JPH05249475A - Production of liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal display element having no possibility of generating the seizure of a display by injecting a liquid crystal contg. substantially no impurity ions into a liquid crystal enclosing region even if the liquid crystal to be injected into a liquid crystal cell contains the impurity ions. CONSTITUTION:A liquid crystal introducing chamber 6 which opens to the outside, is communicated via a liquid crystal injection port 7 with the liquid crystal enclosing region 5 of the liquid crystal cell 1 and is internally provided with an ion adsorptive material 8 for adsorbing the impurity ions in the liquid crystal is previously formed on one end side of the liquid crystal cell 1 and after the liquid crystal LC is injected through this liquid crystal introducing chamber 6 into the liquid crystal enclosing region 5, the liquid crystal introducing chamber 6 is separated and the liquid crystal injection port 7 is sealed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display device has a liquid crystal cell in which a pair of transparent substrates are adhered to each other with a sealing material surrounding a liquid crystal enclosing region, and a liquid crystal injection port formed by partially notching the sealing material. It is manufactured by injecting liquid crystal and then sealing the liquid crystal inlet.

The liquid crystal is injected into the liquid crystal cell by evacuating the liquid crystal cell in the vacuum chamber and then immersing the liquid crystal cell's liquid crystal injection port in a liquid crystal bath. It is performed by a vacuum injection method in which the liquid crystal is returned and liquid crystal is injected into the liquid crystal cell.

By the way, the liquid crystal display elements are currently of the TN type or the STN type, but the matrix liquid crystal display elements used in various OA devices and television receivers have a large screen and a high time division. Since driving and high contrast are required, an active matrix system is adopted as a TN type liquid crystal display device.
Further, although the STN type liquid crystal display element is a simple matrix type, in this STN type liquid crystal display element, in order to improve the contrast at the time of high time division driving, a liquid crystal having a rapid threshold characteristic is used. The change in light transmittance with respect to the change in applied voltage is made rapid.

However, in the above active matrix TN type liquid crystal display element, the pixel electrode and its active element (thin film transistor etc.) are arranged on one of a pair of substrates facing each other across the liquid crystal layer. Since the active element projects above the substrate, a step is formed on the film surface of the alignment film formed on the substrate, and the twist alignment state of the liquid crystal molecules becomes unstable. Note that some active matrix liquid crystal display devices have a non-rubbing film as an alignment film on a substrate on which an active device is formed in order to prevent dielectric breakdown of the active device due to static electricity generated during rubbing of the alignment film surface. In this liquid crystal display element, the alignment state of liquid crystal molecules becomes more unstable.

Further, since the STN type liquid crystal display element may be of a simple matrix type, no step is formed on the alignment film surface, but in this STN type liquid crystal display element, as described above, the threshold value is used as the liquid crystal. It is necessary to use a liquid crystal having rapid characteristics, and a liquid crystal having a rapid threshold characteristic has a low orientation, so that the twist alignment state of liquid crystal molecules becomes unstable.

Therefore, in the above-mentioned active matrix TN type liquid crystal display element and STN type liquid crystal display element, the pretilt angle of the liquid crystal molecules is increased to stabilize the twist alignment state of the liquid crystal molecules.

[0008]

However, the liquid crystal display element in which the pretilt angle of the liquid crystal molecules is large as described above has a problem that display unevenness generally called "burn-in" occurs.

This is due to the influence of impurity ions in the liquid crystal. In the above-described conventional manufacturing method, when the liquid crystal is injected into the liquid crystal cell, the impurity ions contained in the liquid crystal substance and the liquid crystal of the liquid crystal cell are used. Since the impurity ions adsorbed on the outer surface of the bath immersion portion enter the liquid crystal cell together with the liquid crystal, the impurity ions are almost uniformly distributed in the liquid crystal sealed in the liquid crystal cell.

If the impurity ions in the liquid crystal are adsorbed to the film surface of the alignment film before the liquid crystal display element is used, there is no particular problem, but the alignment film for aligning liquid crystal molecules with a large pretilt angle has its surface. Most of the impurity ions are distributed in a floating state in the liquid crystal in a liquid crystal display element using an alignment film having a large pretilt angle because the energy is small and the adsorption force of the impurity ions is weak. However, when the liquid crystal display element is driven for display, the liquid crystal display element is attracted to the alignment film surface of the pixel portion to which the electric field is applied.

The adsorption of impurity ions on the surface of the alignment film due to the application of the electric field occurs especially when the display is driven at a high temperature (45 ° to 50 °), and the same image is displayed for a long time at a high temperature. If so, the impurity ions adsorbed on the alignment film surface of the electric field application pixel portion remain in an adsorbed state, so that the electro-optical characteristics of this portion change and a display burn-in phenomenon occurs.

An object of the present invention is that even if the liquid crystal to be injected into the liquid crystal cell contains impurity ions, the liquid crystal encapsulating region may be injected with the liquid crystal containing almost no impurity ions to cause a display burn-in phenomenon. It is an object of the present invention to provide a method for manufacturing a liquid crystal display element, which can obtain a liquid crystal display element without the above.

[0013]

According to a method of manufacturing a liquid crystal display element of the present invention, one end of a liquid crystal cell is opened to the outside and communicates with a liquid crystal filling area of the liquid crystal cell through a liquid crystal inlet and an internal portion. After forming a liquid crystal introduction chamber provided with an ion adsorbent for adsorbing impurity ions in the liquid crystal, after injecting the liquid crystal into the liquid crystal sealed region through the liquid crystal introduction chamber,
The liquid crystal introducing chamber is separated, and the liquid crystal inlet is sealed.

[0014]

According to the present invention, the impurity ions in the liquid crystal that are injected into the liquid crystal sealed area of the liquid crystal cell are adsorbed and removed by the ion adsorbent in the process of the liquid crystal passing through the liquid crystal introducing chamber. Therefore, even if the liquid crystal to be injected into the liquid crystal cell contains impurity ions, the liquid crystal containing region can be injected with liquid crystal containing almost no impurity ions.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a front view of the liquid crystal cell, and FIG. 2 is a front view of the manufactured liquid crystal display element.

First, the structure of the liquid crystal cell shown in FIG. 1 will be described. In this liquid crystal cell 1, a portion (hereinafter referred to as an element portion) A which finally becomes a liquid crystal display element, and a liquid crystal injection line are indicated by a chain line. It is composed of a portion (hereinafter referred to as a separating portion) B that is broken and separated from the dividing line C shown.

The liquid crystal cell 1 is formed by adhering a pair of transparent substrates 2 and 3 made of glass or the like through a sealing material 4, and the sealing material 4 is a rectangular frame portion formed in the element portion A. , A U-shaped frame portion formed in the separation portion B, the cell end side of which is open, and a narrow passage portion connecting both frame portions.

A region surrounded by the sealing material 4 of the element portion A is a liquid crystal enclosing region (display region) 5, and the portions corresponding to the liquid crystal enclosing region 5 of both substrates 2 and 3 are illustrated. However, the display electrode and the alignment film are formed. The liquid crystal display device manufactured in this example is an active matrix TN type liquid crystal display device or an S-type liquid crystal display device.
In the TN liquid crystal display device, the alignment film is an alignment film having a small surface energy in order to increase the pretilt angle of the liquid crystal molecules and stabilize the twist alignment state of the liquid crystal molecules.

On the other hand, the region surrounded by the sealing material 4 of the separating portion B is a liquid crystal introducing chamber 6 for introducing the injected liquid crystal into the liquid crystal enclosing region 5 when the liquid crystal is injected into the liquid crystal cell 1. The liquid crystal introducing chamber 6 has an opening at the cell end, and the opening serves as a liquid crystal inlet.

The liquid crystal introducing chamber 6 and the liquid crystal sealing area 5 are also provided.
The passage portion formed by the sealing material 4 between the liquid crystal introducing chamber 6 and the liquid crystal introducing chamber 6 serves as a liquid crystal introducing port 7 for injecting liquid crystal from the liquid crystal introducing chamber 6 into the liquid crystal filling region 5. And communicates with the liquid crystal enclosure region 5.

Further, inside the liquid crystal introduction chamber 6, granular ion adsorbents (alumina, silica gel, silica-alumina, porous particles such as activated carbon) 8 for adsorbing impurity ions in the liquid crystal are provided in a dispersed state. Has been. The particle size of the ion adsorbent 8 is almost the same as the gap between the pair of substrates 2 and 3, and the ion adsorbent 8 is sandwiched between the substrates 2 and 3 and is held so as not to slip unintentionally. ing.

Next, a method of manufacturing the liquid crystal display element will be described. In the liquid crystal display element, the step of manufacturing the liquid crystal cell 1 having the above-mentioned structure, the step of injecting liquid crystal into the liquid crystal cell 1, and the liquid crystal cell after injecting the liquid crystal It is manufactured by a step of separating the liquid crystal introduction chamber 6 from the step 1 and a step of sealing the liquid crystal injection port 7 thereafter.

In the liquid crystal cell 1, the sealing material 4 is printed on one of the pair of substrates 2 and 3 in which the display electrodes and the alignment film are formed in the liquid crystal sealing area 5, and the liquid crystal introducing chamber 6 portion of one of the substrates is printed. After the ion adsorbent 8 is sprayed on it (the liquid crystal encapsulation region 5 is masked and sprayed), both substrates 2 and 3 are bonded by the sealant 4.

The liquid crystal is injected into the liquid crystal cell 1 after the liquid crystal cell 1 is evacuated in a vacuum chamber.
The end portion on the side of the separating portion B, that is, the opening portion of the liquid crystal introducing chamber 6 is immersed in a liquid crystal bath (not shown), and in this state, the pressure in the vacuum chamber is returned to atmospheric pressure and liquid crystal is injected into the liquid crystal cell 1. Vacuum injection method. In this way, when the vacuum chamber is brought to atmospheric pressure with the opening of the liquid crystal introducing chamber 6 immersed in the liquid crystal bath,
Due to the pressure difference between the inside and the outside of the liquid crystal cell 1, the liquid crystal flows from the opening of the liquid crystal introducing chamber 6 as shown by the broken line arrow in FIG. Flow into.

Further, in this case, since the ion adsorbing material 8 is provided in the liquid crystal introducing chamber 6 in a dispersed state, the impurity ions in the liquid crystal injected into the liquid crystal enclosing region 5 of the liquid crystal cell 1 are introduced into the liquid crystal. In the process of the liquid crystal passing through the chamber 6, the ion adsorbent 8
Are removed by adsorption. Therefore, even if the liquid crystal injected into the liquid crystal cell 1 contains impurity ions, the liquid crystal encapsulation region 5
A liquid crystal containing almost no impurity ions flows into the.

After injecting the liquid crystal into the liquid crystal enclosing region 5 of the liquid crystal cell 1, the liquid crystal cell 1 is broken from a dividing line C shown by a dashed line in FIG. Separate from cell 1.

Next, the liquid crystal cell 1 in which the liquid crystal introducing chamber 6 is separated
The liquid crystal injection port 7 is sealed with the sealing resin 9 as shown in FIG. 2, and the liquid crystal LC is sealed in the liquid crystal sealing region 5 to complete the liquid crystal display element.

That is, in the method of manufacturing the liquid crystal display element, one end of the liquid crystal cell 1 is opened to the outside and communicates with the liquid crystal filling area 5 of the liquid crystal cell 1 through the liquid crystal injection port 7 and inside the liquid crystal LC. The liquid crystal introducing chamber 6 provided with the ion adsorbent 8 for adsorbing the impurity ions therein is formed, and after the liquid crystal is injected into the liquid crystal sealing region through the liquid crystal introducing chamber 6, the liquid crystal introducing chamber 6 is separated, The liquid crystal injection port 7 is sealed, and according to this manufacturing method, the impurity ions in the liquid crystal LC injected into the liquid crystal encapsulation region 5 of the liquid crystal cell 1 are ionized while the liquid crystal passes through the liquid crystal introduction chamber 6. Since it is adsorbed and removed by the adsorbent 8, even if the liquid crystal to be injected into the liquid crystal cell contains impurity ions, the liquid crystal encapsulating region 5 can be injected with liquid crystal containing almost no impurity ions.

In the liquid crystal display element manufactured by the above manufacturing method, since the liquid crystal LC in the liquid crystal enclosing region 5 contains almost no impurity ions, an electric field was applied when the liquid crystal display element was driven for display. Impurity ions are not adsorbed on the alignment film surface of the pixel portion, and therefore, the image sticking phenomenon of display does not occur.

In the above embodiment, the granular ion adsorbent 8 is provided inside the liquid crystal introducing chamber 6 in a dispersed state.
The ion adsorbent provided in the liquid crystal introducing chamber 6 is the liquid crystal introducing chamber 6
May be provided in the form of a film on the inner surface (the surfaces of the substrates 2 and 3).

[0031]

According to the manufacturing method of the present invention, since the impurity ions in the liquid crystal injected into the liquid crystal sealing region of the liquid crystal cell are adsorbed and removed by the ion adsorbent in the process of the liquid crystal passing through the liquid crystal introducing chamber, Even if the liquid crystal to be injected into the liquid crystal cell contains impurity ions, a liquid crystal containing almost no impurity ions can be injected into the liquid crystal encapsulation region to obtain a liquid crystal display element that is free from the phenomenon of image sticking. it can.

[Brief description of drawings]

FIG. 1 is a front view of a liquid crystal cell showing an embodiment of the present invention.

FIG. 2 is a front view of the manufactured liquid crystal display element.

[Explanation of symbols]

1 ... Liquid crystal cell, A ... Element part, B ... Separation part, C ... Dividing line,
2, 3 ... Substrate, 4 ... Sealing material, 5 ... Liquid crystal enclosing area, 6 ...
Liquid crystal introduction chamber, 7 ... Liquid crystal inlet, 8 ... Ion adsorbent, 9 ...
Sealing resin, LC ... Liquid crystal.

Claims (1)

[Claims] 1. An ion adsorbent, which is open to the outside and communicates with a liquid crystal enclosing region of the liquid crystal cell through a liquid crystal injection port, and which adsorbs impurity ions in the liquid crystal is provided inside one end of the liquid crystal cell. After forming a liquid crystal introduction chamber, and after injecting liquid crystal into the liquid crystal sealing region through the liquid crystal introduction chamber,
A method for manufacturing a liquid crystal display device, characterized in that the liquid crystal introducing chamber is separated and the liquid crystal inlet is sealed.