JPH07117659B2 - Liquid crystal panel manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a liquid crystal display panel, in which upper and lower substrates are bonded together to obtain a liquid crystal layer having a uniform gap.

2. Description of the Related Art Generally, in order to obtain a liquid crystal panel, a seal adhesive mixed with a spacer material is applied to the inner surface of one substrate, the other substrate is overlaid via the spacer, and this cell is added by a weight. The adhesive is cured while being pressed. FIG. 5 is a view showing such a conventional cell pressurizing method.
Substrates 1 are superposed on each other with a spacer 3 and a seal 2 around the substrates between a plurality of substrates 1, and elastic blocks are provided above and below this cell.
A liquid crystal cell was obtained by applying a load from the pressing plate 11 via 10 and curing the seal 2 in this state.

Further, in order to obtain a uniform gap between the substrates, a pressing method in which the pressure on the seal is separated from the pressure on the screen has been considered (see Japanese Patent Application Nos. 61-312268 and 61-302002). FIG. 6 shows a method of pressing the screen portion with an elastic body having a hardness smaller than that of the seal, and FIG. 7 shows a method of pressing the screen portion with an elastic body and the screen portion with gas pressure. According to these methods,
A cell with good gap uniformity can be obtained.

However, the above pressing method has the following problems. First, in the method shown in FIG. 5, the load applied to the seal 2 located around the substrate is smaller than that in the central portion,
When the viscosity of the seal is high, it is difficult to fit the substrate gap to the predetermined gap, and a large load is required to fit the cell gap of the seal 2 part to the predetermined gap. Since a load higher than the seal portion is applied, an excessive load is applied to the spacer 3 of the screen portion, and a large amount of spacers 3 are required.

Further, in the method shown in FIG. 6, although the pressing elastic body is different between the seal portion and the screen portion, since the pressurizing bodies of the seal portion and the screen portion are respectively integrated, an appropriate pressure balance can be applied. It is difficult, and in the method shown in FIG. 7, a large number of spacers 3 are required on the screen portion because the load is evenly applied to the entire screen portion. If the spacers are resin balls, 100 to 300 distribution density of the co / mm ² is spacer in the case of spherical glass was required distribution density of 25 to 100 U / mm ^2. However, the spacer of the screen portion adversely affects the image quality. If this liquid crystal panel is of normally black mode, the light that always passes through the spacer is not blocked, so light will leak when displaying black, and if it is of normally white mode, the light that will always pass through the spacer will be blocked. Is blocked, resulting in a decrease in aperture ratio, and in any case, a decrease in contrast. Therefore, in order to obtain a high quality liquid crystal panel, it is necessary to eliminate or minimize the spacers distributed in the screen portion.

Means for Solving the Problems In order to solve the above problems, the present invention includes a step of applying a seal adhesive containing a spacer to one of the substrates, a step of superposing two substrates, and a superposed cell. Has a step of curing the seal in a state of pressing, and as a means for pressing and holding this substrate, a first pressure member including an elastic body pressing the seal part and a rigid body holding the elastic part, and a screen part An elastic body for pressing a convex portion when pressing the inner seal portion, and a second pressure member including a rigid body for holding the elastic body,
It is characterized in that the upper and lower substrates are bonded while applying a pressing force smaller than that of the first pressing member to the second pressing member.

Action As a pressing method when the two substrates are bonded, the elastic member presses on the seal, and only the screen portion that is convex in this state is pressed by the elastic member with a small force. Since the gap can be narrowed down to the predetermined gap determined by the spacer mixed in the material, and only the force to flatten the convex portion is applied to the screen part, the spacer of the screen part is unnecessary or the distribution density is greatly reduced. Can be done.

Furthermore, since the pressure member of the seal unit and the pressure member of the screen unit are separated from each other, by applying an optimum pressing force to each of them, even if, for example, the substrate size or the substrate thickness is different, A precision gap can be obtained.

EXAMPLES Examples of the present invention will be specifically described below with reference to the drawings.

First, FIG. 1 shows a first embodiment. This is an effective method for assembling a liquid crystal panel of a size of 4 cm square or less in which the warpage of the substrate is relatively small. The upper and lower substrates 1a and 1b are provided with electrodes on one surface, coated with an alignment film, cured, and used for the alignment. The lower substrate 1a is a thermosetting seal containing spacers obtained by finely cutting glass fiber with a diameter of 6 μm. Adhesive 2
Is applied along the seal pattern. This lower board 12
Is set on the bottom plate 8 having a flat surface, and the upper substrate 1b is aligned and superposed. The main holding member 6 is pressed through the elastic body 4 on the seal pattern of the cell in which the upper and lower substrates are stacked in parallel with the bottom plate 8. This load varies depending on the viscosity of the seal adhesive 2, but this load is 1k per 1cm ² of substrate area.
Depending on the difference of gf or more, the thickness of the seal part may be changed by the seal adhesive 2
The thickness can be determined by the spacer mixed in. In this state, the screen portion of the lower substrate 1a becomes substantially flat along the bottom plate 9 due to the pressing of the seal portion, but the screen portion of the upper substrate 1a has a specific undulation due to the size of the substrate and the electrode film forming process. Therefore, only the convex portion of the screen portion is pressed in parallel with the bottom plate 8 using the auxiliary holding member 7 via the elastic body 5. It is desirable to use this elastic body 5 having a hardness smaller than that of the elastic body 4 that presses on the seal, and the load that the screen portion presses greatly differs depending on the size of the substrate and the size of the warp and cannot be generally stated. However, about 1/5 of the load on the seal is suitable. In this way, a liquid crystal cell having no spacer inside the liquid crystal layer, that is, the screen portion is obtained by heating the seal adhesive 2 in a heating furnace at a predetermined temperature for a certain period of time while applying a load on the seal portion and the screen portion. You can After that, by injecting liquid crystal into the liquid crystal layer of this liquid crystal cell, and sticking the deflection plate at a predetermined angle on both sides,
It is possible to obtain a liquid crystal panel having a good contrast without light leakage. As a result of producing a 1-inch size liquid crystal panel by this method, the gap accuracy was ± 0.3 μm or less.

The above method is suitable for a panel having a relatively small substrate size and a large margin of gap accuracy, but when the substrate size is large or high gap accuracy is required, the following method is used. The method of the second embodiment shown is preferred.

This second embodiment is shown in FIG. The difference from the first embodiment is that a spacer 3 is provided in the screen portion between the upper and lower substrates. That is, before laminating the upper substrate 1b and the lower substrate 1a, spherical spacers 3 made of glass and having a diameter of 6 μm are evenly distributed at a density of 15 co / mm ² on the entire lower end plate 1a. The pressing load on the screen is about twice as large as that in the first embodiment. With this method, light leakage occurs somewhat, but a liquid crystal panel having a large screen size and excellent gap accuracy can be obtained. As a result of making a 3-inch size liquid crystal panel by this method, the gap accuracy is ± 0.2 μm or less, which is equivalent to the conventional method, and the light leakage due to the spacer is reduced to less than half.

When spherical spacers made of a resin material are used as the spacers 3, the distribution density needs to be about 40 / mm ² .

Next, as a third embodiment, a case where a resist material is used as a spacer in the screen portion will be described with reference to FIGS. 3 and 4. The purpose of using the resist material as the spacer is also to eliminate the light leakage due to the conventional spacer,
A resist material spacer 9 having a predetermined thickness is selectively provided on a light shielding portion in the screen portion to form a liquid crystal layer. However, the use of this resist material as a spacer has the following problems. FIG. 4 shows a schematic view of the alignment treatment by rubbing performed before bonding the substrates. The alignment film 18 is applied after the resist spacers 9 are formed on the substrate 1.
After curing, the rubbing cloth 19 wound around the rubbing drum 20 is rotated to rub the alignment film 18 for alignment. At this time, the resist spacer 9 becomes an obstacle, and a defective alignment portion 21 is formed around the spacer. The poor alignment near the resist spacer 9 also occurs in the alignment treatment by oblique vapor deposition.
Because light leakage occurs at this misalignment portion 21,
Spacer 9 must be smaller than 22. Further, it is difficult to increase the area of the spacer 9 too much due to restrictions such as the margin of alignment with the light shielding part when the spacer 9 is formed. Moreover, since the hardness of the resist material is not so great, if the pressing force at the time of bonding the upper and lower substrates is large, the resist spacer 9 is crushed and the gap becomes small. Therefore, in this embodiment, since the resist is used as a spacer, as shown in FIG. 3, by assembling in the same manner as in the second embodiment, the resist spacer 9 provided on the screen portion is excessively pressed. I try not to apply pressure. As a result, it is possible to obtain a liquid crystal panel with a small distortion of the resist spacer 9 and a good gap accuracy and no light leakage. The substrate on which the spacer is formed may be either one or both.

EFFECTS OF THE INVENTION As described above, according to the present invention, the spacers distributed on the screen portion are removed by pressing the convex portion when the inner seal portion of the screen portion is pressed with a force smaller than the pressing force of the seal portion. Since the density can be zero or the minimum density, a liquid crystal panel having a good contrast and a good gap accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a method for manufacturing a liquid crystal panel of the present invention, FIG. 2 is a sectional view showing a second embodiment of the present invention, and FIG. 3 is a third embodiment of the present invention. FIG. 4 is a cross-sectional view showing an embodiment, FIG. 4 is a schematic view when rubbing a substrate provided with a resist spacer in the third embodiment, and FIGS. 5, 6, and 7 are cross-sectional views showing a conventional example. . 1,1a, 1b ... Substrate, 2 ... Seal, 3 ... Spacer, 4
...... Elastic body, 5 ...... Elastic body, 9 ...... Resist spacer.

Claims (1)

[Claims] 1. A step of applying a seal adhesive containing a spacer to one of the substrates, a step of superposing two substrates, and a step of curing the seal while pressing the superposed substrates, As a means for pressing and holding the substrate, an elastic body for pressing the seal portion and a rigid body for holding the elastic body are provided.
And a second pressure member including a rigid body that holds the elastic body that presses the convex portion when the inner seal portion of the screen portion is pressed, and the second pressure member. A method for manufacturing a liquid crystal panel, wherein the upper and lower substrates are adhered to each other while applying a pressing force smaller than that of the first pressing member.