JPH02101432A - Method for sealing injection port of liquid crystal cell - Google Patents

Abstract

PURPOSE:To assure sealing of an injection port with an ultraviolet rays curing resin (UV resin) by irradiating the UV resin with ultraviolet rays while a cooling state is maintained, thereby curing the resin. CONSTITUTION:A liquid crystal 4 is injected through the injection port 5 into an empty cell and the port 5 is closed by the uncured UV resin 6. A cooling stage to penetrate the uncured UV resin 6 into the port 5 is executed and the resin is irradiated with the ultraviolet rays while the cooling state is maintained to curve the UV resin 6. Namely, the UV resin can be cured while the thermal expansion of the liquid crystal in the cell is suppressed if the resin is irradiated with the ultraviolet rays while the resin is held cooled. The good sealing to surely prevent the deterioration in moisture resistance and the generation of air bubbles is stably executed in this way and the yield of the liquid crystal cell is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is for sealing the injection port of a liquid crystal cell by curing an ultraviolet curing resin (hereinafter referred to as UV resin) after liquid crystal injection. Regarding the method.

[Conventional technology]

FIG. 2 is a partially cutaway view for explaining the basic structure of a liquid crystal cell. In the liquid crystal cell shown in the figure, an upper glass substrate 1 and a lower glass substrate 2 that face each other are bonded together via a sealant 3 made of epoxy resin or the like applied to the periphery. A liquid crystal 4 is sealed in a space surrounded by a sealant 3 in between. Here, both glass substrates 1
．． Transparent electrodes (not shown) made of an ITO film or the like are patterned on the opposing surfaces of the electrodes 2, respectively, and a voltage can be applied from the outside between the upper and lower transparent electrodes. Furthermore, an injection port 5 for injecting the liquid crystal 4 is sealed with a sealant 6 to prevent moisture and air from entering the liquid crystal 4.

Incidentally, in recent years, UV resins have been increasingly used as the sealant 6 for such liquid crystal cells. That is, an empty cell is formed by bonding the upper and lower glass substrates 1.2 with a sealant 3, liquid crystal 4 is injected into the inside of this empty cell through the injection port 5, and then UV resin is applied and the injection is performed. Close the inlet 5 and close this U.
By irradiating the V resin with ultraviolet rays and curing it, the injection port 5 can be sealed relatively easily.

Next, a conventional injection port sealing method using UV resin will be specifically explained.

First, liquid crystal is injected into an empty cell through an injection port, and then liquid UV resin is applied and the injection port is closed. Next, this cell is placed in a cooling tank and cooled to about -20 DEG C., thereby causing the liquid crystal inside the cell to contract, thereby causing the UV resin to penetrate into the injection port. After that, the cell was taken out from the cooling tank and returned to room temperature, and then placed in an ultraviolet irradiation oven and the UV resin was irradiated with ultraviolet rays for about 1 minute.
The V-resin is cured to complete the sealing work of the injection port.

[Problem to be solved by the invention]

However, in the conventional injection port sealing method described above, if the liquid crystal in the cell rapidly expands thermally in the ultraviolet irradiation furnace before the UV resin is completely cured, the uncured UV resin is pushed back by the liquid crystal. There was a risk that this would happen. In other words, since the temperature inside the ultraviolet irradiation furnace is about 60°C due to the heat generated by the ultraviolet lamp, the rapidly expanding liquid crystal 4 is exposed to the UV resin (sealant) 6, as shown in FIG. The uncured portion may be pushed back and a large hole 7 may be formed in the UV resin 6 inside the injection port 5. In this case, moisture resistance may become insufficient or air bubbles may form inside the hole 7. , the reliability of the liquid crystal cell is significantly degraded. especially,
When the liquid crystal cell is small, the temperature of the liquid crystal rises quickly in the ultraviolet irradiation furnace and thermally expands rapidly, so there is a high risk that the UV resin used to seal the injection port will be pushed back. therefore,
Conventionally, especially when the liquid crystal cell is small, it is necessary to visually inspect the sealing state of the injection port, and the manufacturing yield is also poor.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for sealing an injection port of a liquid crystal cell in which the injection port can be reliably sealed with UV resin and the yield can be increased.

[Means to solve the problem]

In order to achieve the above object, the present invention performs a cooling process in which the applied uncured UV resin is bitten into the inside of the injection port, and then irradiates the UV resin while maintaining the cooling state.
The JV resin was cured.

[Effect]

As mentioned above, by irradiating ultraviolet rays in a cooled state, it is possible to harden the UV resin while suppressing the thermal expansion of the liquid crystal inside the cell, eliminating the risk of undesired holes being formed in the UV resin. .

〔Example〕

Examples of the present invention will be described in detail below.

First, a pair of upper and lower glass substrates with transparent electrodes patterned on their opposing surfaces were bonded together using a sealant such as epoxy resin to form an empty cell, and liquid crystal was injected into the inside of this empty cell through an injection port. After that, a liquid UV resin is applied as a sealant, and the injection port is covered with this UV resin. Next, this cell is placed in a cooling tank and cooled to -20°C. During this cooling process, the liquid crystal inside the cell contracts, so as shown in FIG. Dig into it.

Incidentally, the reference numeral 3 in FIG. 1 indicates a sealant, and the reference numeral 4 indicates a liquid crystal. Further, although not particularly illustrated, a portion of the wall surface of the cooling tank is made of a material that transmits ultraviolet rays.

Thereafter, the UV resin 6 is irradiated with ultraviolet light for 2 minutes from outside the cooling tank while the cell is kept in the cooling tank. At this time, the temperature in the cooling tank rises slightly due to the heat from the ultraviolet lamp, but it is maintained below room temperature, so that the liquid crystal 4 in the cell does not undergo rapid thermal expansion. Therefore, inlet 5
The UV resin 6 that has bitten into the inside of the liquid crystal 4 will not be pushed back by the liquid crystal 4 during ultraviolet irradiation.

Therefore, no undesirable holes are formed in the UV resin 6, which would cause moisture resistance deterioration or bubble generation, and the UV resin 6 cures in substantially the same state as shown in FIG. 1, thereby reliably sealing the injection port 5.

In this way, in the above embodiment, since the thermal expansion of the liquid crystal is suppressed by irradiating ultraviolet rays in the cooling tank, undesirable holes are not formed in the UV resin, and therefore moisture resistance is sufficient and bubbles are prevented. It is possible to stably perform good sealing without generation. As a result, highly reliable liquid crystal cells can be manufactured reliably, yields are significantly improved, and inspection time can be shortened since there is no need to visually inspect the sealing state of the injection port.

〔Effect of the invention〕

As explained above, according to the present invention, since the UV resin is cured by irradiating ultraviolet rays in a cooled state while suppressing the thermal expansion of the liquid crystal inside the cell, undesired holes are not formed in the UV resin. As a result, it is possible to stably perform good sealing that reliably prevents deterioration of moisture resistance and bubble generation, which can be expected to significantly improve the yield of liquid crystal cells, and improve the sealing condition of the injection port. It is possible to provide an injection port sealing method that has remarkable effects, such as eliminating the need for visual inspection (thereby reducing inspection time).

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a main part according to an embodiment of the present invention, FIG. 2 is a partially cutaway view of a liquid crystal cell, and FIG. 3 is an explanatory diagram of a main part showing problems of the conventional technology. 3...Sealant, 4...Liquid crystal, 5...
...Injection port, 6...UV resin (sealant). Figure 2 Figure 3

Claims (1)

[Claims] Liquid crystal is injected into the empty cell through an injection port, the injection port is covered with an uncured ultraviolet curable resin, and the liquid crystal is shrunk by cooling, thereby causing the ultraviolet curable resin to fill the injection port. In a liquid crystal cell injection port sealing method in which the ultraviolet curable resin is penetrated into the interior and then cured by irradiating ultraviolet rays, after the cooling step, the ultraviolet curable resin is irradiated with ultraviolet rays while maintaining the cooling state. A method for sealing an inlet of a liquid crystal cell, characterized by curing the liquid crystal cell.