JPH04123024A - Liquid crystal display device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a two-terminal element type liquid crystal display (LCD) using a sintered varistor element as a nonlinear element.

(Prior Art) At present, image display devices for, for example, liquid crystal televisions are broadly classified into a simple matrix type and an active matrix type.

In the simple matrix method, a plurality of liquid crystal pixels are arranged in a matrix and connected between band-shaped electrode groups (row electrode group and column electrode group) arranged at right angles. A circuit applies a predetermined voltage to activate the liquid crystal pixels. This method has the advantage of being able to realize a system at a low cost because of its simple structure.However, because cross-tocks occur in each LCD pixel, the contrast of the image is low, and it cannot be used for displaying images on LCD TVs. Ta.

On the other hand, in the active matrix method, a switch is provided for each liquid crystal pixel to maintain the voltage, and even if the liquid crystal display device is time-divisionally driven, the liquid crystal pixel can maintain the voltage at the time of selection. It is possible to increase the display capacity, has good image quality characteristics such as contrast, and can realize image display on a liquid crystal television. However, the actitus matrix method has the disadvantage that the structure is complicated and the manufacturing cost is high.

For example, in a TFT type switch that uses a film-like field effect transistor as a switch, it is difficult to increase the yield of the product because five or more photomasks are used in the manufacturing process to stack five or more thin films.

Due to the above-mentioned circumstances, it is desired to realize a liquid crystal display device that has good image quality characteristics such as contrast, has a simple structure, and is low in cost. Sintered varistor elements are a method to achieve these demands. A two-terminal element type liquid crystal display device using a 2-terminal device is attracting attention.

The two-terminal element type liquid crystal display device is an improvement on the simple matrix method, and has row electrodes 1 and column electrodes 2 as shown in FIG.
A liquid crystal pixel 4 and a sintered varistor element 3 that conducts at a predetermined threshold voltage are electrically connected in series between the sintered varistor element 4 and the sintered varistor element 3 shown in FIG. Element 3
This utilizes the nonlinear current-voltage characteristics of In other words, in time-division driving using the simple matrix method, as shown in Figure 8, the liquid crystal pixels are turned on (light transmittance is 90%).
Voltage ■,. and off (light transmittance is 10%) Lumi pressure V
Ratio to IO r (=Vqo/V+o= (v+o+ΔV
)/Vl. ), the maximum number of scanning lines N wax allowed without causing crosstalk between each liquid crystal pixel is:
Nmax=(Cr''+1)/r2-1))2, and the smaller T is, the larger the number of scanning lines becomes, which is advantageous for liquid crystal television display.

On the other hand, in the two-terminal element type, the sintered varistor element 3
A voltage exceeding the threshold voltage V(v) is applied to the liquid crystal pixel 4, and the operating voltage of the liquid crystal pixel when no sintered body varistor element is provided (Fig. 9(a)) ) is increased by its threshold voltage V (v) by providing a sintered body varistor element (see Fig. 9(bl)).
reference). As a result, the above r no 4a qo/V
+o to (V+V*o) / (v+V,.), and the maximum number of scanning lines is N+ due to the decrease in T value! lax can be increased, and a high-quality liquid crystal display can be realized.

2 to 5 show general two-terminal element type liquid crystal display devices.

As shown in FIG. 4, row electrodes 1 are placed on the lower glass substrate 10.
1 and a pixel electrode 12 are provided at a predetermined distance d, and these row electrodes 11 and pixel electrodes 12 are connected by a sintered varistor element 13 of Zn◯.

The upper portions of these are filled with liquid crystal 14, and furthermore, column electrodes 15, color filters 16, and an upper glass substrate 17 are provided.

The sintered varistor element 13, as shown in detail in FIG.
Varistor grains 13a in which ZnO is coated with Mn and Co oxides
is sintered with a glass frit 13b, and a threshold voltage of about 3 V can be obtained for each varistor grain with a grain size of about 5 μm. Therefore, if the distance d between the row electrode 11 and the pixel electrode 12 is set to 25 μm, the row electrode 1
1 and pixel electrode 12 are connected, and these electrodes 11.12
A threshold voltage of 5×3V=15V is obtained between them.

Here, as shown in FIG. 2, a large number of pixel electrodes 12 are provided for each row electrode 11 with a radius W (hereinafter referred to as varistor width) and a constant interval d (hereinafter referred to as varistor gear). row electrode 11 and pixel electrode 12
and are connected with each sintered body varistor element 13 with a certain threshold value . In addition, in the figure, n pixel electrodes 1
2, 1.2...(n-1), a subscript of n is added sequentially.

[Problem to be solved by the invention]

The 281fI type active matrix element can realize a liquid crystal display device with a simple structure and low cost and with good image quality.However, in order to further simplify the conventional manufacturing process and reduce manufacturing costs, printing is required. Attempts have been made to form sintered varistor elements using the method.

However, in order to cause a predetermined current value to flow through the sintered body varistor element, a certain varistor width must be set between the row electrode and the pixel electrode.
The key point. In other words, as shown in FIG. 2, it is necessary to form a somewhat large sintered body varistor element in the direction of the row electrodes, which results in a decrease in the area of the portion through which light passes (hereinafter referred to as the aperture ratio).

The present invention has been made in view of the above-mentioned conventional circumstances, and it is an object of the present invention to provide a liquid crystal display device that allows a predetermined current value to flow without reducing the Sekiguchi rate too much.

[Means for Solving the Problems] A liquid crystal display device according to the present invention includes a sintered varistor element forming portion of a transparent insulating substrate in which a row electrode and a pixel electrode are connected by a sintered varistor element formed by a printing method. The above problem was solved by forming the row electrode and the pixel electrode into a comb shape.

Note that the comb shape in this specification includes a comb shape with a flat tip or a sharp tip as shown in FIG. Because the row electrodes and pixel electrodes in the forming part are comb-shaped, compared to the conventional sintered varistor element in which the row electrode and pixel electrode in the forming part are linear, the sintered varistor element in the row electrode direction is Even if the length of the varistor is short, the same effect can be obtained as if the varistor width was increased.

〔Example〕

The liquid crystal display device according to the present invention will be specifically described based on examples. Note that the same parts as in the conventional example described above are given the same reference numerals, and redundant explanations will be omitted.

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

A varistor paste was applied by screen printing to a transparent insulating substrate in which the row electrode 11 and pixel electrode 12 portions had a comb-shaped shape I8 to form a varistor pattern. The varistor paste used here has ZnO as its main component, and the ZnO production content is 80 parts by weight of the varistor powder.
20 parts of glass flint and 20 parts of propylene glycol were added and mixed to form a paste. Next, the varistor paste was fired to obtain a transparent insulating substrate on which the sintered varistor 13 was manufactured.

Thereafter, a liquid crystal display device was completed by sandwiching a liquid crystal layer between a transparent insulating substrate and a facing transparent electrode substrate on which column electrodes were formed.

In the obtained liquid crystal display device, the necessary varistor width could be secured within a small range, so the aperture ratio decreased little and a bright display screen was obtained.

〔Effect of the invention〕

According to the liquid crystal display device of the present invention, the row electrodes and pixel electrodes in the portion where the sintered body varistor element is formed are comb-shaped, so that the row electrodes and the pixel electrode in the portion where the conventional sintered body varistor element is formed are linear. Even if the length of the sintered varistor element in the row electrode direction is shorter than that of the sintered varistor element, the same effect as the varistor width can be obtained, so the aperture ratio decreases less and a brighter display screen can be obtained. Ta.

[Brief explanation of the drawing]

FIG. 1 is a plan view of one pixel of a liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a conventional liquid crystal display device, and FIG.
The figure is a plan view of one pixel of a conventional liquid crystal display device, Figure 4 is a cross-sectional view of a conventional liquid crystal display device, Figure 5 is an enlarged view of the main parts in Figure 4, and Figure 6 is a two-terminal element type. A schematic configuration diagram of a liquid crystal display device, FIG. 7 is a voltage-current characteristic diagram of a sintered varistor element,
FIG. 8 is an electro-optical characteristic diagram of a liquid crystal pixel, and FIG. 9(a) is an electro-optical characteristic diagram of a liquid crystal pixel explaining the operation of a sintered body varistor element. 11... Row electrode 12... Pixel electrode 13... Sintered body varistor element 18... Comb-shaped portion Patent Applicant Toppan Printing Co., Ltd. Representative Kazuo Suzuki Figure 1 Figure 6

Claims (1)

[Claims] (1) In a liquid crystal display device in which a liquid crystal layer is sandwiched between a transparent insulating substrate in which row electrodes and pixel electrodes are connected by sintered varistor elements formed by a printing method, and a counter transparent electrode substrate on which column electrodes are formed, A two-terminal element type liquid crystal display device, wherein the row electrode of the sintered body varistor element forming portion and the pixel electrode are comb-shaped.