JPH1039310A - Liquid crystal element and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a good switching characteristic and good uniform orientation by preventing the coloration by the movement of liquid crystal molecules when chiral smectic liquid crystals are used. SOLUTION: Monomolecular film accumulative oriented films obtd. by accumulating the monomolecular films formed by dropping monomolecular film materials onto a flowing water surface are used as the oriented films to orient the liquid crystal molecules. The monomolecular films are so accumulated that the flowing water directions at the time of forming the respective monomolecular films of the uppermost layer of the monomolecular film accumulative oriented films and the layer right thereunder are reversed. The monomolecular films are so formed that the flowing water directions at the time of forming the monomolecular films of the respective uppermost layers of the upper and lower substrates are approximately paralleled or approximately counterparalleled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a computer terminal display, a word processor, a typewriter,
The present invention relates to a liquid crystal element used for a television receiver, a viewfinder of a video camera, a light valve of a projector, a light valve of a liquid crystal printer, etc., and particularly relates to a liquid crystal element with improved durability.

[0002]

2. Description of the Related Art As one type of liquid crystal element, a type of liquid crystal display element which controls transmitted light by combining with a polarizing element by using the refractive index anisotropy of ferroelectric liquid crystal molecules is known as Clark (Cl.
ark) and Lagerwall (JP-A-56-107216).
U.S. Pat. No. 4,367,924). This ferroelectric liquid crystal generally has a chiral smectic C phase (SmC ^* ) or H phase (SmH ^* ) in a specific temperature range, and responds to an electric field applied in this state to a first optically stable state. And the second optically stable state and maintain the state when no electric field is applied, that is, it has bistability. In addition, it has a quick response to a change in the electric field, and has a high speed. In addition, wide use as a storage type display element is expected.

[0003]

FIG. 1 is a schematic view of the above-mentioned liquid crystal element. In the figure, (A) shows a plan view and (B) shows liquid crystal molecules.

When the liquid crystal element is driven for a long time to perform a display operation, a phenomenon occurs in which the end region 13 of the display section is colored yellow. Such a phenomenon not only deteriorates the appearance of the screen but also changes the switching characteristics of the liquid crystal pixels, and is particularly remarkable in a cell in a uniform alignment state with high contrast.

It has been found that the coloring phenomenon is caused by the liquid crystal molecules moving in the direction of the region 13 and increasing the thickness of the liquid crystal layer in the region 13 (also referred to as a substrate interval or a cell thickness). In order to solve this problem, the present inventor has tried a method of providing unevenness on the substrate surface to prevent the movement of liquid crystal, but the design and manufacturing process of the unevenness were not simple. Therefore, the inventor has studied a method for solving the above-mentioned problem by a simpler method.

The inventor of the present invention presumes that the cause of the movement of the liquid crystal molecules is due to the electrodynamic effect generated by the dipole moment of the liquid crystal molecules fluctuating due to the alternating electric field generated by the driving pulse. .

Further, the moving direction 12 shown in FIG.
Are the alignment direction 10 and the average molecular axis direction 1 of the liquid crystal molecules.
It is thought that it is determined by 1, 11 'and the like. Since the moving direction of the liquid crystal molecules depends on the orientation direction, this phenomenon depends on the state of the pretilt at the substrate interface or the bending direction of the smectic layer that is stable in terms of elastic energy determined by the pretilt. It is inferred that

Further, the direction and amount of movement of the liquid crystal molecules also tend to change depending on the strength of the interface regulating force which is considered to be regulated by the above-mentioned alignment treatment or the like. However, it is considered that, for example, merely weakening the interface regulating force cannot completely suppress the movement amount while maintaining the orientation of the liquid crystal in a favorable state.

According to the study of the present inventor, the above-mentioned phenomenon that the ferroelectric liquid crystal moves within the cell depends on external factors such as temperature, intensity of electric field applied to the liquid crystal element, frequency, and the like. Was found to be closely tied to. In addition, internal factors, that is, factors on the cell side include interfacial pretilt α, orientation state, spontaneous polarization Ps
, The tilt angle Θ, and the inclination angle δ of the layer of the smectic phase depended on the physical properties of the ferroelectric liquid crystal molecules.

Among them, the temperature, the electric field strength, and the frequency have a trade-off relationship with Ps, which affects the response speed, and are affected by design items such as a frame frequency and a duty ratio as a liquid crystal display device. It was difficult to make a breakthrough improvement in this respect.

An object of the present invention is to solve the above problems and to provide a liquid crystal element in which a coloring phenomenon is prevented. Specifically, a liquid crystal element exhibiting good switching characteristics is provided by a simple and highly reliable means by preventing movement of liquid crystal molecules due to driving in a cell in a uniform state and fluctuation of the thickness of a liquid crystal layer due to the movement. It is in.

[0012]

The inventor of the present invention has conducted many studies by independently operating the combination of the physical properties of the liquid crystal material and the element configuration such as the pretilt angle α, and found that the directionality of the pretilt α was controlled. By doing so, it was found that the movement phenomenon of liquid crystal molecules in the cell can be prevented.

That is, the present invention relates to a liquid crystal element comprising at least two chiral smectic liquid crystals exhibiting an optically stable state sandwiched between upper and lower substrates each having an electrode. Has a monomolecular film cumulative alignment film formed by accumulating a plurality of monomolecular films formed on the substrate by a horizontal deposition method, and flowing water to the substrate when forming at least the uppermost two layers of the monomolecular film. A liquid crystal element having different directions and a method for manufacturing the same.

In the liquid crystal device of the present invention, when the monomolecular film accumulating alignment film is accumulated and a polymer material layer prepared by a method other than the monomolecular film accumulating method is present as a base, the monomolecular film accumulating alignment film The orientation state of the film is excellent, and particularly when a rubbing treatment is applied to the underlying polymer material layer, a favorable orientation state can be obtained. In this case, the polymer material may be the same material as the monomolecular film cumulative alignment film material, or may be a different material, but in many cases, the same material has a better orientation state, In the case of different materials, the switching characteristics are often good.

Further, in the liquid crystal device of the present invention, the conditions of flowing water at the time of forming the uppermost two monomolecular films of the monomolecular film cumulative alignment film are optimized, and the direction of the pretilt angle is completely cancelled. The effect is more remarkable when the average pretilt angle α on the molecular film cumulative alignment film is 0 °. In order to optimize the accumulation condition, the flow rate of water at the time of forming the two monolayers of the uppermost layer may be changed.

According to the present invention, by adopting the above structure, a substantial uniform component is eliminated by eliminating a substantial moving component of liquid crystal molecules. Specifically, the present invention is provided by the uppermost monomolecular film. The movement of the liquid crystal molecules is completely suppressed by canceling the directionality of the pretilt angle by the directionality of the pretilt angle provided by the monomolecular film of the layer immediately below the uppermost layer.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

FIG. 2 is a cross-sectional view of the most typical device of the present invention. In the drawing, reference numerals 21 and 21 'denote glass substrates, and 22, 22' denote tin oxide, indium oxide, and indium tin oxide. Transparent electrodes made of (ITO) or the like, 23, 2
3 'is a polymer material layer, 24 and 24' are monomolecular film cumulative alignment films, 25 is a spacer made of beads such as silica, 26 is a chiral smectic liquid crystal, and 27 and 27 'are polarizing plates. Although not shown in this figure, an insulating film such as Ta ₂ O ₅ or TiSiO _x may be provided between the transparent electrode and the alignment film as a short-circuit prevention layer between the upper and lower substrates, if necessary.

Next, a method for forming a monomolecular cumulative alignment film which is a feature of the present invention will be described in detail.

The monomolecular cumulative alignment film is, for example, described in “Applied Physics Letters (Applied Ph.
ysics Letters), Vol. 63, No. 25
It is prepared by a horizontal deposition method using fluid compression as described on pages 3432-3433. FIG. 3 is a view schematically showing a method for producing a monomolecular film according to the present invention. In this method, flowing water is used to uniaxially orient the molecules. While flowing water at a constant speed in the direction 31 shown in FIG. 3, at the dropping position 32, a polymer material solution for forming a monomolecular film, such as a polyamic acid alkyl ammonium salt solution in the case of a polyimide alignment film, or When the solution of the precursor is dropped, the monomolecular layer on the water surface flows along the water surface, is stopped by the barrier 33, and is stretched in the direction of flowing water so that the molecular axis directions are aligned.
When this is transferred to the substrate 34 by the horizontal attachment method, a monomolecular film having a uniform molecular axis direction can be formed on the substrate. By repeating this operation, a monomolecular film cumulative alignment film having a uniform molecular axis direction is formed on the substrate. In this method, it is not only possible to produce a monomolecular cumulative orientation film having a uniform molecular axis direction more rapidly than in a normal vertical immersion method, and by changing the flow rate of water, the stretching of the polymer can be performed. The degree can be changed over a wide range with good controllability.

In the monomolecular film cumulative alignment film produced as described above, since the direction of the molecular axis is aligned with the flowing water direction as described above, the liquid crystal molecules can be formed on the surface without performing an alignment treatment such as rubbing. It is possible to orient uniaxially.
The number of monomolecular film cumulative alignment films used in the present invention is 2 to 5 layers.
Zero layers are desirable. When, for example, polyimide is used as the material of the monomolecular film, it is necessary to perform firing after forming a monomolecular film cumulative alignment film of polyamic acid. The liquid crystal molecules are maintained and uniaxial alignment is achieved.

In the case where the monomolecular film cumulative alignment film produced by the horizontal deposition method as described above is used, similarly to the case where the alignment treatment such as rubbing is performed, the liquid crystal molecules at the interface have a pretilt angle as shown in FIG. The present inventor has clarified that the direction is determined by the direction of flowing water with respect to the substrate during the formation of a monomolecular film.

Therefore, when producing a multilayer monomolecular film cumulative orientation film by this horizontal deposition method, the flowing water direction with respect to the substrate when forming the layer immediately below the uppermost layer and the flowing water direction when forming the uppermost layer are determined. Conversely, by optimizing the flowing water speed at the time of each film formation, it is possible to cancel the directionality of the average pretilt angle. Specifically, at the time of film formation of each of the uppermost layer and the layer immediately below, the direction of the substrate can be rotated by 180 ° with respect to each other, or the flow direction and the position of the barrier can be reversed. . At that time, the flowing water speed is set individually, and the film is formed under the optimum condition.

As the chiral smectic liquid crystal used in the present invention, in addition to the aforementioned SmC ^* and SmH ^* , a liquid crystal exhibiting a chiral smectic I phase (SmI ^* ), a K phase (SmK ^* ), and a G phase (SmG ^* ). For example, a fluorine-containing liquid crystal compound described in JP-A-2-152755 can be used. More specifically, biphenyl-based, phenylpyrimidine-based, etc. as the main chain, and halogen, hydrocarbon,
There are many things such as those with fluorocarbons,
In the present invention, the degree of freedom in selecting a specific material type is large.

In the liquid crystal device of the present invention, the movement behavior of the liquid crystal molecules is determined by the uniaxial orientation of the liquid crystal molecules, the material of the monomolecular film cumulative alignment film, the number of the monomolecular film cumulative alignment film, the monomolecular film cumulative alignment film composition. It depends on the direction and speed of flowing water at the time of film formation, and in particular greatly depends on the conditions of flowing water when forming the uppermost layer. FIG. 5 shows the liquid crystal when the liquid crystal element was driven under a predetermined driving condition when the water flow velocity at the time of film formation of the uppermost layer was constant and the water flow velocity at the time of film formation of the uppermost layer was changed. FIG. 4 is a diagram showing a change in a moving speed of a molecule. Incidentally, V ₀ in FIG. 5 shows the moving speed of the liquid crystal molecules in the case of forming without changing the water flow direction in the top layer.

As shown in FIG. 6, the measurement of the moving speed of the liquid crystal molecules is performed by assembling the substrate on which the above-described monomolecular film cumulative alignment film is formed with a seal member 63 printed in a clog shape and flowing in a flowing direction 60 during film formation.
Are bonded so as to be perpendicular to each other, and the sample is injected with liquid crystal. Silicon oil 64 is dropped at the open ends on both sides of the element as a marker for observing the liquid crystal movement direction, and a write waveform is input so that the liquid crystal molecular axis is 61 or 61 ′ with respect to the alignment processing direction 60. When the liquid crystal molecules move by driving, the markers are pulled into the cells, and the movement can be confirmed.

In the present invention, the above-mentioned measurement is performed when the liquid crystal molecules are in the state of 11 when the direction of flowing water with respect to the substrate is 10 when the layer immediately below the uppermost layer of the monomolecular film cumulative alignment film in FIG. The case of moving in the direction of was defined as a positive direction.

As shown in FIG. 5, the moving direction of the liquid crystal molecules is reversed at a certain flow rate at the time of forming the uppermost layer of the monomolecular film cumulative alignment film. This point is the flow rate at which the moving speed of the liquid crystal molecules becomes 0, and this point is the alignment film material, the flow rate at the time of forming the layer immediately below the uppermost layer, the number of monomolecular film cumulative alignment films, and the uniaxial orientation of the monomolecular film. Etc. are determined. In the present invention, an element having stable switching characteristics can be obtained by manufacturing a cell satisfying the condition that the moving speed becomes zero.

The pretilt angle was measured in order to examine the alignment state of the liquid crystal molecules at the interface of the liquid crystal layer of the cell where the moving speed was 0. The pretilt angle is Jp
n. J. Appl. Phys. Vo. 119 (198
0) No. 10, Short Notes 2013 (crystal rotation method). The cell for measurement was prepared by bonding two substrates so that the inclination of the liquid crystal at the upper and lower interfaces was parallel and in the same direction. In addition, as a liquid crystal for pretilt angle measurement, a liquid crystal in which a compound represented by the following structural formula was mixed at 20% by weight with a ferroelectric liquid crystal CS-1014 manufactured by Chisso Corporation was sealed as a standard liquid crystal, and measurement was performed. . still,
This mixed liquid crystal shows an SmA phase at 10 to 55 ° C.

[0030]

Embedded image

As a specific measuring method, while rotating the liquid crystal cell on a plane perpendicular to the upper and lower substrates and including the alignment processing axis,
Helium-neon laser light having an angle of 45 ° with the rotation axis was irradiated from a direction perpendicular to the rotation axis, and the transmitted light intensity was measured. The pretilt angle α was obtained by substituting the angle φ between the angle of the center of the group of hyperbolas of the transmitted light intensity generated by the interference and the line perpendicular to the liquid crystal cell into the following equation.

[0032]

(Equation 1)

As a result, under the condition of the device in which the movement of the liquid crystal was not observed in the present invention, the average pretilt angle observed by this crystal rotation method was 0 °.
It became clear that it was. The results show that the liquid crystal element of the present invention can reduce the movement of liquid crystal molecules to zero by canceling out the direction of the pretilt angle.

The effects of the present invention are particularly advantageous in the case of an alignment film material and a liquid crystal material having a small pretilt angle in a liquid crystal cell obtained by subjecting the formed alignment film to a usual rubbing treatment instead of the monomolecular film accumulation method. Is effective when the combination of the present invention is applied to the present invention, and the orientation is particularly good when a combination of a pretilt angle of 5 ° or less, more preferably 3 ° or less is applied in a liquid crystal cell subjected to a normal rubbing treatment. Thus, an element having high contrast can be obtained.

In the liquid crystal device of the present invention, if a thin film of a polymer material is formed as a base layer before forming a monomolecular film cumulative alignment film, the liquid crystal in a cell finally obtained is obtained. The orientation of the molecules becomes better, and a better orientation can be obtained by subjecting the polymer material layer as the underlayer to a rubbing treatment. The underlying polymer material is
The same material as the monomolecular film formed thereon may be the same or different, but in many cases, the same material has a better orientation state, whereas in the case of a different material, the switching characteristics are often better. The material may be selected depending on which effect is prioritized.

[0036]

EXAMPLE 1 A 900 mm thick ITO transparent electrode was formed on a 1.1 mm thick glass substrate. This substrate A was coated with an NMP (N-methylpyrrolidone) solution of a polyamic acid by spin coating, baked at 300 ° C. for 1 hour, and imidized to form a polyimide. Further, a substrate obtained by subjecting the substrate B on which the polyimide alignment film was formed to a rubbing treatment under the rubbing conditions shown in Table 1 was used as a substrate C. In this example, a liquid crystal cell was fabricated by combining the three types of substrates A to C.

[0037]

[Table 1]

On the three types of substrates A to C prepared as described above, 10 monolayer cumulative alignment films were formed by the above-described monolayer cumulative method. FIG. 7 shows the monomolecular film accumulator used. In the figure, 71 is a pump, 72 is a water tank, 7
Reference numeral 3 denotes a Teflon plate, 74 denotes a barrier, and 76 denotes a microsyringe for dropping a monomolecular film material. The water tank used in this example has a length of 170 cm, a width of 10 cm, and a depth of 0.5 cm. This water tank was filled with ultrapure water, and water was flowed in one direction by a pump 71. At the inlet and outlet of the flowing water, there are provided water tanks 72 for reducing the water flow, each of which is provided with a Teflon plate 73 having 80 small circular holes, so that a uniform laminar flow can be created. It has become. In addition, a syringe position 7 where a solution for forming a monomolecular film is dropped.
The distance from 6 to the film formation position is 100 cm.

The monomolecular film is formed by dropping an NMP solution of an alkylammonium salt of polyamic acid used for forming the underlayer of the substrates B and C on flowing water at a flow rate of 8 mm / sec for a sufficient time. After the elapse of the above, the operation of contacting the substrate in parallel with the water surface is repeated to form nine layers of the polyammonium alkylammonium film, and then the substrate is rotated 180 ° so that the direction of flowing water with respect to the substrate is reversed. To form a tenth layer. In the horizontal deposition method, two layers of film may adhere to the substrate in one deposition operation. In order to prevent this, in this embodiment, the deposition is performed after surrounding the substrate with a barrier each time. Operation was performed.
With respect to the substrate C in which the rubbing treatment was performed on the polyimide film as the base layer, the flowing water direction and the rubbing direction at the time of forming the first to ninth layers were set to be the same. The flow rate at the time of forming the uppermost layer was changed in five ways: 6, 8, 10, 12, and 14 mm / sec.

The monomolecular film cumulative alignment film thus produced was baked at 300 ° C. for 1 hour to imidize it, thereby preparing a sample cell.

The prepared sample cells were of the same type for the upper and lower substrates, and were parallel cells in which the directions of flowing water at the time of forming the uppermost monomolecular film were substantially parallel between the upper and lower substrates, and were substantially antiparallel. There are three types of anti-parallel cells, ie, an anti-parallel cell, and an asymmetric cell in which a monomolecular cumulative alignment film is formed only on one substrate, and a vertical alignment process is performed on ITO on the other substrate.
There are five types. Cell gap is 2 μm for all samples
And

The sample cell is bonded so that the clogged seal member 63 and the rubbing direction (or flowing water direction) 60 are orthogonal to each other in order to see the direction of movement of the liquid crystal during driving. The liquid crystal was injected into the isotropic phase to obtain a sample. The injected liquid crystal is C
crystal → SmC ^* → SmA → Iso. This mixed liquid crystal has SmC ^* under a temperature condition of 30 ° C., and has a tilt angle Θ of 25 ° C.
As described above, the spontaneous polarization has a characteristic of ²⁰ nC / cm ² .

After injecting the above liquid crystal into the sample cell, the temperature was returned to room temperature, and the alignment state at SmC ^* was observed. As a result, all of the fabricated devices showed a good uniform alignment state, and the apparent tilt angle θ _a was The average was as large as 21.5 °. The theta _a there was no significant variation due to sample.

In order to quantitatively evaluate the uniformity of the orientation,
The value of the maximum value / minimum value of the transmittance under crossed Nicols (the transmittance in a white state / the transmittance in a black state) was determined. Table 2 shows the results.

[0045]

[Table 2]

As is clear from Table 2 above, it is found that the orientation is particularly good in the cell manufactured using the substrate C on which the polyimide underlayer is formed and subjected to the rubbing treatment. Also, little difference was observed in the cell bonding direction and cell asymmetry. Regarding the flow rate dependency when forming the uppermost monomolecular film, 8 to 14 mm /
In the range of sec, there is no significant change in the orientation, but 6 mm /
In the case of sec, the orientation was low.

The moving speed of the liquid crystal molecules in the liquid crystal cell of this embodiment was measured by the measuring method of the moving speed of the liquid crystal shown in FIG. The writing waveform at the time of measurement has a pulse width of 30 μm, 1 /
The liquid crystal was driven with a write pulse voltage of 20 V and a pulse width of 1.2 times the threshold value at 3 biases and 1/1000 duty. The moving speed of the liquid crystal was calculated from the penetration distance of the marker 5 hours after the start of driving. The result is shown in FIG. This figure shows the results for the asymmetric cell using the substrate C, and the horizontal axis shows the flow rate at the time of forming the uppermost monomolecular film. V ₀ in the figure is a moving speed when the direction of flowing water is not reversed at the time of forming the uppermost monomolecular film, as in FIG.

As is apparent from FIG. 8, when the direction of flowing water is not reversed (V ₀ ) at the time of forming the uppermost monomolecular film, the moving speed of the liquid crystal molecules is relatively high. It can be seen that the moving speed of the liquid crystal molecules can be changed by reversing the direction of flowing water at the time of film formation, and the moving speed of the liquid crystal molecules can be made almost zero by changing the flow speed.

The same tendency as in FIG. 8 is shown in the device using the substrates A and B, and in the device of any of parallel and anti-parallel, and in the device in which the uppermost layer is formed at a flow rate of 12 mm / sec. The moving speed became almost zero.

Further, regarding the anti-parallel cells of the substrates A to C,
One sample was prepared in addition to the sample used for measuring the liquid crystal moving speed, and the above-mentioned liquid crystal for pretilt measurement was injected, and the pretilt angle of each sample cell was measured by a crystal rotation method. FIG. 9 shows the result. FIG. 9 shows the result for the substrate C. In the drawing, α ₀ is a pretilt angle when the direction of flowing water is not reversed at the time of forming the uppermost monomolecular film.

As is apparent from FIG. 9, the flow rate during film formation when the moving speed of the liquid crystal molecules was almost 0 was 12 mm / sec.
In the condition of, the average pretilt angle is also almost 0 °
It turned out that it became. Substantially similar results were obtained for the substrates A and B.

In the sample in which the movement of the liquid crystal molecules was not confirmed in the present embodiment, the liquid crystal molecules did not move even when the driving voltage, the temperature, etc. were changed, and a liquid crystal element showing a stable switching behavior was obtained. Was completed.

Further, even when a material other than the polyamic acid used as the material of the monomolecular film and the underlayer in this embodiment is used, the moving speed of the liquid crystal molecules is 0, although the optimum flow rate at the time of film formation changes. The present inventors have found that there is an optimum value at which the pretilt angle is almost 0 °.

Further, in the present embodiment, the sample cells manufactured using the substrates A and B were driven under the above-described driving conditions for measuring the moving speed of the liquid crystal molecules, and the white display was continued and the black display was continued. When the change of the threshold voltage afterward was examined, the threshold shift after driving for 3 hours was about 1.0%.

[0055]

Example 2 On a substrate A formed in Example 1, a polyamic acid having a composition different from that used in Example 1 was applied by NMP solution by spin coating, and baked at 270 ° C. for 1 hour to imidize. Substrate B '. This substrate B 'was subjected to a rubbing treatment under the conditions shown in Table 3 below to obtain a substrate C'.

[0056]

[Table 3]

The substrates B 'and C' thus prepared
Example 1 was repeated using the polyamic acid used in Example 1.
A monomolecular film cumulative alignment film exactly the same as that formed in the above was formed, and the same sample cell as in Example 1 was produced. Further, a sample cell for pretilt angle measurement was prepared in the same manner as in Example 1.

In this embodiment, the apparent tilt angle θ
_a was as large as 22 ° on average.

Table 4 shows the maximum value / minimum value of the transmittance under crossed Nicols for each cell of this embodiment.

[0060]

[Table 4]

Compared with the data of Example 1, the overall tendency is the same, but the device of Example 1, that is, the same material of the underlayer and the monomolecular film has better orientation uniformity, Further, it can be seen that good alignment uniformity can be obtained by performing a rubbing treatment. Other polyimides, polyamides, and the like were also studied as the underlayer, but in many cases, the uniformity of the alignment was slightly inferior when a different material was used as compared to when the same material as the monomolecular film was used.

In this embodiment, the change in the threshold voltage after the white display and the black display were continued under the same driving conditions as in the first embodiment was examined. 0.5% or less, showing better characteristics as compared with Example 1. Even when other polyimides or polyamides are used, the threshold deviation tends to be small when the materials of the underlayer and the monomolecular film are different.

The moving speed of the liquid crystal molecules in the sample cell of the present example was measured in the same manner as in Example 1. The result is shown in FIG. This figure shows the results for the asymmetric cell using the substrate C, but shows the same tendency when the substrate B is used and for the parallel and anti-parallel elements, and 12 mm / sec.
When the uppermost monomolecular film was formed at the flow rate of, the moving speed of the liquid crystal molecules became zero.

FIG. 11 shows the result of measuring the pretilt angle in the same manner as in Example 1. Regarding the pretilt angle, the same tendency as in Example 1 was observed, and the pretilt angle was 12 mm / s.
It was 0 ° at ec.

[0065]

As described above, according to the present invention,
The movement of liquid crystal molecules in the cell due to driving is prevented, the thickness of the liquid crystal layer does not fluctuate, and a liquid crystal element exhibiting good switching characteristics and good uniform alignment can be manufactured with a simple method with good reproducibility. .

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining movement of liquid crystal molecules.

FIG. 2 is a cross-sectional view of the liquid crystal element of the present invention.

FIG. 3 is a schematic view showing a monomolecular film forming process according to the present invention.

FIG. 4 is an explanatory diagram of pretilt of liquid crystal molecules at an interface.

FIG. 5 is a diagram showing the relationship between the flow velocity and the moving velocity of liquid crystal molecules at the time of forming the uppermost layer of the monomolecular film cumulative alignment film in the present invention.

FIG. 6 is a schematic diagram for explaining a method for measuring a moving speed of liquid crystal molecules.

FIG. 7 is a schematic view of a monomolecular film accumulating apparatus.

FIG. 8 is a diagram showing the flow velocity dependence of the liquid crystal moving speed of the liquid crystal element of Example 1 of the present invention.

FIG. 9 is a view showing the flow velocity dependence of the pretilt angle of the liquid crystal element of Example 1 of the present invention.

FIG. 10 is a view showing the flow velocity dependence of the liquid crystal moving speed of the liquid crystal element of Example 2 of the present invention.

FIG. 11 is a view showing the flow velocity dependence of the pretilt angle of the liquid crystal element of Example 2 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Alignment processing direction 11, 11 'Average molecular axis direction 12 Liquid crystal molecule movement direction 13 Edge area (colored area) of display part 21 Glass substrate 22 Transparent electrode 23 Polymer material layer 24 Monomolecular film cumulative alignment film 25 Spacer 26 Liquid crystal 27 Polarizing Plate 31 Flowing Direction 32 Monomolecular Film Material Solution Dropping Position 33 Barrier 34 Substrate 35 Monomolecular Film Material 61, 61 ′ Average Molecular Axial Direction 62, 62 ′ Drive Waveform 63 Sealing Material 64 Silicon Oil 71 Pump 72 Reservoir 73 Teflon Plate 74 Barrier 75 Flow direction 76 Micro-syringe for dropping monomolecular film material

Claims (15)

[Claims] 1. A liquid crystal element comprising at least two chiral smectic liquid crystals exhibiting an optically stable state sandwiched between upper and lower substrates each having an electrode, wherein the liquid crystal element is formed on at least one substrate and on a flowing water surface. Having a monomolecular film cumulative orientation film formed by accumulating a plurality of monomolecular films by the horizontal deposition method, and flowing water to the substrate at the time of forming at least each of the uppermost two layers of the monomolecular film cumulative orientation film. A liquid crystal element characterized by different directions. 2. The liquid crystal device according to claim 1, wherein at least two of the uppermost layers of the monomolecular film cumulative alignment film have different flowing velocities at the time of film formation. 3. The method according to claim 1, wherein the underlayer of the monomolecular film cumulative alignment film has a polymer material layer made of the same material as the monomolecular film cumulative alignment film and manufactured by a method other than the monomolecular film accumulation method. 3. The liquid crystal device according to 1 or 2. 4. The method according to claim 1, wherein the underlayer of the monomolecular film cumulative alignment film has a polymer material layer made of a material different from that of the monomolecular film cumulative alignment film and manufactured by a method other than the monomolecular film accumulation method. 3. The liquid crystal device according to 1 or 2. 5. The liquid crystal device according to claim 3, wherein a rubbing treatment is performed on the polymer material layer of the underlayer. Wherein said two when the tilt angle theta _a apparent half spread angle between optically stable states, theta _a and the chiral smectic relationship theta / 2 of the liquid crystal tilt angle theta < The liquid crystal device according to claim 1, wherein θ _a ≦ Θ. 7. The liquid crystal device according to claim 1, wherein an average pretilt angle α on the monomolecular film cumulative alignment film is 0 °. 8. The monomolecular film cumulative alignment film is formed on both the upper and lower substrates, and directions of flowing water with respect to the substrate when forming the uppermost two layers are substantially parallel to each other. Item 8. The liquid crystal element according to any one of Items 1 to 7. 9. The monomolecular film cumulative alignment film is formed on both the upper and lower substrates, and the directions of flowing water with respect to the substrate when forming the two uppermost layers are substantially anti-parallel to each other. A liquid crystal device according to claim 1. 10. The liquid crystal device according to claim 1, wherein the monomolecular film cumulative alignment film is formed only on one substrate, and the other substrate is subjected to a vertical alignment process. 11. An upper and lower substrate each having an electrode,
What is claimed is: 1. A method for manufacturing a liquid crystal device comprising a chiral smectic liquid crystal exhibiting at least two optically stable states sandwiched between at least one substrate side, a plurality of monomolecular films formed on a flowing water surface by a horizontal deposition method. In the step of accumulating and forming a monomolecular film cumulative alignment film, when the monomolecular film is accumulated, at least the uppermost two layers have different directions of flowing water with respect to the substrate at the time of film formation. Production method. 12. The method for manufacturing a liquid crystal device according to claim 11, wherein at least two of the uppermost layers have different flowing velocities during film formation. 13. Prior to the step of forming the monomolecular film cumulative alignment film, a polymer material layer made of the same material as the monomolecular film cumulative alignment film is used as a base layer by a method other than the monomolecular film cumulative method. The method for manufacturing a liquid crystal element according to claim 11, further comprising a step of manufacturing. 14. Prior to the step of forming a monomolecular film cumulative alignment film, a polymer material layer made of a material different from that of the monomolecular film cumulative alignment film is used as a base layer by a method other than the monomolecular film accumulation method. The method for manufacturing a liquid crystal element according to claim 11, further comprising a step of manufacturing. 15. The method for manufacturing a liquid crystal element according to claim 13, further comprising a step of performing a rubbing treatment on the polymer material layer as the underlayer.