JP3168690B2 - Liquid crystal injection method for liquid crystal 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 method for injecting liquid crystal into a liquid crystal panel used for an image display device or the like.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal panel is filled with a liquid crystal material by a so-called vacuum injection method. This system is disclosed, for example, in Japanese Patent Publication No. 58-49853. The conventional vacuum injection method will be briefly described with reference to FIG. Liquid crystal panel 101 and liquid crystal reservoir 102 containing liquid crystal
Is placed in a vacuum chamber 103. First, valve 10
4 and open the inside of the vacuum chamber 103 with the vacuum pump 105.
To exhaust. Next, the injection hole 105 of the liquid crystal panel 101
Is brought into contact with the liquid crystal material 106 stored in the liquid crystal reservoir, and the valve 104 is opened to the atmosphere side to introduce air into the chamber 103. The liquid crystal material 106 is pushed to the atmospheric pressure and
The liquid crystal is injected into the liquid crystal panel 101 through the liquid crystal panel 105.

[0003]

However, the above-mentioned conventional vacuum injection method has several problems or problems. First, depending on the structure of the liquid crystal panel, there is a possibility that a negative pressure under a high vacuum condition may cause breakage or destruction. For example, a plasma addressed liquid crystal panel has a flat panel structure in which a liquid crystal cell constituting a display screen and an addressing or switching plasma cell are stacked. The plasma cell is filled with an ionizable gas at a predetermined pressure. In this state, when a liquid crystal material is charged into a vacuum chamber to fill the liquid crystal cell side, a large negative pressure is applied to the plasma cell side, and in the worst case, the liquid crystal cell may burst and be fatal.

[0004] As a second problem, there is a problem that air bubbles remain inside, especially when liquid crystal is injected into a large panel. When the liquid crystal is introduced without sufficiently evacuating the inside of the panel, the air remaining in the empty panel is condensed and finally left as bubbles. In order to prevent bubbles from remaining, the degree of vacuum in the chamber must be sufficiently increased. However, an oil diffusion pump having a high evacuation capacity cannot be used because of fear of contamination of the liquid crystal material. Further, if evacuation is performed for a long time to achieve a high vacuum state, the composition of the liquid crystal material exposed to the vacuum atmosphere may change. For this reason, it is practically difficult to perform sufficiently high vacuum evacuation.

[0005] With reference to FIG. 5, the cause of the remaining air bubbles will be briefly described. After leaking the chamber 103 as shown, a liquid crystal material 106 is introduced from the injection hole 105. At this time, since the portion of the space 107 where the liquid crystal material 106 has not yet reached is a closed region, the pressure in the space 107 increases as the liquid crystal injection proceeds. Here, assuming that the degree of vacuum in the chamber before the start of the injection is about 4 × 10 ⁻¹ Pa and the atmospheric pressure, that is, 10 ⁵ Pa at the start of the injection, this space 107 has an initial volume (effective display area and panel gap). the liquid crystal injection is terminated when compressed up to 4 × 10 ^-1 / 10 ⁵ product) in size. For example, if the liquid crystal panel is 48
In the case where pixels are composed of 0 × 640 dots, bubbles of about 1 dot in size are left. That is,
If the air trapped in the panel hardly dissolves in the liquid crystal, bubbles of a finite size will inevitably remain. It is understood that the size of the bubbles is proportional to the panel size, and increases as the degree of vacuum is worse. However, it is difficult to sufficiently increase the degree of vacuum in the chamber for the reasons described above.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems or problems of the prior art, the present invention has been improved in that liquid crystal can be injected into a panel without causing damage due to negative pressure and remaining bubbles. The purpose is to provide a method. The following measures were taken to achieve this purpose. That is, at least one injection hole is formed in the outer peripheral portion of the liquid crystal panel.
Means for providing a plurality of exhaust holes, exhausting the air in the liquid crystal panel through the injection hole and the exhaust hole, and then supplying the liquid crystal from the outside to the injection hole and injecting the liquid crystal while exhausting from the exhaust hole. Was taken. The present invention also relates to an empty
At least one injection hole and at least one
Providing a plurality of exhaust holes, through the injection holes and the exhaust holes.
After exhausting the air in the panel,
Do not supply liquid crystal from the
A step of injecting the liquid crystal and sealing the injection hole and the exhaust hole.
Encapsulating the liquid crystal panel.
You. Further, the present invention relates to a method in which one of the cells into which the liquid crystal is injected is connected to the other.
Stacked with another cell filled with gas that can be turned on
One cell containing a plasma-addressed liquid crystal panel
At least one injection hole and at least one
An exhaust hole is provided at a predetermined distance, and the liquid crystal is
The other cell may be damaged through the injection hole and the exhaust hole.
After exhausting the air from one of the cells,
Note that the gas was injected from the injection hole while evacuating.
Sign.

[0007]

According to the present invention, the liquid crystal panel has at least one injection hole and at least one exhaust hole. The inside of the panel is evacuated through the exhaust hole at the same time as the liquid crystal is introduced from the injection hole. Therefore, unlike the conventional vacuum injection method, there is no possibility that the residual air is trapped inside the panel, so that the generation of bubbles can be effectively prevented. In addition, according to the present invention, the injection hole and the exhaust hole are provided separately. Therefore, the liquid crystal can be injected and the inside of the panel can be injected through the injection hole and the exhaust hole under the atmospheric pressure without storing the panel itself in the vacuum chamber. Therefore, there is no fear of damage to the panel due to the negative pressure.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an injection device used to execute a liquid crystal injection method for a liquid crystal panel according to a first embodiment of the present invention. This device is an independent vacuum chamber A
And a vacuum chamber B. Inside the vacuum chamber A, a container 2 for accommodating the liquid crystal 1 is accommodated. The container 2 is driven by a motor 3 and drops the liquid crystal 1 as needed.

On the other hand, a liquid crystal panel 4 to be subjected to a liquid crystal injection operation has, for example, a plasma address flat panel structure, and has a configuration in which a liquid crystal cell 5 and a plasma cell 6 are stacked. The application range of the present invention is not limited to this, and is similarly applicable to a liquid crystal panel including a single liquid crystal cell. A gas that can be ionized at a predetermined pressure is sealed in the plasma cell 6 in advance, and the inside of the liquid crystal cell 5 is still empty. At least one injection hole 7 and at least one exhaust hole 8 are provided on the surface of the liquid crystal cell 5 in advance. It is desirable that the pair of holes be formed at positions farthest from each other. For example, one side of the liquid crystal cell 5 may be arranged diagonally. The injection hole 7 is in airtight communication with the chamber A via an O-ring 9. The exhaust hole 8 also communicates with the chamber B via an O-ring 10 in an airtight manner.

Referring to FIG. 1, a first embodiment of a liquid crystal injection method for a liquid crystal panel according to the present invention will be described in detail. First, both the chamber A and the chamber B are evacuated, and the inside of the liquid crystal cell 5 is sufficiently evacuated through the injection hole 7 and the exhaust hole 8. Next, the container 2 housed in the chamber A is tilted by the drive of the motor 3 and the liquid crystal 1 is dropped near the injection hole 7 surrounded by the O-ring 9 to form a liquid crystal reservoir. As a result, the injection hole 7 is closed by the liquid crystal 1. Thereafter, the chamber A leaks and liquid crystal injection is started. During the liquid crystal injection, the chamber B continues the evacuation operation, and the liquid crystal cell 5
Continue to suck inside air. Therefore, almost no air bubbles, which have conventionally been a problem, are generated.

According to the method shown in FIG. 1, it is not necessary to put the entire liquid crystal panel 4 into the vacuum chamber. Therefore, even in a liquid crystal panel including a portion weak to negative pressure such as the plasma cell 6 as in this example, liquid crystal can be injected without any problem. The chambers A and B only need to have a function of performing vacuum evacuation, and it is not necessary to house the liquid crystal panel 4 itself as described above. Therefore, the same injection device can be used regardless of the size of the liquid crystal panel 4. Even if the liquid crystal panel 4 is large, it is not necessary to make the chamber itself large. Further, unlike the conventional vacuum injection method, the degree of vacuum required for the chambers A and B used here may be relatively low, so that the entire liquid crystal injection time can be reduced. The present invention is not limited to the method shown in this embodiment. For example, a tube or pipe may be used instead of the O-ring for the airtight connection between the liquid crystal panel 4 and the chambers A and B. That is, the tubes may be hermetically attached to the injection hole 7 and the exhaust hole 8 and joined to the chambers A and B, respectively.

A second embodiment of the method for injecting liquid crystal in a liquid crystal panel according to the present invention will be described with reference to FIG. First, an injection hole 22 and an exhaust hole 23 are provided on the surface of the liquid crystal panel 21. In this example, the pair of holes 22 and 23 are provided at the most distant positions along the diagonal line of the panel 21. A needle-shaped tube or pipe 24 is hermetically attached to the injection hole 22. In addition, pipe 2
5 is hermetically inserted.

First, for example, a rubber-like sealing plug 26 having excellent elasticity is crimped to the tip of a pipe 24 connected to the injection hole 22 to temporarily seal it. Next, in this state, the inside of the panel 21 is sufficiently exhausted through the other pipe 25 connected to the exhaust hole 23.

Thereafter, a liquid crystal material 27 is supplied around the crimping portion at the tip of the pipe 24. In this example, a concave portion serving as a liquid crystal reservoir is formed at the center of the sealing plug 26 so that the liquid crystal 27 does not spill.

Subsequently, from this state, the tip of the pipe 24 is gently separated slightly from the sealing plug 26, and the airtight state at the tip of the pipe 24 is maintained so as not to be broken. When the panel 21 is evacuated through the pipe 23 in this state, the liquid crystal 27 is injected. Since the panel is evacuated simultaneously with the liquid crystal injection, no air bubbles remain inside.

In this embodiment, a means for press-fitting and sealing the tip of the pipe 24 using the sealing plug 26 is used, but the present invention is not limited to this. The present invention can be similarly applied to any structure that can be switched from the closed state to the open state without breaking the airtight state at the end of the pipe 24.

As described above, the present invention is characterized by simultaneous injection and exhaust of the liquid crystal panel. FIG. 3 shows a state change in the liquid crystal panel when the simultaneous exhaust gas injection is performed. At the same time as the liquid crystal 33 is introduced into the panel 32 from the injection side 31, the exhaust of the panel 32 is continuously performed on the exhaust side 34. Therefore, the liquid crystal 33 is the panel 32
Progress gradually inside. Normally, the evacuation is completed with the liquid crystal 33 completely filling the inside of the panel 32, and no air bubbles are left inside. However, in some cases the panel 32
There is a possibility that the advancing surface of the liquid crystal 33 is partially depressed and left behind 35 due to a variation in flow resistance or the like. However, the remaining portion 35 has a certain area during the exhaust, but when the exhaust is completed and the atmospheric pressure is applied, it is compressed and reduced to a size that cannot be visually recognized. On the other hand, according to the conventional vacuum injection method, in principle, the entire space in the panel corresponds to the remaining space, and bubbles having a certain size remain.

Finally, FIG. 4 shows an example of a liquid crystal panel to which the liquid crystal injection method according to the present invention is applied. The illustrated example is a plasma addressed liquid crystal panel, and a liquid crystal cell 4
1 and a plasma cell 42, and a common intermediate plate 43 interposed therebetween. The liquid crystal cell 41 is configured using an upper glass substrate 44, and a plurality of signal electrodes 45 made of a transparent conductive film are formed on the inner main surface thereof in parallel with each other. The substrate 44 is bonded to the intermediate plate 43 with a predetermined gap using a spacer 46. The gap is filled with a liquid crystal 47. The substrate 44 is provided with an injection hole 48 and an exhaust hole 49 in advance, and the liquid crystal 47 is sealed and filled by performing simultaneous exhaust injection according to the present invention. Thereafter, the injection hole 48 and the exhaust hole 49 are sealed.

On the other hand, the plasma cell 42 is constituted by using a lower glass substrate 50. On the inner main surface of the substrate 50, a plasma electrode 51 orthogonal to the signal electrode 45 is formed. Further, partition walls 52 are formed in the row direction along the plasma electrodes 51. The upper end of the partition wall 52 is in contact with the intermediate plate 43 and also serves as a spacer. The substrate 50 is fused to the intermediate plate 43 using a frit seal material 53. A plasma chamber 5 hermetically sealed between the two
4 are formed. The plasma chamber 54 is divided by a partition wall 52 and individually constitutes a discharge region serving as a row scanning unit. An ionizable gas is sealed in the hermetic plasma chamber 54 at a predetermined pressure.

Generally, the assembly of the plasma cell 42 is a high temperature process, and the assembly of the liquid crystal cell 41 is a low temperature process. Therefore, after forming the plasma cell 42 first, the liquid crystal cell 41 is formed. For this reason, when the liquid crystal is injected, a gas having a predetermined pressure is already sealed in the plasma cell 42. If the conventional vacuum injection method is performed in this state, the plasma cell 42 will burst due to the negative pressure. On the other hand, according to the present invention, no problem occurs because the liquid crystal cell can be injected under the atmospheric pressure.

[0021]

As described above, according to the present invention, liquid crystal is injected into a panel by simultaneous exhaust injection. For this reason, there is an effect that the generation of bubbles can be sufficiently prevented even when a relatively low vacuum exhaust system is used. Further, since the liquid crystal can be injected under the atmospheric pressure, the panel cannot be destroyed by the negative pressure. Further, there is an effect that the injection time can be greatly reduced as compared with the conventional vacuum injection method. In addition, cost reduction of the implantation process can be expected.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an injection device used in an embodiment of a liquid crystal injection method for a liquid crystal panel according to the present invention.

FIG. 2 is a process diagram showing a second embodiment of a liquid crystal injection method for a liquid crystal panel according to the present invention.

FIG. 3 is a schematic diagram showing a change in an injection state when simultaneous exhaust injection is performed.

FIG. 4 is a schematic sectional view showing an example of a liquid crystal panel to which the liquid crystal injection method according to the present invention is applied.

FIG. 5 is a schematic diagram for explaining a conventional vacuum injection method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal 2 Container 3 Motor 4 Liquid crystal panel 7 Injection hole 8 Exhaust hole 9 O-ring 10 O-ring A chamber B chamber

Claims (2)

(57) [Claims] At least one injection hole and at least one exhaust hole are provided in an outer peripheral portion of a liquid crystal panel, and after the air in the liquid crystal panel is exhausted through the injection hole and the exhaust hole, the injection hole is formed. A liquid crystal injection method for a liquid crystal panel, characterized in that the liquid crystal is supplied from outside and the liquid crystal is injected while exhausting the liquid through the exhaust hole. 2. A step of providing at least one injection hole and at least one exhaust hole in an outer peripheral portion of an empty panel, and after exhausting air in the panel through the injection hole and the exhaust hole, A method for manufacturing a liquid crystal panel, comprising: a step of supplying a liquid crystal from the outside to an injection hole and injecting a liquid crystal while exhausting the gas through the exhaust hole; and a step of sealing the injection hole and the exhaust hole.