JP2774714B2 - Liquid crystal panel manufacturing method and sealant printing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal panel and a printing apparatus for a sealant for a liquid crystal panel.

[0002]

2. Description of the Related Art In general, in a liquid crystal panel manufacturing process, a transparent conductive film is deposited on opposing surfaces of two glass substrates, respectively.
Patterning is performed, and a resin serving as an alignment film is applied thereon. This resin is subjected to an alignment process by rubbing to form an alignment film, and a liquid crystal injection port is formed on a peripheral portion of the facing surface of these glass substrates. Print sealant leaving a part,
Spraying granular spacers on the inner surface that will be the display area, bonding two glass substrates together with the sealant printing surfaces facing each other, applying pressure, injecting liquid crystal from the liquid crystal inlet, To end production.

[0003] Among these steps, a method for printing a sealant is based on screen printing. In the case of screen printing, a screen is used as a plate, and a sealant 3 is placed on a screen 1 stretched over a frame 2 as shown in FIG. 7, and a squeegee 4 made of urethane or the like is placed on the screen 1 in one direction. By proceeding, the screen 1 is pressed on the glass substrate 5, and the sealing agent 3 penetrates through the mesh 1 a of the portion where the resin has been removed in advance at the outer edge of the screen 1, and the sealing area 20 of the glass substrate 5 The sealant 3 is printed.

FIG. 8 is an enlarged perspective view showing a part of the screen. The screen 1 is entirely treated with a resin for water repellency.
Is removed from the predetermined area corresponding to, and the sealant can be penetrated.

When printing the sealant 3, FIG.
As shown in the partial enlarged view, the screen 1 keeps the mesh projection 6 in contact with the display area 21 formed in the center of the glass substrate 5.

Prior to the printing of the sealant 3, an orientation film 7 having a direction is formed on the glass substrate 5 by rubbing. The squeegee 4 advances to the alignment film 7 via the screen 1, and a load is applied to the alignment film 7 by the advance, thereby causing a change in the directionality of the alignment film surface. Note that 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 a microscope. In FIG. 10, a portion 8 where the mesh convex portion 6 is in contact with the alignment film 7 and a portion (normal portion) 9 where the mesh convex portion 6 is not in contact with the alignment film 7 appear as a difference in density (hereinafter referred to as damage). This damage may occur when the portion 8 in contact with the mesh convex portion 6 appears lighter than when it comes to the normal portion 9 or when it appears darker.

[0008]

The directionality of the alignment film 7 given by the rubbing varies depending on the moving direction of the squeegee 4, but according to the conventional method, the moving direction of the squeegee 4 is constant. Because it is limited only in the direction, it necessarily ends up with only one defined change.

On the other hand, the orientation film 7
The squeegee 4 that comes into contact with the surface of the squeegee has irregularities in the contact surface due to uneven polishing during manufacture and friction with the screen 1 during use.
Due to the unevenness, when the glass substrate 5 comes into contact with the glass substrate 5, uneven pressure is applied to the alignment film 7 on the substrate. As a result, there is a partial difference in the damage. If the difference between the partial damages is large, when the liquid crystal panel is turned on, contrast unevenness appears in the display area 21, and the liquid crystal panel becomes a defective product.

Although it has been practically clarified that the squeegee advancing direction has an effect on the rubbing direction as a cause of the above-mentioned damage, it has heretofore been reluctant to take countermeasures.

Accordingly, an object of the present invention is to freely change the angle between the rubbing direction of the alignment film and the squeegee advancing direction in order to prevent damage to the alignment film which causes uneven contrast of the liquid crystal panel. An object of the present invention is to provide a liquid crystal panel manufacturing method and a liquid crystal panel sealant printing apparatus.

[0012]

According to the present invention, in order to achieve the above object, a squeegee is advanced and a sealant placed on the screen is printed on a glass substrate on which an alignment film is formed via a screen. In the method for manufacturing a liquid crystal panel, an angle between a rubbing direction of the alignment film and a traveling direction of the squeegee is controlled so that damage to the alignment film is reduced. . The present invention also provides a sealant printing apparatus for a liquid crystal panel, in which a squeegee is advanced and a sealant placed on the screen is printed on a glass substrate on which an alignment film is formed through a screen. An apparatus for printing a sealant for a liquid crystal panel, comprising: means for controlling an angle between a direction and a traveling direction of the squeegee so that damage to the alignment film is reduced.

[0013]

According to the present invention, the angle α between the rubbing direction of the alignment film formed on the glass substrate and the squeegee advancing direction.
Is controlled so that the damage, which is the difference in shading of the sealant, between the part where the mesh convex part of the screen is in contact and the part where it does not contact is minimized, thereby solving the uneven contrast of the liquid crystal panel and improving the quality of the liquid crystal panel. Can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the inventor of the present application has determined that the orientation of the alignment film 7 given by rubbing changes in a direction dependent on the moving direction of the squeegee 4. The present invention has been achieved by focusing on the fact that the contrast unevenness of the liquid crystal panel can be reduced by setting the squeegee advancing direction that causes the least damage to the orientation of the alignment film by the mesh convex portion of the screen.

Therefore, the sealant printing method of the present invention uses a printing machine capable of adjusting the advancing direction of the squeegee around a vertical axis 22 perpendicular to the advancing direction within an angle range of 180 degrees. And controlling the alignment regulating force by the squeegee in the rubbing direction of the alignment film.

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

In these figures, the configuration is similar to that of the prior art, and the corresponding parts are denoted by the same reference numerals.

In a printing press 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 thereon, and a squeegee 4 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 1 a of the screen 1 from which the resin has been removed in advance. Is done.

That is, the traveling direction of the squeegee 4 is freely adjustable within a range of 180 degrees around the vertical axis 22. Thereby, the squeegee advancing direction angle is appropriately selected with respect to the rubbing direction to the alignment film 7 on the glass substrate 5, the squeegee 4 is advanced in that direction (the direction of the arrow A in FIG. 4), and the sealant 3 is printed. 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 press 10 according to the present invention has an annular turn block 13 that is rotatable 180 degrees around a vertical axis 22 that is a central axis on an annular turn rail 12. And two rod-shaped sliding rails 14 supported in parallel with the turn block 13, and a printing press main body 15 supported by the sliding rails 14 and slidable in the longitudinal direction of the sliding rails 14. . The direction in which the slide rail 14 extends, which is the direction in which the squeegee 4 advances, is perpendicular to the vertical axis 22.

The turn block 13 is turned by the rotation of a rotating roller 13a attached to its lower part.
2, but can also be fixed in place.

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

A drive roller 16a is provided below the leg 16 of the printer body 15, and each leg 16 rotates on the turn rail 12 via the drive roller 16 when the turn block 13 rotates. It moves, but moves in a linear direction when the sealant 3 is printed.

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

When the sealant 3 is printed using the squeegee 4 having such irregularities, pressure unevenness is generated on the glass substrate 5, and as a result, a partial difference occurs in the damage. When a partial difference occurs in the damage, if the difference is large, the contrast in the display area appears when the liquid crystal panel is turned on, and the liquid crystal panel becomes defective. Regarding this phenomenon, the squeegee advancing direction Q (that is, the arrow A direction in FIG. 4) with respect to the rubbing direction P in FIG.
Are varied to obtain these straight lines P and Q
The experimental results for each angle α formed by are shown in the following section (5). However, the panels and squeegees used in the experiment are in accordance with the items (1) to (3).

(1) The panel to be used is provided with a display screen of 640 × 480 dots, and employs 1 / 240D (duty) drive (segment is divided into two for 480 common patterns). 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 × 200 μm deep (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) The experimental results are shown in Table 1 below.

[0031]

[Table 1]

According to the results of this experiment, the damage was the angle α
Changed from light to dark as the value of became smaller, and good results were obtained when the contrast unevenness was larger than 90 degrees. Inferring from these results, the squeegee advancing direction Q is set to the angle α at which the damage is the smallest and the contrast unevenness 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 about its central axis to select an appropriate traveling direction of the squeegee 4.

The squeegee advancing direction selecting means is not limited to the above-described mechanism in which the turn block 13 rotates on the turn rail 12, and other mechanisms provided that the sliding rail 14 in the printing press 10 can rotate within an angle range of 180 degrees. It may be.

The printing press body 15 may have a structure in which the leg 16 slides directly on the turn rail 12, or a structure in which the leg 16 does not have the leg and therefore does not contact the turn rail 12.

[0036]

According to the liquid crystal panel manufacturing method and the sealant printing apparatus of the present invention, the angle α between the rubbing direction of the alignment film formed on the glass substrate and the squeegee advancing direction.
Is controlled so that the damage, which is the difference in the shade of the sealant, between the portion where the mesh convex portion of the screen is in contact and the portion where it is not in contact is reduced, so that there is no contrast unevenness in the liquid crystal panel and the quality is improved. Promoted.

[Brief description of the drawings]

FIG. 1 is a front view of a printing press provided with a squeegee rotating unit 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. 1;

FIG. 4 is a longitudinal sectional 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 sectional view showing an operation mode of screen printing.

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

FIG. 9 is a cross-sectional view illustrating 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]

 DESCRIPTION OF SYMBOLS 1 Screen 3 Sealant 4 Squeegee 5 Glass substrate 7 Alignment film 10 Printing machine 14 Sliding rail 15 Printing machine main body 18 Piston cylinder mechanism 20 Sealing area 21 Display area

Claims (2)

(57) [Claims] 1. A method of manufacturing a liquid crystal panel, wherein a squeegee is advanced and a sealant placed on the screen is printed through a screen on a glass substrate on which an alignment film is formed. A method for manufacturing a liquid crystal panel, wherein an angle between the squeegee and a traveling direction is controlled so that damage to the alignment film is reduced. 2. A sealant printing apparatus for a liquid crystal panel, wherein a squeegee is advanced and a sealant placed on the screen is printed through a screen on a glass substrate on which an alignment film is formed. A device for printing a sealant for a liquid crystal panel, comprising: means for controlling an angle between a direction and a traveling direction of the squeegee so as to reduce damage to the alignment film.