JPH0943560A - Production of liquid crystal display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the yield of production and to reduce a manufacturing cost while attaining good display characteristics. SOLUTION: This process for producing a liquid crystal display panel consists successively of a stage A to a stage E. The stage A: Transparent electrode patterns 9, 10 consisting of ITO and having a thickness of 1700 to 1900Å are formed on glass substrates 5, 6 to form display regions. The stage B: Oriented films 11, 12 consisting of a polyimide resin and having a thickness of 1450 to 1550Å are formed on the display region of the glass substrates 5, 6. The stage C: The surfaces of the oriented films 11, 12 existing on the respective display regions on the glass substrates 5, 6 are subjected to rubbing treatments. The stage D: The glass substrate 5 and the glass substrate 6 are stuck to each other via sealing parts 7 disposed along the circumference of the display regions to form an empty cell. The stage E: A liquid crystal material 8 is injected into the display region in the empty cell to form a liquid crystal cell 4.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to indium tin oxide (IT) on a glass substrate or an organic film.
The present invention relates to a method for manufacturing a liquid crystal display panel in which a transparent electrode pattern made of O) is formed, and then an alignment film made of a polyimide resin is applied and formed.

[0002]

A matrix type in which a transparent electrode pattern made of ITO is formed on a glass substrate, and then an alignment film made of a polyimide resin is formed, and two such substrates are bonded together via a liquid crystal layer. The liquid crystal display panel of has been commercialized.

In designing this matrix type liquid crystal display panel, regarding the respective film thicknesses of the transparent electrode pattern and the alignment film, it is necessary to improve the display characteristics such as the transmittance and the voltage characteristic, and the resistance value of the transparent electrode pattern. Is to be optimized.

Therefore, the film thickness range of the transparent electrode pattern is set to 1500 to 1700Å and the film thickness range of the alignment film is set to 1450 to 1550Å as the optimum range for the following reasons. That is, the film thickness of the transparent electrode pattern is optimal so that the resistivity is reduced and the display characteristics are improved, crosstalk and contrast are not reduced, and the screen brightness is increased so that the transparent electrode pattern is not visible. Set,
Regarding the film thickness range of the alignment film, wetting is moderate and repellency does not occur, sufficient coating printing is possible, and response is good, crosstalk does not occur, and contrast and voltage drop Has been optimally set so that is not caused.

[0005]

As described above, the reason for determining the optimum range of each film thickness of the conventional transparent electrode pattern and the alignment film is to maximize the display characteristics. The manufacturing technology, especially the technical idea of improving the manufacturing yield, has not been studied at all.

Therefore, when the transparent electrode pattern and the alignment film are sequentially formed, there is a problem that a defect as shown in FIG. 4 occurs. That is, in the figure, 1 is a glass substrate, 2 is a transparent electrode pattern made of ITO provided on the glass substrate 1, and 3 is an alignment film made of a polyimide resin provided on the transparent electrode pattern 2. Two
Is formed by vapor deposition or sputtering, and the alignment film 3 is formed by coating. However, if there is a foreign substance in the alignment film 3 or if the transparent electrode pattern 2 is contaminated, the alignment film 3 may have a non-uniform thickness, and the wettability may be poor, resulting in cissing. There was a problem.

In addition, when the foreign matter is large, rubbing the alignment film 3 causes damage such as scratches to the rubbing roller, and if the rubbing roller is continuously used, rubbing streaks (alignment flaws) occur. There was a problem to do.

Therefore, in order to maximize the display characteristics, the optimum range of each film thickness of the transparent electrode pattern and the alignment film is determined. When a final inspection was performed after assembling the liquid crystal display panel, these defects were found, which resulted in a defective product, resulting in a decrease in manufacturing yield. For example, in the final inspection, the unevenness of the film thickness of the alignment film 3 is confirmed as the light and shade of the display at the time of lighting because the optimum drive voltage Vop is different.

As a result of earnest studies in view of the above circumstances, the present inventor has made the film thickness of the transparent electrode pattern thicker than the conventional one, and further enhances the reflectance at the interface between the transparent electrode pattern and the alignment film. This facilitates visual inspection, which makes it possible to easily find defects such as film thickness unevenness and cissing of the alignment film, so it is possible to make a pass / fail judgment in advance before assembling as a liquid crystal display panel, and further, it is possible to check the lines during rubbing. In addition, the light transmittance can be prevented within a range that does not hinder practical use, and the screen brightness can be increased to the extent that the transparent electrode pattern cannot be visually confirmed, and good characteristics can be obtained. I found out that.

Therefore, the present invention has been completed based on the above findings, and an object thereof is to achieve good display characteristics, increase the manufacturing yield, and reduce the manufacturing cost.
Accordingly, it is to provide a high quality and low cost liquid crystal display panel.

[0011]

A method of manufacturing a liquid crystal display panel according to the present invention is characterized by comprising the following steps A to E in sequence.

Step A: A transparent electrode pattern made of ITO and having a thickness of 1700 to 1900Å is formed on one transparent substrate and the other transparent substrate by a thin film forming means to provide a display area. Step B: An alignment film made of a polyimide resin and having a thickness of 1450 to 1550Å is applied and formed on the transparent electrode pattern of one transparent substrate and the transparent electrode pattern of the other transparent substrate. Step C: The surface of each alignment film on one transparent substrate and the other transparent substrate is rubbed. Step D: One transparent substrate and the other transparent substrate are bonded together via a sealing member made of an adhesive resin arranged along the periphery of the display area to form an empty cell. Step E: A liquid crystal material is injected into a display region between two transparent substrates in an empty cell to form a liquid crystal cell.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to FIGS. FIG. 1 and FIG. 2 show a configuration before mounting a driving semiconductor element of a COG type liquid crystal display panel, which is called a liquid crystal cell 4. FIG. 1 is a front view of the liquid crystal cell 4,
FIG. 2 is a sectional view taken along the section line X-X shown in FIG.
FIG. 3 is an enlarged sectional view of a main part of the liquid crystal cell 4.

First, according to the liquid crystal cell 4 shown in FIGS. 1 and 2, the (signal side) glass substrate 5 as the one transparent substrate and the (scanning side) glass substrate 6 as the other transparent substrate are sealed. The liquid crystal material 8 is sealed in the inner region surrounded by the seal portion 7 to form a display region H. ITO transparent electrodes 9 and 10 (film thickness: 1700 to 1900Å) as the transparent electrode pattern are arranged on the inner main surfaces of the glass substrates 5 and 6, respectively. These ITO transparent electrodes 9 and 10 are arranged so as to be orthogonal to each other, and alignment films 11 and 12 (film thickness after firing: 1450 to 1550Å) are formed thereon, and the surfaces of the alignment films 11 and 12 are rubbed. By processing, the orientation of the liquid crystal molecules is set to a predetermined direction.

According to the present invention, the liquid crystal cell 4 described above is used.
In sequentially manufacturing Steps A to E,
In the process A, the thickness of the ITO transparent electrodes 9 and 10 is set to 1500 to 1700 Å (excluding 1700 Å) of the conventional
To 1700 to 1900Å, and by combining the alignment films 11 and 12 having a thickness of 1450 to 1550Å to increase the light reflectance at the interface between the ITO transparent electrodes 9 and 10 and the alignment films 11 and 12. Since the reflected light on the surface of the alignment film becomes relatively small, detection of the presence of foreign matter and film thickness unevenness is not hindered by the reflected light, visual inspection becomes easy, and the liquid crystal cell 4 is assembled. Good or bad can be determined in advance, and as a result, the manufacturing yield can be increased and the manufacturing cost can be reduced.

Moreover, even if the thickness of the ITO transparent electrodes 9 and 10 is made thicker than in the conventional case and the light transmittance is reduced, the brightness of the screen can be increased to the extent that the transparent electrode pattern cannot be visually confirmed. Good characteristics are obtained.

[0017]

EXAMPLE Next, an example of steps for producing the liquid crystal cell 4 will be described in detail. Step A : An ITO film (thickness 1750Å) is formed on one main surface of the glass substrate 6 by sputtering using an in-line sputtering device manufactured by ULVAC, Inc., and a plurality of I's are formed in a square or rectangular display region H by photoetching.
The TO transparent electrodes 10 are arranged in a line. Although not shown, a silver paste for conducting the ITO transparent electrode 10 of the glass substrate 6 on the glass substrate 5 is applied.

ITO is also formed on one main surface of the other glass substrate 5.
A film is formed and a plurality of ITO transparent electrodes 9 are linearly arranged in the display area H by photoetching, and the ITO transparent electrodes 9 are extended to the non-display area of the glass substrate 5. After that, a Ni-P layer is provided over the entire ITO transparent electrode 9 by electroless plating, and then the Ni-P layer on the display area H is removed by etching. Thus, the Ni-P layer is formed on the ITO transparent electrode 9 in the non-display area. Provide layers.

Step B : N in the non-display area of the glass substrate 13
An insulating film is formed on a part of the i-P layer. Then, the transparent electrode patterns 9, 10 in the respective display areas H of the glass substrates 4, 5 are formed.
Alignment films 11 and 12 are formed by coating. For this coating, a polyimide material of SE3510 manufactured by Nissan Kagaku Co., Ltd. was used, and coating was performed using Angstromer manufactured by Nissha Printing Co., Ltd. After that, it was calcined at about 100 ° C., dried, and then further calcined at about 230 to 300 ° C. and solidified by heating, so that it contracted by about 5% to a thickness of 1500 Å.

Step C : each display area H of the glass substrates 4 and 5
The surface of the upper alignment films 11 and 12 is rubbed.

Step D : The glass substrates 4 and 5 are arranged such that the ITO transparent electrode lines 9 and 10 intersect and face each other, and then the periphery of the display region H is bonded via the seal portion 7. To form an empty cell.

Step E : In this empty cell, the display area H
A liquid crystal material 8 is injected thereinto to form a liquid crystal cell. After the above steps, a lighting inspection can be performed to remove defective products.

Thus, after the above series of steps, a COG type liquid crystal display panel in which a driving semiconductor element is mounted on the liquid crystal cell 4 can be formed.

According to the above manufacturing method, in the step A, the thickness of the transparent electrode patterns 9 and 10 is increased to 1750Å and the alignment films 11 and 1 having a thickness of 1500Å are formed.
When combined with 2, transparent electrode patterns 9, 10
It is possible to increase the light reflectance at the interface between the alignment film 11 and the alignment films 11 and 12, whereby the reflected light on the surface of the alignment films 11 and 12 becomes relatively small, and before the bonding in the process D (process C). It was possible to easily detect the presence of foreign matter and the unevenness of the film thickness by the visual inspection later. Therefore, it is possible to make a quality decision in advance before assembling the liquid crystal display panel, and as a result, it is possible to increase the manufacturing yield and reduce the manufacturing cost.

Furthermore, the transparent electrode patterns 9, 10
Even if the light transmittance is reduced due to the thickness of 1, the brightness of the screen could be increased to the extent that the transparent electrode patterns 9 and 10 could not be visually confirmed, and good characteristics were obtained.

In the above embodiment, the transparent electrode patterns 9 and 10 have a thickness of 1750Å and the alignment films 11 and 12 have a thickness of 1500Å. Was done. The others were the same as in this example.

Example 1 Thickness of transparent electrode patterns 9 and 10: 1810Å Thickness of alignment films 11 and 12: 1540Å Example 2 Thickness of transparent electrode patterns 9 and 10: 1840Å Thickness of alignment films 11 and 12: 1510Å Example 3 Transparent electrode pattern Thickness of 9 and 10: 1890 Å Thickness of alignment films 11 and 12: 1480 Å Example 4 transparent electrode patterns 9, 10 thickness: 1680 Å Thickness of alignment films 11 and 12: 1500 Å Example 5 thickness of transparent electrode patterns 9 and 10: 1920 Å Alignment Thickness of the films 11 and 12: 1500Å As a result, in each of Examples 1 to 3, the light reflectance at the interface between the transparent electrode patterns 9 and 10 and the alignment films 11 and 12 can be increased. It was possible to easily detect the presence of foreign matter and the unevenness of the film thickness by visual inspection before laminating. In addition, the brightness of the screen could be increased to the extent that the transparent electrode patterns 9 and 10 could not be visually confirmed, and good characteristics were obtained.

However, in Example 4, the presence of foreign matter and the unevenness of the film thickness could not be detected by visual inspection before the bonding in the D step, and when the final inspection was performed after the liquid crystal cell 4 was assembled, those There were cases where defects were discovered.

In Example 5, transparent electrode patterns 9, 1
The light transmittance of 0 was reduced, whereby the transparent electrode patterns 9 and 10 could be visually confirmed on the display screen.

The present invention is not limited to the above embodiments, and various modifications and improvements may be made without departing from the scope of the present invention.

[0031]

As described above, according to the manufacturing method of the present invention, the thickness of the transparent electrode pattern is set to 170 in the step A.
Thick to 0 to 1900Å, and 1450 in thickness
When the light reflectance at the interface between the transparent electrode pattern and the alignment film is increased by combining with the alignment film of ˜1550 Å, the light reflected on the surface of the alignment film becomes relatively small, whereby before assembling as a liquid crystal display panel. Moreover, since the visual inspection can be easily performed, the manufacturing yield can be increased and the manufacturing cost can be reduced. As a result, the manufacturing cost can be reduced and a low-cost liquid crystal display panel can be provided.

In addition, in the manufacturing method of the present invention, even if the thickness of the transparent electrode pattern is thicker than that of the conventional one, the brightness of the screen can be increased within a range where there is no practical problem, and the transparent electrode pattern can be visually observed. It was not confirmed, and a high-performance liquid crystal display panel that achieved good display characteristics could be provided.

[Brief description of drawings]

FIG. 1 is a front view of a liquid crystal cell of an example.

2 is a cross-sectional view taken along a section line XX in the liquid crystal cell of FIG.

FIG. 3 is an enlarged view of a main part of the liquid crystal cell of the example.

FIG. 4 is a cross-sectional view in which a transparent electrode pattern and an alignment film are provided on a glass substrate.

[Explanation of symbols]

 4 Liquid crystal cell 5, 6 Glass substrate 7 Seal part 8 Liquid crystal material 9, 10 ITO transparent electrode 11, 12 Alignment film H Display area

Claims (1)

[Claims] 1. A method of manufacturing a liquid crystal display panel, which comprises the following steps A to E in sequence. Step A: ITO on one transparent substrate and the other transparent substrate
A transparent electrode pattern having a thickness of 1700 to 1900Å is formed by a thin film forming means to provide a display region. Step B: An alignment film made of a polyimide resin and having a thickness of 1450 to 1550Å is applied and formed on the transparent electrode pattern of one transparent substrate and the transparent electrode pattern of the other transparent substrate. Step C: The surface of each alignment film on one transparent substrate and the other transparent substrate is rubbed. Step D: One transparent substrate and the other transparent substrate are bonded together via a sealing member made of an adhesive resin arranged along the periphery of the display area to form an empty cell. Step E: A liquid crystal material is injected into a display region between two transparent substrates in an empty cell to form a liquid crystal cell.