JPH07113721B2 - LCD display panel - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display panel used as a thin, lightweight and low power consumption display.

[0002]

2. Description of the Related Art Today, liquid crystal display panels are widely used in various fields such as calculators as thin, lightweight and low power consumption displays, and it is expected that their utilization will increase in the future. There is a situation.

Conventionally, the following methods have been proposed as a method for manufacturing the liquid crystal display panel.

(A) A net amount of liquid crystal is dropped by a pipette or a syringe onto one of the opposite electrode substrates, and the other electrode substrate is placed in the atmosphere through a spacer. , A method of wiping off the liquid crystal protruding to the surroundings and then sealing and adhering the outer circumference with an adhesive or the like.

(B) The oppositely arranged electrode substrates are adhered and fixed by using a sealing material, a container having a sandwich type cell structure is prepared in advance, and liquid crystal is injected into the electrode substrate through a liquid crystal injection port provided in advance to cause a capillary phenomenon. A method of injecting and sealing using pressure, vacuum, etc.

(C) As shown in FIGS. 13 (A) to 13 (D), the electrode substrates 1 and 2 arranged to face each other are adhered and fixed by using the sealing material 3, and a container having a sandwich type cell structure is prepared in advance. A method of injecting and sealing the liquid crystal 4 using a vacuum injection method through an opening provided in advance in the seal portion. Further, in the figure, 5 is a spacer for keeping the substrate spacing constant, 6 is a conductive resin for conducting the upper and lower electrodes, and 7 is a sealing resin.

[0007]

However, the conventional method as described above has the following drawbacks.

First, in the method (a), the method disclosed in Japanese Patent Laid-Open No.
As described in JP-A-79541, JP-A-55-6881, and JP-A-55-6882, it is difficult to control air bubbles in the cell together with the liquid crystal, which makes it difficult to control the cell volume. If you drop the appropriate amount of liquid crystal to be used, bubbles will always remain. In addition, even if a small amount of liquid crystal is used even if it exceeds the net usage amount, bubbles may or may not remain even if a constant amount of liquid crystal is dropped, so in order to not leave bubbles in the cell, a large amount of liquid crystal is dropped. There is a need. Therefore, if the sealing material is formed before the substrates are bonded and the liquid crystal is dropped, the sealing material is washed away by the liquid crystal, or the liquid crystal adheres to the sealing material and the seal bonding surface on the electrode substrate. Limited in quality and very unreliable in terms of quality. If the thickness of the sealing material formed in advance is large, liquid crystal excess of the net required amount is sealed in the cell before leaking out to the outside, and the sheet-shaped spacer is not formed because a uniform liquid crystal layer thickness cannot be obtained. It is used, and a method of later applying a sealing material to the outer periphery and adhering it is adopted. In this case, various measures have been taken to improve reliability and workability as shown in JP-A-51-10711 and JP-A-51-11934, but nonetheless one cell at a time. Since it is necessary to apply a sealant to the outer periphery of the resin and cure it, mass productivity is very poor, and the loss of liquid crystal material is large, so this method is not used at all today.

Next, in the above method (b), Japanese Patent Laid-Open No.
As disclosed in JP-A-4548, JP-A-49-79541 and JP-A-55-6881,
Although the device has been devised for reliability, workability, and cost reduction, it has a drawback that it requires drilling of the electrode substrate, not only causes cost increase, but also has poor mass productivity.

For the above reasons, the above (a),
The method (b) is rarely used today, and the liquid crystal display panel is produced exclusively by the method (c).

However, this method (c) is also devised as shown in JP-A-58-37527 and JP-A-58-40726, but the end face of the injection port always contacts the liquid crystal. Therefore, (1) the amount attached to the end face of the inlet becomes a loss of the liquid crystal material. (2) Since the sealing material is used to seal the liquid crystal, the adhesive strength of the sealing material is weak, which causes quality problems. (3) Since the end face of the injection port comes into contact with the liquid crystal, the liquid crystal is contaminated or dust is mixed, which causes quality trouble of the liquid crystal display panel. Further, in this method, (4) it takes a long time to inject the liquid crystal, and sometimes it takes 60 minutes or more for a large-sized panel. (5) When liquid crystal is injected, if the electrode substrate is a flexible material such as a film, the upper and lower electrode substrates come into contact with each other due to the difference in atmospheric pressure, resulting in defective alignment. (6) When manufacturing a liquid crystal display panel in which spacers are mixed in the liquid crystal in order to keep the electrode substrate spacing constant, it is not possible to mix and inject the liquid crystal in advance, and the electrodes are formed before the opposing electrode substrates are bonded and fixed. Since it is necessary to spray spacers on the entire surface of the substrate,
The loss of the spacer material is very large although it is expensive when the amount attached to the equipment is included. (7) In a multi-layer panel in which two or more cells sharing at least one electrode substrate are vertically overlapped, it is necessary to change the liquid crystal in each cell to two or more so that these liquid crystals are mixed with each other. And it is very difficult. Similarly, for a liquid crystal display panel in which two or more cells are connected in a plane, it is possible to configure the liquid crystal in each cell into two or more types.
It has problems that it cannot be manufactured by the current technology and that it is not proposed.

Further, except for the method (a), the methods (b) and (c) are composed of three steps of an electrode substrate adhering step, a liquid crystal injecting step, and a sealing step. It takes. The conventional method has such drawbacks.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, the loss of the liquid crystal material does not occur, the liquid crystal is not contaminated and dust is not mixed, and the process is simplified. It is an object of the present invention to provide a liquid crystal display panel having a novel structure with features such as

[0014]

In order to achieve this object, a liquid crystal display panel of the present invention has a liquid crystal sealing so that a liquid crystal sealing portion is formed on at least one of the facing substrates by the facing substrate. A continuous sealant is placed around the entire circumference of the part, and the liquid crystal is placed inside the sealant.
The dropwise form <br/> configured by filling a liquid crystal into the liquid crystal sealing portion, the sealing member comprising a radical polymerization type ultraviolet curable resin to the inner sealing side in contact with the liquid crystal, the cationic polymerization type ultraviolet outside seal A double seal is made by using a sealing material made of a curable resin.

[0015]

According to this structure, the cation polymerization type ultraviolet curable resin tends to increase the current consumption value of the liquid crystal, but since it is excellent in heat resistance and moisture resistance, it is used as a radical seal for the radical seal. A highly reliable and high quality liquid crystal display panel can be made by using a double-sided seal using a polymerizable resin for the inner seal that contacts the liquid crystal.

The double seal using the UV-curable resin can significantly shorten the curing time as compared with the double seal using the thermosetting resin or the thermoplastic resin. Since the gap does not change, there is no need to press for a long time until curing in order to make the gap uniform.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(Embodiment 1) FIGS. 1 (A) to 1 (C) and FIG. 2 are schematic explanatory views for showing one embodiment of a manufacturing process according to the present invention, and FIG. 3 is a vacuum bonding used in this embodiment. FIG. 4 is a perspective view of the machine, and FIG. 4 shows a sectional view thereof.

First, as shown in FIG. 1 (A), an electrode substrate such as glass on which a treatment for aligning liquid crystal molecules is completed (a pattern is formed by transparent electrodes, but it is omitted in the drawing). ) 11 and 12 are prepared and one substrate 1
1, a sealing material 13 made of, for example, an ultraviolet curable resin containing 1% of benzoin ethyl ether added to polyester acrylate, and a conductive resin 14 for conducting upper and lower electrodes on the other substrate 12 by screen printing. Print. Here, the sealing material 13 is provided on the electrode substrate 11.
The entire circumference of the liquid crystal sealing part is formed so as to form the liquid crystal sealing part.
Are provided in a continuous square shape, and the conductive resin 14 is printed at a required place. Next, FIG.
As shown in (B), one drop or a few drops of the liquid crystal 15 are dropped on each of the two portions surrounded by the sealing material 13 on the one electrode substrate 11 at substantially the center. At this time, as will be described later, the liquid crystal 15 is mixed with a spacer 16 for maintaining a constant substrate interval.
It is also possible to drop the liquid crystal 15 in a form in which 6 is not mixed. Here, when using a liquid crystal in which the spacers are not mixed, the spacers may be sprinkled on the alignment-treated substrate as is conventionally done, but the one in which the spacers are mixed in the alignment film material is used, It is also effective to provide a spacer at the same time as printing the alignment film.

The above-mentioned dropping of the liquid crystal 15 is performed by a microsyringe and controlled within ± 7% of the net usage amount. Here, it should be noted that if the dropping place is too close to the sealing material 13, the liquid crystal 15 flows to the sealing portion before the electrode substrates 11 and 12 are bonded together, and when the electrode substrates 11 and 12 are bonded together. Liquid crystal 1
5 may overflow to the outside of the seal part, and if the number of drops is small, the thickness of the liquid crystal layer (hereinafter referred to as a gap) is likely to be uneven between the drop place and the other place, so divide it into as many as possible. It is better to drip it evenly,
Furthermore, the precision of the amount of the liquid crystal 15 is the gap precision as it is.

Therefore, these conditions must be individually determined according to the shape, size, and gap accuracy of the liquid crystal display panel to be produced. For example, when the size of the liquid crystal sealing portion is 33 mm × 17 mm × 90 μm, the liquid crystal 15 is set to 5.
When one drop is dropped in the center of the 05 μl seal, the liquid crystal 15
Flowed out and overflowed to the outside of the seal portion, but when this was divided into 3 drops and arranged side by side at regular intervals in the longitudinal direction inside the seal part, good results were obtained without the liquid crystal 15 overflowing. It is within a preferable range obtained by various experiments that the dropping amount of the liquid crystal 15 is controlled within ± 7% of the net use amount. Further, although the liquid crystal 15 is dropped by the microsyringe in the above-mentioned embodiment, it is also possible to drop the liquid crystal by using a metering pump.

Next, after dropping the above-mentioned liquid crystal 15,
As shown in (C), the two electrode substrates 11 and 12 are bonded together under reduced pressure. For that purpose, first, as shown in FIG. 2, the two electrode substrates 11 and 12 are assembled to have a thickness of 1 mm. The spacers 17 are superposed so that the electrode patterns are correctly aligned.

Next, the two stacked electrode substrates 1 are stacked.
1 and 12 are put in the space (recess) 20 formed in the base 19 of the vacuum laminating machine 18 shown in FIGS. 3 and 4, and covered with a sheet 21 of silicon rubber or the like, and the lid 22 is closed so as not to open. Secure with a bolt (not shown). And FIG.
The space 23 shown by is evacuated by a vacuum pump (not shown) connected to the exhaust port 24, and then the electrode substrates 11 and 12 are evacuated.
The space 20 containing the gas is exhausted by a vacuum pump (not shown) connected to the exhaust port 25. Here, although the required degree of vacuum differs depending on the shape and size of the liquid crystal display panel to be produced, in the present embodiment, the degree of vacuum in this space 20 is 10
^When it becomes ^-1 torr or less, the exhaust of the space 23 is stopped, and the air is gradually leaked through the exhaust port 24 by the leak valve (not shown). At this time, it is more preferable to use nitrogen gas for leakage in order to prevent deterioration of the liquid crystal 15.

When this air is leaked, the sheet 21 made of silicon rubber or the like swells downward, and the two electrode substrates 11 and 12 are totally pressurized by the atmosphere, and as a result, the electrode substrates 11 and 12 are bent. The central part is laminated. Next, the handle 26 is turned to remove the spacer 17, the leak valve is completely opened, and the space 23 is at atmospheric pressure (1 atm).
Return to. Here, when the vacuum degree of the space 20 becomes equal to or less than the above numerical value, after the exhaust of the space 23 is stopped, a mechanism for holding the central part of the substrate is provided, and while holding the central part of the substrate, the spacer 17 is removed and leaked to the entire surface. You may use the method of pressurizing. At this point, the two electrode substrates 11 and 12 are completely pressure-bonded in a vacuum, and the liquid crystal 15 is divided into two places between the electrode substrates 11 and 12 by the sealing material 13 and sealed. When pressurization is insufficient, high-pressure nitrogen gas or air may be sent through the exhaust port 24.

Next, the exhaust of the space 20 is stopped, and the exhaust port 25
Leaks through and returns to atmospheric pressure. In this case as well, it is more preferable to use nitrogen gas for leakage as described above in order to prevent deterioration of the liquid crystal 15. Then the lid 22
Then, the bonded electrode substrates 11 and 12 are taken out and the sealing material 13 is cured.

After that, the liquid crystal display panel as shown in FIG. 5 is obtained by cutting and dividing into predetermined dimensions. 2 in FIGS.
7 is an O-ring.

In the present embodiment, the sealing material 13 is hardened outside the vacuum laminating machine 18, but it may be hardened inside.
However, the sealing material 1 is pressed while pressing the electrode substrates 11 and 12.
The gap of the liquid crystal display panel was more uniform when 3 was cured than when it was not pressed. Further, the method of applying pressure in the vacuum bonding machine 18 is not a method of uniformly applying pressure to the entire electrode substrates 11 and 12 as described above, but a method of applying pressure partially (for example, only the sealing material 13 portion). But it is okay. further,
There are various methods of pressurizing, but if the pressure difference is used as in this example, a flexible film-like or sheet-like material such as silicone rubber can be applied sufficiently uniformly and the sealing can be performed. By using a sealing material other than the material 13 so as to keep the atmospheric pressure of at least part of the space between the electrode substrates 11 and 12 smaller than the external atmospheric pressure, the electrode can be used without using any weight. The substrates 11 and 12 can be pressed. In this method, the electrode substrates 11 and 12 are laminated in advance,
Although it is also effective in the conventional manufacturing method of injecting liquid crystal later, when the ultraviolet curable resin is used as both the seal material 13 and another seal material, the ultraviolet light may block the weight. It is very effective because it can be easily irradiated.

Further, in the present invention, it is necessary to bond the electrode substrates 11 and 12 by using the sealing material 13 in a vacuum and at the same time seal the liquid crystal 15 therein, and the sealing material 15 is cured while the liquid crystal 15 is sealed. Therefore, it is necessary to obtain a uniform gap, and therefore, a material such as a thermosetting resin or a thermoplastic resin that requires heating for adhesive curing is slightly difficult to handle. On the other hand, the ultraviolet curable resin can be cured at room temperature in a short time and has a long pot life. Therefore, it is very suitable as the sealing material 13 used in the present invention.

In this embodiment, a radical-polymerizable polyester acrylate is used as the UV-curable resin, but other radical-polymerizable resins such as epoxy acrylate and urethane acrylate can be used without adversely affecting the liquid crystal. Is. However, although there is no problem in normal use, when the liquid crystal display panel is used under severe conditions of temperature and humidity, these resins have some problems in heat resistance and moisture resistance.

On the other hand, the cation-polymerization type UV-curable resin tends to increase the current consumption value of the liquid crystal, but since it is excellent in heat resistance and moisture resistance, this resin is used as an outer seal.
By using a radical polymerization type resin as the inner seal in contact with the liquid crystal and forming a double seal, a highly reliable and high quality liquid crystal display panel can be manufactured. When this double sealing is performed, a radical polymerization type ultraviolet curable resin (sealing material 13 of this embodiment) is provided as an inner seal on the side of the electrode substrate 11 on which the liquid crystal 15 is dropped, and the other electrode substrate is used. 12
It is sufficient to provide a cationic polymerization type ultraviolet curable resin as an outer seal on the side, and the outer seal is provided so as to be located slightly outside the inner seal.

The double seal using the UV-curable resin can significantly shorten the curing time when both UV-curable resins are used as compared with the double seal using the thermosetting resin or the thermoplastic resin. Becomes The double seal is also very effective in the conventional manufacturing method in which the liquid crystal is injected after the electrode substrates are bonded together, for the same reason as above.

In order to realize the double seal, at least one of the outer seal, the inner seal, and the conductive resin may be formed by a fixed amount discharge method without using the screen printing method.

Although glass substrates are used as the electrode substrates 11 and 12 in this embodiment, even if the electrode substrates are film-like flexible materials, before pressure bonding in the vacuum laminating machine 18, By devising such that these substrates do not bend and come into contact with each other, a liquid crystal display panel can be manufactured in the same manner as this embodiment.

(Embodiment 2) As shown in FIG. 7, electrodes (not shown) having a predetermined pattern are formed on both front and back surfaces, and then two electrode substrates 28a and 29a and electrodes (not shown) only on one surface are formed. Using a total of four substrates, that is, the two electrode substrates 28 and 29 on which is formed, three layers of good GH (guest-host) type liquid crystal as shown in FIG. 8 in the same manner as in Example 1. I got a display panel. Moreover, the liquid crystal 30, 31, 32 of each layer is different from the three layers, and the ones in which the red, blue, and yellow dyes are mixed are used. In the conventional method, there was a problem that the liquid crystal was mixed and the injection port of the other layer was blocked by the liquid crystal at the time of injecting the first layer, but this time, it did not occur at all. In addition, according to the present invention, it is apparent that a multi-layer liquid crystal display panel can be manufactured. 33, 33a, 33 in FIG.
b is a sealing material.

(Embodiment 3) As shown in FIG. 9, it has 81 liquid crystal sealing parts and the liquid crystal is classified into three types.
A liquid crystal display panel as shown in 0 was produced in the same manner as in Example 1. The liquid crystal used here is three kinds of liquid crystal 3 containing the same red, blue and yellow dyes as those used in Example 2.
0, 31, 32. Such a liquid crystal display panel is
It could not be made by the conventional method. That is, it is difficult to manufacture such as perforating the electrode substrate corresponding to each cell, and the quality of the display panel is impaired because the injection port is in the display section. It was not proposed by the technology of. 9 and 10, 34 and 35 are electrode substrates, and 36 is a sealing material for forming 81 liquid crystal sealing parts.

(Embodiment 4) As shown in FIG. 11, one large electrode substrate 37 and three small electrode substrates 38, 3
A liquid crystal display panel was prepared in the same manner as in Example 1 except that Nos. 9, 40 were used and three sealing members for liquid crystal were provided at the center by using the sealing materials 41, 41a, 41b. In this case 3
One type of liquid crystal 42 was injected into the two liquid crystal sealing parts. Such a liquid crystal display panel cannot be manufactured by the conventional method as described in the third embodiment, and is not proposed.

Further, in the present invention, the diameter of the spacer in the sealing material is changed for each cell, the electrode substrate spacing of the liquid crystal is changed for each cell, or the alignment treatment and the combination of liquid crystal materials having different twist directions are used to change the viewing angle direction. It is needless to say that can be changed for each cell.

[0038]

The present invention is configured as described above and has the following features. That is, since the liquid crystal is placed on the electrode substrate and then the electrode substrates can be quickly combined under reduced pressure, bonding of the electrode substrates,
The steps of injecting the liquid crystal, sealing and spraying spacers as necessary can be performed in a short time and in one step. Furthermore, since it has a double seal structure and uses a radical polymerization type UV-curing resin for the inner seal and a cation polymerization type for the outer seal, the number of process days from conventional substrate cleaning to finished product inspection is 3 It is possible to drastically reduce what has been more than one day to less than one day, and to provide a highly reliable and high quality liquid crystal display panel.

[Brief description of drawings]

FIG. 1 is a perspective view for explaining a manufacturing process of a liquid crystal display panel according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of the same.

FIG. 3 is a perspective view showing a vacuum laminating machine for carrying out the manufacturing method of the panel.

FIG. 4 is a schematic sectional view of the same.

FIG. 5 is a top view of the liquid crystal display panel of the present invention.

FIG. 6 is a schematic sectional view of the same.

FIG. 7 is a perspective view in the process of manufacturing illustrating a liquid crystal display panel in a second embodiment of the present invention.

FIG. 8 is a perspective view showing the same completed state.

FIG. 9 is a perspective view of a liquid crystal display panel according to a third embodiment of the present invention during manufacturing.

FIG. 10 is a perspective view showing the same completed state.

FIG. 11 is a perspective view of a liquid crystal display panel according to a fourth embodiment of the present invention during manufacturing.

FIG. 12 is a perspective view showing the completed state.

FIG. 13 is a perspective view showing a manufacturing process for explaining a conventional method for manufacturing a liquid crystal display panel.

[Explanation of symbols]

11, 12, 28, 28a, 29, 29a, 34, 3
5, 37, 38, 39, 40 Electrode substrate 13, 33, 33a, 33b, 36, 41, 41a, 4
1b Sealing material 15, 30, 31, 32, 42 Liquid crystal 16 Spacer

Claims (1)

[Claims] 1. A continuous sealing material is arranged on at least one of the opposing substrates so as to form a liquid crystal sealing portion with the opposing substrate, and a continuous sealing material is disposed over the entire circumference of the liquid crystal sealing portion. by dropping the liquid crystal inside forms configured by filling a liquid crystal into the liquid crystal seal, consisting of a radical polymerization type ultraviolet curable resin to the inner sealing side in contact with the liquid crystal <br/> sealant, cationic outside seal A liquid crystal display panel with a double seal using a sealing material made of a polymerized UV curable resin.