JPS61182016A - Preparation of liquid crystal display apparatus - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal cell having an uniform layer of the liquid cell in an image part of said cell and giving an uniform and a stable image by a very simple method, in which a liquid cell is pressed with two sheets of plate, and the liquid crystal poured in the liquid cell is heated followed by allowing to stand to a room temp. CONSTITUTION:The titled apparatus comprises a front glass plate 3 attached a transparent electrode 1 and an orientation film 2 thereon; a substrate 6 which is attached a TFT element part 4 (a thin film transistor element used as a switch of an image element electrode applied voltage), an image element part 5 and an orientation film 2 thereon; a sealing agent 7 premixed a prescribed spacer which is provided between the plate 3 and the substrate 6 at the periphery of these; and a liquid crystal 8 incorporated plenty of spacer 9 which is injected into the formed space of panel surrounded by the sealing agent 7. The liquid crystal cell 15 composed of the two sheets of the substrates 14a, 14b lying the first adhesives 13 is attached with crips 16a, 16b so as to press the cell 15 by the two plates 17, 18. The two sheets of the plates imposes the liquid crystal cell are necessary to correct a rough camber of the substrates of the liquid crystal. The rough camber of the substrates 14a, 14b of the liquid crystal cell are corrected by the plates 17, 18.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a liquid crystal display device for displaying characters or images, and in particular to a method for manufacturing a liquid crystal display device for displaying characters or images, and in particular, a liquid crystal display device having a structure in which the thickness of the liquid crystal layer in each pixel portion is constant to obtain a uniform image. The present invention relates to a method of manufacturing a display device.

2. Description of the Related Art Conventional technologies include, for example, a liquid crystal display in which spacers are dispersed within a liquid crystal cell so that the internal pressure of the liquid crystal cell is lower than atmospheric pressure at room temperature and atmospheric pressure, as shown in Japanese Patent Application Laid-open No. 56-146122. There is a method for manufacturing equipment. When this method is used, spacers are dispersed within the liquid crystal cell so that the two substrates of the liquid crystal cell do not come into contact with each other.

Other conventional techniques include, for example, Japanese Patent Application Laid-Open No. 68-193
As shown in Publication No. 518, the diameter of the spacer included in the seal within the liquid crystal cell is made larger than the diameter of the spacer dispersed within the liquid crystal cell, and the internal pressure of the liquid crystal cell at room temperature and atmospheric pressure is made lower than atmospheric pressure. There is a method for manufacturing a liquid crystal display device. When this method is used, the diameter of the spacer included in the seal is dispersed within the liquid crystal cell so that the two substrates of the liquid crystal cell do not come into contact with each other, and in order to obtain a tightening effect near the seal from the viewpoint of reliability. larger than the diameter of the spacer.

Here, there are two methods for making the internal pressure of the liquid crystal cell lower than atmospheric pressure at room temperature and atmospheric pressure. The first method is to heat the liquid crystal cell and the liquid crystal at a temperature higher than room temperature and seal the liquid crystal cell.The difference in thermal contraction between the liquid crystal cell and the liquid crystal inside the liquid crystal cell causes the inside of the liquid crystal cell to be in a depressurized state, and the liquid crystal is heated to a temperature higher than room temperature. This is a method of keeping the liquid crystal layer between the two substrates constant. The second method is to inject liquid crystal into a liquid crystal cell and then forcibly discharge a portion of the liquid crystal and seal the cell to make the internal pressure of the liquid crystal cell smaller than atmospheric pressure.

However, in the first method, the volume of thermal contraction relative to the volume of liquid crystal in the liquid crystal cell is minute, and in order to obtain the effect of thermal contraction to the extent that the two substrates come into contact, the liquid crystal cell and the liquid crystal must be heated to a considerably high temperature. There is a disadvantage that it must be done. For example, when a liquid crystal cell is heated and liquid crystal is injected into the liquid crystal cell, the liquid crystal is heated at the same time, but it is necessary to adjust the temperature to a temperature that does not cause compositional deformation of the liquid crystal. The temperature at which compositional changes occur in general liquid crystals is about 90°C. If boric acid glass is used for the substrate of the liquid crystal cell, the coefficient of thermal expansion is approximately 1.
cr6/℃, and the coefficient of thermal expansion of liquid crystal is approximately 10-'
/'C. Therefore, since the numbers of orders of magnitude are different, ignoring the thermal expansion of the glass and focusing on the thermal expansion of the liquid crystal, if the volume of the liquid crystal cell is about 16 B3, the volume change will be about 0.1 B3 for a temperature difference of at most 70°C.

On the other hand, the warp of the liquid crystal cell substrate is 3 μm and 8 degrees, and a volume change of about 11 M3 is required to flatten the warp, so it is difficult to flatten the warp of the liquid crystal cell substrate only by changing the volume of the liquid crystal. It seems to be.

In addition, in the second method, if the liquid crystal discharge port is on the substrate, this method is suitable for reducing the pressure inside the liquid crystal cell, but if the liquid crystal injection port is between the substrates, the discharge port is provided on the substrate. It would be difficult to reduce the pressure inside the liquid crystal cell unless there is.

Problems to be Solved by the Invention In such a conventional manufacturing method of a liquid crystal display device, the internal pressure of a liquid crystal cell injected with liquid crystal at room temperature and atmospheric pressure is lower than atmospheric pressure, and the thickness of the liquid crystal layer in the pixel area is uniform. It was difficult to obtain this by simply utilizing the difference in thermal contraction between the liquid crystal cell and the liquid crystal. The present invention has been made in view of these points, and an object thereof is to make it possible to make the internal pressure of a liquid crystal cell lower than atmospheric pressure at room temperature and atmospheric pressure with a simple configuration, and to obtain a uniform liquid crystal layer in the pixel area. It is said that

Means for Solving the Problems The means for solving the above problems in the present invention are as follows. The rough warpage of the liquid crystal cell substrate can be made substantially flat by pressurizing the liquid crystal cell with two plates and using spacers dispersed within the liquid crystal cell. However, since minute warpage of the substrate of the liquid crystal cell remains, the temperature appropriate for the thickness of the liquid crystal cell, for example, the gap between the liquid crystal cells must be set to
m and the heating temperature is t1°C, the liquid crystal cell is heated at a temperature where I and tl satisfy the relationship of 26 o/x-10≦t1≦260/x+10, and liquid crystal is injected in vacuum.
When applying an adhesive to a liquid crystal cell at a temperature that is heated to the liquid crystal cell and curing it in an air-cooled state, or when applying an adhesive to a liquid crystal cell,
The temperature at the time of curing, t2°C, has a relationship of t2≧t1+10 with respect to the temperature at the time of heating the cell, t1°C, and after applying the adhesive and curing, removing the two plates with the liquid crystal cell interposed therebetween, The purpose is to obtain a uniform liquid crystal layer thickness in a pixel portion of a liquid crystal display device.

For production The effect of this technical means is as follows.

That is, by pressurizing the liquid crystal cell with two plates, the rough warpage of the liquid crystal cell substrate is flattened, and the liquid crystal injected into the liquid crystal cell is heated and then air cooled to room temperature, causing thermal contraction of the liquid crystal, which causes the temperature to rise to room temperature. At atmospheric pressure, the internal pressure of the liquid crystal cell becomes smaller than atmospheric pressure, and after pressurizing the liquid crystal cell with two plates,
The remaining warpage of the substrate of the liquid crystal cell is corrected to obtain a uniform liquid crystal layer in the pixel portion of the liquid crystal cell.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings. FIG. 2 is a cross-sectional view of the assembled panel. In FIG. 2, a liquid crystal display device includes a transparent electrode 1 and an alignment film 2 on it.
, a front glass plate 3 with a TPT element (a transistor element composed of a thin film transistor and used for switching the voltage applied to a pixel electrode) part 4, a pixel part 5, and a liquid crystal display substrate 6 with an alignment film 2 thereon. In between, there is a sealant 7 mixed with a predetermined spacer in advance in the periphery, and a liquid crystal 8 and a large number of spacers 9 are placed in the panel surrounded by the sealant.
exists. Polarizing plates 10 and 11 are attached to both sides of the front glass plate 3 and the liquid crystal display substrate 60, and an electroluminescent plate 12 serving as a light source is further attached to the polarizing plate 11 on the liquid crystal display substrate θ. be done.

In FIG. 1, a liquid crystal cell 15 consisting of two substrates 14a and 14b with a first adhesive 13 interposed therebetween is connected to a clip 16a.
, 16b and pressurized by two plates 17 and 18. Correcting the rough warpage of the liquid crystal cell substrate requires two plates with the liquid crystal cell interposed therebetween. These plates 17 and 18 can correct rough warping of the substrates 14a and 14b of the liquid crystal cell. Furthermore, this liquid crystal cell 15 is heated.

Figure 3 shows the temperature t1℃ at which the liquid crystal cell is heated and the gap between the liquid crystal cells! This is a relationship between Ilm. t1=26o/x is represented by a solid line, and tl:260/X±10 is represented by a broken line.

The permissible range of heating temperature is ±10"C. For example, if the gap between the liquid crystal cells is 6 .mu.m, the heating temperature t1 is about 43.degree. C., but the liquid crystal cell is heated within the range of 33.degree. C. to 53.degree. C.. When the gap between liquid crystal cells is 6 μm, when the liquid crystal cell is heated at a temperature lower than 43°C, for example, 26°C, liquid crystal is injected, sealed and cured, and then returned to room temperature, the liquid crystal panel is placed under Na light and observed. It was found that the liquid crystal panel had about 3 interference fringes and it was not possible to obtain a gap between the liquid crystal layers with sufficient precision.
When the liquid crystal cell was heated at ℃, sealed and cured, and then returned to room temperature, when the liquid crystal panel was placed under Na light and observed, no interference fringes were observed in the center of the liquid crystal panel.
It has been found that at most two interference fringes occur near the seal around the liquid crystal panel. Therefore, if the heating temperature is lower than the appropriate heating temperature, the depressurizing effect inside the liquid crystal panel will be small and the gap between the liquid crystal layers will not be obtained, and if the heating temperature is higher than the heating temperature considered to be appropriate, the liquid crystal Although the gap between the layers was almost constant, interference fringes appeared near the seal area around the LCD panel, indicating that the decompression effect was quite large.By tightening the two substrates more than necessary, the TFT elements inside the LCD panel It was found that there is a risk of injuring people. Therefore, it was found here that there is an appropriate temperature for heating the liquid crystal panel, and it was determined experimentally that if the gap between the liquid crystal cells is X μm and the heating temperature is t1°C, then X and tl are t1 = 260/! The relationship was Furthermore, we fabricated liquid crystal panels by varying the heating temperature, placed the liquid crystal panels under Na light, observed them, and determined the range of heating temperatures for liquid crystal cells in which the gap between the liquid crystal layers is approximately constant: 260/! The relationship -10≦t1≦260/x+10 was obtained. Further, while the liquid crystal cell is kept in a heated state, liquid crystal is injected into the liquid crystal cell in a vacuum.

There are two injection methods:

The first method is as follows. After about 1/6 of the liquid crystal has been injected into the liquid crystal cell, when the injection port is immersed in the liquid crystal and the vacuum is returned to atmospheric pressure, the pressure difference causes the liquid crystal to be injected into the liquid crystal cell. Alternatively, as another method, the liquid crystal cell is immersed in liquid crystal in a vacuum, and the liquid crystal is injected into the liquid crystal cell using capillary action. In either method, air bubbles do not enter the liquid crystal cell. Furthermore, after injecting liquid crystal into the liquid crystal cell, a second adhesive is applied to the liquid crystal injection port. At this time, there are two methods for applying the second adhesive to the liquid crystal cell and curing it by exposing it to the liquid crystal cell.

The first method is as follows.

That is, the second adhesive is applied to the liquid crystal injection port while the liquid crystal cell is heated, and then cured at room temperature. In this case, as shown in FIG.
The adhesive 2o entered into the liquid crystal cell and ended near the liquid crystal screen 21, where it hardened. The entry of the second adhesive to this extent is a phenomenon caused by the difference in thermal contraction between the liquid crystal cell and the liquid crystal, but even if the second adhesive enters and hardens, the liquid crystal still tends to continue to undergo thermal contraction, so the liquid crystal The pressure inside the cell is lower than atmospheric pressure. Moisture resistance reliability test 60”C.

At 90% RH, the resistance value of the liquid crystal, 10 11 Ωα, hardly changed and showed good results. Another method is as follows. In other words, when applying the second adhesive to the liquid crystal cell, the temperature at which the liquid crystal cell is heated is, for example, 43°C when the gap between the liquid crystal cells is 6 μm;
The liquid crystal cell is further heated at 55°C, which is higher than 55°C, and a second adhesive is applied to the liquid crystal injection port of the liquid crystal cell, and the second adhesive is left in that state to harden. In this case, as shown in Figure 6. As shown, the second layer applied to the liquid crystal injection port 22 of the liquid crystal cell
Although only a small amount of the adhesive 23 penetrated into the liquid crystal cell, the resistance value of the liquid crystal (approximately 1011Ω) hardly changed in the moisture resistance reliability test at 60'C and 90% RH, showing good results. After confirming that the second adhesive applied to the liquid crystal cell has hardened, the two plates interposed between the liquid crystal cell and the liquid crystal cell are removed and the liquid crystal cell is taken out.

Effects of the Invention As described above, according to the present invention, it is possible to obtain a uniform liquid crystal layer thickness in the pixel portion of a liquid crystal cell using an extremely simple manufacturing method, and to obtain a uniform and stable image. It is extremely useful.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a method for manufacturing a liquid crystal cell according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a liquid crystal cell according to an embodiment of the present invention, and FIG. 3 is a cross-sectional view of a liquid crystal cell according to an embodiment of the present invention. FIGS. 4 and 5 are plan views of the liquid crystal injection port and adhesive of the liquid crystal cell. 1...Transparent electrode, 2...Alignment film, 3.
...Front glass plate, 4...TFT element section, 5...Pixel section, 6...Liquid crystal display substrate, 7...Seal Agent, 8...Liquid crystal, 9
...Spacer, 10.11...Polarizing plate, 12...Electroluminescent, 13. Mountain...First adhesive, 14a, 14b... ·substrate,
16...LCD Cenope 16a, 16b...
...Clip, 17.18...Plate material, 19...
...Liquid crystal injection port, 2o...Second adhesive,
21...Liquid crystal screen, 22...Liquid crystal injection port, 23...Second adhesive. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 11g Clearance 0 Figure 3 LCD 1 χ Figure 4 Figure 5 225 & Product Seat O

Claims (4)

[Claims] (1) A step of pressurizing a cell consisting of two substrates with a first adhesive interposed therebetween using a pressure body, a step of heating the cell, and a step of injecting the liquid crystal into the cell in a vacuum. A method for manufacturing a liquid crystal display device, comprising: applying a second adhesive to the cell and curing it; cooling the cell and the liquid crystal; and removing the pressurizing body. (2) The step of heating the cells is performed so that the gap between the cells is x μm.
If the heating temperature is t_1℃, then x and t_1 are 260/
2. The method of manufacturing a liquid crystal display device according to claim 1, wherein the manufacturing method is performed under the relationship x-10≦t_1≦260/x+10. (3) The step of applying a second adhesive to the cell and curing it and the step of cooling the liquid crystal to the cell are the steps of applying the second adhesive to the cell in a heated state and curing it in an air-cooled state. A method for manufacturing a liquid crystal display device according to claim 1, characterized in that: (4) The step of applying the second adhesive to the cell and curing the cell has a relationship such that the temperature t_2°C during curing is t_2≧t_1+10 with respect to the temperature t_1°C when heating the cell; 2. The method of manufacturing a liquid crystal display device according to claim 1, further comprising the step of applying a second adhesive to and curing the second adhesive.