JPH0572568A - Production of liquid crystal display device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for easily manufacturing a large-screen liquid crystal display device that achieves even and clear image display. [Composition] In a varistor element used as an active matrix element, varistor particles forming the element are mixed with a thermally decomposable or combustible organic binder, and this is transferred onto a substrate by screen printing or the like, and then heated. The organic binder is removed so that only the varistor particles are present on the substrate. This is pressed by mechanically applying an external force, and a mixture of glass frit and an organic binder having thermal decomposability or combustibility is transferred onto the varistor particles on the substrate by screen printing,
Then, the glass frit is melted by heating, and the organic binder is removed to fix the varistor particles on the substrate to form a varistor element as an active matrix element to manufacture a liquid crystal display device.

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. 8, a liquid crystal 14 and a predetermined threshold voltage are applied between the scanning electrode 11 and the signal electrode 16. A varistor element 13 that conducts is electrically arranged in series and connected, and utilizes the non-linear current-voltage characteristics of the varistor element 13 as shown in FIG.

FIG. 9 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. 10, the varistor element 13 has a varistor particle 13 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. 11, these varistor particles 13a are fixed on a substrate with a glass frit 13b. For this reason, usually, a sintered varistor element is made into a paste by adding glass frit, an organic binder, and an organic solvent to varistor particles to form a varistor ink, which is applied to a printing method such as screen printing on a glass substrate having an electrode. It is formed by printing and then heating to melt the glass frit and fix the varistor particles on the substrate.

[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. However, when forming a varistor element, an organic binder is added to the varistor particles to give printability, and a glass frit is added to fix the varistor particles on the substrate after heating. The organic binder is a component that is removed by heating after printing, and the glass frit particles are transferred along with the varistor particles onto the substrate and then melted. For this reason, the completed element inevitably has a portion where no varistor particles are present. Therefore, the packing density of the varistor particles in the varistor element becomes small.

In the varistor element, current flows through individual varistor particles. Therefore, the smaller packing density of the varistor particles means that the conduction path inside the varistor element becomes longer. This causes variations in the electrical characteristics among the varistor elements. The small packing density also affects the thickness direction of the device. This is related to the variation in the thickness of the element and causes unevenness of the cell gap of the liquid crystal panel. 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, and in each varistor element, the packing density of varistor particles is high, the electric characteristics of the element are high, and the variation in thickness is high. It is an object of the present invention to provide a method for manufacturing a liquid crystal display device which has a constant value.

[0011]

In forming a varistor element used as an active matrix element in a method of manufacturing a liquid crystal display device, a varistor paste containing a mixture of varistor particles and an organic binder as a main component is used for screen printing or the like. The organic binder component is removed by transferring to a substrate by a printing method and heating it so that only the varistor particles are present on the substrate. By pressing the element with a means such as a roll press, the packing density in the horizontal direction and the thickness direction is improved. After that, a paste containing glass frit as a main component is transferred by a printing method such as screen printing so as to cover the varistor particles, and the glass frit is melted by heating to fix the varistor particles on the substrate to form a varistor element. Form. After that, an upper glass substrate provided with a signal electrode and a color filter was bonded to the upper part of them at a predetermined interval, and liquid crystal was injected and filled between them to manufacture a liquid crystal display device.

[0012]

In the present invention, when a varistor element is formed, a paste containing only varistor particles and an organic binder and containing no glass frit used for fixing varistor particles is used and transferred to a substrate. The organic binder is removed by heating. After that, by pressing this, the arrangement of the varistor elements on the substrate is adjusted in advance, and the packing density of varistor particles in the element is improved. Further, a paste containing glass frit as a main component is transferred onto it, and the glass frit is melted by heating the paste, and the glass frit fixes the varistor particles to the substrate to form a varistor element. After that, the upper glass substrate is bonded, and liquid crystal is injected and filled between them to manufacture a liquid crystal display device. Therefore, it is easy to provide a method of manufacturing a liquid crystal display device in which the packing density of varistor particles in each varistor element is high, the electrical characteristics of the element are high, and the variation in thickness is high and the performance is constant between elements. To

[0013]

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

(Embodiment 1) FIGS. 1 to 5 are cross-sectional views of forming a varistor element in a liquid crystal display device according to the present invention.
FIG. 6 is a plan view of a liquid crystal display device according to the present invention, and FIG. 7 is a sectional view taken along the line AA ′ of FIG.

As shown in FIG. 6, 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 is provided as a two-terminal element. A TN type liquid crystal is injected and filled as the liquid crystal 14 between the upper glass substrate 17 provided with the signal electrode 16 and the color filter 18 and the lower glass substrate 10.

Since the TN type liquid crystal 14 is used here,
Alignment film 1 for aligning liquid crystal 14 between lower glass substrate 10, layer of liquid crystal 14, and 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 paste containing varistor particles as a main component was transferred onto the lower glass substrate 10 using a 325 mesh screen plate as shown in FIG.

The paste used here is mainly composed of varistor particles and polymethylmethacrylate, and 20 parts of varistor particles are mixed with 15 parts of polymethylmethacrylate.
Parts, and a mixture of 5 parts of ethyl carbitol as a solvent was used. As shown in detail in FIG. 10, 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.

The substrate to which this paste was transferred was placed in air,
It was heated at 420 ° C. for 1 hour to remove polymethyl methacrylate and ethyl carbitol so that only the varistor particles remained on the substrate as shown in FIG.

By passing this through a roll press and pressing it, the space occupied by the removed components was eliminated as shown in FIG. 3 so that the varistor particles were densely arranged.

Further, a paste consisting of 5 parts of glass frit, 15 parts of polymethylmethacrylate and 5 parts of ethylcarbitol was used with a 325 mesh screen plate.
As shown in FIG. 4, it was transferred onto the varistor particles.

This was heated in air at 420 ° C. for 1 hour to melt the glass frit and fix the varistor particles to the substrate to form the lower glass substrate 10 having varistor elements as shown in FIG.

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 18, the alignment film 15, and the signal electrode 16 formed 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 14 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,
A liquid crystal display device having a high packing density of varistor particles in each varistor element, high performance with respect to the electrical characteristics and thickness of the element, and constant performance among the elements was obtained.

(Embodiment 2) FIGS. 1 to 5 are sectional views showing formation of varistor elements in a liquid crystal display device according to the present invention.
FIG. 6 is a plan view of a liquid crystal display device according to the present invention, and FIG. 7 is a sectional view taken along the line AA ′ of FIG.

As shown in FIG. 6, 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 is provided as a two-terminal element. A TN type liquid crystal is injected and filled as the liquid crystal 14 between the upper glass substrate 17 provided with the signal electrode 16 and the color filter 18 and the lower glass substrate 10.

Since the TN type liquid crystal 14 is used here,
Alignment film 1 for aligning liquid crystal 14 between lower glass substrate 10, layer of liquid crystal 14, and 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 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.

The paste containing varistor particles as a main component was transferred onto this lower glass substrate 10 using a 325 mesh screen plate as shown in FIG.

The paste used here was mainly composed of varistor particles and ethyl cellulose, and used was a mixture of 20 parts of varistor particles with 5 parts of ethyl cellulose and 10 parts of ethyl carbitol as a solvent.
As shown in detail in FIG. 10, 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.

The substrate to which this paste was transferred was placed in air,
It was heated at 420 ° C. for 1 hour to remove ethyl cellulose and ethyl carbitol so that only the varistor particles remained on the substrate as shown in FIG.

This was passed through a roll pressing machine and pressed to eliminate the space where the binder was removed as shown in FIG. 3 so that the varistor particles were densely arranged.

Further, a paste consisting of 5 parts of glass frit, 5 parts of ethyl cellulose and 15 parts of ethyl carbitol was transferred onto the varistor particles as shown in FIG. 4 using a 325 mesh screen plate.

This is heated in air at 420 ° C. for 1 hour to melt the glass frit so that the glass frit binds the varistor particles to each other and also binds to the substrate to form a varistor element as shown in FIG. The side glass substrate 10 was formed.

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 18, the alignment film 15, and the signal electrode 16 formed 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 14 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, the polarizing plate 19 is placed outside the lower glass substrate 10 and the upper glass substrate 17. As a result,
A liquid crystal display device having a high packing density of varistor particles in each varistor element, high performance with respect to the electrical characteristics and thickness of the element, and constant performance among the elements 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 the 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.

[0043]

According to the method of manufacturing a liquid crystal display device of the present invention, in each varistor element used as an active matrix element, the packing density of varistor particles is high, the electrical characteristics and the thickness are high, and the element has high performance. It is possible to obtain a constant element between them. As a result, it is possible to obtain a large-screen liquid crystal display device that achieves even and clear image display.

[0044]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an element formation in a manufacturing method of a liquid crystal display device of the present invention in the order of steps.

FIG. 2 is a cross-sectional view showing an example of an element formation in the method of manufacturing a liquid crystal display device of the present invention in the order of steps.

FIG. 3 is a cross-sectional view showing an example of an element formation in the method of manufacturing a liquid crystal display device of the present invention in the order of steps.

FIG. 4 is a cross-sectional view showing an example of an element formation in the method of manufacturing a liquid crystal display device of the present invention in the order of steps.

FIG. 5 is a cross-sectional view showing, in the order of steps, an embodiment of forming an element in the method for manufacturing a liquid crystal display device of the present invention.

FIG. 6 is a plan view of a liquid crystal display device according to an embodiment of the present invention.

7 is a cross-sectional view showing a section taken along line AA ′ in FIG.

FIG. 8 is an equivalent circuit diagram of a two-terminal element type liquid crystal display device.

FIG. 9 is a plan view showing an example of a general two-terminal element type liquid crystal display device.

FIG. 10 is a cross-sectional view of varistor particles.

FIG. 11 is an enlarged view of a main part of a varistor element.

FIG. 12 is a graph showing voltage-current characteristics of a varistor element.

[Explanation of Codes] 10 Lower Glass Substrate 11 Scanning Electrode 12 Pixel Electrode 13 Varistor Element 13a Varistor Particle 13b Glass Frit 131 ZnO Single Crystal Particle 132 Inorganic Insulating Film 14 Liquid Crystal 15 Alignment Film 16 Signal Electrode 17 Upper Glass Substrate 18 Color Filter 19 Polarizer

Claims (1)

[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. Mixing varistor particles with an organic binder having thermal decomposability or flammability,
This is transferred to the substrate by the printing method and then heated to remove the organic binder, leaving only the varistor particles on the substrate, mechanically applying external force and pressing, and then glass frit and thermal decomposition on it. A mixture of organic and flammable organic binders is transferred onto the varistor particles on the substrate by the printing method, and then the glass frit is melted by heating, and the organic binder is removed to form the varistor particles on the substrate. A method for manufacturing a liquid crystal display device, which comprises fixing and forming a varistor element as an active matrix element.