JPH0572567A - Production of liquid crystal display device - Google Patents

Abstract

PURPOSE:To easily produce a liquid crystal display device with a large screen attaining clear image display free from uneveness. CONSTITUTION:A resin layer 14 is previously formed by coating with a photosensitive resin on a substrate on which a varistor element 13 is formed and only the part of the layer 14 corresponding to the element 13 is removed by photolithography. The resulting hole is filled with varistor paste based on a mixture of varistor particles with an org. binder by means of a doctor blade, etc., and the paste is hardened to form a varistor element 13. Function as a color filter can also be imparted by coloring the resin layer 14.

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 two-terminal element type liquid crystal display device using a varistor element as a non-linear element.

[0002]

2. Description of the Related Art At present, image display devices such as liquid crystal televisions are roughly classified into a simple matrix system and an active matrix system. In the simple matrix system, a plurality of liquid crystal pixels are arranged in a matrix between a pair of strip-shaped electrode groups (a signal electrode group and a scanning electrode group) that are provided at a right angle, and the liquid crystal pixels are connected between these strip-shaped electrodes. A predetermined voltage is applied by a driving circuit to operate the liquid crystal pixels. This method has an advantage that the system can be realized at a low cost due to its simple structure, but since crosstalk occurs in each liquid crystal pixel, the pixel contrast is low, and the image quality is improved when displaying an image on a liquid crystal television. The decline was inevitable.

On the other hand, in the active matrix system, a switching element is provided for each liquid crystal pixel to hold the voltage, and the liquid crystal pixel holds the voltage at the time of selection even when the liquid crystal display device is time-division driven. Therefore, the display capacity can be increased, the characteristics relating to the image quality such as the contrast are good, and the high image quality display of the liquid crystal television can be realized. However, the active matrix method has a drawback that the structure is complicated and the manufacturing cost is increased. For example, in a TFT type using a thin film transistor as a switching element, it is difficult to increase the product yield because five or more thin films are stacked in the manufacturing process.

In view of the above, it is desired to realize a liquid crystal display device having good characteristics relating to image quality such as contrast and having a simple structure and low cost. As a method for realizing such a demand, A two-terminal element type liquid crystal display device using a varistor element is drawing attention.

The two-terminal element type liquid crystal display device is an improvement of the simple matrix system, and as shown in FIG. 4, a liquid crystal 18 and a predetermined threshold voltage are provided between the scanning electrode 11 and the signal electrode 16. The varistor element 13 which is conductive is electrically connected in series and connected, and utilizes the non-linear current-voltage characteristic of the varistor element 13 as shown in FIG.

FIG. 5 shows a general two-terminal element type liquid crystal display device using a varistor element as an active matrix element. As shown here, the scanning electrodes 11 and the pixel electrodes 12 are provided on the lower glass substrate at a constant distance d, and the scanning electrodes 11 and the pixel electrodes 12 are fixed in threshold voltage V _{V in} each varistor element 13. Connected with. Then, liquid crystal is injected and filled between the upper glass substrate on which the signal electrodes and the color filters are provided at a predetermined distance above them. The liquid crystal used here is generally a TN (twisted nematic) type liquid crystal.

As shown in detail in FIG. 6, the varistor element 13 has a varistor particle 13a in which the surface of a ZnO single crystal particle 131 is covered with an inorganic insulating film 132 such as Mn or Co oxide.
As shown in detail in FIG. 7, these varistor particles 13a are fixed on a substrate with a binder resin 13b. Therefore, normally, the varistor element substrate is made into paste by adding resin as a binder to varistor particles,
A varistor ink is used, which is printed on a glass substrate provided with an electrode by a printing method such as screen printing, and then the resin is cured to form the varistor ink.

[0008]

In particular, the image quality of 2 is excellent.
In order to realize the terminal element type liquid crystal display device, it is necessary that the varistor element has high performance and high stability, and the performance is constant between the elements. Further, it is required that the distance between the upper glass substrate and the lower glass substrate is uniform over the entire surface. However, for example, when an element is printed by screen printing by using varistor particles as an ink and screen printing is performed, there are plate elongation and distortion, which are essential problems of screen printing, and printing position deviation occurs. In addition, changes in the ink viscosity during printing, changes in printing conditions due to wear of the squeegee, and the like have a great influence on the element shape, thickness, and the like. Therefore, the positional deviation of the varistor element on the substrate and the variation in thickness are large. This causes variations in the electrical characteristics among the varistor elements. For this reason, it is difficult to manufacture a liquid crystal display device having good characteristics relating to image quality such as contrast.

The present invention has been made in view of the above-mentioned conventional circumstances. In each varistor element, the position on the substrate is accurate, the thickness variation is small, and the varistor element can be manufactured in a good shape, and the performance is high. An object of the present invention is to provide a method for manufacturing a liquid crystal display device in which the performance is constant between elements.

[0010]

In a method of manufacturing a liquid crystal display device, a resin layer is formed by applying a photosensitive resin in advance on a substrate on which a varistor element is formed, and then a varistor element is formed by photolithography. Only the part you want to remove, fill the varistor paste mainly composed of a mixture of varistor particles with an organic binder with a doctor blade or the like, and then cure the paste to form a varistor element. The upper glass substrate provided with the column electrodes and the color filters is attached to the upper part with a predetermined space,
The problem was solved by manufacturing a liquid crystal display device by injecting and filling liquid crystal in the meantime.

When the resin layer is formed on the substrate, the resin is colored in three colors of red, green and blue,
This can also be used as it is as a color filter. In that case, the color filter provided on the upper glass substrate can be omitted.

[0012]

In the present invention, a resin layer is formed by applying a photosensitive resin in advance on a substrate on which a varistor element is formed, and only the portion where the varistor element is to be formed is removed by photolithography. A varistor element is formed by filling the removed portion with a doctor blade or the like and containing the varistor paste whose main component is a mixture of varistors and then curing the paste. A liquid crystal display device is manufactured by bonding an upper glass substrate provided with a column electrode and a color filter on the upper part thereof with a predetermined gap, and injecting and filling a liquid crystal therebetween. Therefore, the position of the element on the substrate is determined by photolithography. Therefore, high reproducibility and high position accuracy can be obtained. Further, since the element thickness is defined by the thickness when the photosensitive resin is applied on the substrate, there is little variation in the thickness, and an element having a better shape than the printing method can be obtained. As described above, since the position of the varistor element on the substrate is accurate, the variation in thickness is small, and the shape is good, it is easy to obtain a varistor element substrate with high performance and constant performance between elements. ..

[0013]

Embodiments will be specifically described based on embodiments of the present invention.

(Embodiment 1) FIG. 1 is a plan view of a liquid crystal display device according to the present invention. FIG. 2 is a sectional view taken along the line AA ′ of FIG.

As shown in FIG. 2, in the liquid crystal display device of this embodiment, the scanning electrode 11 and the pixel electrode 1 are provided on the lower glass substrate 10.
2. A varistor element 13 and a resin layer 14 are provided as a two-terminal element. Then, a TN type liquid crystal is injected and filled as the liquid crystal 18 between the upper glass substrate 17 provided with the signal electrode 16 and the color filter 20 and the lower glass substrate 10.

Since the TN type liquid crystal 18 is used here,
Alignment film 1 for aligning the liquid crystal 18 between the lower glass substrate 10, the layer of the liquid crystal 18, and the upper glass substrate 17.
5 is installed, the lower glass substrate 10 and the upper glass substrate 1
In this configuration, the polarizing plate 19 is installed on the outside of 7.

The liquid crystal display device having the above structure is manufactured by the following steps.

First, an ITO film (indium oxide / tin oxide film) having a thickness of 1100 Å is formed on the lower glass substrate 10 by using a magnetron sputtering device, and a resist pattern is formed on the ITO film (photolithography process) to oxidize the film. The scan electrode 11 and the pixel electrode 12 are formed with an etching solution of ferric: hydrochloric acid = 1: 3.

A photosensitive resin containing methyl methacrylate as a main component is applied to the lower glass substrate 10 by screen printing so as to have a thickness of 8 μm, and a portion for forming a varistor element on the substrate is removed by a photolithography process. The resin layer 14 thus formed is formed.

A paste containing varistor particles as a main component was filled in the resin-removed portion using a doctor blade and dried at 100 ° C. for 20 minutes to be cured to form a varistor element 13, and then a polyimide-based orientation was performed. Membrane 15
Apply 00Å.

The paste used here is mainly composed of varistor particles and polymethylmethacrylate, and 20 parts of varistor particles and 30 parts of polymethylmethacrylate are used.
Parts, and a mixture of 70 parts of ethyl carbitol as a solvent was used. As shown in detail in FIG. 6, the varistor particles are obtained by coating the surface of ZnO single crystal particles 131 with an inorganic insulating film 132 such as Mn or Co oxide.

Next, an epoxy resin for adhesion containing 2.5% by weight of glass beads is printed by screen printing on the upper glass substrate 17 composed of the color filter 20, the alignment film 15, and the signal electrode 16 made of the ITO film, and the lower side is printed. After being aligned with the glass substrate 10, they are bonded together and pressure-bonded.

Then, a TN type liquid crystal as the liquid crystal 18 is filled into this panel through an injection port provided in a part of the adhesive portion, and after the filling, the injection port is sealed.

Then, a polarizing plate 19 is set outside the lower glass substrate 10 and the upper glass substrate 17. As a result,
The position of the varistor element 13 on the substrate is accurate,
A liquid crystal display device using a varistor element having high performance and constant performance among the elements as an active matrix element because the variation in thickness is small and the shape is good was obtained.

(Embodiment 2) FIG. 1 is a plan view of a liquid crystal display device according to the present invention. FIG. 3 is a sectional view taken along line AA ′ of FIG.

As shown in FIG. 3, in the liquid crystal display device of this embodiment, the scanning electrode 11 and the pixel electrode 1 are provided on the lower glass substrate 10.
2. A varistor element 13 and a resin layer 14 are provided as a two-terminal element. A TN type liquid crystal is injected and filled as the liquid crystal 18 between the upper glass substrate 17 provided with the signal electrode 16 and the lower glass substrate 10.

Since the TN type liquid crystal is used here, an alignment film layer 15 for aligning the liquid crystal is provided between the lower glass substrate 10, the layer of the liquid crystal 18, and the upper glass substrate 17, and the lower layer is provided. A polarizing plate 19 is installed outside the glass substrate 10 and the upper glass substrate 17.

The liquid crystal display device having the above structure is manufactured by the following steps.

First, an ITO film (indium oxide / tin oxide film) having a thickness of 1100 Å was formed on the lower glass substrate 10 by using a magnetron sputtering apparatus, and a resist pattern was formed on the ITO film by a photolithography process to oxidize the film. The scan electrode 11 and the pixel electrode 12 are formed with an etching solution of ferric: hydrochloric acid = 1: 3.

Next, a red photosensitive pigment-dispersed resist is spin-coated on the lower substrate 10 and patterned by a photolithography process so that the portion forming the varistor element 13 is removed, and then baked to form a pattern. It was fixed to form a red colored layer. The green colored layer and the blue colored layer were similarly processed to form the resin layer 14 as a color filter.

A paste containing varistor particles as a main component was filled in the resin-removed portion using a doctor blade and heat-cured at 100 ° C. for 20 minutes to form a varistor element 13, and then a polyimide-based alignment film 15 was formed. Apply 500Å.

The paste used here is mainly composed of varistor particles and polymethylmethacrylate, and 20 parts of varistor particles and 30 parts of polymethylmethacrylate are used.
Parts, and a mixture of 70 parts of ethyl carbitol as a solvent was used. In addition, the varistor element, as shown in detail in FIG.
It is covered with an inorganic insulating film 132 such as an oxide.

Next, an epoxy resin for adhesion containing 2.5% by weight of glass beads is printed by screen printing on the upper glass substrate 17 composed of the alignment film 15 and the signal electrode 16 made of an ITO film to form the lower glass substrate 10. After aligning, align and pressure bond.

Then, a TN type liquid crystal as the liquid crystal 18 is filled into this panel through an injection port provided in a part of the adhesive portion, and after the filling, the injection port is sealed.

Then, a polarizing plate 19 is set outside the lower glass substrate 10 and the upper glass substrate 17. As a result,
The position of the varistor element 13 on the substrate is accurate,
A liquid crystal display device using a varistor element having high performance and constant performance among the elements as an active matrix element because the variation in thickness is small and the shape is good was obtained.

In the present invention, it is possible to use a metal thin film such as Cr as a row electrode material for reducing wiring resistance. Further, the liquid crystal can be applied not only to the TN type, but also to a liquid crystal display device using a guest host type, a polymer dispersed type, or the like.

[0037]

According to the method of manufacturing a liquid crystal display device of the present invention, it is possible to obtain an element which is formed at a desired position for a varistor element used as an active matrix element and has a small thickness variation and a good shape. As a result, it is easy to obtain a varistor element having high performance and constant performance among the elements, and it is possible to obtain a large-screen liquid crystal display device that achieves even and clear image display.

[0038]

[Brief description of drawings]

FIG. 1 is a plan view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of Example 1 showing a section taken along line AA ′ in FIG.

FIG. 3 is a cross-sectional view of a second embodiment showing a section taken along line AA ′ in FIG.

FIG. 4 is an equivalent circuit diagram of a two-terminal element type liquid crystal display device.

FIG. 5 is a plan view showing an example of a general two-terminal element type liquid crystal display device.

FIG. 6 is a cross-sectional view of varistor particles.

FIG. 7 is an enlarged view of a main part of a varistor element.

FIG. 8 is a graph showing voltage-current characteristics of a varistor element.

[Explanation of symbols]

 10 Lower Glass Substrate 11 Scanning Electrode 12 Pixel Electrode 13 Varistor Element 13a Varistor Particle 13b Binder 131 ZnO Single Crystal Particle 132 Inorganic Insulating Film 14 Resin Layer 15 Alignment Film 16 Signal Electrode 17 Upper Glass Substrate 18 Liquid Crystal 19 Polarizing Plate 20 Color Filter

Claims (2)

[Claims] 1. A varistor element is formed in a method of manufacturing a liquid crystal display device, in which a varistor element used as an active matrix element and a liquid crystal pixel are electrically connected in series between a signal electrode and a scanning electrode. Form a resin layer by applying a photosensitive resin in advance on the substrate
This is removed by photolithography only the part where the varistor element is to be formed, and the removed part is filled with a varistor paste whose main component is a mixture of varistor particles with an organic binder, and then the paste is cured. A method for manufacturing a liquid crystal display device, which comprises forming a varistor element. 2. The method of manufacturing a liquid crystal display device according to claim 1, wherein the resin layer which has not been removed is colored to form a color filter.