JP2000081625A - Substrate for liquid crystal panel body and liquid crystal panel body using the substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the rectilinear penetratability in the major axis direction of liquid crystals to a liquid crystal panel body by providing the substrate with striped periodic ruggedness and barriers of specific value intervals extending approximately parallel with the extending direction of the ruggedness. SOLUTION: This substrate has the striped periodic ruggedness 303 and the barriers 305 of the intervals of 20 &mu;m to 3 mm extending approximately parallel with the extending direction of the ruggedness 303. The pitch of the ruggedness 303 is <=10 &mu;m and the amplitude thereof is <=1 &mu;m. The shape thereof is preferably sinusoidal or triangular. An org. film or inorg. film 304 may be applied on the substrate 301 having the ruggedness 303. As a result, the movement of the liquid crystal molecules accompanying the volume shrinkage at the time of self-cooling of the liquid crystals is extremely accelerated and the aligning property of a smectic layer may be improved. In addition, an alignment layer which is uniform and has high transparency may be formed without using a rubbing method and a diagonal vapor deposition method as a uniaxial alignment treatment for the smectic liquid crystals having a cholesteric layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal panel substrate which can be used for a display as an information display terminal for home business, and a liquid crystal panel using the same. More specifically, the present invention relates to a substrate surface shape related to alignment control of a liquid crystal panel using a smectic layer such as a ferroelectric liquid crystal or an antiferroelectric liquid crystal.

[0002]

2. Description of the Related Art Liquid crystal panel bodies have been most widely used as flat panel displays because of their advantages such as light weight, space saving and low power consumption. It is expected to replace it.

[0003] Among them, a liquid crystal panel using a smectic liquid crystal of ferroelectric and antiferroelectric liquid crystal has a high responsiveness.
Simple matrix drive is possible due to high viewing angle and memory. However, with respect to the orientation, zigzag defects and linear defects characteristic of the smectic layer occur, and it is hard to say that the display quality is sufficient. Furthermore, unlike the liquid nematic liquid crystal, which uses a semi-solid smectic phase, once the liquid crystal layer structure is destroyed by the deformation of the panel, there is no self-healing property and it cannot be used continuously. Disadvantages.

As means for solving these two problems at the same time, a pair of glass substrates are completely bonded via a stripe-shaped partition member, and these liquid crystals are sealed in a linear space formed by a temperature gradient cooling method. The present applicant has disclosed a technique for improving the alignment state of liquid crystal by using the method described in Japanese Patent Application Laid-Open Nos. Hei 7-318912 and Hei 7-159792.

In this method, the liquid crystal panel is constructed as shown in FIG.
As shown in FIG.
Then, an alignment film 103 for alignment control is formed thereon, and a stripe-shaped partition member 104 is formed as a spacer on one substrate by a conventional photolithography method. The width of the partition member 104 is about the width between the electrodes and is 5 to 30 μm.
The thickness is almost the same as the cell gap, and is set to a desired value in the range of 1 to 2 μm. Pitch is 30 ~ 300μ at electrode pitch or multiple pitches
m. By bonding the upper and lower substrates by heat and pressure through such a partition member 104, an elongated space that is substantially closed except for the opening is obtained, and the liquid crystal 105 is sealed and held therein. The alignment film 103 has a uniaxial orientation by a rubbing treatment, UV irradiation, or the like in a direction substantially parallel to the partition wall. The uniaxial orientation is imparted by an obliquely deposited silicon dioxide film in addition to the organic alignment film. It doesn't matter.

[0006] A smectic liquid crystal is sealed in a liquid state or a cholesteric phase in a liquid crystal panel body having this structure, and a temperature gradient cooling is performed to gradually move the panel body from a high temperature constant temperature bath to a room temperature constant temperature bath. The moving direction is substantially parallel to the partition walls, whereby a temperature gradient is generated in each linear space as shown in FIG. 2, and the liquid crystal inside is cooled sequentially from one end of the space to the other end. . Due to the temperature gradient cooling, the volume shrinkage of the liquid crystal occurs sequentially from the low temperature side, and the flow of the liquid crystal in a certain direction is thereby induced. By doing so, the orientation of the smectic A phase is improved, and as a result, a chiral smectic phase free of zigzag defects and linear defects can be formed.

In order to induce effective liquid crystal flow in the smectic A phase in this temperature gradient cooling method, it is necessary to make the cross-sectional area of the elongated space surrounded by the partition member and the upper and lower substrates smaller than a certain critical value. is there. For this purpose, the distance between the partition members is optimized, not the cell gap, which cannot be largely changed. This value is about 800 μm or less.

[0008] Regarding the temperature gradient, the smectic A phase needs to be at least 2 ° C per mm. Desirable temperature gradient is 1 m for antiferroelectric liquid crystal without cholesteric phase
4 ° C. or more per m. As a method of applying the temperature gradient, the liquid crystal panel body is moved between thermostats of two kinds of temperature atmospheres, and the thermostat is selected from liquid, solid, and gas. Such a strong temperature gradient can be applied only to the above-mentioned adhesive liquid crystal panel body. If not adhered, the glass substrate shrinks sharply, the liquid crystal is rubbed on the glass surface, and the smectic layer becomes sandy, so that a desirable alignment state cannot be obtained.

As described above, the adhesive type panel having the partition member is used for the temperature gradient cooling method. This can solve not only the problem of controlling the alignment of the smectic liquid crystal but also the problem of impact resistance. By the partition member, the liquid crystal panel body becomes robust and can withstand a pressing impact up to about 100 N / cm ² . Yet another advantage is that the cell gap can be controlled with very high precision by the partition walls. Still another advantage is that since the liquid crystal is partitioned by the partition walls, the direction of permeation of the liquid crystal is linearly restricted and does not meander.

The combined use of the above-mentioned adhesive panel with the partition member and the temperature gradient cooling method not only significantly improves the impact resistance of the liquid crystal panel body, but also provides a substantially defect-free alignment layer for the ferroelectric liquid crystal. Can be manufactured stably. An unprecedented orientation can be obtained even with an antiferroelectric liquid crystal.

[0011]

However, as long as the rubbing method is used, unevenness of rubbing and adhesion of foreign matter due to generation of static electricity during rubbing are serious problems, and the above-mentioned problems of defect control and impact resistance are solved. However, this problem still remains. Further, it has been found that there is a qualitatively different problem from the above defect control and impact resistance in the orientation of the liquid crystal group exhibiting smectic properties. In general, liquid crystals exhibiting smectic properties include a liquid crystal exhibiting a phase change of liquid phase → cholesteric phase → smectic A → chiral smectic phase and a liquid crystal exhibiting a liquid phase → smectic A → chiral smectic phase. Practical antiferroelectric liquid crystals belong to the latter. Most ferroelectric liquid crystals belong to the former, but some materials do not go through a cholesteric phase and may be put to practical use. The cholesteric phase can significantly improve the orientation of the smectic A layer.Comparing the orientation, the liquid crystal passing through the cholesteric phase has better orientation. It can flow and can completely eliminate zigzag defects and linear defects by the temperature gradient cooling method. However, when observed in close detail, it is an aggregate of fine domains having slightly different extinction positions, which causes a problem of low contrast, and there is still room for improvement in the alignment state. The alignment state is rough and flocculent, and the alignment state is not highly transparent. It has been found from observation that this is one of the causes of surface roughness caused by rubbing the surface of an alignment film such as polyimide as a uniaxial alignment treatment by rubbing.

Still another problem is that in the rubbing process, it is not easy to form a uniform high-contrast orientation, and often a twisted state is exhibited. This is because the interaction between the liquid crystal molecules and the polyimide surface causes the spontaneous polarization components of the liquid crystal molecules to face the inside of the cell or the liquid crystal molecules are arranged in the layer so as to face the outside of the cell. If the rubbing directions of the upper and lower substrates are slightly crossed or the material of the alignment film is selected, the uniformity can be increased, but the above-mentioned problem still remains. Therefore, it is not preferable to use a highly polar polyimide-based alignment film in order to form a desirable uniform alignment. That is, in order to solve the above two problems of the ferroelectric liquid crystal, an alignment processing technique which is an alternative to the rubbing processing is expected. From the above, in the alignment control of the smectic liquid crystal having a cholesteric phase, rubbingless alignment control without using polyimide is necessary for further improving the alignment.

An antiferroelectric liquid crystal and a ferroelectric liquid crystal that do not have a cholesteric phase for improving the alignment further have a problem that it is generally difficult to produce a defect-free smectic layer comparable to a ferroelectric liquid crystal. In other words, the application of the temperature gradient cooling method can achieve a significant improvement in the orientation, such as the removal of zigzag defects, but generally does not reach the orientation of the ferroelectric liquid crystal in the same order as the smectic layer. In this case, it is desired to develop means for further improving the effect of the temperature gradient cooling method.

[0014]

According to the present invention, in order to solve the above-mentioned problems, the invention according to claim 1 is directed to a method in which a periodic unevenness in the form of stripes and 20 .mu.m extending substantially parallel to the extending direction of the unevenness. It is a substrate for a liquid crystal panel body having partition walls at 3 mm intervals. The invention described in claim 2 is
2. The substrate for a liquid crystal panel according to claim 1, wherein the pitch of the periodic unevenness is 10 μm or less, more preferably 3 μm or less, and the amplitude is 1 μm or less. The invention according to claim 3, wherein an organic film or an inorganic film is formed on a surface in contact with the liquid crystal above the irregularities, wherein the liquid crystal according to any one of claims 1 to 2 is provided. It is a substrate for a panel body. The invention according to claim 4 is the substrate for a liquid crystal panel body according to any one of claims 1 to 3, wherein the unevenness is formed on a linear electrode side. The invention according to claim 5 is the substrate for a liquid crystal panel body according to any one of claims 1 to 4, wherein the organic film or the inorganic film has uniaxial orientation. The invention according to claim 6 is
In a liquid crystal panel body that holds liquid crystal in a gap between a pair of substrates, at least one substrate that is in contact with the liquid crystal has periodic irregularities in a stripe shape, and is substantially parallel to an extending direction of the irregularities between the pair of substrates. A liquid crystal panel having partition walls extending in a direction at intervals of 20 μm to 3 mm. The invention according to claim 7 is the liquid crystal panel body according to claim 6, wherein the pair of substrates is bonded by the partition. The invention according to claim 8 is the liquid crystal panel according to any one of claims 6 to 7, wherein the liquid crystal is a smectic liquid crystal.

The present applicant has found that the two seemingly separate problems of improving the orientation qualitatively different depending on the presence or absence of the cholesteric phase without using the rubbing method can be solved from a common phenomenon. I found it. In order to improve the alignment of the smectic liquid crystal, it is decisive and effective to make the liquid crystal go straight in the molecular long axis direction when the liquid crystal penetrates, and to memorize the state on the alignment film. One means for this purpose is to partition the inside of the liquid crystal panel into an elongated space having a linear and appropriate cross-sectional area (JP-A-7-31891).
No. 2, JP-A-7-159792). The present invention has found a means to push this point more positively, and reflects this in the panel structure.

The means is to control the manner in which liquid crystal molecules permeate into the panel in a more preferable direction. As a method of penetration, it is conceivable that the liquid crystal molecules penetrate in a state where the major axis direction is parallel to the penetration direction, penetrate so as to roll vertically, or an intermediate state or a mixed turbulent penetration, The state is stored in the surface in contact with the liquid crystal, and the orientation is defined. Experiments by the present inventors have revealed that the former has much better initial orientation and then the latter. This is a result obtained by observing a process in which the liquid crystal permeates in a cholesteric state into the inside of the panel having the periodic unevenness as shown in FIG.

In the cholesteric phase, the major axis direction of the liquid crystal molecules is aligned as a whole. The current case is a flow-regulating alignment phenomenon in which the direction is defined by the flow of the entire liquid crystal. In order for the long axis direction to effectively face the permeation direction, it is important to appropriately design the cross-sectional area of the linear space and control the meniscus fluid level. This is because at the cholesteric (nematic) phase temperature, liquid crystal molecules tend to be oriented perpendicular to the fluid surface if there are no irregularities, and even if there are irregularities, the effect of the fluid surface and the shape effect of the irregularities are superimposed. This is because liquid crystal alignment is obtained as a result of the alignment. That is, if the flowing liquid surface is significantly disturbed, the resulting liquid crystal alignment will be disturbed even if there are irregularities. Further, it was effective to control the chemical state of the substrate surface, the permeation rate, and the periodic uneven structure formed in the permeation direction formed on the surface in contact with the liquid crystal. The present invention specifies what the shape of the periodic irregularities should be, and what should be the partition necessary to form a linear space. When the irregularities, the partition walls, and the appropriate surface state and permeation rate were given, the direction of the permeation state was memorized on the surface in contact with the liquid crystal, and a good smectic layer could be formed. Since this method has no rubbing orientation, the problems of rubbing unevenness and foreign matter can be solved, and the room for selection as a film material is expanded, and a uniform orientation exhibiting high contrast can be formed by appropriately selecting a material.

The second is to promote the movement of the liquid crystal molecules accompanying the volume contraction when cooling the liquid crystal. It was found that the unevenness function not only aligns the long axis direction during permeation but also has such a function. This effect was particularly effective for antiferroelectric liquid crystals having no cholesteric phase. That is, since the antiferroelectric liquid crystal does not have a cholesteric phase, it is permeated with a liquid phase. In this case, however, the orientation is better when irregularities are formed. One reason is that the narrow portion of the low portion of the unevenness promotes the straight penetration of the liquid crystal due to the geometrical constraint with respect to the initial alignment. Another reason is that the movement of the liquid crystal molecules based on the volume shrinkage at the time of the temperature gradient cooling is strengthened by the uneven structure.

The irregular shape effective for the linear permeation of the liquid crystal molecules in the major axis direction and the movement of the liquid crystal molecules at the time of volume contraction can be defined by the pitch p and the amplitude d shown in FIG. The pitch is preferably narrower, but the lower limit is about 1 to 0.6 μm in consideration of the size of the display and the pattern accuracy of photolithography. When this pitch is standard, d is 0.01 μm
If it is more than the degree, the unevenness effect (improvement of orientation) was found. If this ratio (p / d) is small, the valley is relatively deep and the linear mobility of the liquid crystal at the bottom increases, but d cannot be blindly increased. This is determined by a relative ratio to the cell gap D. This is because if the amplitude d is larger than the cell gap D, the electric field applied to the liquid crystal changes due to the cell gap fluctuation. However, there is an exception in the case of, for example, a ferroelectric liquid crystal in which a threshold value is changed by fluctuation of a gap to perform gradation display. In this case, the ratio between the cell gap D and the amplitude d can be reduced. The cell gap D of a smectic liquid crystal is generally about 2.5 to 1 μm.

The optimum value of the distance between the partition walls forming a linear space important for controlling the flow of the liquid crystal and aligning the major axis direction of the liquid crystal depends on the type of liquid crystal, the cell gap, and the shape of the irregularities. Is preferably about 20 μm to 3 mm. In a case where a liquid crystal having a chevron structure such as a ferroelectric or antiferroelectric liquid crystal is used, a more desirable mode is one in which the distance is about 20 μm to 800 μm. This is because a large temperature gradient cooling effect can be expected in this range, and zigzag and linear defects can be eliminated or greatly reduced. Further, the impact resistance is greatly improved.

In an antiferroelectric liquid crystal capable of expressing an analog gradation, d is desirably set to 0.1 so that the same voltage is applied as a whole.
The thickness is preferably not more than 05 μm, more preferably not more than 0.03 μm. In this case, the pitch d was desirably about 10 to 0.6 μm. The shape of the concavities and convexities is preferably a triangular wave, and the bottom of the concave portion is preferably sharp.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention, particularly, structural features will be described. FIG. 3 shows an example of a typical panel configuration in the present invention. In the present invention,
It is preferable that the pitch of the unevenness 303 on the substrate 301 on which the liquid crystal driving electrode 302 is formed is 10 μm or less, the amplitude is 1 μm or less, and the shape thereof is sinusoidal, rectangular, or triangular. Note that the liquid crystal driving electrode 302 may be below the unevenness 303 (between the substrate 301 and the unevenness 303) or above the unevenness 303 (between the unevenness 303 and the liquid crystal 306). Specifically, this position is determined in consideration of the cell gap D, the amplitude d of the unevenness, and the thickness of the unevenness, from the viewpoint of what voltage should be applied to the liquid crystal.
The present invention can also be applied to a TFT drive type in which one side is a solid electrode. Further, a color filter can be formed below the electrode.

As a method for forming the periodic irregularities 303, there is a regular photolithography method using a photoresist. Another simple means of forming a mask is to expose the resist with a mask and then heat-treat to give a relative difference in the height direction of the resist between the high and low exposure areas or the unexposed areas. There is a way to do that. Amplitude d
Is about 0.2 μm or less, it can be formed without a developing step, though it depends on the thickness of the underlying resist layer. In this case, the shape of the irregularities 303 is sinusoidal 40 as shown in FIG.
It was 2 or triangular 401. Regarding the pitch p, 0.6 μ was obtained by reducing exposure using an i-line stepper.
m. When development is performed, the thickness of the uneven surface is not substantially limited, but the amplitude d depends on the thickness of the underlying resist layer only by exposure and baking of the resist. Also,
When an electrode is formed on the base, a voltage drop may occur depending on the thickness of the resist layer.

As another method of forming the periodic unevenness 303, desired unevenness can be formed on the electrode. For example, it is possible to pattern a photoresist applied on a metal electrode, peel off the resist after etching the electrode, form irregularities directly on the electrode, and uniformly align the smectic liquid crystal without an organic film and rubbing. .

Further, if a mold is prepared by a generally used method such as an electroforming method, a method used at the time of forming an information recording medium such as embossing using a stamper or injection molding can be used. Irregularities can also be transferred by UV / thermosetting resin. That is, the present invention is applicable to mass production and is industrially useful.

An organic film or an inorganic film 304 can be applied on the substrate having the irregularities 303. Of course, the uneven surface substrate and the organic film may be the same. The purpose of forming another film is to prevent the elution of the compound contained in the base or to adjust the chemical bonding force with the liquid crystal. In addition, regardless of organic or inorganic, even if an optical film such as a light reflection film or a light scattering film is formed on the unevenness, or the unevenness is formed directly on the film having those characteristics by the method described above. Good.
When a film having such characteristics is used, the unevenness may be formed only on the counter substrate side. For example, a polyimide film or the like which is chemically stable and has good interaction with the liquid crystal can be applied, for example, when the memory of the conformation when the liquid crystal permeates is insufficient. Further, the organic film may have a uniaxial orientation substantially in parallel with the extension direction of the unevenness 303, and the rubbing treatment is performed in a conventional manner in the unevenness direction. In this case, the direction controllability by the unevenness 303 and the uniaxial alignment force of the organic alignment film 304 were added, and a significant increase in the direction control force at the time of liquid crystal permeation and cooling was recognized. The rubbing direction and the extending direction of the unevenness need not necessarily be parallel. When the rubbing direction and the normal direction of the smectic layer form a finite angle, it is desirable to intersect the angle by that angle.

It is preferable that the unevenness is provided so as to be parallel to both of the pair of opposing substrates. However, if it is difficult to configure the device, it may be provided on either one of them. When a pair of substrates having orthogonal electrode groups is used, on which side the uneven surface is formed, the direction of extension of the unevenness is not parallel to the substrate on the side orthogonal to the stripe electrode, but parallel to the liquid crystal injection direction. It is desirable to provide it on a substrate having a simple electrode. This is preferable because the influence of the electrode step is small. If they are formed on the substrate on the side of the orthogonal electrodes, a step between the electrodes will occur in the direction in which the unevenness extends, and the effect of controlling the flow of the liquid crystal will be reduced. However, irregularities may be formed on the side where the electrode is perpendicular to the liquid crystal injection direction as long as there is no problem in the orientation. In the case where the unevenness is formed directly on the electrode and the unevenness is present only on one of the substrates, the unevenness parallel to the flow direction may be formed on the electrode perpendicular to the flow direction of the liquid crystal. As described above, even when the irregularities are directly formed, it is preferable to form the irregularities on the electrodes perpendicular to each other on both sides as described above, or to form the irregularities even on one side on the electrodes parallel to the flow direction of the liquid crystal. It is desirable to do.

The periodic irregularities 30 formed in this way are
3 is used on at least one side of a pair of substrates of the panel, and preferably extends at a distance of 20 μm to 3 mm, more preferably 20 μm, extending in the extension direction of the unevenness between the pair of substrates.
Partition walls 305 at intervals of up to 800 μm are formed by photolithography. By optimizing the partition wall pitch in this range, the straightness of penetration of the liquid crystal in the major axis direction is improved, and the mobility at the time of temperature gradient cooling is increased. The partition may be cut off to the extent that this function is not impaired. A more desirable mode is that the pair of substrates are bonded by the partition walls. A linear space which is almost completely sealed by bonding is the most desirable form. This is because the impact resistance is remarkably improved, and the effect of the temperature gradient cooling method is remarkable.

[0029]

(Embodiment 1) Embodiment 1 is the first embodiment of the present invention.
4, 6, 7, and 8. The schematic structure of the liquid crystal panel is shown in FIG. The size of the substrate used was 6 inches diagonally, a transparent electrode was formed on the liquid crystal side by a standard method, and the electrodes were patterned in a stripe shape as necessary. The following three types of liquid crystal panel frames were prepared. (1) a conventional polyimide rubbing mold (see FIG. 5 (1)), (2) a substrate having uneven surfaces on both inner surfaces (rubbingless) (see FIG. 5 (2)),
(3) A polyimide film is further applied (rubbingless) to the uneven surface (see FIG. 5 (3)).

In (1), a polyimide solution (HL1110 (trade name, manufactured by Hitachi Chemical Co., Ltd.)) was applied as an organic film 503 on a substrate, dried at 180 ° C., and then subjected to a rubbing treatment.
Next, after forming a partition group 504 at a distance of 300 μm as a spacer / adhesive layer on one substrate by a method described later,
The liquid crystal panel frame was obtained by bonding the pair of substrates. The rubbing directions of the upper and lower substrates are parallel in principle, but they may intersect as required. On the substrate on which the partition group was formed, a rubbing process was performed in the partition direction after the formation of the partition.

In (2), an uneven layer 5 is provided on the liquid crystal side of the transparent electrode.
06 is formed, but may be formed on the glass substrate side (between the electrode and the substrate) from the electrode if necessary. One of the following two methods was appropriately adopted as a specific method of manufacturing the unevenness. First
Is to form an uneven surface by exposing a selected portion using a negative resist such as an acrylic or rubber-based resist or a bisphenol-based positive resist and then heating the selected portion. As an example, a negative resist is applied on a substrate with electrodes to a thickness of 1.5 μm by spin coating and prebaked, and a selected portion is exposed to about 180 mJ / cm ² (UV 350 nm) with a stripe mask having a pitch p of 2 μm. After that, by baking at 150 ° C. for 1 hour, the exposed portion was relatively raised with respect to the unexposed portion to form a sinusoidal uneven surface. The amplitude d and the shape of the unevenness can be changed by changing the film thickness, exposure and heating conditions and procedures.

The second method is a standard photolithography method. A positive resist (MP1400-25 manufactured by Shipley) is applied to the substrate with electrodes by spin coating to a thickness of 0.12.
After coating and pre-baking, and exposing selected portions using a stripe mask having an appropriate pitch p, development was performed with an alkaline aqueous solution. Then, by baking at 170 ° C. for 1 hour, a rectangular uneven surface having an amplitude d of 0.1 μm could be formed. In both the first method and the second method, the pitch p can be reduced to about p = 0.6 μm by reduction projection exposure using an i-line stepper.

A substrate having an uneven surface formed by the above-mentioned method is prepared, and a substrate having a width of 20 μm extending in the extension direction of the unevenness is provided thereon.
m, a height of 1.5 μm, and a spacing of 300 μm were formed by a conventional photolithography method using an acrylic negative resist. Rinsing was performed with an organic solvent to remove the remaining resist film. The upper and lower substrates were brought into close contact using the atmospheric pressure so that the extending directions of the concavities and convexities of the pair of substrates opposed to each other were substantially parallel, and the substrates were completely bonded by heating and holding at 150 to 170 ° C. for about 1 hour.

The liquid crystal panel frame of (3) is a polyimide solution (Hitachi Chemical Co., Ltd.) as an organic film 507 on the uneven surface of (2).
HL1110) was applied and dried by heating at 180 ° C., followed by forming and adhering the partition group 504 by the above procedure to obtain a liquid crystal panel frame.

A ferroelectric liquid crystal (SCE9 I → 115 manufactured by Hoechst Co., Ltd.) is provided on the liquid crystal panel frame thus produced.
C → N ^* → 91 ° C. → SmA → 61 ° C. → SmC ^* ) infiltrated with the cholesteric phase N ^* . Table 1 summarizes the results of a comparison between the normal rubbing orientation and the orientation due to the surface unevenness effect in a three-step evaluation (非常 = very good, Δ = good, × =
The (bad) criterion is defined as △, which is the alignment state obtained in the liquid crystal panel (1) subjected to a conventional rubbing treatment. In this orientation state (△), zigzag defects and linear orientation defects are present, but the orientation state is good except for the defective part. In a smectic liquid crystal having a cholesteric layer, these defects completely disappear when a temperature gradient cooling is applied. The liquid crystal which does not exist does not completely disappear but the alignment state is improved. However,
In each case, as described above, fine domains with slightly different orientation directions are observed, and the orientation state has room for improvement.
That is why this is △. The amplitude d of the uneven part is 0.05 μm
And 0.1 μm, but the same result was obtained.

[Table 1] Conventional type rubbing cell Asperities only Asperities + polyimide film (1) (2) (3) Liquid crystal filling temperature Liquid phase △ △ △ N ^* phase △ ○ △-○ After cooling down temperature gradient △ ○ ○ ～ △ After thermal cycle △ △ ○

As can be seen from Table 1, the rubbingless having irregularities had better orientation than the normal rubbing orientation. In particular, in (2) and (3), slight fluctuations in the alignment direction, which are considered to be caused by rubbing marks, were not observed at all.
In (2), uniform alignment was further obtained, and an alignment state with high transparency, that is, high contrast was obtained. About 8
A 0% contrast improvement was found. (3) had a twisted state and was slightly colored.

Comparing the liquid crystal permeation speeds (1), (2), and (3), it is observed that the permeation along the irregularities is slightly faster when the irregularities are formed, regardless of the presence or absence of the alignment film. Was.

In all liquid crystal panels, zigzag defects and linear defects were found in the initial alignment after liquid crystal penetration, but when the above-mentioned temperature gradient cooling method (temperature gradient of about 2 ° C./mm) was applied, (2) ( In 3), the orientation was greatly improved and the defect disappeared. This is because the flow of the liquid crystal was promoted by the smectic A phase due to the unevenness. In addition, the interval between partition walls is approximately 800 μm
As a result, no effect of the temperature gradient cooling was observed. In addition, it was found that the flow in the tunnel was not uniform, and the orientation state was different between the left and right sides of the center. This pitch may change depending on the liquid crystal or cell gap used. In the case of a liquid crystal panel that was not bonded, the substrate was deformed due to a strong temperature gradient, and no alignment phenomenon occurred.

When the cycle of reheating to the cholesteric phase and cooling the temperature to room temperature is repeated,
After 4 to 15 times, the initial alignment was not reproduced in (2) and (3), but the degree of deterioration was smaller when the polyimide film was applied. This is because the interaction between the polyimide and the liquid crystal is strong, so that the memory effect is stronger than the glass surface, and the orientation is stabilized.

(Embodiment 2) This embodiment is characterized in that
3, 4, 6, 7, and 8, the pitch p of the unevenness and the amplitude d
And the shape. The schematic configuration of the liquid crystal panel is shown in FIG. In the case of a ferroelectric liquid crystal, the structure of the panel body is the same as that of the first embodiment (FIG. 5B). In the case of a smectic liquid crystal having no cholesteric phase, a desirable alignment state could not be obtained only by the unevenness, but the alignment was much better than that without the unevenness. For these liquid crystals, after forming the concavities and convexities, after applying the above-mentioned polyimide solution, a substrate subjected to a rubbing treatment in parallel with the extension direction of the concavities and convexities was prepared, and then a partition member was formed in the same manner as in Example 1. And laminated to form a panel body.

As the method of forming the unevenness, the pitch, amplitude and shape were controlled by selectively using the above-described first method and second method. The relationship between the pitch, the amplitude and the shape of the concavities and convexities in this forming method is roughly as follows. In the first method, the pitch p is small and the amplitude d
The shape of the irregularities tended to be triangular as increased, and to a rectangular shape in the opposite case. The intermediate region had a sinusoidal shape. In the second method using photolithography, the shape of the unevenness was rectangular regardless of the pitch.
However, by adjusting the conditions such as exposure and development, it was possible to obtain a substantially sinusoidal or substantially triangular uneven surface with a desired amplitude.

The liquid crystal is sealed at a cholesteric phase temperature for a ferroelectric liquid crystal (SCE9, trade name CS10 manufactured by Chisso Corporation).
14 I → 81 ° C → N ^* → 69 ° C → SmA → 54 ° C → SmC ^* ), liquid crystal without cholesteric phase such as antiferroelectric liquid crystal was performed at isotropic phase temperature (CS4000 I → 101 ° C → SmA → 84 ℃ → SmC
→ 82 ℃ → SmCA 、 TM-C108 I → 75.9 ℃ → SmA → 22 ℃ → SmC
).

Table 2 summarizes the results when the pitch is changed while the amplitude and shape are fixed. Table 3 summarizes the results when the amplitude is changed while the pitch and shape are fixed. The evaluation was performed in the same manner as in Example 1 in the three-stage evaluation of ○, Δ, and ×, and the orientation was evaluated after cooling the temperature gradient.

[Table 2] Amplitude d = 0.05 μm, shape: sinusoidal p = 2 p = 3 p = 8 p = 12 CS1014 ○ ○ △ × SCE9 ○ ○ △ × CS4000 ○ ○ △ × TM-C108 ○ ○ △ ×

[Table 3] Pitch p = 3 μm, shape: sinusoidal 0.01 ≦ d ≦ 0.05 d = 0.1 d = 0.2 CS1014 ○ ○ ○ SCE9 ○ ○ ○ CS4000 × ○ ○ TM-C108 △ ○ ○

In the shape of the unevenness, a sine shape visually looks better than a rectangular shape, and a triangular shape looks better than a sine shape in the orientation, but the essential difference is Did not.

As can be seen from Tables 2 and 3, in general, the smaller the pitch p and the larger the amplitude d, the better the orientation.
When using a photoresist, the minimum value of the pitch p is about 1 to 0.6 μm, and the maximum value of p that gives good orientation is about 10 μm (d =
0.05-0.2 μm). As a display, the maximum value of the amplitude d is 0.5 μm or less, preferably 0.1 to 0.05 in consideration of the cell gap (about 1 to 2 μm).
μm, and about 0.03 μm for antiferroelectric liquid crystals. The unevenness itself was confirmed at about 0.01 μm or more. p and
In some cases, the maximum and minimum values of d are determined by factors other than the alignment ability of the unevenness, but the range of the maximum and minimum values is increased when only the orientation is considered. For example, even if P = 12 μm, if d = 0.3 μm, there is an effect of unevenness, but the cell gap and amplitude are too large to be used for LCD. There was also a tendency that d could be reduced as the cell gap became smaller. Desirably, the ratio of pitch to amplitude is in the range described above and P / d <20
In this case, it is desirable to form irregularities of about 120, more preferably about 120.

(Embodiment 3) Embodiment 3 relates to the first to eighth aspects and relates to the case where unevenness is formed only on one substrate. Although it is desirable to form the irregularities on the substrates on both sides, there are cases where only one side must be limited due to cost and structural restrictions. For example, in the case of an antiferroelectric liquid crystal in which the change in the cell gap is larger than a desired value on both sides. In this case, in the case of a matrix electrode, the irregularities can be formed either in parallel with the stripe-shaped electrodes or perpendicularly to the electrodes. If it is parallel to the electrodes, there is no effect of the step between the electrodes (the thickness of the electrode) in the direction in which the unevenness extends, but if it is orthogonal, a step appears in the direction in which the unevenness extends due to the step between the electrodes. This effect was investigated.

The panel body was prepared according to Example 1. A substrate with stripe-shaped electrodes (270 μm in width, 300 μm in pitch) was used. The uneven pitch p was fixed at 2 μm, and the amplitude d was fixed at 0.05 μm. After coating the polyimide film, a partition group was formed thereon as a spacer / adhesive layer. A polyimide film was formed on a substrate having the same electrode as a counter substrate, and a rubbing treatment was performed. The substrate with and without the concavities and convexities was opposed to each other so that the rubbing directions were parallel and the electrodes were perpendicular to each other, and heated to obtain an adhesive panel. On the one hand, there is no height difference in the direction in which the unevenness extends, while on the other hand there is a height difference due to the step between the electrodes.

An antiferroelectric liquid crystal CS4000 was sealed in these liquid crystal panels and a conventional panel having no irregularities. Thereafter, the results of observation with cooling in a temperature gradient are shown in Table 4.

[0052]

As can be seen from the above results, it was found that the texture was continuously smoother and the orientation was better when there was unevenness on one side. The reason for this is that when the irregularities are formed so as to extend in the direction in which the electrode extends, the tendency of the liquid crystal to penetrate in the major axis direction at the time of permeation increases, and the flow of the liquid crystal during volume contraction occurs smoothly. Comparing the contrast of light and dark with a concavo-convex pattern (parallel) with that of the conventional type, when the former is 1, the latter is improved to 1.8 to 1.6. However, it is needless to say that it is more desirable to form unevenness on both sides.

(Embodiment 4) Embodiment 4 is the first and second aspects of the present invention.
6, 7 and 8 are used to define the distance between the partition walls when a substrate having irregularities is used. As described above, the partition walls play a major role in controlling the flowing liquid surface and aligning the molecular long axes of the liquid crystal. The smaller the space between the partition walls, the easier it is to control the fluid level.
Further, the effect of the temperature gradient cooling is great. However, if the width is too small, the liquid crystal may not be injected properly. The influence on the orientation by such a partition interval was examined.

The panel body was prepared according to Example 1 ((2) in FIG. 5).
And the same configuration). An uneven surface is formed on electrodes of a pair of substrates, and a width of 20 μm and an interval of 10 μm are formed on one of the substrates.
A group of striped partition walls having a height of 1.5 μm and a height of 4 mm from m was formed. The pair of substrates was heated and pressure-bonded to face each other so that the extending directions of the concavities and convexities were parallel to each other to obtain an adhesive panel. The liquid crystal enclosure is SCE9, CS1014, manufactured by Merck Japan K4 (I → 40.5 ℃ → N → 33.5 ℃ →
SmA) was performed in the cholesteric or nematic phase, and was performed by Hoechst Co., Ltd. under the trade name of FELIX015 (I → 86 ° C → N ^* → 83
℃ → SmA → 72 ℃ → SmC ^* ) was performed in the isotropic phase.

Table 5 summarizes the results of evaluating the initial orientation based on the rib spacing and the orientation after the temperature gradient cooling was performed in four stages of ◎, △, Δ, and ×. Separately from this, Table 6 summarizes the results of evaluating the initial orientation by rib spacing and the orientation change after temperature gradient cooling for FELIX015 in a conventional polyimide rubbing cell without unevenness.

[Table 5] Roughness Initial orientation Rib spacing / μm Rib spacing / mm 10 20 50 150 300 500 800 800 1 2 3 4 SCE9 × ○ ○ ○ ○ △ × × × × × CS1014 × × ○ ○ △ △ × × × × × K24 × ○ ○ ○ ○ △ △ △ △ △ △ FELIX015 × × △ ○ ○ ○ ○ ○ ○ ○ △ With irregularities After cooling down the temperature gradient Rib spacing / μm Rib spacing / mm 10 20 50 150 300 500 500 800 1 2 3 4 SCE9 × ◎ ◎ ◎ ◎ △ × × × × × CS1014 × × ◎ ◎ △ △ × × × × × K24 × ○ ○ ○ ○ △ △ △ △ △ △ FELIX015 × × △ ◎ ◎ ◎ ◎ ○ ○ ○ ○ ○ △

[Table 6] Conventional type without unevenness FELIX015 Rib spacing / μm Rib spacing / mm 10 20 50 150 300 500 800 800 1 2 3 4 Initial × × △ ○ ○ ○ ○ ○ ○ ○ ○ Temperature gradient × × △ ○ ◎ ◎ ◎ ○ ○ ○ ○ ○ After cooling

According to Table 5, although the optimum rib interval differs depending on the liquid crystal, good alignment in the long axis direction of the liquid crystal was obtained in the range of 20 μm to 3 mm. More preferably, in order to enhance the effect of the temperature gradient cooling, 20 μm to 800 μm
The partition walls may be formed at intervals of. Comparing Tables 5 and 6, even when the same liquid crystal is used, the maximum height of the partition walls at which the effect of the temperature gradient cooling appears is as large as 800 μm, and the unevenness is higher than that of the conventional type. Strengthens the effect of gradient cooling.

[0060]

As described above, according to the present invention, it is possible to remarkably improve the transmissivity of the liquid crystal in the longitudinal direction of the liquid crystal into the liquid crystal panel body, and it is possible to align the liquid crystal by itself. is there. Further, the movement of the liquid crystal molecules accompanying the volume shrinkage when the liquid crystal self-cools is remarkably promoted, and the orientation of the smectic layer is improved. In particular, according to the first and second aspects of the invention, in a smectic liquid crystal having a cholesteric layer, a uniform and highly transparent alignment layer can be formed without using a rubbing method or oblique deposition as a uniaxial alignment treatment. In addition, uniform orientation can be easily formed. Claims 1 to 6
Further, according to the invention of claim 8, even in a smectic liquid crystal having no cholesteric, it is possible to form a smooth alignment layer with few domains having different alignment direction fluctuations. According to the third and fifth aspects of the present invention, the state of the liquid crystal when the liquid crystal permeates can be stored for a long time. In addition, leakage of unnecessary substances from the underlayer to the liquid crystal layer can be prevented. According to the fourth aspect, the stripe-shaped unevenness can be easily formed. According to the invention of claims 6 to 8, a liquid crystal panel frame having excellent impact resistance can be manufactured, a strong temperature gradient can be applied to the liquid crystal held therein, and it cannot be removed by a simple cooling method. Various zigzag defects and linear defects can be finally removed.

[0061]

[Brief description of the drawings]

FIG. 1 is an oblique sectional view of a panel body according to a conventional technique.

FIG. 2 is an explanatory view showing a layer structure change in a panel in a temperature gradient cooling method.

FIG. 3 is an oblique sectional view of the panel body according to the present invention.

FIG. 4 is an explanatory diagram showing types of uneven shapes.

FIG. 5 is a side sectional view of the panel body according to the first embodiment.

FIG. 6 is a side sectional view of a panel body according to the second embodiment.

[Explanation of symbols]

 101 substrate 102 liquid crystal driving electrode 103 alignment film 104 partition member 105 liquid crystal 301 substrate 302 liquid crystal driving electrode 303 unevenness 304 inorganic or organic film 305 partition member 306 liquid crystal 401 triangular shape 402 sinusoidal shape 403 rectangular shape 501 substrate 502 Liquid crystal drive electrode 503 Organic film (with rubbing) 504 Partition member 505 Liquid crystal 506 Unevenness 507 Organic film (rubbingless) 601 Substrate 602 Liquid crystal drive electrode 603 Unevenness 604 Partition member 605 Liquid crystal 606 Alignment film (with rubbing)

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Katsuhiro Suzuki 1-5-1, Taito, Taito-ku, Tokyo Letterpress Printing Co., Ltd.

Claims (8)

[Claims] 1. A liquid crystal panel substrate comprising: stripe-shaped periodic irregularities; and partition walls extending at 20 μm to 3 mm intervals substantially parallel to the direction in which the irregularities extend. 2. The substrate for a liquid crystal panel according to claim 1, wherein the pitch of the periodic unevenness is 10 μm or less, more preferably 3 μm or less, and the amplitude is 1 μm or less. 3. The substrate for a liquid crystal panel according to claim 1, wherein an organic film or an inorganic film is formed on a surface of the upper surface of the unevenness which is in contact with the liquid crystal. . 4. The substrate for a liquid crystal panel according to claim 1, wherein the unevenness is formed on a linear electrode side. 5. The substrate for a liquid crystal panel according to claim 1, wherein the organic film or the inorganic film has a uniaxial orientation. 6. A liquid crystal panel body in which liquid crystal is held between a pair of substrates, wherein at least one of the substrates in contact with the liquid crystal has periodic irregularities in the form of stripes. 20 μm extending almost parallel to the extension direction
A liquid crystal panel body having partition walls at intervals of up to 3 mm. 7. A liquid crystal panel according to claim 6, wherein said pair of substrates are bonded by said partition. 8. The liquid crystal panel according to claim 6, wherein the liquid crystal is a smectic liquid crystal.