JP3010456B2 - Orientation treatment method and orientation treatment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment processing method and an alignment processing apparatus for manufacturing a liquid crystal display device.

[0002]

2. Description of the Related Art In a liquid crystal display device, a transparent electrode layer (hereinafter abbreviated as an ITO layer) generally made of indium / tin oxide is provided on a liquid crystal support plate such as a glass substrate or the like. A rubbing method is used in which a coating film of a molecular resin is provided, and immediately after that, the film is rubbed in a specific direction using a roller around which a buff cloth made of organic fibers is wound. FIG. 3 is a diagram schematically showing an apparatus for performing this alignment treatment.

A conventional rubbing stage 11 is provided in a conventional alignment processing apparatus. On the rubbing stage 11, a glass substrate 12 provided with an orientation film 14 of polyimide or the like and an ITO layer 13 is arranged. afterwards,
A rubbing process is performed by rotating a rubbing roller 15 around which a rubbing cloth 16 made of organic fibers is wound and rubbing the surface of the alignment film 14 while relatively moving the rubbing roller 15 and the rubbing stage 11. By this rubbing treatment, the polymer chains of the alignment film 14 are aligned in a certain direction, and the alignment film 14 having such a completed state enables the liquid crystal molecules to be regularly aligned.

[0004]

However, in the above-described method, the rubbing treatment is required to regularly align the polymer chains of the alignment film 14 by the rubbing treatment.
5 must be rotated at a high speed. For this reason, a large amount of foreign matter or the like is generated at the time of rubbing, or the alignment film 14 or the rubbing cloth 16 is charged. This causes a problem that the display appearance of the liquid crystal display element is impaired and the reliability of the liquid crystal display element is reduced.

The present invention has been made in consideration of the above-described conventional problems, and reduces the generation of foreign substances and the like during the alignment process and the electrification to prevent the display appearance of the liquid crystal display element from being impaired and the reliability from being lowered. It is an object of the present invention to provide an alignment treatment method and an alignment treatment device that can be used.

[0006]

SUMMARY OF THE INVENTION The present invention is an alignment treatment method for an alignment film for a liquid crystal, wherein the alignment treatment is performed while applying ultrasonic vibration to a surface of the alignment film in a direction parallel to the surface.

[0007]

[Function] By applying ultrasonic vibration to the alignment film surface in a direction parallel to the surface, the deformation resistance of the alignment film material itself is reduced, and the alignment film becomes extremely unstable. The polymer chains are easily arranged in a certain direction, so that the effect of the alignment treatment is improved, and the generation of static electricity and foreign substances during the alignment treatment is reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing embodiments thereof.

FIG. 1 is a view showing an orientation processing apparatus according to one embodiment of the present invention. That is, the alignment treatment device includes:
A rubbing stage 21 provided with an ultrasonic vibration device 27 for applying ultrasonic vibration is provided, and a fixing plate 28 is connected to one end of the ultrasonic vibration device 27. On the rubbing stage 21, a glass substrate 22 having a transparent electrode layer (ITO layer) 23 provided with an alignment film 24 made of a coating film of a polymer resin is arranged. One end of the glass substrate 22 is fixed by a fixing plate 28 and the ultrasonic vibration device 2
By actuating 7, ultrasonic waves that vibrate in a direction parallel to the surface of the alignment film 24 can be applied to the alignment film 24. or,
Above the glass substrate 22, a rubbing roller 2 around which a rubbing cloth 26 made of, for example, rayon woven cloth is wound.
5 are arranged. The above-mentioned rubbing stage 21 is a stage means, the ultrasonic vibration device 27 and the fixing plate 28 are ultrasonic vibration means, the rubbing cloth 26 and the rubbing roller 2.
Numerals 5 constitute rubbing means.

In the case where the alignment processing is performed by the alignment processing apparatus configured as described above, first, the glass substrate 22 is placed on the rubbing stage 21 and fixed by the fixing plate 28. Next, the ultrasonic vibration device 27 is operated to propagate the ultrasonic vibration to the glass substrate 22 in the direction of the arrow 29, so that the ultrasonic vibration is given to the alignment film 24 applied to the glass substrate 22, and the alignment process is performed. As a result, the rubbing roller 25 can be easily operated, and a sufficient alignment state can be obtained even if the rotation speed of the rubbing roller 25 is lower than that of the related art.

Hereinafter, the orientation treatment method according to one embodiment of the present invention will be described in detail with specific examples.

Example 1 First, a commercially available polyimide-based alignment film was diluted with a special thinner to prepare a 3.0% by weight solution. Next, this solution was spin-coated at 2300 rpm for 1 minute on a glass substrate on which an ITO electrode pattern had been formed. After application, the coating was dried at 80 ° C. for 15 minutes to evaporate the solvent, and then cured at 250 ° C. for 1 hour to form a polyimide coating film on a glass substrate.

Thereafter, the frequency of 20
While applying ultrasonic vibration to the alignment film by generating ultrasonic vibration of 35 kHz / cm ² in intensity, the surface of the alignment film is rubbed with a rubbing roller around which a woven cloth of rayon is wound. Rubbing treatment was performed four times to complete an alignment film for liquid crystal. The rotation speed of the rubbing roller at this time was 100 rpm, and the amount of charge on the coating film surface during rubbing was measured using a surface potential measuring device. As a result, it was about -80 V at a distance of 1.0 cm from the film surface.

When the surface of the alignment film subjected to the rubbing alignment treatment in this way was observed with a microscope, foreign substances such as shavings of the alignment film were hardly observed. Next, two liquid crystal support plates on which a liquid crystal alignment film of polyimide is formed by such a process are prepared, and as shown in FIG. 2, the alignment film of one of the support plates (for example, the lower liquid crystal support plate 32) is prepared. On the surface on which is formed, a spacer / seal resin 35 having a diameter of 6.0 μm
An acid anhydride-curable epoxy resin in which glass fibers are dispersed is printed with a width of 0.2 mm around the center of one side, leaving a width of 5 mm at the center of only one side, and then the upper liquid crystal support plate 31 and the lower side. The rubbing directions 33 and 34 of the alignment films formed on the liquid crystal support plate 32 were parallel to each other, and the surfaces of the alignment films were opposed to each other. After bonding,
Nematic liquid crystal (Merck, product name Z
LI-2293) was injected, and after the injection, the opening 36 was sealed with a commercially available acid anhydride-curable epoxy resin. After sealing, the liquid crystal was heated to a temperature at which the liquid crystal exhibited isotropic properties, annealed at that temperature for 1 hour, and then gradually cooled to complete a liquid crystal display device. The liquid crystal display device thus completed exhibited a uniform display state with almost no foreign matter.

(Comparative Example 1) First, the same polyimide-based alignment film as in Example 1 was diluted with a special thinner, and then 3.0% by weight.
Was prepared. Next, this solution was applied to a glass substrate on which an ITO electrode pattern was formed by a spinner at 2300 revolutions / hour.
For 1 minute. After application, 15 at 80 ° C
After drying for 5 minutes to evaporate the solvent, the coating was cured at 250 ° C. for 1 hour to form a coating film on a glass substrate.

Thereafter, the surface of the coating film was rubbed four times in the same direction using a rubbing roller around which a woven fabric of rayon was wound, and a rubbing treatment was performed to complete an alignment film for liquid crystal. The rotation speed of the rubbing roller at this time was 100 rpm, and the amount of charge on the coating film surface during rubbing was measured using a surface potential measuring device. As a result, it was about -80 V at a distance of 1.0 cm from the film surface.

When the surface of the alignment film subjected to the rubbing alignment treatment in this way was observed with a microscope, no foreign matter such as shavings of the alignment film was observed. Next, in the liquid crystal display element manufactured by the same operation as in Example 1 using the polyimide liquid crystal alignment film by such treatment, the liquid crystal molecules were not aligned and a uniform display state could not be obtained.

(Comparative Example 2) First, the same polyimide-based alignment film as in Example 1 was diluted with a special thinner, and then 3.0% by weight.
Was prepared. Next, this solution was applied to a glass substrate on which an ITO electrode pattern was formed by a spinner at 2300 revolutions / hour.
For 1 minute. After application, 15 at 80 ° C
After drying for 5 minutes to evaporate the solvent, the coating was cured at 250 ° C. for 1 hour to form a coating film on a glass substrate.

Thereafter, the surface of the coating film was rubbed four times in the same direction using a rubbing roller around which a woven fabric of rayon was wound to complete a rubbing treatment to complete a liquid crystal alignment film. The rotation speed of the rubbing roller at this time was 400 rpm, and the amount of charge on the surface of the coating film during rubbing was measured using a surface potential measuring device. As a result, it was about -600 V at a distance of 1.0 cm from the film surface.

When the surface of the alignment film subjected to the rubbing alignment treatment in this manner was observed with a microscope, many foreign substances were observed. When the foreign substance was identified by measuring the fluorescence spectrum and the infrared absorption spectrum (IR spectrum), it was found that the foreign substance was mainly shavings of polyimide of the alignment film.

Next, in the liquid crystal display device manufactured by the same operation as in Example 1 using the polyimide alignment film for liquid crystal by such treatment, dust such as shavings of polyimide is conspicuous, and the display appearance is impaired. A uniform display state could not be obtained.

In the above embodiment, the propagation direction of the ultrasonic vibration on the alignment film surface was parallel to the rubbing direction.
The direction is not limited as long as it is parallel to the alignment film surface.

[0023]

As is apparent from the above description, the present invention reduces the occurrence of foreign substances and the like and the electrification during the alignment treatment,
The liquid crystal display device has advantages in that the display appearance of the liquid crystal display device can be prevented from being deteriorated and the reliability can be prevented from being lowered.

[Brief description of the drawings]

FIG. 1 is a view showing an alignment processing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a liquid crystal display element manufactured using an alignment film formed of a polymer resin coating film manufactured using the alignment treatment method according to one embodiment of the present invention.

FIG. 3 is a view showing a conventional coating film rubbing process.

[Explanation of symbols]

 11, 21 rubbing stage 12, 22 glass substrate 13, 23 transparent electrode layer 14, 24 alignment film 15, 25 rubbing roller 16, 26 rubbing cloth 27 ultrasonic vibrator 28 fixing plate 29 ultrasonic vibration propagation direction 31 upper liquid crystal support Plate 32 Lower liquid crystal support plate 33 Rubbing direction of upper liquid crystal support plate 34 Rubbing direction of lower liquid crystal support plate 35 Spacer and seal resin 36 Opening

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1337

Claims (2)

(57) [Claims] 1. An alignment treatment method for a liquid crystal alignment film, wherein an alignment process is performed while applying ultrasonic vibration to a surface of the alignment film in a direction parallel to the surface. 2. An alignment processing apparatus for performing alignment processing on an alignment film provided on a substrate, comprising: a stage for attaching and moving the substrate; and a direction parallel to a surface of the alignment film for liquid crystal. A device for applying ultrasonic vibration to the
Rubbing means for rubbing the surface of the liquid crystal alignment film in a predetermined direction.