JPH06313877A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent an insulation film or the like from being broken due to static electricity, and enable the occurrence of improper display to be prevented by connecting a picture element electrode formed on an insulation substrate, or scanning or signal wiring adjacent to the electrode via a high resistance connector. CONSTITUTION:A thin film transistor(TFT) composed of a gate electrode 5, a source electrode 6 and a drain electrode 7, and a picture element electrode 8 composed of ITO are formed near the intersection of signal wiring 3 and scanning wiring 4 laid in a matrix. The TFT gate electrode 5 is connected to the scanning wiring 4, the source electrode 6 is connected to the signal wiring 3 and the drain electrode 7 is connected to the picture element electrode 8. A high resistance connector 9 made of phosphorus doped a-Si or the like is used to connect the electrode 8 to the wiring 4 for the control thereof. Static electricity generated in the electrode 8 at a manufacturing process for this liquid crystal display device, particularly at a rubbing process, flows to the signal wiring 3 or scanning wiring 4 via the connector 9 and, therefore, the break of a gate insulation film due to discharge can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device having switching elements such as MIM and TFT.

[0002]

2. Description of the Related Art Recently, as a large liquid crystal display device, a switching element such as a two-terminal element such as a diode or MIM or a three-terminal element such as a MOS transistor or a thin film transistor (TFT) is used for driving a pixel electrode. An active matrix type liquid crystal display device is used. In the active matrix type liquid crystal display device, since the video signal can be applied only to necessary picture element electrodes by turning ON / OFF the switching elements, crosstalk is reduced as compared with the simple matrix system in which the electrodes are simply arranged. For this reason, a large screen of 10 inches or more is possible, and the twist angle of the liquid crystal molecules can be reduced to about 90 °, which has the advantage of increasing the response speed.

FIG. 11 shows a conventional active matrix substrate using a TFT as a switching element. Figure 1
In No. 1, 101 is a signal electrode terminal for applying a video signal, and 102 is a scanning electrode terminal for applying a scanning signal.
Signal wiring 103 and scanning wiring 1 from each electrode terminal
04 are wired in a matrix, and each signal wiring 1
A pixel electrode 108 and a TFT are formed at each intersection of 03 and the scanning wiring 104. The TFT part is the gate electrode 10
5, the gate electrode 105 is connected to the scanning wiring 104, the source electrode 106 is connected to the signal wiring 103, and the drain electrode 107 is connected to the pixel electrode 108.

FIG. 12 shows a sectional structure view of a TFT which is a general switching element. In the figure, 109 is a glass substrate, a transparent insulating substrate made of a transparent resin substrate, and 110 is Si.
A transparent insulating film made of O ₂ and others, 111 is, for example, T
a, a gate electrode made of other metal material, 112 is Ta
Anodized film Ta ₂ O _{5 of the} gate electrode and a two-layer structure gate insulating film of silicon dioxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ , SiN _x ), 113 is an Si intrinsic semiconductor film terminated by hydrogen, 115 Is a phosphorus-doped Si semiconductor, 114 is an etch stopper film, 116 is a source electrode,
Reference numeral 117 is a drain electrode, and 118 is a pixel electrode made of a transparent conductive film such as ITO.

A switching element such as the above-mentioned three-terminal element or a two-terminal element whose detailed description is omitted is generally constituted by a combination structure of a conductor and an insulator (or a semiconductor). For example, alignment control of liquid crystal molecules is performed. There is a problem in that the gate insulating film 112 and the semiconductors 113 and 115 are destroyed by static electricity generated in the alignment treatment step to be performed, resulting in a display defect. In addition, static electricity generated during use of the liquid crystal display device is applied to the counter electrode or the pixel electrode, and the discharge between the counter electrode and the pixel electrode damages the pixel portion, resulting in deterioration of display quality. It was In order to prevent this, conventionally, as shown in FIG. 11, each signal electrode terminal 101 and each scanning electrode terminal 102 is connected to, for example, the scanning wiring 103 or the signal wiring 104.
Short ring 1 formed of Ta, Al, etc., which is formed on the outer periphery of each signal electrode terminal 101 and each scanning electrode terminal 102
19 are connected to each other to prevent electrostatic breakdown between the source and the gate during the manufacturing process of the liquid crystal display device. However, the short ring 119 is separated by chamfering the insulating substrate 109 along the cutting line indicated by the line ab in FIG. 11 when the liquid crystal panel is completed. After the short ring 119 is separated in this manner, there is no protection means against static electricity. In addition, static electricity generated by this chamfering process is also a problem.

Japanese Unexamined Patent Publication No. 2-1825 discloses that scanning wiring and signal wiring are partially or entirely connected in series.
The disconnection inspection of the scanning wiring and the signal wiring is performed, and thereafter, the ends of the scanning wiring and the signal wiring are short-circuited by the transparent electrodes to prevent electrostatic breakdown. The short circuit portion due to the transparent electrode is removed by an ITO etchant after the liquid crystal panel is completed.

In Japanese Patent Application Laid-Open No. 2-1826, short-circuit wiring for short-circuiting all signal wiring terminals and scanning wiring terminals is formed of a conductive material having a smaller etching resistance than the materials of the signal wiring terminals and scanning wiring terminals. To do. Therefore, the short-circuit wiring can prevent electrostatic breakdown, and when various inspections are required during the manufacturing process, the short-circuit wiring can be etched and the end portions of the signal wiring and the scanning wiring can be separated and inspected. Since the signal wiring terminal and the scanning wiring terminal portion have etching resistance higher than that of the short-circuited wiring, they remain without being removed, and after the inspection, the conductive paste is again used between the end portions of the signal wiring and the scanning wiring by the screen printing method. The short-circuit wiring can be formed again, and electrostatic breakdown that occurs in the subsequent manufacturing steps can be prevented. The short-circuit wiring is cut in the final step, and the liquid crystal display device is completed.

[0008]

As described above, the liquid crystal panel is completed by removing the short ring 119 by chamfering, but static electricity generated in the chamfering process may damage the liquid crystal display device. Moreover, a chamfering process is required. The method described in the above publication requires a step of etching the short-circuited portion and a step of cutting the short-circuited portion.

An object of the present invention is to solve these problems and prevent the occurrence of display defects by preventing the insulating film, the semiconductor film and the pixel portion from being destroyed by static electricity generated in the manufacturing process such as alignment treatment and chamfering. And Another object of the present invention is to provide a low-cost active matrix liquid crystal display device by a process that can omit the chamfering step. Further, according to the present invention, after the liquid crystal display device is assembled, for example, static electricity generated during use or static electricity applied from the outside is prevented from damaging the insulating film and the semiconductor film to prevent the occurrence of display defects.

[0010]

According to the present invention, a pixel element, a scanning wiring and / or a signal wiring and a switching element are formed on at least one of two insulating substrates sandwiching a liquid crystal layer,
In an active matrix type liquid crystal display device in which a pixel electrode is driven by this switching element, a pixel electrode or a scanning wiring and / or a signal wiring adjacent to the pixel electrode is connected by a high resistance connector, and each scanning wiring and / Or connecting a part or all of each signal wiring with a high resistance connection, or grounding the high resistance connection or a part or all of each scanning wiring and each signal wiring and the counter electrode through a high resistance connection It is characterized by connecting by.

[0011]

According to the present invention, since the pixel electrode formed on the insulating substrate and the scanning wiring are connected by the high resistance connecting body, after the alignment treatment in the manufacturing process or the assembling of the liquid crystal display device. Since the static electricity generated in the chamfering process and the like escapes to the scanning wiring through the high resistance connector, the scanning wiring and the pixel electrode have the same potential, and it is possible to prevent electrostatic breakdown of the insulating portion of the switching element. Furthermore, by connecting a part or all of each scanning wiring and each signal wiring with a high resistance connector, each connected signal wiring also becomes equipotential, so that it is possible to prevent electrostatic breakdown more effectively. is there. By connecting a part or all of the scanning wiring and the signal wiring to the counter electrode with a high resistance connector, the counter electrode and the pixel electrode become equipotential, and the pixel due to discharge of static electricity generated in the counter electrode and the pixel electrode. It is possible to prevent damage to parts. Furthermore, by grounding a part or all of the high resistance connection body, it is possible to more effectively remove static electricity to the outside. Since the high resistance connector of the present invention exhibits the property of being a conductor for a high voltage such as static electricity and a high resistance for a low voltage such as a driving voltage, it is not necessary to remove it after assembling the liquid crystal display device. Instead, it provides a permanent means of protecting the liquid crystal display device from static electricity.

[0012]

EXAMPLE FIG. 1 shows a first example of a TFT matrix substrate according to the present invention. The TFT matrix substrate is
A signal wiring 3 for transmitting a video signal and a scanning wiring 4 for transmitting a scanning signal and a scanning wiring 4 for transmitting a scanning signal are arranged in a matrix. ing. The scanning wiring is, for example, T
The film thickness is 3000 Å and the signal wiring is, for example, Ti and the film thickness is 4000 Å. The intersections of the scanning lines and the signal lines are insulated from each other with a gate insulating film formed on the scanning lines interposed therebetween. A pixel electrode 8 made of ITO and a TFT composed of a gate electrode 5, a source electrode 6 and a drain electrode 7 is formed in the vicinity of the intersection of each signal wiring 3 and scanning wiring 4. The gate electrode 5 of the TFT is the scanning wiring 4, the source electrode 6 is the signal wiring 3, and the drain electrode 7
Is connected to the pixel electrode 8. The gate insulating film is formed of a two-layer structure of an anodic oxide film Ta ₂ O _{5 of} scanning wiring made of Ta and Si ₃ N ₄ . The sectional structure of the TFT is similar to that shown in FIG.

The high resistance connector 9 is formed of phosphorus-doped a-Si or the like, and connects the picture element electrode 8 and the scanning wiring 4 for controlling the picture element electrode 8. In FIG. 1, the high resistance connection body 9 is connected to the scanning wiring 4 on the TFT side to which the pixel electrode 8 is connected on one side of the pixel electrode 8, but is adjacent to the scanning wiring 4a on the opposite side. And the picture element electrode 8 may be connected. (Not shown) In this embodiment, for example, the high resistance connection body 9 is formed by the phosphorus-doped a-Si semiconductor film 115 that constitutes the TFT. The high-resistance connector 9 is the above-mentioned TF
In the manufacturing process of T, when patterning the etch stopper 114 by photolithography,
As shown in the line sectional view of FIG. 2, a gate insulating film 112 is opened in a region where the scanning wiring 111 and the pixel electrode 118 overlap. Then, the phosphorus-doped Si semiconductor 115 of the TFT
Is also deposited on this window opening portion by the plasma CVD method. Simultaneously with the patterning of the phosphorus-doped Si semiconductor TFT portion, the window opening portion is also patterned. The pixel electrode 118 is formed so as to partially overlap the phosphorus-doped Si semiconductor 115a. In the above-mentioned embodiment, the example in which the scanning wiring and the picture element electrode are connected by the high resistance connection body 9 is shown.
You may connect with a signal wiring as shown in FIG. C in FIG.
A cross-sectional view taken along line D is shown in FIG.

This TFT matrix substrate is completed through steps such as rubbing after forming the alignment film. on the other hand,
A counter substrate on which a counter electrode made of ITO and a color filter are formed is manufactured. The TFT matrix substrate and the counter substrate are attached to each other, and liquid crystal is injected between the two substrates to manufacture a liquid crystal display device.

During the above-described manufacturing process, static electricity is generated in the pixel electrode 8 especially during the rubbing process. The generated static electricity passes through the high resistance connector 9 and the signal wiring 3 or the scanning wiring 4.
To the drain electrode 7, the gate electrode 5 and the drain electrode 7 of the TFT have the same potential, and the gate insulating film can be prevented from being destroyed by discharge. The high resistance connection body 9 does not adversely affect the display operation of the liquid crystal display device because it exhibits a high resistance property with respect to a low voltage such as a drive voltage of the liquid crystal display device. Therefore, it is not necessary to remove the high resistance connection body even after the liquid crystal display device is assembled, and it becomes a permanent means for protecting the liquid crystal display device from static electricity generated during use or static electricity applied from the outside.

In the embodiment of the present invention, the high resistance connector 9
Has a resistance of several KΩ to several 100 MΩ, preferably several 10 MΩ
Ω to several hundreds Ω, and several tens of MΩ in this embodiment. The static electricity is about several KV, and the driving voltage is about several tens of V.

The second embodiment shown in FIG. 5 has a structure in which the picture element electrode 8a and the picture element electrode 8a which are adjacent to each other with the scanning wiring 4a interposed therebetween are simultaneously connected to the scanning wiring 4a by the high resistance connector 11. In this case, all the pixel electrodes and all the scanning wirings connected to each other have the same potential.

Further, in the third embodiment shown in FIG. 6, the scanning wiring 4 and the pixel electrodes 8 and 8a are connected by using a high resistance connecting body 12 formed continuously. In this case as well, the scanning lines and the picture element electrodes 8 and 8a have the same potential.

In the embodiments of FIGS. 5 and 6, the picture element electrode may be connected to the signal wiring.

Next, FIG. 7 shows a fourth embodiment. The present embodiment has the configuration of FIG. 1 and includes a display area having a large number of picture element electrodes, a signal electrode terminal 1 and a scanning electrode terminal 2.
By continuously forming the high resistance connection body 10 so as to connect each scanning wiring and each signal wiring in the area between
Since all the pixel electrodes, the scanning wirings, and the signal wirings on the substrate are connected through the high resistance connection body 10, they have the same potential,
It is possible to prevent dielectric breakdown due to discharge between the drain / source and between the gate / source.

Further, as shown in FIG. 8 as a fifth embodiment,
The same applies to the case where the electrodes 8 and 8a and the scanning wiring 4 are connected by using the high resistance connection body 12 formed continuously.

Next, FIG. 9 shows a sixth embodiment. In this embodiment, the structure of the fifth embodiment is provided, and further, by grounding a part of the high resistance connection body 10 by using the grounding means 13, the static electricity generated in the TFT matrix substrate is released to the outside and the potential is increased. By setting 0 to 0, the protection effect is further increased.

Further, in the seventh embodiment shown in FIG. 10, the connecting means 15 is formed by connecting the counter substrate 14 and the high resistance connector 10 with a good conductor such as carbon (C) or aluminum (Al).
By connecting with each other by discharging the static electricity generated on the counter substrate 14 to the outside, it is possible to prevent the pixel portion from being damaged by the discharge between the counter substrate 14 and the pixel electrode.
Even when the connecting means 15 is used alone without using the grounding means, the pixel electrodes and the counter substrate have the same potential, and the same effect can be obtained. Further, the grounding means 13 and the connecting means 15
Need not necessarily be restricted to the position and shape in FIG. 10 as long as the same effect can be obtained.

Although the above-mentioned embodiment shows the inverted stagger type thin film transistor structure, the present invention is also applicable to the case of using a transistor of other structure, a three-terminal element other than the transistor, a two-terminal element such as MIM. is there.

[0025]

As described above, according to the present invention, there is no defect due to electrostatic breakdown during the manufacturing process of the liquid crystal display device and after the liquid crystal display device is assembled, and the high resistance connector 9 is removed when the liquid crystal panel is completed. Since the process for performing the process is not required, a low cost active matrix type liquid crystal display device can be provided.

[Brief description of drawings]

FIG. 1 is a plan view showing a TFT matrix substrate of an active matrix type liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AB of FIG.

FIG. 3 is a plan view of a TFT matrix substrate of an embodiment different from FIG.

FIG. 4 is a cross-sectional view taken along the line CD of FIG.

FIG. 5 is a plan view showing a TFT matrix substrate of an active matrix type liquid crystal display device according to a second embodiment of the present invention.

FIG. 6 is a plan view showing a TFT matrix substrate of an active matrix type liquid crystal display device according to a third embodiment of the present invention.

FIG. 7 is a plan view showing a TFT matrix substrate of an active matrix type liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 8 is a plan view showing a TFT matrix substrate of an active matrix type liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 9 is a perspective view showing a TFT matrix substrate of an active matrix type liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 10 is a perspective view showing a TFT matrix substrate of an active matrix type liquid crystal display device according to a seventh embodiment of the present invention.

FIG. 11 is a plan view showing a TFT matrix substrate of a known active matrix type liquid crystal display device.

FIG. 12 is a cross-sectional structural diagram of a known TFT.

[Explanation of symbols]

 1 Signal Electrode Terminal 2 Scanning Electrode Terminal 3 Source Wiring 4 Gate Wiring 5 Gate Electrode 6 Source Electrode 7 Drain Electrode 8 Pixel Electrode 9, 10, 11, 12, 16 High Resistance Connection 13 Grounding Means 14 Opposing Substrate 15 Connection Means

Claims (5)

[Claims] 1. A plurality of scanning wirings or signal wirings formed on an insulating substrate, and a plurality of signal wirings or scanning wirings intersecting the scanning wirings or signal wirings with an insulator or liquid crystal interposed therebetween, In an active matrix liquid crystal display device having switching elements formed at intersections of scanning wirings and signal wirings and picture element electrodes connected to the switching elements, each picture element electrode, each scanning wiring and
Alternatively, a liquid crystal display device is characterized in that each signal wiring is connected to each other by a high resistance connection body. 2. The liquid crystal display device according to claim 1, wherein a part or all of each scanning wiring and / or each signal wiring is mutually connected by the high resistance connection body. 3. The liquid crystal display device according to claim 1, wherein a part or all of the high resistance connection body is grounded. 4. The liquid crystal display device according to claim 1, wherein a part or all of the high resistance connection body is connected to a counter electrode. 5. The liquid crystal display device according to claim 1, wherein the high resistance connection body is made of a semiconductor film that constitutes a switching element.