JPH05100233A - Sealant printing method for liquid crystal panel - Google Patents

Abstract

PURPOSE:To prevent a contrast irregularity from being generated by selecting the advance direction of a squeeze and controlling the orientation control force of the squeeze in the rubbing direction of an oriented film. CONSTITUTION:On a printer 10, a screen 1 is arranged on a glass substrate 5 mounted on a stage 11, a sealant is placed thereupon, and the squeeze 4 while pressed against a glass substrate 5 is moved on the screen 1 in one direction to print the sealant in the sealing area of the outer edge part of the glass substrate 5 through meshes of the screen 1 where resin is previously removed. Namely, the advance direction of the squeeze 4 can freely be adjusted within a 180 deg. angle range. Consequently, the advance direction angle of the squeeze 4 is properly selected for the rubbing direction of the oriented film on the glass substrate 5 and the squeeze 4 is advanced in the direction to print the sealant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for printing a sealant for laminating liquid crystal panels.

[0002]

2. Description of the Related Art In a liquid crystal panel manufacturing process, transparent conductive films are generally deposited on opposite surfaces of two glass substrates,
Patterning is applied, and a resin to be an alignment film is applied on top of this, and the resin is subjected to an alignment treatment by rubbing to form an alignment film, which becomes a liquid crystal injection port in the peripheral portion of the facing surface of these glass substrates. Printing the sealant leaving a part,
Disperse the granular spacers on the inner surface that will be the display area, attach the two glass substrates with the sealant printing surfaces facing each other, pressurize, and inject the liquid crystal from the liquid crystal injection port, then the injection port. Is closed and the manufacturing is finished.

Of these steps, the method of printing the sealant is screen printing. In the case of screen printing, a screen is used as a plate. As shown in FIG. 7, a sealant 3 is placed on a screen 1 stretched on a frame 2 and a squeegee 4 made of urethane or the like is placed on the screen 1 in one direction. By advancing the screen 1, the screen 1 is pressed onto the glass substrate 5, and the sealing agent 3 is permeated through the mesh 1a at the outer edge portion of the screen 1 where the resin component has been removed in advance to seal the sealing area 20 of the glass substrate 5. Then, the sealant 3 is printed.

FIG. 8 is an enlarged perspective view showing a part of the screen. Although the screen 1 is entirely resin-treated for water repellency, the seal area 20 of the glass substrate 5 is used.
The resin component is removed from the predetermined area corresponding to, and the sealant is allowed to penetrate.

When printing the sealant 3, FIG.
As shown in the partially enlarged view of FIG. 3, the screen 1 is inevitably in contact with the display area 21 formed in the central portion of the glass substrate 5 with the mesh convex portion 6 thereof.

Prior to the printing of the sealant 3, an orientation film 7 having a directionality is formed on the glass substrate 5 by rubbing. A squeegee 4 advances to the alignment film 7 via the screen 1, and a load is applied to the alignment film 7 by the progress, and the orientation of the alignment film surface changes. Reference numeral 5a in FIG. 9 indicates a conductive film.

FIG. 10 is a plan view when the alignment film 7 in the display area 21 of the liquid crystal panel is polarized and observed under magnification with a microscope. In FIG. 10, a portion 8 of the alignment film 7 in contact with the mesh convex portion 6 and a portion not in contact (normal portion) 9 appear as a light and shade difference (hereinafter referred to as damage). This damage may appear lighter or darker than the normal portion 9 in the portion 8 in contact with the mesh convex portion 6.

[0008]

The directionality of the alignment film 7 given by the rubbing changes depending on the moving direction of the squeegee 4, but according to the conventional method, the moving direction of the squeegee 4 is constant. Since it is only limited to the direction, it necessarily goes through only one defined change.

On the other hand, the alignment film 7 is formed through the screen 1.
The squeegee 4 that comes into contact with the squeegee has irregularities on the contact surface due to uneven polishing during manufacture and friction with the screen 1 during use.
Due to the unevenness, pressure unevenness occurs on the alignment film 7 on the glass substrate 5 when it comes into contact with the glass substrate 5, resulting in a partial difference in the damage. If this difference in partial damage is large, the liquid crystal panel becomes a defective product when the liquid crystal panel is turned on, which causes uneven contrast in the display area 21.

Although it has been substantially clarified that the direction in which the squeegee travels influences the rubbing direction as a cause of the damage, it has been reluctant to take measures against it.

Therefore, an object of the present invention is to provide a method for printing a sealant for a liquid crystal panel, which is capable of freely changing the advancing direction of a squeegee in order to prevent damage to the glass substrate which causes uneven contrast of the liquid crystal panel. That is.

[0012]

In order to achieve the above object, the present invention provides a sealant printing method for a liquid crystal panel in which a squeegee is advanced to print a sealant placed on the screen through a screen onto a glass substrate. In the method, the advancing direction of the squeegee is selected by using a printing machine capable of adjusting the advancing direction of the squeegee within a range of 180 degrees around an axis, and the alignment regulating force of the squeegee with respect to the rubbing direction of the alignment film is controlled. A method for printing a sealant for a liquid crystal panel, which is characterized by the above.

[0013]

According to the present invention, the advancing direction of the squeegee is selected at an appropriate angle within the range of 180 degrees around the axis of the printing machine,
By controlling the alignment regulation force of the alignment film with respect to the rubbing direction by the squeegee, damage to the glass substrate is eliminated and uneven contrast in the liquid crystal panel is prevented.

[0014]

EXAMPLE As described above, the inventor of the present application arbitrarily sets the squeegee advancing direction based on the fact that the orientation of the alignment film 7 given by rubbing changes in correlation with the moving direction of the squeegee 4. The present invention has been achieved by focusing on the fact that the unevenness of contrast of the liquid crystal panel can be reduced by selecting the squeegee in the advancing direction of the squeegee which has the least damage to the orientation of the alignment film by the convex portions of the screen.

Therefore, the sealant printing method according to the present invention selects the advancing direction of the squeegee by using a printing machine capable of adjusting the advancing direction of the squeegee within an angle range of 180 degrees, and uses the squeegee with respect to the rubbing direction of the alignment film. It is to control the orientation regulating force.

The printing machine and its squeegee advancing direction selecting means used in the present invention are shown in the front view of FIG. 1, the perspective view of FIG. 2, the plan view of FIG. 3 and the front view of FIG.

In these figures, the structure is similar to that shown in the prior art, and corresponding parts are designated by the same reference numerals.

In the printing machine 10 according to the present invention, a screen 1 is placed on a glass substrate 5 placed on a stage 11, a sealant 3 is placed on the screen 1, and a glass squeegee 4 is placed on the screen 1. The squeegee 4 is moved in one direction while being pressed against the substrate 5, and the sealant 3 is printed on the seal area 20 at the outer edge of the glass substrate 5 through the mesh 1a in the portion of the screen 1 where the resin content has been removed in advance. To be done.

That is, the traveling direction of the squeegee 4 can be freely adjusted within an angle range of 180 degrees. As a result, the squeegee advancing direction angle is appropriately selected with respect to the rubbing direction of the alignment film 7 on the glass substrate 5, and the squeegee 4 is advanced in that direction (arrow A direction in FIG. 4) to print the sealant 3. I do.

The screen 1 is mounted on the frame 2 incorporated in the stage 11 and fixed corresponding to the glass substrate 5.

As shown in FIGS. 1 and 2, the printing machine 10 according to the invention of the present application includes an annular turn block 13 which is rotatable 180 degrees around a central axis on an annular turn rail 12 and a turn block 13. It has two rod-shaped slide rails 14 supported in parallel, and a printer main body 15 supported by the slide rails 14 and slidable in the longitudinal direction of the slide rails 14.

The turn block 13 is rotated by a rotating roller 13a attached to the lower portion of the turn block 13.
It rotates on 2, but can also be fixed in place.

The printer body 15 is long in the direction orthogonal to the sliding rails 14, has leg portions 16 at both ends, and is slidably inserted by the two sliding rails 14. The printing machine body 15 is provided with a squeegee 4 that is sandwiched by a squeegee holder 17 that is hung vertically from the printing machine body 15, and a piston cylinder mechanism 18 that raises and lowers the squeegee 4 and regulates the vertical position. The squeegee 4 moves forward and backward as the printer body 15 moves forward and backward.

A drive roller 16a is installed below the leg portion 16 of the printer body 15, and each leg portion 16 is rotated on the turn rail 12 via the drive roller 16 when the turn block 13 is rotated. Although it moves, it moves in a linear direction when the sealant 3 is printed.

The squeegee 4 is made of urethane and preferably has a Shore hardness of about 80 °. The squeegee 4 has unevenness on the tip surface due to uneven polishing during manufacture and sliding contact with the screen 1 during use.

When the sealant 3 is printed by using the squeegee 4 having such unevenness, uneven pressure is generated on the glass substrate 5, and as a result, a partial difference occurs in the damage. When a partial difference in damage occurs, if the difference is large, unevenness in contrast appears on the display area when the liquid crystal panel is turned on, and the liquid crystal panel becomes a defective product. Regarding this phenomenon, the following (5) item shows the experimental result for each angle α formed by the straight line P and the straight line Q by variously changing the squeegee traveling direction Q with respect to the rubbing direction P in FIG. .. However, the panels and squeegees used in the experiment are according to the items (1) to (3).

(1) The panel used has a display screen of 640.times.480 dots, and 1 / 240D (duty) drive (480 segments of common pattern are divided into two segments for drive) is applied. CO. The ratio (contrast ratio between display ON and OFF) is 20: 1, and the cell thickness is 7.
It is set to 5 μm.

(2) The concave shape of the used squeegee has a width of 50
It is 0 μm × depth 200 μm (see FIG. 6).

(3) The screen used is made of polyester and has a thickness of 70 μm. (4) The number of panels to be evaluated is 50.

(5) Experimental results are shown in Table 1 below.

[0031]

[Table 1]

According to the result of this experiment, the damage is the angle α.
The value changed from light to dark as the value of decreased, and good results were obtained when the contrast unevenness was greater than 90 degrees. Based on this result, the squeegee advancing direction Q should be selected as the angle α with which the damage is smallest and the contrast unevenness occurrence rate is low with respect to the rubbing direction P, that is, the directionality of the liquid crystal molecules formed on the alignment film 7. Is desirable.

According to the present invention, the printing machine 10 can be rotated around its central axis to select the proper traveling direction of the squeegee 4.

The squeegee advancing direction selecting means is not only a mechanism in which the turn block 13 rotates on the turn rail 12 described above, but also another mechanism if the sliding rail 14 in the printing machine 10 is rotatable within an angle range of 180 degrees. It may be one.

The main body 15 of the printing press may have a structure in which the leg portions 16 slide directly on the turn rails 12 or a structure in which the leg portions 16 do not have the leg portions and therefore do not come into contact with the turn rails 12.

[0036]

According to the method of printing a sealant for a liquid crystal panel of the present invention, a squeegee advancing direction is selected by using a printing machine that can be adjusted within a range of 180 degrees around a central axis, and the squeegee with respect to the rubbing direction of the alignment film is selected. Controls the alignment control force by. According to this method, the squeegee advancing direction is arbitrarily selected, and the unevenness in contrast of the alignment film due to the contact of the convex portions of the mesh of the screen, which occurs at the time of printing the sealant, is minimized, so that the unevenness of contrast in the liquid crystal panel is prevented. It does not occur and promotes quality improvement.

[Brief description of drawings]

FIG. 1 is a front view of a printing machine provided with a squeegee rotating means according to the present invention.

FIG. 2 is a partially enlarged perspective view of FIG.

FIG. 3 is a plan view showing a part of FIG.

FIG. 4 is a front view of FIG.

FIG. 5 is an explanatory diagram of a relationship between a rubbing direction and a squeegee advancing direction.

FIG. 6 is a partially enlarged perspective view of a squeegee.

FIG. 7 is a cross-sectional view showing an operating mode of screen printing.

FIG. 8 is a partially enlarged perspective view of the screen.

FIG. 9 is a cross-sectional view showing a contact state between a glass substrate and a screen.

FIG. 10 is a partial plan view of a liquid crystal panel by a microscope under polarized light.

[Explanation of symbols]

 1 Screen 3 Sealant 4 Squeegee 5 Glass Substrate 7 Alignment Film 10 Printing Machine 14 Sliding Rail 15 Printer Main Body 18 Piston Cylinder Mechanism 20 Sealing Area 21 Display Area

Claims (1)

[Claims] 1. A method for printing a sealant for a liquid crystal panel, which comprises advancing a squeegee and printing a sealant placed on the screen through a screen onto a glass substrate, wherein the squeegee travels in an axial direction of 180 degrees. A method for printing a sealant for a liquid crystal panel, which comprises controlling the alignment regulating force of the squeegee with respect to the rubbing direction of the alignment film by selecting the advancing direction of the squeegee using a printing machine that can be adjusted within a range of degrees.