JPH02139518A - Production of liquid crystal panel - Google Patents

Abstract

PURPOSE:To drastically decrease spacers and to obtain the panel having a good contrast by pressing the screen part which forms a projection when a sealing part is pressed by the force smaller than the pressing force on the sealing part. CONSTITUTION:The thermosetting sealing adhesive agent 2 into which the spacers are incorporated is applied on a lower substrate 1a and an upper substrate 1b is registered and superposed thereon. This sealing part 2 is pressed by a main holding part 6 in parallel with a bottom plate 8 via an elastic material 4. The waving specific to a stage for forming the films of electrodes is generated in the image part on the upper substrate 16 at this time. While this projecting part is pressed by the load smaller than the load of the main holding member 6 via the elastic material 5 and an auxiliary holding member 7, the upper and lower substrates 1b and 1a re heated and stuck. Since the spacers are thereby decreased to zero or to the min. density, the panel having the good contrast and high gap accuracy is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display panel by bonding upper and lower substrates to obtain a liquid crystal layer with a uniform gap.

Conventional technology Generally, in order to obtain a liquid crystal panel, a sealing adhesive mixed with a spacer material is applied to the inner surface of one substrate, the other substrate is stacked with the spacer in between, and this cell is applied with a weight. The adhesive is cured by applying pressure. FIG. 5 is a diagram showing such a conventional cell pressurization method.
The substrates 1 are stacked between the two substrates 1 with a spacer 3 and a seal 2 around them, and a load is applied to the top and bottom of this cell by a suppression plate 11 via an elastic block 10, and in this state, the seal 2 is cured. By doing so, a liquid crystal cell was obtained.

In addition, in order to obtain uniformity of the gap between the substrates, a pressing method was devised in which the pressure on the seal and the screen were separated (see Japanese Patent Application No. 81-312268 and Japanese Patent Application No. 61-302002). Fig. 6 shows a method of pressing the screen part with an elastic body having a harder hardness than the seal, and Fig. 7 shows a method of pressing the seal with an elastic body and the screen part with gas pressure. According to these methods, cells with good gap uniformity can be obtained.

Problems to be Solved by the Invention However, the above-mentioned suppression method has the following problems. First, in the method shown in Figure 5, the load applied to the seal 2 located around the substrate is smaller than that at the center, and if the viscosity of the seal is high, it is difficult to narrow the distance between the substrates to a predetermined gap. Therefore, a large load is required to narrow the cell spacing between the second part of the seal to a predetermined gap, and moreover, a load greater than that of the seal part is applied to the screen part.
An excessive load was applied to the spacers 3 in the screen portion, and a large amount of spacers 3 were required.

In addition, in the method shown in FIGS. 6 and 7, a large number of spacers 3 are required on the screen because the load is applied uniformly to the entire surface of the screen, and if the spacers are resin balls, 100
The distribution density is ~300 pieces/mm2, but when the spacer is a glass ball, it is 25-100 pieces/! A distribution density of 1112 was required. However, this screen spacer has a negative effect on image quality. If this liquid crystal panel is in normally black mode, the light that always passes through the spacer is not blocked, resulting in light leakage when displaying black.
In a normally white mode, light passing through the spacer is always blocked, resulting in a decrease in aperture ratio, and in either case, a decrease in contrast. Therefore, in order to obtain a liquid crystal panel with high image quality, 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 sealing adhesive containing a spacer to one of the substrates, a step of overlapping two substrates, and a step of overlapping cells. an elastic body that presses the seal portion as means for suppressing and holding the substrate;
It has an elastic body that presses the convex portion when the inner seal part of the screen part is pressed, and is characterized by adhering the upper and lower substrates while suppressing the screen part with a force smaller than the pressing force of the seal part. .

Function: As a pressing method when bonding two substrates together, the seal is pressed with an elastic body, and in this state, only the convex screen part is pressed with a small force with the elastic body, so that the seal part is The gap can be narrowed to a predetermined value determined by the spacer mixed in the sealing material, and only the force applied to the screen part is enough to flatten the convex part, so spacers in the screen part are not needed or the distribution density is significantly reduced. I can do it.

EXAMPLES Hereinafter, examples of the present invention will be explained in detail with reference to the drawings.

First, FIG. 1 shows a first embodiment. This is an effective method for assembling a liquid crystal panel with a size of 4 cm square or less, where the warpage of the substrate is relatively small. The upper and lower substrates lamb have electrodes on one side and are coated with an alignment film that has been cured and oriented, and the lower substrate 1a is a thermosetting sealing adhesive mixed with spacers made of finely cut glass fibers with a diameter of 6 μm. Apply 2 along the seal pattern. This lower substrate 12 is set on the flat bottom plate 8, and the upper substrate 1
Align and overlap b. The seal pattern of the cell in which the upper and lower substrates are stacked is pressed parallel to the bottom plate 8 using the main holding member 6 via the elastic body 4 . Although it varies somewhat depending on the viscosity of the sealing adhesive 2, by setting this load to 1 kgf or more for the substrate area I Cm2, the thickness of the sealing part can be determined by the spacer mixed in the sealing adhesive 2. . In this state, the screen portion of the lower substrate 1a becomes almost flat along the bottom plate 9 due to the suppression of the seal portion, but the screen portion of the upper substrate 1a has undulations due to the size of the substrate and the electrode film forming process. . Therefore, only the convex portion of the screen portion is pressed parallel to the bottom plate 8 using the auxiliary holding member 7 via the elastic body 5.

It is desirable to use an elastic body 5 that has a lower hardness than the elastic body 4 that presses on the seal, and the load that presses the screen section varies greatly depending on the size of the board and the size of the warpage, but Approximately one-fifth of the load is appropriate.

In this way, by heating the seal adhesive 2 for a certain period of time in a heating furnace at a predetermined temperature while applying a load on the seal part and the screen part, a liquid crystal cell without a spacer inside the liquid crystal layer, that is, in the screen part can be obtained. Can be done. Thereafter, by injecting liquid crystal into the liquid crystal layer of this liquid crystal cell and pasting polarizing plates on both sides at a predetermined angle, a liquid crystal panel with good contrast and no light leakage can be obtained. Note that when a 1-inch liquid crystal panel was produced using this method, the gap accuracy was ±0.3 μm or less.

The above method is suitable for panels with a relatively small substrate size and a large margin of gap accuracy. However, when the substrate size is large or high gap accuracy is required, the following method can be used. The method of the second embodiment shown is preferred.

This second embodiment is shown in FIG. The difference between this and the first embodiment is that a spacer 3 is provided in the screen area between the upper and lower substrates. That is, before bonding the upper substrate 1b and the lower substrate 1a, a diameter 6.
The spherical spacers 3 of μm are uniformly distributed at a density of 15 pieces/ff1m2, and the pressing load within the screen is
It is approximately twice as large as that in the example. Although this method causes some light leakage, it is possible to obtain a liquid crystal panel with a large screen size and excellent gap accuracy. As a result of creating a 3-inch LCD panel using this method, the gap accuracy was ±0.
．． The thickness was 2 μm or less, which is equivalent to the conventional method, and the light leakage due to the spacer was less than half.

Further, when using a spherical spacer made of resin material as the spacer 3, the distribution density needs to be about 40 pieces/ll1ffi2.

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 resist material as a spacer is to eliminate light leakage caused by conventional spacers.
A resist material spacer 9 having a predetermined thickness is selectively provided in a light-shielding portion within the screen portion to form a liquid crystal layer. However, when using this resist material as a spacer, there are the following problems. FIG. 4 shows a schematic diagram of the alignment process by rubbing performed before bonding the substrates. After resist spacers 9 are formed on the substrate 1, an alignment film 18 is applied, and after curing, a rubbing cloth 19 is wrapped around a rubbing drum 20. The alignment film 18 is rubbed while rotating to achieve alignment. At this time, the resist spacer 9 becomes an obstacle, and a defective alignment portion 21 is formed around the spacer. This alignment defect near the resist spacer 9 also occurs in alignment processing by oblique evaporation. Since light leakage occurs in this orientation defective portion 21, the spacer 9 must be made smaller with respect to the light shielding portion 22. Furthermore, it is difficult to make the area of the spacer 9 too large due to constraints such as margin of alignment with the light shielding part when forming the spacer 9. Moreover, since the hardness of the resist material is not very high, if the pressing force when bonding the upper and lower substrates is large, the resist spacer 9 will be crushed and the gap will become small. Therefore, in this embodiment, in order to use the resist as a spacer, as shown in FIG. Make sure no pressure is applied. As a result, resist spacer 9
The distortion is small, and a liquid crystal panel with good gap accuracy and no light leakage can be obtained. Note that the spacers may be formed on one or both substrates.

Effects of the Invention As described above, according to the present invention, by pressing the convex portion when the inner seal part of the screen part is pressed with a force smaller than the suppressing force of the seal part, the spacers distributed in the screen part can be suppressed. Since the density can be set to zero or the minimum density, a liquid crystal panel with good contrast and good gap accuracy can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a first embodiment of the method for manufacturing a liquid crystal panel of the present invention, FIG. 2 is a cross-sectional view showing a second embodiment of the present invention, and FIG. FIG. 4 is a schematic diagram of a substrate provided with resist spacers in the third embodiment during rubbing; FIGS. 5, 6, and 7 are cross-sectional diagrams showing conventional examples. . L 1 a, 1 b * @ @ board, Q I
@ #Seal, 3.Fist/Spacer, 4...Elastic body,
5...Elastic body 9 fists...Resist spacer. Name of agent: Patent attorney Shigetaka Awano (1 person)

Claims (1)

[Claims] The method includes a step of applying a sealing adhesive containing a spacer to one of the substrates, a step of stacking the two substrates, and a step of curing the seal while pressing the stacked substrates,
The means for pressing and holding the board includes an elastic body that presses the seal part and an elastic body that presses the part that becomes convex when the inner seal part of the screen part is pressed. A method for manufacturing a liquid crystal panel characterized by adhering upper and lower substrates while pressing with a force smaller than that of the substrate.