JPS59105616A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce the cost in production of a liquid crystal device by forming a non-linear resistance element MIM in the intersected part of a longitudinal metallic electrode and a coupled electrode, thereby enabling the use of the full surface electrode like a three-terminal element while maintaining the simple construction of a two-terminal element. CONSTITUTION:A potential VD is impressed on a signal electrode 1 and a potential VS on a scanning electrode 2. A scanning potential VS is taken to increase ¦VD-VS¦ in the section for selecting time-divided driving and is taken to decrease the same in the section where said driving is not selected, thereby selecting the writing of the signal potential VD into the liquid crystal. A novel principle of driving is thus used for a liquid crystal display device with a two- terminal element having a non-linear resistance characteristic, so that the advantage of a three-terminal element is provided while the simple construction of the two-terminal element is maintaind. A photoetching stage for the counter substrate is thus omitted and the formation of a color filter with high quality and high stability on the counter substrate side is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display device using a two-terminal element having nonlinear resistance characteristics, and an object thereof is to provide a liquid crystal driving method that is fundamentally new using the two-terminal element. The object of the present invention is to simplify the structure of a liquid crystal display device, and to simplify the mounting method for connecting the liquid crystal cell section and drive circuit section of the liquid crystal display device.

Currently, liquid crystal display devices are moving toward higher density and more pixels in response to the demand for large-capacity display. The simple voltage-averaging driving method that has been widely used up until now has already reached its limit, and in order to realize liquid crystal display devices with even more pixels, electrically nonlinear characteristics are being added to the inside of the liquid crystal cell. Research is currently underway on methods of driving liquid crystals by incorporating elements with the same technology.

Elements with electrically nonlinear characteristics can be classified into two types according to the number of terminals of the element: two-terminal elements and three-terminal (or more) elements. An example of a two-terminal element is a diode.

There are baristas, or M-workers, and their chiefs are:
It has a simple structure and is easy to manufacture. On the other hand, an example of a three-terminal device is a transistor device such as TII'T, and its advantage is that one of the two substrates supporting the liquid crystal layer can have a full-surface electrode. That is, when one side of the substrate is an electrode on the entire surface, there is no need for a photoetching process, and in connection with this, when coloring is performed using a color filter or the like, a high quality and stable color filter can be formed on the substrate. Furthermore, in the case of a three-terminal element,
All the terminals of the liquid crystal cell except for one terminal on the entire surface electrode are on a substrate having a three-terminal element, and one terminal on the entire surface electrode is connected using the vertical conduction method, which is widely used in liquid crystal cells. Since it can be transferred to the substrate side having a three-terminal element using the same method, it has the advantage that it becomes easy to mount the connection between the liquid crystal cell and the circuit. On the other hand, in the case of a conventional liquid crystal display device using a two-terminal element, the electrode on the opposing substrate, which faces the element substrate on which the two-terminal element is formed, with a liquid crystal layer in between, is divided into multiple pieces. Since the counter substrate also requires a photo-etching process, the above-mentioned advantages of a liquid crystal display device using a three-terminal device do not exist in the case of a two-terminal device.

As mentioned above, although the structure of the conventional liquid crystal display device using a two-terminal element is simple, the overall liquid crystal display device is similar to that of a liquid crystal display device using a three-terminal element. It has some disadvantages in comparison.

The present invention relates to a liquid crystal display device using a two-terminal element with nonlinear resistance characteristics, and uses a new structure and a new driving principle to eliminate the above-mentioned drawbacks, while maintaining the simple structure of the two-terminal element. The present invention provides a liquid crystal display device that also has the above-mentioned advantages of a liquid crystal display device using terminal elements.

The present invention will be explained below using the drawings.

FIG. 1 shows an equivalent circuit of the liquid crystal display device according to the present invention, particularly an equivalent circuit for four pixels, where 1 is the signal 1f pole, 2 is the signal 1f pole, and
is a scanning electrode, 3 is a nonlinear resistance element, 4 is a resistor, and 5
is the equivalent capacitance of the liquid crystal. Equivalent capacitance fi of liquid crystal
5, all ends indicated by arrows are grouped together as one electrode, and the same potential is applied to them. Next, FIG. 2 shows the voltage-current characteristics of the nonlinear resistance element 6, where the horizontal axis shows the applied voltage and the vertical axis shows the current flowing through the nonlinear resistance element. As can be seen from the characteristics shown in Figure 2, nonlinear resistance elements have the property that when the applied voltage is low, the resistance is high and almost no current flows, and when the applied voltage is high, the resistance is low and a large current flows. There is. Among existing devices, Nonorisk, M-Ko-M, etc. have such characteristics. Now, the operation of the equivalent circuit shown in FIG. 1 constructed using the nonlinear resistance element having the characteristics shown in FIG. 2 will be explained as follows. The resistance of the nonlinear resistance element 3 is r
, the resistor 4 is R, the potential of the signal electrode 1 is VD, and the potential of the scanning electrode 2 is ys, then the potential VP divided by the nonlinear resistance element 3 and the resistor 4 and applied to the liquid crystal is yp =; (VD - VB) + Vl! becomes. Vp is approximately VD when r(H, and r>>H
When , it becomes almost VS. If the potential applied to the side opposite to the side to which Vp is applied in the equivalent capacitance 5 of the liquid crystal is ■0, then the voltage 'VLO applied to the liquid crystal is MLO='IJp-■Q=positive (VD-Vs) +
V8-v.

=-”-1’VD +-1=-ys-y.

1 + r/R1+ R/r is given by therefore r << When R(7) VLO5VD-T.

r) When R, VLO:VB-VO. Here, the relationship between r and R is determined by the voltage V D −V ! due to the characteristics of the nonlinear resistor element 3. +1v determined by
When n-vsl is small: r) R When IVD-VSI is large: r<<R. From the above, assuming that a signal potential is applied as the potential Vn of the signal electrode 1, and a scanning potential is applied as the potential VS of the scanning electrode 2, the scanning potential 8 is set to 1vn- in the selected section of time-division driving.
If the value is set so that vsl becomes large, the nonlinear resistance element +3
The resistance r becomes smaller and the signal potential VD is written to the liquid crystal, and in the non-selected section, the scanning potential
If the resistance r of the nonlinear resistance element 3 is set to a value such that the signal potential VD is small, the resistance r of the nonlinear resistance element 3 becomes large, and the signal potential VD is not written to the liquid crystal. The applied voltage vr,o of the liquid crystal in the non-selected section of time-division driving is finally approximately v
s − v o, but r >> R, and R)
If the nonlinear resistance element 3 and the resistor 4 are designed so that the value of , during that time, the written signal potential Vt+ is held and the voltage Vf-V is applied to the liquid crystal.

is being applied. Conversely, in the selected section, r<<R, but in this case, the resistance r of the nonlinear resistance element needs to be designed to be low enough to cause no problem in writing the signal potential VD.

The above is the basic operating principle of the liquid crystal display device according to the present invention.

Next, FIG. 3 shows the structure of one pixel of a liquid crystal display device according to an embodiment of the present invention, in which 6 is a vertical metal electrode whose surface has been oxidized, 7 is a horizontal metal electrode, 8 is a resistive element, 9
is a pixel electrode, and 1o is a coupling electrode that electrically connects the non-pixel electrode to the nonlinear resistance element and the resistance element. The nonlinear resistance element in this embodiment is an M having a three-layer structure of metal-insulator-metal, and is formed at the intersection of the vertical metal electrode 6 and the coupling electrode 1o. The manufacturing process for forming the structure of this example and the materials of each part will be explained below. first,
Tantalum or tantalum nitride is formed on a substrate by sputtering, patterned, and then surface oxidized by anodic oxidation to form vertical metal electrodes. Next, chromium and gold or nichrome and gold are formed using a vacuum evaporation method, and then patterned to form a lateral metal electrode 7. A resistive element 8 and a coupling electrode 10 are formed. Electrodes 7 and 10 are electrodes having a two-layer structure of chromium and gold or nichrome and gold, and resistance element 8 is a resistance electrode made only of chromium or nichrome. Since chromium or nichrome has a relatively high resistivity, it can be used as it is as a resistance element. Note that the resistance value of the resistive element 8 can be adjusted by changing the width and length of the pattern, and when it is desired to increase the length of the pattern, the shape of the pattern must be complicated rather than simply lengthened linearly. By doing so, it is possible to obtain the same effect as actually increasing the length of the pattern. On the other hand, for the electrodes 7 and 10, since gold has poor adhesion to the substrate, a two-layer structure of chromium and gold or nichrome and gold is required. Finally, indium oxide, tin oxide, or indium oxide containing tin oxide is formed using a sputtering method, and further patterned to form the pixel electrode 9.

The above is the manufacturing process for forming the structure of this example.

The manufacturing process described here is basically the same as the manufacturing process of the substrate on the side having the M process M in a liquid crystal display device using a conventional M process M, except for the shape of the pattern, and is not complicated in any way.

FIG. 4 shows an equivalent circuit of a liquid crystal display device comprising a substrate having the structure shown in FIG. 3 and a counter substrate having electrodes on the entire surface, particularly an equivalent circuit for one pixel. In Figure 4,
Reference numerals 1 to 5 correspond to the same reference numerals in FIG. 1, respectively, and 11 is an auxiliary nonlinear resistance element necessarily formed from the structure of FIG. To explain the correspondence between FIG. 4 and FIG. 3, signal electrode 1 is connected to vertical metal electrode B,
The scanning electrode 2 corresponds to the horizontal metal electrode 7, the nonlinear resistance element 6 corresponds to the M formed at the intersection of the vertical metal electrode 6 and the coupling electrode 10, and the resistor 4 corresponds to the resistance element 8. , and the auxiliary nonlinear resistance element 11 corresponds to an M construction M formed by intersecting the vertical metal electrode 6 and the horizontal metal electrode 7. Comparing the equal number of circuits in FIG. 4 and FIG. 1, FIG. 4 includes an extra auxiliary nonlinear resistance element 11 that does not exist in FIG. 1. but,
The basic operating principle of the present invention is to utilize voltage division by a series connection system consisting of a nonlinear resistance element 3 and a resistor 4, and an auxiliary nonlinear resistance element 11 is connected in parallel to the series connection system. , the basic operating principle of the present invention holds true in the system shown in FIG. That is, the presence of the auxiliary nonlinear resistance element 11 does not change or impede the present invention. However, if the auxiliary nonlinear resistance element 11 is present, a current flows due to the potential difference between the signal electrode 1 and the scanning electrode 2, so that the current consumption of the liquid crystal display device increases. If it is desired to avoid this increase in current consumption, an insulating layer may be formed at and near the intersection of the vertical metal electrode 6 and the horizontal metal electrode 7 to provide an auxiliary nonlinear resistance. It is only necessary to make the element 11 disappear.

As explained above, according to the present invention, it is possible to drive a liquid crystal display device using a two-terminal nonlinear resistance element based on a different principle from the conventional driving method, and it also maintains the advantage of the simple structure of a two-terminal element. Therefore, as in the case of using a three-terminal element, it is possible to use a full-surface electrode as the electrode on the opposing substrate side.

Therefore, when the present invention is used, the electrode patterning process for the counter substrate can be omitted, which has a significant effect on reducing the cost of manufacturing a liquid crystal display device. Furthermore, according to the present invention,
Since it is possible to form color filters whose quality is susceptible to changes in quality due to the influence of other processes with high quality and high stability on the opposing substrate side, if the present invention is applied to color liquid crystal display devices, the effect will be great. be.

[Brief explanation of drawings]

Fig. 1: Equivalent circuit diagram of the liquid crystal display device according to the present invention Fig. 2: Diagram showing the voltage-current characteristics of a nonlinear resistance element Fig. 3: The present invention Figure 4 shows the pixel structure in the embodiment of the present invention.Equivalent circuit diagram of the pixel structure in the embodiment of the present invention.1...Signal electrode 2...Scanning electrode 3...Nonlinear resistance element 4...Resistance 5...Equivalent capacitance of liquid crystal 6...Vertical metal electrode 7... Lateral metal electrode 8... Resistance element 9... Pixel electrode 10... Coupling electrode 11... Auxiliary nonlinear resistance element and above Applicant: Suwa Seikosha Co., Ltd. 3 Figure 1 21st [: ni

Claims (1)

[Claims] 1. In a liquid crystal display device in which a two-terminal element having nonlinear resistance characteristics is formed on one of two substrates supporting a liquid crystal layer, the two-terminal element and a resistor are connected in series and connected to both ends of the two-terminal element. A liquid crystal display device characterized in that a signal voltage is applied and a potential divided by the two-terminal element and the resistor is applied to the liquid crystal to drive the liquid crystal. 2. Of the two substrates supporting the liquid crystal layer, the number of electrodes on the substrate facing the substrate on which the two-terminal element is formed and the liquid crystal layer is one is one. The liquid crystal display device according to scope 1. 6. On the substrate on which the two-terminal element is formed, signal electrodes and scanning electrodes are arranged in a matrix pattern, and a series connection system of the two-terminal element and a resistor is constructed near the intersection of these electrodes, Claim 1, wherein the signal electrode and the scanning electrode are connected to both ends of the series connection system.
The liquid crystal display device according to item 1 or 2. 4. Claims 1, 2, or 6, characterized in that the two-terminal element having nonlinear resistance characteristics is a metal M having a three-layer structure of metal-insulator-metal. LCD display device.