JPH06118413A - Orientation method for liquid crystal molecule - Google Patents

Abstract

PURPOSE:To prevent the generation of rust and to improve the uniformity of orientation and the yield of the product by applying specified dispersed liq. on the main surface of a base plate to obtain a coating film, evaporating a solvent moderately, after impressing magnetic field, evaporating the solvent completely, then allowing it to contact with a liquid crystal. CONSTITUTION:The dispersed liq. obtained by dispersing the molecule of the material whose molecule orients in the magnetic field and the molecule of the resin consisting of a long chain molecule in the suitable solvent is applied on the main surface of a base plate glass 1 and the coating film 4 is obtained, the solvent is evaporated moderately, magnetic field is impressed, moreover, the solvent is evaporated completely, then, the main surface is allowed to contact with liquid crystal molecule. In such a case, the magnetic field is a magnetostatic field or an alternate magnetic field, the direction of impressing the magnetic field relates to the direction of liquid crystal molecule at the desire interface containing pretilt. Then, when the surface of the resin film 4 is allowed to contact with the liquid crystal molecule, the liquid crystal molecule is affected by the molecule on the surface of the resin film 4 to orient toward desired direction with desired pretilt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for aligning liquid crystal molecules in manufacturing a liquid crystal display device or the like.

[0002]

2. Description of the Related Art In manufacturing a liquid crystal display device, a resin film is rubbed with a fiber such as rayon at a high speed to stretch an organic long chain molecule constituting the resin film, and the resin surface and the liquid crystal molecule are separated from each other. The liquid crystal molecules are aligned by bringing them into contact with each other. The technical contents are detailed in, for example, "Thin Film Handbook", edited by Japan Society for the Promotion of Science, 131st Committee, published by Ohmsha.

[0003]

The conventional rubbing technique has the following problems.

In the first place, the liquid crystal panel manufacturing process dislikes dust, and is therefore performed in a dust-free chamber. But,
The fibers used in the rubbing process are highly likely to generate dust, and it is basically inconvenient to bring them into a dust-free chamber. Dust and debris is caused by fiber scraps, resin film shavings,
It is abrasion and debris of machine parts due to high-speed motion of the machine, which naturally causes a reduction in product yield.

In order to prevent this situation, the substrate is cleaned after the so-called rubbing operation, but the cleaning process is very delicate and the controllability is poor.

Further, in such a rubbing operation, it is difficult to stretch the organic long chain molecules constituting the uniform resin film,
As a result, uniform display may be difficult.

Further, in the recent liquid crystal display device, when the liquid crystal molecules are aligned at the liquid crystal-substrate interface, the angle between the longitudinal direction of the liquid crystal molecules and the substrate (so-called pretilt angle) is about 5 ° or more. The in-plane uniformity of this corner is important. This pretilt angle slightly changes due to local variations in the rubbing strength, and this is reflected in the display. Also,
It is necessary to change the structure of molecules forming the resin film depending on the desired pretilt range. Further, ensuring the uniformity and reproducibility of pretilt of about 10 ° or more has not been successful as an industry.

Further, since the rubbing operation is high-speed friction, the adhesive force of the resin film to the substrate is important. In order to secure this, it is general to introduce a silane coupler or the like into the resin film. However, this silane coupler tends to adsorb liquid crystal molecules and impurity molecules in the liquid crystal, thus making the display dirty.

An object of the present invention is to provide a liquid crystal molecule alignment method that does not have many problems, taking into consideration the problems of the conventional liquid crystal molecule alignment method by the rubbing method.

[0010]

According to the present invention, a material in which molecules can be oriented in a magnetic field and a resin consisting of long-chain molecules are dispersed in a suitable solvent to obtain a dispersion liquid, and the main surface of a substrate is obtained. A liquid crystal molecule alignment method in which this dispersion is applied to obtain a coating film, the solvent is appropriately evaporated, a magnetic field is applied, the solvent is completely evaporated, and then the liquid crystal molecules are contacted It is provided.

At this time, the magnetic field is a static magnetic field or an alternating magnetic field in a fixed direction, and the direction of magnetic field application is related to the direction of liquid crystal molecules at a desired interface including pretilt.

When applying this magnetic field, it is desirable to slightly heat the substrate.

Further, according to the present invention, a volatile material and long-chain molecules in which molecules can be oriented in a magnetic field are dispersed in an appropriate solvent to obtain a dispersion liquid, and the dispersion liquid is obtained on the main surface of the substrate. This dispersion is applied to obtain a coating film, and the solvent is appropriately evaporated,
Then, a magnetic field is applied to further evaporate the solvent and volatilize the volatile material completely, and then bring the liquid crystal molecule into contact with the liquid crystal molecule.

At this time, the magnetic field is a static magnetic field or an alternating magnetic field in a fixed direction, and the direction of magnetic field application is related to the direction of liquid crystal molecules at a desired interface including pretilt.

When applying the magnetic field, it is desirable to slightly heat the substrate.

[0016]

In order to solve the above-mentioned problems, the present invention disperses in a suitable solvent the molecules of a material whose molecules can be oriented in a magnetic field and the molecules of a resin consisting of long chain molecules. A dispersion liquid is obtained by applying the dispersion liquid on the main surface of the substrate glass to obtain a coating film, the solvent is appropriately evaporated, and then a magnetic field is applied to further evaporate the solvent completely. The present invention provides a method for aligning liquid crystal molecules in which the main surface is brought into contact with liquid crystal molecules.

At this time, the magnetic field is a static magnetic field or an alternating magnetic field in a fixed direction, and the direction of magnetic field application is related to the direction of liquid crystal molecules at a desired interface including pretilt.

When applying this magnetic field, the substrate is slightly heated,
It is desirable to make the molecules in the coating film move easily.

In the present invention, in the coating film, first, material molecules whose molecules can be oriented in a magnetic field and a resin composed of long chain molecules are made to coexist. At this time, the solvent component is allowed to remain in a slight amount to ensure the easiness of movement of the material molecule and the long chain molecule.

Next, a unidirectional magnetic field is applied to orient the material molecules in which the molecules in the coating film can be oriented by the magnetic field. The order in the coating film also affects the order of the long-chain molecules, and the long-chain molecules also line up. After achieving this state, the residual solvent component is evaporated.

Thus, when the surface of the resin film comes into contact with the liquid crystal molecules, the liquid crystal molecules are influenced by the molecules on the surface of the resin film and are oriented in a desired direction with a desired pretilt.

A material whose molecules can be oriented in a magnetic field,
That is, as a material sensitive to a magnetic field, for example, a material containing a benzene ring rich in π electrons as a structure can be considered.

Further, according to the present invention, it is well known that the obliquely vapor-deposited film of silicon monoxide (which is capable of uniformly aligning liquid crystal molecules is used. No.) to obtain a membrane similar to the above. This will be described below.

That is, in the present invention, a volatile material in which molecules can be oriented in a magnetic field and a resin composed of long-chain molecules are dispersed in an appropriate solvent to obtain a dispersion liquid, This dispersion is applied on the main surface to obtain a coating film, the solvent is appropriately evaporated, and then a magnetic field is applied to further evaporate the solvent completely and volatilize the volatile material. In addition, a method for aligning liquid crystal molecules in which this main surface is brought into contact with liquid crystal molecules is also provided.

When applying this magnetic field, the substrate is slightly heated,
It is desirable to make the molecules in the coating film move easily. Next, a unidirectional magnetic field is applied to orient the material molecules in which the molecules in the coating film can be oriented by the magnetic field. The order in the coating film also affects the order of the long-chain molecules, and the long-chain molecules also line up. At this time, there is a tendency that the material molecules whose molecules can be oriented by the magnetic field and the long-chain molecules tend to be phase-separated. This is estimated by observation with a scanning tunneling microscope or a scanning electron microscope.

Next, volatile material molecules whose molecules can be oriented in a magnetic field are also volatilized. Observation of the surface of the resin film produced revealed that the surface was highly uneven, and the pore-like structure was statistically oriented in a certain direction related to the direction of the applied magnetic field. This situation was similar to the oblique deposition film of silicon monoxide.

When the surface of the resin film comes into contact with the liquid crystal molecules as described above, the liquid crystal molecules are oriented in a desired direction with a desired pretilt.

[0028]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view for explaining a liquid crystal molecule alignment method according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a glass substrate, on which a transparent electrode (ITO electrode) 2 is formed, which is further covered with a top coat 3 made of silicon dioxide, and a resin film 4 is formed thereon. In addition, 5 is a plate with a heater, 6 is warm air, 7 is an electromagnet shown schematically, and 8 is a plate with a heater.

Next, the actual manufacturing process will be described.

A Corning # 7059 glass substrate 1 was obtained. The ITO film 2 is attached to this, and further,
The ITO film 2 was finely processed by corrosion using a commercially available salt iron solution by a known photolithography method. Next, the organic silicon compound was printed and thermally decomposed to form the top coat 3.

An ethanol solution of anthracene was prepared. In addition, JIB-1, a solution of an alicyclic polyimide in a γ-butyl lactone solvent, was manufactured by Nippon Synthetic Rubber Co., Ltd.
Obtained from. Finally, the anthracene solid content is about 0.8% with respect to the total amount of the solution, the alicyclic polyimide solid content is about 3.5 w%, the solvent is a mixed solvent of ethanol and γ-butyl lactone solvent, A coating liquid was obtained.

This coating solution was applied onto the top coat 3 with a spinner to obtain a substrate as shown in FIG.

Next, the substrate was brought into close contact with the heater-equipped plate 5 set at about 70 ° C., and the solvent was considerably evaporated to obtain a substrate as shown in FIG. 1 (b).

Further, the substrate was exposed to warm air 6 at about 45 ° C., and the substrate was exposed to a static magnetic field of about 60 kGauss by the electromagnet 7. The direction of the lines of magnetic force was controlled so as to be a desired direction with respect to the substrate (FIG. 1 (c)).

Next, the substrate was kept at about 150 ° C. (see FIG. 1).
(D)).

When the surface of this substrate was observed with a scanning atomic force microscope, the surface irregularities were observed to be related to the direction of the magnetic field application. Anthracene was not observed to be volatile.

Two such substrates were attached so that the ITO films 2 face each other and the gap was 7.1 μm, and the gap was filled with the nematic liquid crystal composition for STN. Furthermore, a retardation plate and a polarizing plate were provided to complete the liquid crystal display panel. When the alignment of the liquid crystal was observed, it was judged that the desired pretilt was realized. The contrast is improved by about 50%. The yield has also improved by several tens of percent. Above all, no foreign matter was mixed into the panel. The uniformity of display is also greatly improved.

Next, a surface-stabilized ferroelectric liquid crystal panel was prepared. Two such substrates were bonded so that the ITO films 2 face each other and the gap was 1.5 μm, and the gap was filled with a chiral smectic C phase liquid crystal composition. Further, a polarizing plate was provided to make a liquid crystal display panel. Uniform orientation is obtained, and zigzag defects are also
It was small and practically acceptable. The yield is also
It improved by several tens of percent. Above all, no foreign matter was mixed into the panel.

Example 2 A # 7059 glass substrate 1 manufactured by Corning Inc. was obtained. The ITO film 2 is attached to this, and further by a known photolithography method,
The ITO film 2 was finely processed by corrosion with a commercially available salt iron solution. Next, the organosilicon compound is printed and pyrolyzed,
Topcoat 3 was formed.

Further, an ethanol solution of naphthalene was prepared. A solution of alicyclic polyimide in a γ-butyl lactone solvent, JIB-1, was obtained from Nippon Synthetic Rubber Co., Ltd. Finally, the naphthalene solid content is about 0.5 w% with respect to the total amount of the solution, the alicyclic polyimide solid content is about 3.5 w%, and the solvent is a mixed solvent of ethanol and γ-butyl lactone-based solvent, A coating liquid was obtained.

This coating solution was applied onto the top coat 3 with a spinner to obtain a substrate as shown in FIG.

Next, the substrate was brought into close contact with the plate 5 set at about 50 ° C., and the solvent was considerably evaporated to obtain a substrate as shown in FIG. 1 (b).

Further, the substrate was exposed to warm air 6 so that the temperature became about 45 ° C., and the substrate was exposed to a static magnetic field of about 60 kGauss by the transfer magnet 7. The direction of the lines of magnetic force was controlled so as to be a desired direction with respect to the substrate (FIG. 1 (c)).

Next, the substrate was kept at about 85 ° C. for about 2 hours. This temperature is a sufficient temperature for the naphthalene to volatilize (FIG. 1 (d)).

Next, the substrate was kept at about 150 ° C. (also, FIG. 1D).

When the surface of this substrate was observed with a scanning atomic force microscope, the surface irregularities were observed to be related to the direction of the magnetic field application. Further, the surface was considerably uneven, and naphthalene seemed to be volatilized.

Two such substrates were bonded together so that the ITO films 2 face each other so that the gap was 7.1 μm, and the gap was filled with the nematic liquid crystal composition for STN. Further, a retardation plate and a polarizing plate were provided in a known manner to obtain a liquid crystal display panel. The contrast is improved by about 50%. The yield has also improved by several tens of percent. Above all,
No foreign matter was mixed into the panel. The uniformity of display is also greatly improved.

Next, a surface-stabilized ferroelectric liquid crystal panel was prepared. Two such substrates were bonded so that the ITO films 2 face each other and the gap was 1.5 μm, and the gap was filled with a chiral smectic C phase liquid crystal composition. Further, a polarizing plate was provided to make a liquid crystal display panel. Uniform orientation is obtained, and zigzag defects are also
It was small and practically acceptable. The yield is also
It improved by several tens of percent. Above all, no foreign matter was mixed into the panel.

The molecules can be oriented by a magnetic field,
In addition, as the volatile material, naphthalene or anthracene was used in the above embodiment, but other materials may be used.

Further, as the resin composed of long-chain molecules, in the above-mentioned embodiment, a resin made of Japan Synthetic Rubber, a polyimide resin, JIB is used.
It was a series, but other materials are acceptable.

Further, a solvent evaporation method, a magnetic field application method,
The heating method and the like are not limited to the method of the above embodiment.

Further, the formation of the dispersion liquid is performed in the above-mentioned embodiment.
Although it depends on the coating method, other methods are also possible.

[0054]

As is apparent from the above description,
In the present invention, the generation of dust is eliminated in principle, and the yield of products can be improved.

Further, in this manufacturing process, there is almost no dust generation from the substrate, so that there is an advantage that the substrate cleaning after the alignment treatment is not necessary. Therefore, there is an advantage that this delicate cleaning step can be omitted.

Further, in principle, the present invention can improve the uniformity as compared with the conventional rubbing method.

The pretilt control method is simpler than the conventional method. Excellent uniformity. In order to realize a pretilt of about 10 ° or more uniformly and with good reproducibility,
There is no obstacle.

Further, the adhesion of the resin film to the substrate is not required as in the conventional case. Therefore, there is no need for a silane coupler or the like. This situation results in improved image quality.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a liquid crystal molecule alignment method according to an embodiment of the present invention.

[Explanation of symbols]

 1 Glass Substrate 2 Transparent Electrode (ITO Electrode) 3 2 Top Coat Made of Silicon Oxide 4 Resin Film 5 Plate with Heater 6 Hot Air 7 Electromagnetic Schematically 8 Plate with Heater

Claims (4)

[Claims] 1. A step of dispersing a material whose molecules can be oriented in a magnetic field and a resin composed of long-chain molecules in a predetermined solvent to obtain a dispersion, and a film of the dispersion on the main surface of a substrate. And a step of appropriately evaporating the solvent,
A method for aligning liquid crystal molecules, which comprises contacting liquid crystal molecules with a liquid crystal substrate manufactured by using a step of applying a magnetic field and a step of completely evaporating the solvent. 2. A step of dispersing a material in which molecules can be oriented in a magnetic field and long-chain molecules in a predetermined solvent to obtain a dispersion, and forming a film of the dispersion on the main surface of a substrate. Contacting a liquid crystal substrate with a liquid crystal substrate manufactured by using a step, a step of appropriately evaporating the solvent, a step of applying a magnetic field while heating the substrate, and a step of completely evaporating the solvent. A liquid crystal molecular alignment method characterized by: 3. A step of dispersing a volatile material in which molecules can be oriented in a magnetic field and a volatile material and a long-chain molecule in a suitable solvent to obtain a dispersion, and the dispersion on the main surface of the substrate. Utilizing the steps of forming a liquid film, appropriately evaporating the solvent, applying a magnetic field, and completely evaporating the solvent and completely volatilizing a volatile material. A method for aligning liquid crystal molecules, which comprises contacting the manufactured liquid crystal substrate with liquid crystal molecules. 4. A step of dispersing a volatile material in which molecules can be oriented in a magnetic field and a resin composed of long-chain molecules in a suitable solvent to obtain a dispersion, and on the main surface of the substrate. A step of forming a film of the dispersion liquid, a step of appropriately evaporating the solvent, a step of applying a magnetic field while heating so that the volatile material is not substantially volatilized, and the solvent completely. A method for aligning liquid crystal molecules, which comprises contacting a liquid crystal substrate manufactured by utilizing a step of evaporating and completely volatilizing a volatile material.