with reference to FIG. 3, for example, when the electric field Ea is applied, the liquid crystal molecules are oriented in a first stable state 33a, and this state remains stable even when the electric field is turned off. Furthermore, when an electric field Eb in the opposite direction is applied, the liquid crystal molecules are oriented to the second stable state 33b and the orientation of the molecules is changed.
It remains in this state even if the electric field is turned off. In order to effectively realize such fast response speed and memory effect due to bistability, it is preferable for the cell to be as thin as possible. is suitable. A liquid crystal-electro-optical device having a matrix electrode structure using ferroelectric liquid crystals of this kind is disclosed, for example, by Clark and Lagahar in US Pat. No. 4,367,992.
This is proposed in Specification No. 4.

Examples of the ferroelectric liquid crystal that can be used in the liquid crystal of the present invention include p-decyloxybenzylidene-p'-
Amino-2-methylbutylcinnamate (DOBAMB)
C), p-hexyloxybenzylidene-p'-amino-2-chloropropyl cinnamate (HOBACPC
), p-decyloxybenzylidene-p'-amino-2-
Methylbutyl-α-cyanosinname)-(DOBAM
BCC), P-tetradecyloxybenzylidene-p'-
Amino-2-methylbutyl-α-cyanosinname)-
(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)butylresocylidene-4'-octylaniline, 4-(2'-methylbutyl)phenyl-4'-octyloxybiphenyl-4-carboxylate, 4-hexyloxyphenyl-4- (2″-methylbutyl)biphenyl-4′-carboxylate, 4-
methyloxyphenyl-4-(2″-methylbutyl)
Biphenyl-4'-carboxylate, 4-hebutylphenyl-4-(4''-methylhexyl)biphenyl-4
'-Carboxylate, 4- (2''-methylbutyl)
Phenyl-4-(4”-methylhexyl)biphenyl-
Examples include 4'-carboxylate, which may be used alone or in combination of two or more, and may contain other cholesteric liquid crystals or smectic liquid crystals as long as they exhibit ferroelectricity.

Furthermore, in the present invention, a chiral smectic phase can be used as the ferroelectric liquid crystal, and specifically, chiral smectic C phase (S+s(:''), H phase (SIIH''))
, I phase (Sml''), K phase (SaK'), or G phase (SsG'') can be used.

Next, in the present invention, the uniaxial alignment axes of the upper and lower alignment control films controlled by the group axis or rubbing axis as described above can be parallel to or intersect with each other, but in the present invention, as shown in FIG. It is preferred that the uniaxial orientation axes intersect.

That is, as shown in FIG. 5, on the uniaxially oriented surfaces formed on the upper and lower substrates, in the absence of an electric field, the uniaxially oriented axes 51 and 52 are twisted in the direction 44 shown in FIG. 4. They intersect at angles in opposite directions 55. When the chiral smectic phase is aligned in the presence of such a uniaxially aligned surface by lowering the temperature of the phase higher than the phase, the axes 53 of the liquid crystal molecules adjacent to the upper and lower substrates become parallel to each other. In this chiral smectic phase, the uniaxial orientation axes 51 and 5 are
The smectic A phase (S
The liquid crystal molecules are aligned with a tilt angle θ (or -〇) from the axis 54 of the liquid crystal molecules at mA), and the first and second stable states (
When the tilt angle is θ, a first stable state can be formed, and when the tilt angle is −θ, a second stable state can be formed.

In this liquid crystal element, when one polarization axis 56 of crossed Nicols is set parallel to the axis 53 of the liquid crystal molecules corresponding to the molecular axis direction in the first stable state, and the other polarization axis 57 is made orthogonal to the polarization axis 56, the maximum You can get contrast.

In a preferred embodiment of the present invention, the above-mentioned tilt θ is made equal to the tilt 0 in the helical structure by the AC application pre-processing.
Alternatively, the angle can be increased to the same degree. Let the tilt angle at this time be θ'. The alternating current used in this case has a voltage of 20 to 500 volts, preferably 30 to 15 volts.
At 0 volts the frequency lO~5OOIIz, preferably 1
0 to 20011z can be used, and AC application pretreatment can be performed with the application time being about several seconds to about 10 minutes. Further, such AC application pre-processing is performed at a stage before writing is performed on the liquid crystal element in response to, for example, a video signal or an information signal, and is preferably performed to reduce the wait time when such a liquid crystal element is incorporated into a device and the device is operated. The above-mentioned alternating current application pretreatment can be performed, or alternatively, the alternating current application pretreatment can be performed during the manufacture of such a liquid crystal element.

Such alternating current application pretreatment is based on experiments conducted by the present inventors,
In other words, when an alternating current electric field is applied to a ferroelectric liquid crystal element having a bistable state as shown in Fig. 4 or Fig. 5, the tilt angle θ before application increases to the same extent as the tilt ■ in the helical structure. Moreover, in the case of the state shown in FIG. 5, the increased tilt angle θ' can be maintained even after the alternating current application is removed.

In addition, such AC application pretreatment is performed on a ferroelectric liquid crystal with a large spontaneous polarization (for example, 5 nc/c at 25°C or more, preferably 10 nc/c or 2 to 300 nc/cm):
(nc is a unit indicating nanocoulombs). This spontaneous polarization can be measured by the triangular wave application method 8 in a 100 JL cell.

8 Japanese Journal of Applied Physics
Applied Physics) 22 (10), pp. 661-663 (1983).
“Direct Method Quiz Drying Waves for Measuring Subontaneous Polarization in Ferroelectric Liquid Crystals” co-authored by Miyasato et al.
with Triangular Waves
for Measuring 5pontaneous
Po1arization 1nFerrroelec
tric Liquid Crystal”).

In the present invention, the use of the orientation amount g4H of one of the orientation side gI films 14a and 14b described above can be omitted. Moreover, in another specific example of the present invention, the above-mentioned orientation control W
It is also possible to use one of the alignment control films of J 14 a and 14b as another alignment control film. Other orientation amount g
Examples of the coating forming lW1 include coatings of polyvinyl alcohol, polyamide, polyester, polyimide, polyamideimide, polyesterimide, and the like. In addition, as other orientation control films, SiO and Si
It is also possible to use an inorganic material such as n, formed by oblique vapor deposition.

[Example] The present invention will be described below by showing Examples and Comparative Examples, and further by giving specific examples.

Example 1 Two glass plates with a thickness of 0.7 am were prepared, each was scrubbed with a neutral detergent, and heat treated at 120°C for 30 minutes. 2500 rpm, 30 sec) L/L, and further heat-treated at 150° C. for 10 minutes.

A negative resist agent HD-2000N-10 [Hitachi Chemical v.
4] under the following conditions, and the first (I ST)
40 (10 rpm 1 sec 2nd time (2ND)
) A resist film having a film thickness of 0.71 Lffi was formed by performing heat treatment at 3000 rpm, 405 ec, and 80° C. for 20 minutes.

This negative resist is exposed to deep UV exposure equipment, PL
After forming a latent image of the mask pattern by exposing for 2.5 counts using 8-5oos, this latent image was developed using a special developing solution at 23"C for 80 seconds.Finally, it was washed with pure water. , dry, and perform a 60 second Bostris to create a 1 pm pitch (LO,5H/S0.5p
+*) was formed on the surface of the glass substrate.

Using the resist pattern formed as described above as a mask, a group (grating pattern) with a groove depth of 500 A was etched on the surface of the glass substrate using a parallel plate dry etching apparatus under the following conditions.

Etching gas CF.

Flow rate 10 3 CCM Pressure 7 Pa Input power too w Etching rate 250 A/win In this example, a dry etching method was used to form a pattern on the surface of the glass substrate, but a conventional lift-off method such as EB evaporation of Sin may also be used. is also possible.

An ITO electrode having a film thickness of 100 OA was formed on the glass surface with groups thus prepared by a lift-off method.

Next, the synthetic polypeptide polyγ-benzyl-glutamate (PBLG, molecular weight 640,000) was dissolved in methylene chloride (1 mg/aR) at a temperature of 17
It was developed on pure water (conductivity 0.03 s/cm ) at °C.

After removing the solvent methylene chloride by evaporation, the surface pressure was reduced to 5
dyn/cm was increased to form a monolayer film on the water surface. After keeping the surface pressure at 5 dyn/c and leaving it for 1.5 hours, the group axis of the ITO electrode substrate was moved vertically or approximately vertically across the water surface at a vertical speed of 2.5 IIIl1.
It quietly rose and fell in minutes, accumulating 20 layers.

Under these accumulation conditions, PBLG was accumulated only during pulling, yielding a Z-type monomolecular accumulated film (film n approximately 22 OA).

Two glass substrates were assembled into cells so that the group axes of the upper and lower electrode substrates were parallel to each other.

The cell thickness (distance between the upper and lower substrates) was maintained by photoresist spacers previously formed on the lower substrate.

Into this liquid crystal cell (this is called a 1.8μm cell), the mixed liquid crystal of the lower temperature is injected under vacuum in the Tokichi phase, and then
．． Orientation could be achieved by slow cooling to 30°C at a rate of 5°C/h. Subsequent experiments were conducted at 30°C.

mixed lcd (weight ratio) C.I.

CH3 CH.

(SIIC" temperature range: 3-35°C) When this cell was inspected under crossed nicol conditions, monodomains were obtained that formed a chiral smectic C phase with a uniform, defect-free, non-helical structure. A pulsed electric field (20
V, 500 psec) to align the direction of the liquid crystal molecules in one stable state, and under crossed Nicols, find the darkest position where the amount of transmitted light is the lowest while rotating the liquid crystal cell, and then: By applying a pulsed electric field (-20 V, 500 lacquer) with the opposite polarity to the previous pulse, the state is transferred to the other stable molecular alignment state and brought to a bright state.The liquid crystal cell is then rotated again to bring it to the darkest state. I found the angle. The positions of the above two darkest states correspond to the detection of a stable average molecular axis of the liquid crystal, and the angle between these two states corresponds to the tilt angle 2θ.

When we measured the tilt angle of the liquid crystal cell mentioned above, we found that
It was 14°. That is, the liquid crystal cell of this example exhibited a large tilt angle that was not found in the conventional cell under the memory state achieved by the bistable chiral smectic phase. Further, when the amount of transmitted light of this liquid crystal cell in the brightest state was measured, it was 12%. The amount of transmitted light at this time was measured using Photomul.

Next, the present inventors measured the twist alignment angle and direction of the liquid crystal molecules with respect to the normal direction of the substrate in the liquid crystal cell described above. For this measurement, instead of the 1.8 gm photoresist spacer used in the liquid crystal cell described above, a 3.0 gm photoresist spacer was used.
In addition to using μl alumina beads as spacers,
A liquid crystal cell (referred to as a 3.0 gm cell) was created in exactly the same manner.

To measure the twist alignment angle of liquid crystal molecules, rotate one analyzer from the intersection angle in the darkest state under crossed Nicols.
By changing the intersection angle, we found a position where the light became even darker, and measured the angle at which one analyzer was rotated from the orthogonal position. This angle corresponds to the twist angle δ mentioned above.

Therefore, regarding the above-mentioned 3.0H cell, from the observer's perspective, the clockwise direction is positive (1) and the counterclockwise direction is negative (-).
Then, the analyzer could be rotated 5 to 6 degrees in the negative direction from the crossed Nicols, and then the liquid crystal cell could be rotated to search for a dark state. Also, move the polarizer 5 to 6 degrees in the positive direction from crossed Nicols.
Even with rotation, a dark state was similarly obtained. Therefore, the liquid crystal molecules in this device form a twisted arrangement in the positive direction,
It was found that the long sleeves of liquid crystal molecules on the adjacent surfaces of the upper and lower substrates were twisted with a twist angle δ of 5-6°.

Example 2 Example 1 except that rubbing axes intersecting at angles of 45° and 20° in the negative direction (-) were used in place of the parallel flipping axes used in the 1.8μ Maro cell of Example 1. A liquid crystal cell was created in exactly the same manner.

When the tilt angle of this liquid crystal cell was measured, it was 14
Both of these two liquid crystal cells were Sac”.
It was found that SmA exists on the high temperature side of 5taA, or that the optical axis of 5taA exists on the bisector of the angle formed by the crossed rubbing axes.

Next, a high electric field alternating current with a voltage of 70 volts and a frequency of 70 Hz was applied to each of the two types of liquid crystal cells described above for about 5 minutes (alternating current application pretreatment). The tilt angle θ' at this time was measured. The results are shown in Table 1 below.

Table 1 For these two types of liquid crystal cells, the twist angle δ shown in Figure 4 was measured in the same manner as the method used to measure the twist angle δ in the liquid crystal element of the 3 μm cell described above.
In the liquid crystal device using crossed rubbing axes of 5" and 120@, no twist angle δ of the liquid crystal molecules with respect to the normal to the upper and lower substrates was observed, indicating that the liquid crystal molecular axes adjacent to the upper and lower substrates were parallel to each other. Furthermore, in a liquid crystal device using crossed rubbing axes with crossing angles of -45° and -20°, even if driving rectangular pulses of +20 volts and 120 volts are continued to be applied alternately at 1 asec, the tilt angle θ shown in Table 1 will not change. . This is because the liquid crystal element is actually adjusted according to the video signal or information signal as disclosed in, for example, JP-A-59-19:1426 and JP-A-59-19:147. Even when applying the time-division driving method as described, the maximum tilt angle θ
′ can be maintained. Also, when the transmittance was measured at this time, it was about 17% in both cases.

The direction of the twisted state with twist angle δ is determined by the interaction between the substrate and the liquid crystal near its interface. In other words, whether the polarization direction of the liquid crystal molecules near the interface is inward with respect to the substrate,
The outward direction is determined by the properties of the substrates, and when the same alignment control film is used for both the upper and lower substrates, the liquid crystal between the substrates is forcibly oriented in a twisted alignment.

If the direction of the twisted arrangement along the normal line of the substrate and the shift direction of the uniaxial alignment axis are in the same direction, the molecules near the interface of the substrates are aligned in the direction of the orientation axis of each substrate, making the twisted arrangement state more stable. After the above-mentioned alternating current application pretreatment, a state of tilt angle θ' results in a metastable orientation state.

In the state of tilt angle θ' after the above-mentioned alternating current application pretreatment, it is necessary that the polarization of molecules near the interface be oriented inward on one substrate and outward on the other substrate.

When the uniaxial alignment axis is shifted in the opposite direction to the twisted alignment direction of the liquid crystal, that is, when the uniaxial alignment axis is crossed at an angle opposite to the twisted alignment direction, the stabilization energy due to the interaction between molecular polarization and the interface The stabilizing energy due to forced anchoring by the -axis orientation axis is larger than that, and therefore a state with a stable tilt angle θ' can be realized.

Therefore, in order to realize a strongly electrostatic liquid crystal element with high transmittance, it is necessary to eliminate the twisted alignment state and to stabilize the ideal alignment state added by the AC application pretreatment. It is necessary to offset the orientation axis from each other. This direction is opposite to the direction in which the liquid crystal is twisted and arranged at a twist angle δ determined by the interface between the liquid crystal and the substrate.

Comparative Example 1 As the alignment control film used when creating the 1,81 cell of Example 1, 3.3',4,4'-diphenyltetracarboxylic acid anhydride and P-phenylenediamine were mixed in a ratio of 1:1.
3 of polyamic acid obtained by dehydration condensation reaction at a molar ratio of
．． The method was exactly the same, except that the coating film of 5% by weight N-methyl-2-pyrrolidone solution was replaced with a polyimide coating film formed by dehydration and ring closure, and then rubbed, and a substrate without groups was used. A liquid crystal cell was created.

When the tilt angle θ and transmittance of this liquid crystal cell were measured in the same manner as in Example 1, the tilt angle 0 was 6″ to 8′.
The transmittance at that time was about 3 to 5%. That is, the five comparative cells have a small tilt angle under the memory state realized by the bistable chiral smectic phase, and their transmittance is completely insufficient for application to a display device.

Comparative Example 2 Example 1! As the orientation control 11 used when creating the 8% lI cell, 3.3',4.4'-diphenyltetracarboxylic anhydride and 4.4'-diaminodiphenyl were dehydrated at a molar ratio of l=1. A polyimide coating film formed by dehydrating and ring-closing a coating film of a 3.5% by weight N-methyl-2-pyrrolidone solution of polyamic acid obtained by a condensation reaction was replaced with a rubbing treatment, and a substrate without groups. A liquid crystal cell was created in exactly the same manner, except that .

When the tilt angle 0 and transmittance of this liquid crystal cell were measured in the same manner as in Example 1, the tilt angle θ was 6 m to 7°.
The transmittance at that time was about 3 to 4%.

Comparative Example 3 As the alignment control film used when creating the 1,81 cell of Example 1, co, co', 4,4'-diphenyltetracarboxylic acid anhydride and 4,4'-diaminoterphenyl were mixed into 1
A polyimide coating film formed by dehydrating and ring-closing a coating film made from a 3.5% by weight 1% N-methyl-2-pyrrolidone solution of polyamic acid obtained by dehydration condensation reaction at a molar ratio of :1 was replaced with a polyimide coating film formed by rubbing. Furthermore, a liquid crystal cell was created in exactly the same way, except that a substrate without groups was used.

When the tilt angle θ and transmittance of this liquid crystal cell were measured in the same manner as in Example 1, the tilt angle θ was 5° to 7°.
The transmittance at that time was about 3 to 4%.

Example 3 Example 1-1. A liquid crystal cell was prepared in exactly the same manner as in Example 1, except that a transparent electrode substrate with ITO electrodes subjected to rubbing treatment was used in place of the grouped transparent electrode substrate used in the static cell.

When the tilt angle 0 and transmittance of this liquid crystal cell were measured in the same manner as in Example 1, the tilt angle 0 was 12°;
The transmittance at that time was 9%.

Example 4 Instead of the grouped transparent electrode substrate used in the 1.8H cell of Example 1, 3.3',4.4'-diphenyltetracarboxylic acid anhydride and P-phenylenediamine were used.
After forming a coating film on the ITO electrode using a 3.511% N-methyl-2-pyrrolidone solution of polyamic acid obtained by dehydration condensation reaction at a molar ratio of 1:1.

Example 1 was performed using a transparent electrode substrate in which a polyimide coating film formed by dehydrating and ring-closing the coating film was subjected to a rubbing treatment.
Two layers of PBLG were accumulated in a similar manner. A liquid crystal cell was then produced in exactly the same manner as in Example 1. When the tilt angle θ and transmittance of this liquid crystal cell were measured in the same manner as in Example 1, the tilt angle 0 was 13° and the transmittance at that time was 10%.

Examples 5 to 9 The same procedure as in Example 1 was used, except that the orientation-controlled IWA used in the 1.8 pm cell in Example 1 was used in place of the monomolecular cumulative tB film of the polymer compound listed in Table 2 below. A liquid crystal cell was created in the same manner, and then the tilt angle θ and the transmittance at that time in the liquid crystal cell were measured in the same manner. Table 2 shows the results.
Shown below.

[Effects of the Invention] According to the alignment control using the liquid crystal element of the present invention, it is possible to obtain a ferroelectric liquid crystal, particularly a monodomain of a ferroelectric liquid crystal that has at least two stable states obtained by a non-helical structure. The first effect is to increase the tilt angle θ under at least two stable states, especially a bistable state (i.e., under a memory state) developed by the non-helical structure of the ferroelectric liquid crystal. The second point is that you can do it.
It has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the liquid crystal device of the present invention, FIG. 2 is a perspective view schematically showing a liquid crystal device using a ferroelectric liquid crystal with a helical structure, and FIG. 3 is a non-helical structure. FIG. 4 is an explanatory diagram showing the relationship between the uniaxial orientation axis of the substrate and the axis of the ferroelectric liquid crystal molecules having a non-helical structure, and FIG. The figure is an explanatory diagram showing the relationship between the uniaxial alignment axis and the axis of liquid crystal molecules used in the liquid crystal element of the present invention. 11a... Upper substrate 11b... Lower substrate 12
a, 12b...Transparent electrode 13...Ferroelectric liquid crystal 14a, 14b -...Orientation control film 21...Substrate 2
2...Liquid crystal molecule layer 23...Liquid crystal molecule 24.
...Dipole moment 33a...First stable state 3
3b...Second stable state 34a...Upward dipole moment 34b...Downward dipole moment ■...Tilt angle in helical structure 0...Tilt angle in non-helical structure Ea, Eb・··electric field

Claims (7)

[Claims] (1) In a liquid crystal element having a pair of parallel substrates and a ferroelectric liquid crystal having a molecular arrangement forming a plurality of layers perpendicular or substantially perpendicular to the planes of the pair of parallel substrates, At least one of the parallel substrates has a coating of a polymeric substance that preferentially orients the plurality of layers in one direction, and in particular, the coating of the polymeric substance has a hydrophilic portion and a hydrophobic portion in the same molecule. The substrate is formed of a monomolecular film or a monomolecular cumulative film of a polymer compound having a part, and is further subjected to an orientation treatment on the surface of the substrate to preferentially orient the monomolecular film or monomolecular cumulative film in one direction. A liquid crystal element characterized by: (2) The liquid crystal element according to claim 1, wherein the alignment treatment applied to the substrate surface is minute irregularities formed on the substrate surface. (3) The liquid crystal element according to claim 1, wherein the alignment treatment applied to the substrate surface is a rubbing treatment. (4) The liquid crystal element according to claim 1, wherein the ferroelectric liquid crystal is a liquid crystal having at least two stable states. (5) The liquid crystal element according to claim 1, wherein the ferroelectric liquid crystal is a bistable liquid crystal. (6) The liquid crystal device according to claim 1, wherein the ferroelectric liquid crystal is a chiral smectic liquid crystal. (7) The liquid crystal device according to claim 1, wherein the ferroelectric liquid crystal is a chiral smectic liquid crystal with a non-helical structure.