JPH1124086A - Manufacture of liquid crystal display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacture of the liquid crystal display panel which can suppress the decomposition of liquid crystal molecules at the time of irradiation with ultraviolet rays for the curing of ultraviolet-ray setting resin and the suppression of display unevenness. SOLUTION: For a TN type liquid crystal display device, vertical orientation films 13b and 23b are formed at the periphery of a display area. Consequently, the liquid crystal is oriented in the propagation direction of ultraviolet rays when irradiated with the ultraviolet rays, to the absorption of the ultraviolet rays by the liquid crystal molecules 2 is suppressed to evade deterioration of the liquid crystal molecules 2. Further, an AC voltage may be applied between a pixel electrode 12 and a counter electrode 22 to change the director direction of the liquid crystal molecules 2 to the propagation direction of the ultraviolet rays and on a light shield plate 31, a polarizer which presses only light of a polarized component perpendicular to the azimuth angle of the liquid crystal molecules 2 may be arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display panel using ultraviolet rays for curing a sealing material or a sealing material and preventing display unevenness.

[0002]

2. Description of the Related Art Liquid crystal display devices have the advantages that they are thin and lightweight, can be driven at a low voltage, and consume little power. In recent years, liquid crystal display devices have been widely used for displays of personal computers and televisions. Generally, a display panel constituting a liquid crystal display device has a structure in which liquid crystal is sealed between two transparent glass substrates. Of two surfaces (opposing surfaces) of the glass substrates facing each other, a black matrix, a color filter, a counter electrode, an alignment film, and the like are formed on one surface side, and a TFT, A pixel electrode, an alignment film, and the like are formed.
Further, a polarizing plate is attached to a surface of each glass substrate opposite to the facing surface. These two polarizing plates are arranged, for example, such that the polarization axes of the polarizing plates are orthogonal to each other. According to this, a mode in which light is transmitted when no electric field is applied and light is blocked when an electric field is applied, That is, a normally white mode is set. When the polarization axes of the two polarizing plates are parallel to each other, the mode is a mode in which light is blocked when no electric field is applied and light is transmitted when an electric field is applied, that is, a normally black mode.

[0003] In the following description, of the two substrates constituting a liquid crystal display panel, a substrate on which a TFT or the like is formed is called a TFT substrate, and a substrate on which a color filter or the like is formed is called a CF substrate. Hereinafter, a method called a dip injection method will be described as an example of a method of manufacturing a liquid crystal display panel.

First, a black matrix, a color filter, a counter electrode, an alignment film, and the like are formed on a first transparent substrate to form a CF substrate, and a TFT, a pixel electrode, an alignment film, and the like are formed on a second transparent substrate. To form a TFT substrate. Then, T
Display area (area where pixel electrodes or color filters are formed) on one of FT substrate and CF substrate
A sealing material (ultraviolet curable resin) is applied in a substantially frame shape so as to surround the frame. At this time, a sealing material is not applied to a portion serving as a liquid crystal injection port for injecting liquid crystal between panels in a later step. After that, the TFT substrate and the CF substrate are overlapped with a spacer for maintaining a constant interval between the substrates, and the TFT substrate and the CF substrate are temporarily joined with a sealant.

Next, after a light-shielding plate for covering the display area is disposed on one of the substrates, ultraviolet light is irradiated from the side on which the light-shielding plate is disposed to cure the sealing material. Next, after the space between the substrates is sufficiently evacuated by a vacuum device, the liquid crystal injection port is immersed in the liquid crystal to return to the atmospheric pressure, and the liquid crystal is injected between the substrates by a pressure difference. Next, a sealing material (ultraviolet curable resin) is filled in the liquid crystal injection port, and the display region is covered with a light-shielding plate and irradiated with ultraviolet rays to cure the sealing material. Thereby, the liquid crystal display panel is completed.

As another method of manufacturing a liquid crystal display panel, there is a method called a drop-injection method. In this method, first, a sealing material is applied to the outside of the display region of one of the TFT substrate and the CF substrate so as to completely surround the display region. Then, liquid crystal is dropped on the substrate, and the other substrate is overlapped with a spacer interposed therebetween. After that, a light-shielding plate that covers the display area is arranged on the substrate, and the sealing material is cured by irradiating ultraviolet rays. Thereby, the liquid crystal display panel is completed.

[0007] If impurity ions are contained in the liquid crystal sealed in the liquid crystal display panel, the electric field holding ratio is greatly reduced, causing display unevenness such as color omission and deteriorating the display quality. Conventionally, in order to avoid such a problem, a pair of ion trap electrodes is provided near the liquid crystal injection port, and when injecting liquid crystal, an AC voltage having a DC offset component is applied between the electrodes to apply a voltage to the ion trap electrode. It has been proposed to adsorb impurity ions (JP-A-6-33199).
No. 5). It has also been proposed to form an alignment film having a higher ion adsorption capacity than the alignment film on the pixel electrode around the pixel electrode, and to adsorb impurity ions by the alignment film (Japanese Patent Application Laid-Open No. Hei 7-110479). ).

[0008]

However, even if impurity ions in the liquid crystal are adsorbed to the ion trap electrode during liquid crystal injection, when the application of the voltage is stopped, the ions adsorbed to the ion trap electrode are dissociated again and the heat is removed. Diffusion into the liquid crystal due to movement causes display unevenness. FIG.
As shown in FIG. 1, when irradiating ultraviolet rays for curing the ultraviolet curable resin 33, the ultraviolet rays enter the liquid crystal from the edge of the light-shielding plate 31 to decompose the liquid crystal molecules and generate ions to generate a display. There is also a problem that the quality is deteriorated. Even in the method of adsorbing impurity ions with an alignment film having a high ion adsorption ability, it is inevitable that the liquid crystal molecules are decomposed when the ultraviolet curable resin is cured.

Further, in recent years, it has been proposed to irradiate the entire surface of a liquid crystal display panel with ultraviolet rays in order to suppress uneven display contrast (Japanese Patent Laid-Open No. 7-152034). In this case, the decomposition of the liquid crystal molecules by the ultraviolet rays cannot be prevented. An object of the present invention is to provide a method of manufacturing a liquid crystal display panel that can suppress the decomposition of liquid crystal molecules when irradiating ultraviolet rays for curing of an ultraviolet curable resin and suppressing display unevenness.

[0010]

An object of the present invention is to provide a method of manufacturing a liquid crystal display panel having a step of irradiating a pair of substrates enclosing liquid crystal with ultraviolet light, wherein the director direction of liquid crystal molecules is parallel to the propagation direction of ultraviolet light. In this case, the problem is solved by the method for manufacturing a liquid crystal display panel according to the first invention of the present application, which comprises irradiating ultraviolet rays.

[0011] An object of the present invention is to provide a method of manufacturing a liquid crystal display panel in which a pair of substrates are joined with an ultraviolet curable resin, wherein a vertical alignment film is formed on a substrate outside a display area, and the pair of substrates are arranged to face each other. After that, the display area is covered with a light-shielding plate and irradiated with ultraviolet rays to cure the ultraviolet-curable resin.

An object of the present invention is to provide a method of manufacturing a liquid crystal display panel in which a pair of substrates are joined with an ultraviolet curable resin, and the display regions of the pair of substrates are irradiated with ultraviolet rays while applying an electric field in a direction perpendicular to the substrate surfaces. Then, the problem is solved by a method of manufacturing a liquid crystal display panel according to the third invention of the present application, wherein the ultraviolet curable resin is cured. The above-mentioned object is to provide a liquid crystal display device according to the fourth aspect of the present invention, wherein a liquid crystal is sealed between a pair of substrates, and then a display region of the pair of substrates is irradiated with ultraviolet rays while applying an electric field in a direction perpendicular to the substrate surfaces. The problem is solved by a display panel manufacturing method.

An object of the present invention is to provide a method of manufacturing a liquid crystal display panel including a step of irradiating a pair of substrates enclosing liquid crystal with ultraviolet light, wherein the directions of the liquid crystal molecules are aligned in one direction, and the pair of substrates and the ultraviolet light source are provided. The polarizer is arranged so that the amplitude plane of the transmitted light is perpendicular to the direction of the liquid crystal molecules, and the liquid crystal display panel is irradiated with ultraviolet light. I do.

An object of the present invention is to provide a method of manufacturing a liquid crystal display panel in which a pair of substrates are joined with an ultraviolet-curable resin, wherein director directions of liquid crystal molecules sealed between the pair of substrates are aligned. A polarizer disposed so that an amplitude plane of transmitted light is perpendicular to an azimuth of the liquid crystal molecules between the polarizer and a light source for irradiation, and irradiating ultraviolet rays to cure the ultraviolet curable resin. The problem is solved by the liquid crystal display panel manufacturing method according to the invention.

[0015] The above-described problem is that after the liquid crystal is sealed between the pair of substrates, the director directions of the liquid crystal molecules are aligned, and the amplitude plane is perpendicular to the direction of the liquid crystal molecules between the pair of substrates and the ultraviolet light source. The seventh aspect of the present invention is directed to a method for manufacturing a liquid crystal display panel, which comprises arranging a polarizer so that a display region of the pair of substrates is irradiated with ultraviolet rays.

Hereinafter, the operation of the present invention will be described. FIG. 1 is a schematic diagram showing liquid crystal molecules on a substrate surface of a liquid crystal display panel. The liquid crystal molecules are rod-like molecules having many unsaturated bonds in the structure, rise at an angle determined by an alignment film (not shown) on the surface of the substrate, and are oriented in a certain direction. The major axis direction n of the liquid crystal molecules is referred to as a director direction, the rising angle の of the liquid crystal molecules is referred to as a tilt angle, and the angle Φ between the projection line of the major axis of the liquid crystal molecules on the substrate surface and the x-axis direction of the substrate is referred to as an azimuth angle.

When the director direction of the liquid crystal molecules in the liquid crystal is not uniform, or when the liquid crystal molecules are aligned in a twisted state such that the azimuth angle gradually changes from one substrate side to the other substrate side, the ultraviolet light In a liquid crystal having a large absorption and particularly a highly reactive atomic group (> C = O, etc.), the liquid crystal is more activated by ultraviolet rays, and many ions are generated. On the other hand, when the director direction of the liquid crystal molecules coincides with the propagation direction of light, light absorption is significantly reduced as compared with the case where the director direction of the liquid crystal molecules is perpendicular to the propagation direction of ultraviolet light. Therefore, in the first to fourth inventions of the present application, the director direction of the liquid crystal molecules is made substantially the same as the light propagation direction by applying a vertical alignment film or a voltage. For example, in the case of a TN (twisted nematic) type liquid crystal display panel, by forming a vertical alignment film outside the display region, the liquid crystal molecules between the substrates are aligned in a direction perpendicular to the substrate surface. Therefore, even if ultraviolet light enters the liquid crystal from the edge of the light-shielding film when the sealing material or the sealing material is cured, the decomposition of the liquid crystal molecules by the ultraviolet light is suppressed. In addition, if an electric field is applied in a direction perpendicular to the substrate surface and the director direction of the liquid crystal molecules is aligned with the direction perpendicular to the substrate surface, the liquid crystal molecules are irradiated when the entire panel is irradiated with ultraviolet rays to suppress display unevenness. Of the liquid crystal molecules is suppressed, and the decomposition of the liquid crystal molecules is suppressed.

In the case of a so-called narrow frame liquid crystal display panel in which the distance between the display area and the panel edge is narrow, the distance between the sealing material or the sealing material and the display area is narrow, and the display is performed by ultraviolet rays entering from the edge of the light shielding plate. The liquid crystal in the region may be decomposed. However, by applying a voltage in a direction perpendicular to the substrate surface at the time of irradiating ultraviolet rays as described above, deterioration of liquid crystal molecules at the time of curing the sealing material can be avoided.

The liquid crystal has birefringence due to its molecular structure. When the director direction of the liquid crystal molecules is the same and the liquid crystal molecules are horizontal or tilted with respect to the substrate surface, the amplitude plane of the incident light and the liquid crystal molecules When the angle between the azimuth and the azimuth angle is vertical, the collision rate between the liquid crystal molecules and the light is minimized, and when the angle is parallel, the property is maximized. Then, the fifth to seventh of the present application
In the invention, the liquid crystal panel is irradiated with ultraviolet light via a polarizer. In this case, the director directions of the liquid crystal molecules are aligned, and the polarizer is arranged so that the azimuth angle of the liquid crystal molecules and the light amplitude plane are at right angles. Thereby, the absorption of ultraviolet rays by the liquid crystal molecules is greatly reduced, and the deterioration of the liquid crystal molecules in the curing step of the sealing material or the sealing material or the ultraviolet irradiation step for preventing display unevenness is prevented.

In order to align the director direction of the liquid crystal molecules horizontally with the substrate surface, for example, in a TN type liquid crystal display panel, an AC voltage is applied between adjacent pixel electrodes (drive electrodes) on the TFT substrate, and a horizontal direction is applied. Generate an electric field. Thereby, the director direction of the liquid crystal can be aligned with the substrate surface horizontally and in the same direction. In the case of an IPS (in-plane switching) type liquid crystal display panel in which both a driving electrode and a counter electrode are formed on one of a pair of substrates, a voltage is applied to the driving electrode and the counter electrode during ultraviolet irradiation. By applying the voltage, the director direction of the liquid crystal molecules can be aligned in the horizontal direction with respect to the substrate surface.

[0021]

Embodiments of the present invention will be described below with reference to the accompanying drawings. (First Embodiment) FIGS. 2 and 3 are schematic views showing a method for manufacturing a liquid crystal display panel according to a first embodiment of the present invention. This embodiment is an example of a case where a TN type liquid crystal display panel is manufactured by a dip injection method.

First, a pixel electrode 12 made of ITO (indium tin oxide), a TFT (not shown), and a bus line (not shown) are formed in a display area on a transparent substrate 11 serving as a TFT substrate. A horizontal alignment film 13a is formed so as to cover the electrode 12 and the TFT. Also, substrate 1
A vertical alignment film 13b is formed outside the display area on the first alignment layer 13b.
After that, the surfaces of the alignment films 13a and 13b are rubbed.

On the other hand, a color filter (not shown) and a black matrix (not shown) for shielding light between pixels are formed in a display area of a transparent substrate 21 serving as a CF substrate, and a counter electrode 22 made of ITO is formed thereon. To form And
A horizontal alignment film 23a is formed on the display area of the transparent substrate 21, and a vertical alignment film 23b is formed outside the display area.
After that, the surfaces of the alignment films 23a and 23b are rubbed.

Next, the alignment film forming surfaces of the substrates 11 and 21 are opposed to each other, and a spacer (not shown) is provided between the substrates 11 and 21.
And joined by a sealing material (ultraviolet curable resin) to form a panel. Next, a liquid crystal is injected between the substrates 11 and 21, and a sealing material (ultraviolet curable resin) 3 is filled in the liquid crystal injection port. After that, the light shielding plate 31 covering the display area is
1 and irradiate ultraviolet rays from the substrate 21 side to form a sealing material 3
To cure. Thereby, the liquid crystal display panel is completed.

In this case, in this embodiment, since the vertical alignment films 13b and 23b are formed outside the display region, the liquid crystal molecules 2 outside the display region are formed as shown in FIGS. They are arranged in a direction perpendicular to the substrates 11 and 21.
The ultraviolet light propagates in the direction of the director of the liquid crystal molecules 2. When the director direction of the liquid crystal molecules 2 is aligned with the propagation direction of the ultraviolet light, the ultraviolet absorptivity of the liquid crystal molecules 2 becomes extremely small. As a result, the amount of ultraviolet light absorbed by the liquid crystal molecules 2 is significantly reduced, and deterioration of the liquid crystal molecules 2 is avoided. Although the director direction of the liquid crystal molecules 2 in the display area is not perpendicular to the substrate surface, since the display area is covered with the light shielding plate 31, the liquid crystal molecules 2 in the display area are not covered.
Is also avoided.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
FIG. 7 is a schematic view illustrating a method for manufacturing the liquid crystal display panel of the embodiment. The present embodiment is an example of a manufacturing method suitable for manufacturing a so-called narrow frame liquid crystal display panel in which the distance between the display region and the panel edge is short. First, a pixel electrode 12 and a TFT are provided in a display area on a transparent substrate 11 serving as a TFT substrate.
(Not shown), these pixel electrodes 12 and TF
The horizontal alignment film 13 is formed so as to cover T. Thereafter, the surface of the alignment film 13 is subjected to a rubbing treatment.

On the other hand, a color filter (not shown) and a black matrix (not shown) are formed in a display area of a transparent substrate 21 serving as a CF substrate, and a counter electrode 22 is formed thereon.
To form Then, the horizontal alignment film 23 is formed on the counter electrode 22.
Is formed, and the surface of the alignment film 23 is rubbed. Next, a sealing material (ultraviolet curable resin) 4 is applied on the substrate 11 so as to surround the display area. After the liquid crystal is dropped on the substrate 11, the substrates 11 and 21 are bonded together with a spacer interposed therebetween. Then, the light-shielding plate 31 covering the display area is
The sealing material 4 is cured by irradiating ultraviolet rays from the substrate 21 side while applying an AC voltage between the pixel electrode 12 and the counter electrode 22 so as to overlap the sealing member 4. Thereby, the liquid crystal display panel is completed.

In this case, in the present embodiment, since a voltage is applied between the pixel electrode 12 and the counter electrode 22 when irradiating ultraviolet rays, the liquid crystal molecules 2 are perpendicular to the substrate surface along the electric field. They are arranged in the direction, that is, the light propagation direction. Thus, similarly to the first embodiment, the ultraviolet absorptivity of the liquid crystal molecules 2 becomes extremely small, and the deterioration of the liquid crystal molecules 2 is avoided.

In this embodiment, since the liquid crystal molecules in the entire display area are arranged in the light propagation direction, the deterioration of the liquid crystal molecules does not occur even when the entire panel is irradiated with ultraviolet rays in order to make the display uneven. Be avoided. In this case, by forming the vertical alignment film outside the display region as in the first embodiment, it is possible to prevent the liquid crystal from being deteriorated due to ultraviolet rays at the edge of the panel.

(Third Embodiment) FIGS. 5 and 6 are schematic views showing a method for manufacturing a liquid crystal display panel according to a third embodiment of the present invention. First, a pixel electrode 12 and a TFT (not shown) are formed in a display region on a transparent substrate 11 serving as a TFT substrate, and a horizontal alignment film 13 is formed so as to cover the pixel electrode 12 and the TFT. Thereafter, the surface of the alignment film 13 is subjected to a rubbing treatment.

On the other hand, a color filter (not shown) and a black matrix (not shown) are formed in a display area of a transparent substrate 21 serving as a CF substrate, and a counter electrode 22 is formed thereon.
To form Then, the horizontal alignment film 23 is formed on the counter electrode 22.
Is formed, and the surface of the alignment film 23 is rubbed. Then, the respective alignment film forming surfaces of the substrates 11 and 21 are opposed to each other, a spacer (not shown) is scattered between the substrates 11 and 21, and both are joined with a sealant (ultraviolet curable resin) to form a panel and a panel. I do. At this time, a liquid crystal injection port for injecting liquid crystal between the substrates 11 and 21 is formed in a later step.

Next, liquid crystal is injected between the substrates 11 and 21, and a sealing material (ultraviolet curable resin) 3 is filled in the liquid crystal injection port. After that, the light-shielding plate 31 covering the display area is overlaid on the substrate 21, the polarizer 32 is arranged between the substrate 21 and the light source, and the sealing material 3 is cured by irradiating ultraviolet rays. At this time, as shown in FIG. 6, the polarizer 32 is arranged between the ultraviolet light source and the light shielding plate 31 so that the amplitude plane of the light passing through the polarizer 32 is perpendicular to the azimuth of the liquid crystal 2. . Thus, a liquid crystal display panel is manufactured.

In the TN type liquid crystal display panel, the alignment film 1
The liquid crystal molecules 2 near the liquid crystal molecules 3 and 23 are aligned in a direction determined by the alignment films 13 and 23 while being tilted at a certain angle. In the present embodiment, the polarizer 32 is used to enter only the linearly polarized light component whose amplitude plane of the ultraviolet light is perpendicular to the azimuthal angle of the liquid crystal molecules, as in the first and second embodiments. In addition, the effect that deterioration of liquid crystal molecules due to ultraviolet rays is prevented can be obtained.

(Fourth Embodiment) FIGS. 7 and 8 are schematic views showing a method for manufacturing a liquid crystal display panel according to a fourth embodiment of the present invention. First, a pixel electrode 12 and a TFT (not shown) are formed in a display region on a transparent substrate 11 serving as a TFT substrate, and a horizontal alignment film 13 is formed so as to cover the pixel electrode 12 and the TFT. Thereafter, the surface of the alignment film 13 is subjected to a rubbing treatment.

On the other hand, a color filter (not shown) and a black matrix (not shown) are formed in a display area of a transparent substrate 21 serving as a CF substrate, and a counter electrode 22 is formed thereon.
To form Then, the horizontal alignment film 23 is formed on the counter electrode 22.
Is formed, and the surface of the alignment film 23 is rubbed. Next, the respective alignment film forming surfaces of the substrates 11 and 21 are opposed to each other, a spacer (not shown) is scattered between the substrates 11 and 21, and both are joined with a sealing material (ultraviolet curable resin). At this time, a liquid crystal injection port for injecting liquid crystal between the substrates 11 and 21 is formed in a later step.

Next, a liquid crystal is injected between the substrates 11 and 21, and a sealing material (ultraviolet curable resin) 3 is filled into the liquid crystal injection port. Thereafter, the light-shielding plate 31 covering the display area is overlaid on the substrate 21, and the polarizer 32 is arranged between the substrate 21 and the light source. At this time, the amplitude plane of the light passing through the polarizer 32 is set to be perpendicular to the azimuth of the liquid crystal molecules 2. And
As shown in FIG. 7, an AC voltage is applied between the adjacent pixel electrodes 12. By applying this voltage, the adjacent pixel electrode 1
An electric field in the horizontal direction with respect to the substrate surface is generated between the two, and the director direction of the liquid crystal molecules 2 is aligned in one direction parallel to the substrate surface as shown in FIG. After aligning the director directions of the liquid crystal molecules 2 in one direction in this way, the sealing material 3 is cured by irradiating ultraviolet rays. Thereby, the liquid crystal display panel is completed.

In this embodiment, the same effects as in the third embodiment can be obtained. In the above example, the method of manufacturing the TN type liquid crystal display panel has been described.
In a liquid crystal display panel, the driving electrode and the counter electrode are formed on the same substrate, so that by applying a voltage between the driving electrode and the counter electrode, the liquid crystal molecules are arranged in one direction parallel to the substrate surface. I do. In the IPS type liquid crystal display panel, the same effect as in the above-described example can be obtained by irradiating the ultraviolet rays while applying the voltage between the driving electrode and the counter electrode.

(Fifth Embodiment) FIG. 9 shows a fifth embodiment of the present invention.
FIG. 7 is a schematic view illustrating a method for manufacturing the liquid crystal display panel of the embodiment. First, a pixel electrode 12 and a TFT (not shown) are formed in a display area on a transparent substrate 11 serving as a TFT substrate.
A horizontal alignment film 13 is formed so as to cover the pixel electrode 12 and the TFT, and then the surface of the alignment film 13 is subjected to a rubbing process.

On the other hand, a color filter (not shown) and a black matrix (not shown) are formed in a display area of a transparent substrate 21 serving as a CF substrate, and a counter electrode 22 is formed thereon.
To form Then, the horizontal alignment film 23 is formed on the counter electrode 22.
Is formed, and the surface of the alignment film 23 is rubbed. Then, the respective alignment film forming surfaces of the substrates 11 and 21 are opposed to each other, a spacer is scattered between the substrates 11 and 21, and both are joined with a sealant (ultraviolet curable resin). At this time, a liquid crystal injection port for injecting liquid crystal between the substrates 11 and 21 is formed in a later step.

Next, a liquid crystal is injected between the substrates 11 and 21, and a sealing material (ultraviolet curable) 3 is filled into the liquid crystal injection port. Thereafter, the light-shielding plate 31 covering the display area is overlaid on the substrate 21, and the polarizer 32 is arranged between the substrate 21 and the light source.
Then, a voltage is applied to the pixel electrode slightly inside the edge of the display area. Thereby, as shown in FIG. 9, the director directions of the liquid crystal molecules 2 at the edges of the display area are aligned obliquely to the substrate surface. After aligning the director directions of the liquid crystal molecules 2 in this way, ultraviolet rays are irradiated through the polarizer 32 to cure the sealing material 3. In this case, it is necessary to arrange the polarizer 32 so that the amplitude plane of the light passing through the polarizer 32 is perpendicular to the direction of the liquid crystal molecules 2. Thus, the liquid crystal display panel is completed.

In this embodiment, the polarizer 32 is arranged so that the amplitude plane of the light passing through the polarizer 32 is perpendicular to the azimuth of the liquid crystal 2, so that the deterioration of the liquid crystal molecules due to ultraviolet rays is prevented. . In this embodiment mode, a voltage is applied between the pixel electrode near the edge of the display area of the plurality of pixel electrodes and the opposing substrate to generate an electric field oblique to the substrate surface. In the case of the switching type liquid crystal display panel in which the upper and lower electrodes are arranged in an oblique direction and the oblique electric field is used for driving, the pixels in the oblique direction are An AC voltage may be applied to the electrodes.

Hereinafter, the results of forming an evaluation liquid crystal display panel by the method described in each of the above embodiments and examining the electrical characteristics thereof will be described. (Electrical property evaluation by single cell) Nippon Synthetic Chemical's polyimide (JALS-644) for vertical alignment film, Nissan Chemical's polyimide (SE-7792) for horizontal alignment film, Merck standard liquid crystal (ZL) for liquid crystal
I-4792), the first embodiment (Example 1), the third embodiment (Example 2), and the fourth embodiment (Example 3) using the conventional method (Comparative Example). In addition, a liquid crystal display panel for evaluation of a TN type single cell structure having a twist angle of 90 ° was produced by the method described in the fifth embodiment (Example 4).

These liquid crystal display panels for evaluation are formed by forming an ITO electrode pad on one substrate side and etching it in a stripe shape at a pitch of 100 μm, and forming an electrode pad on the other substrate side on one surface. The structure is close to that of the liquid crystal display panel. The curing of the ultraviolet curable resin is performed by using a medium-high pressure mercury lamp made of oak, and from the upper side of the substrate surface.
Irradiation was performed under the conditions of 00 mJ / cm ² (I-line reference).

When an AC voltage was applied between the electrodes during the irradiation of ultraviolet rays (Examples 2 to 4), a high-frequency voltage having a frequency of 30 kHz was applied to prevent ion adsorption on the electrode surface. In order to sufficiently orient the liquid crystal molecules by an electric field, a voltage of 10 V, which is about twice the saturation voltage of the liquid crystal, was applied between the electrodes. Table 1 below shows the results of examining the ion density and the voltage holding ratio of the liquid crystal display panels for evaluation manufactured according to Comparative Examples and Examples.

[0045]

[Table 1]

As is clear from Table 1, in the case of the comparative example, the ion density was greatly increased by the irradiation of ultraviolet rays, and the voltage holding ratio was decreased by 2.4%. When the voltage holding ratio is reduced, the active matrix drive liquid crystal display panel does not hold the voltage until the next data writing time and leaks, causing a problem that uneven display (color loss) occurs. . On the other hand, in the liquid crystal display panels of Examples 1 to 4, the decrease in the voltage holding ratio was as small as 0.3 to 0.7%, which indicates that the light deterioration of the liquid crystal was suppressed.

(Lighting Test of Liquid Crystal Display Panel) Next, a liquid crystal display panel was formed by a drop injection method, and it was examined whether or not display unevenness was caused when the liquid crystal display panel was lit for a long time. That is, a liquid crystal display panel was manufactured by a drop-injection process using the alignment film and the liquid crystal used in the above evaluation of the electrical characteristics. TF
A horizontal alignment film was applied to the display regions of the T substrate and the CF substrate, and a vertical alignment film was applied between the region where the sealing material was applied and the display region, and was thermally cured.

After each of the alignment films of the TFT substrate and the CF substrate was rubbed so that the twist angle was 90 °, an ultraviolet curable resin (epoxy acrylate resin: manufactured by Kyoritsu Chemical) was applied to one of the substrates in a frame shape. . Then, liquid crystal was dropped at multiple points on the display region of one of the substrates so that the liquid crystal was uniformly diffused when the two substrates were bonded together. A gap material (adhesive spacer 5 μm: made by Hayakawa Rubber) is used for the other substrate.
Was sprayed. Thereafter, both substrates were set on a bonding machine and bonded in a vacuum.

Next, an alternating voltage (f = 30 kHz, V = 1) is applied between the pixel electrode and the counter electrode near the edge of the display area.
While applying a voltage of 0 V), the sealing material was irradiated with ultraviolet rays to be cured. Thus, the liquid crystal display panel shown in FIG. 10 was completed. In FIG. 10, a region indicated by hatching is a display region. A horizontal alignment film is formed in this display area, and vertical alignment films 13b and 23 are formed outside the display area.
b is formed. Further, a voltage was applied between the pixel electrode outside the position indicated by the alternate long and short dash line and the counter substrate. Reference numeral 15 denotes a terminal area in which a plurality of terminals connected to the bus line are arranged, and a driving voltage is supplied to each terminal from a driving circuit board.

The liquid crystal display panel thus manufactured was made into a unit, and a driving test was performed at 50 ° C. using an environmental tester. As a result, display unevenness did not occur near the resin portion even after 500 hours had passed. On the other hand, a liquid crystal display panel was formed in the same manner as described above except that no voltage was applied during ultraviolet irradiation. Then, a driving test was performed using an environmental tester under the same conditions as described above. as a result,
From the initial stage of lighting, display unevenness occurred due to a decrease in the voltage holding ratio in the vicinity of the seal portion, and the area expanded with the passage of time. This indicates that the present invention is extremely useful for improving the reliability of the liquid crystal display panel.

[0051]

As described above, according to the present invention,
When curing the sealing material or sealing material or irradiating ultraviolet rays to prevent display unevenness, direct the director direction of the liquid crystal molecules in the direction of propagation of the ultraviolet rays, or in a direction perpendicular to the orientation of the liquid crystal molecules through a polarizer. Irradiation of ultraviolet light with only the polarization component suppresses deterioration of the liquid crystal due to ultraviolet light. This makes it possible to reliably cure the sealing material or the sealing material using ultraviolet light, and to cure the sealing material in the drop-injection process, greatly improving the production yield and productivity of the liquid crystal display panel. Also, in the case where ultraviolet light is applied to the entire surface of the panel in order to prevent display unevenness, deterioration of the liquid crystal is avoided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing liquid crystal molecules on a substrate surface of a liquid crystal display panel.

FIG. 2 is a schematic diagram (part 1) illustrating the method for manufacturing the liquid crystal display panel of the first embodiment of the present invention.

FIG. 3 is a schematic diagram (part 2) illustrating the method for manufacturing the liquid crystal display panel of the first embodiment of the present invention.

FIG. 4 is a schematic view illustrating a method for manufacturing a liquid crystal display panel according to a second embodiment of the present invention.

FIG. 5 is a schematic view (part 1) illustrating the method for manufacturing the liquid crystal display panel of the third embodiment of the present invention.

FIG. 6 is a schematic view (part 2) illustrating the method for manufacturing the liquid crystal display panel of the third embodiment of the present invention.

FIG. 7 is a schematic view (part 1) illustrating the method for manufacturing the liquid crystal display panel of the fourth embodiment of the present invention.

FIG. 8 is a schematic diagram (part 2) illustrating the method for manufacturing the liquid crystal display panel of the fourth embodiment of the present invention.

FIG. 9 is a schematic view illustrating a method for manufacturing a liquid crystal display panel according to a fifth embodiment of the present invention.

FIG. 10 is a schematic diagram showing a liquid crystal display panel used for a lighting test.

FIG. 11 is a schematic view showing a conventional problem.

[Explanation of symbols]

 2 Liquid Crystal Molecule 3 Sealing Material 4 Sealing Material 11, 21 Substrate 12 Pixel Electrode 13, 13a, 13b, 23, 23a, 23b Alignment Film 22 Counter Electrode 31 Light Shield 32 Polarizer

Claims (11)

[Claims] 1. A method of manufacturing a liquid crystal display panel, comprising the step of irradiating a pair of substrates enclosing liquid crystal with ultraviolet light, wherein the ultraviolet light is irradiated with the director direction of liquid crystal molecules being parallel to the propagation direction of the ultraviolet light. Manufacturing method of a liquid crystal display panel. 2. A method for manufacturing a liquid crystal display panel in which a pair of substrates is joined with an ultraviolet curable resin, comprising: forming a vertical alignment film on a substrate outside a display area; A method for manufacturing a liquid crystal display panel, wherein the display area is covered with a light-shielding plate and irradiated with ultraviolet rays to cure the ultraviolet-curable resin. 3. A method of manufacturing a liquid crystal display panel in which a pair of substrates are joined with an ultraviolet curable resin, wherein a display region of the pair of substrates is irradiated with ultraviolet rays while applying an electric field in a direction perpendicular to the substrate surfaces. A method for manufacturing a liquid crystal display panel, comprising curing an ultraviolet curable resin. 4. A method of manufacturing a liquid crystal display panel, comprising: after sealing liquid crystal between a pair of substrates, irradiating a display region of the pair of substrates with ultraviolet light while applying an electric field in a direction perpendicular to the substrate surfaces. . 5. The electric field is generated by applying a voltage between a pixel electrode formed on one of the pair of substrates and a counter electrode formed on the other substrate. Or the manufacturing method of the liquid crystal display panel of 4. 6. A method of manufacturing a liquid crystal display panel, comprising the step of irradiating a pair of substrates enclosing liquid crystal with ultraviolet light, wherein the directions of liquid crystal molecules are aligned in one direction, and the position between the pair of substrates and the ultraviolet light source is adjusted. A method for manufacturing a liquid crystal display panel, comprising arranging a polarizer such that an amplitude plane of transmitted light is perpendicular to an azimuth of the liquid crystal molecules and irradiating ultraviolet rays. 7. A method for manufacturing a liquid crystal display panel in which a pair of substrates are joined with an ultraviolet-curable resin, wherein director directions of liquid crystal molecules sealed between the pair of substrates are aligned, and the pair of substrates and an ultraviolet light source are provided. Manufacturing a liquid crystal display panel, wherein a polarizer is arranged so that the amplitude plane of transmitted light is perpendicular to the direction of the liquid crystal molecules during the irradiation, and the ultraviolet curable resin is cured by irradiating ultraviolet light. Method. 8. After the liquid crystal is sealed between the pair of substrates, the director directions of the liquid crystal molecules are aligned so that the amplitude plane is perpendicular to the direction of the liquid crystal molecules between the pair of substrates and the ultraviolet light source. A method for manufacturing a liquid crystal display panel, comprising arranging a polarizer and irradiating a display region of the pair of substrates with ultraviolet rays. 9. The liquid crystal display panel according to claim 7, wherein a director direction of the liquid crystal molecules is aligned by applying an electric field between the pair of substrates in a direction parallel or oblique to the substrate surface. Manufacturing method. 10. A director direction of said liquid crystal molecules is made parallel to a substrate surface by applying a voltage between adjacent pixel electrodes among a plurality of pixel electrodes formed on one of said pair of substrates. The method for manufacturing a liquid crystal display panel according to claim 7, wherein: 11. A method of applying a voltage between a specific pixel electrode of a plurality of pixel electrodes formed on one of the pair of substrates and a counter electrode formed on the other substrate to thereby form the liquid crystal molecules. 9. The method for manufacturing a liquid crystal display panel according to claim 7, wherein a director direction is aligned in a direction oblique to a substrate surface.