JPH07175075A - Active matrix type liquid crystal panel - Google Patents

Abstract

PURPOSE:To suppress the generation of a defect in nonlinear element by dividing short circuit bus lines to respectively plural blocks in the terminal region of scanning wiring and/or signal wiring. CONSTITUTION:Short circuit bus lines 5 are formed at all the ends of gate bus lines 1 and source bus line 2 by superposing all these ends and a part thereof. These short circuit bus lines 5 are provided to prevent the destruction of thin-film transistor 3 by the static electricity generated in a process for producing liquid crystal display panels. The short circuit bus lines 5 are so disposed as to equally divide plural pieces of the gate bus lines 1 and plural pieces of the block and source bus lines 2 into plural pieces of the blocks. Further, the MIM(metal-insulating film-metal) elements 6 which function as the nonlinear elements by connecting the short circuit bus lines 5 and the gate bus lines 1 and connecting the short circuit bus lines 5 and the source bus lines 2 are provided.

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, and more particularly to protection against static electricity and redundancy against disconnection.

[0002]

2. Description of the Related Art As described in JP-A-3-134628, an active matrix type liquid crystal display panel having an equivalent circuit shown in FIG. 4 is known. This liquid crystal panel has, as a display medium, an active matrix substrate and a counter substrate which are arranged to face each other with a liquid crystal layer interposed therebetween. A counter electrode 27 is formed on the counter substrate over substantially the entire surface of the display medium. A gate bus line 2 as a scanning electrode is provided on one of the active matrix substrates.
1 and a source bus line 22 as a signal line are arranged in a state of intersecting each other, and a thin film transistor 23 and a pixel electrode 26 are arranged in a region surrounded by both bus lines 21 and 22. The thin film transistor 23 includes a gate bus line 21, a source bus line 22, and a pixel electrode 26.
Is turned on and off by a gate signal sent to the gate bus line 21, and supplies a source signal input via the source bus line 22 to the pixel electrode 26 when turned on. The pixel electrode 26 and the counter electrode 27 formed on the counter substrate side face each other with the liquid crystal layer interposed therebetween, and form a liquid crystal cell 24 that functions as a capacitor.

A short circuit bus line 25 is connected to all ends of the gate bus line 21 and the source bus line 22. The short circuit bus line 25 is provided to prevent the thin film transistor 23 from being broken by static electricity generated in the process of manufacturing the liquid crystal display panel. Further, the non-linear element 10 is provided by connecting the short-circuit bus line 25 and the gate bus line 21 and connecting the short-circuit bus line 25 and the source bus line 22. Since the non-linear element 10 is electrically coupled to the short-circuit bus line 25 which is the reference potential wiring as a non-linear resistance, it controls the voltage between the gate bus line 21 and the source bus line 22 generated by static electricity. There is. Conventionally, a structure such as a thin film transistor has been used.

The reason for providing the non-linear element 10 is as follows. That is, the short circuit bus line 25 is generally removed by cutting off the end portion of the active matrix substrate when the manufacture of the liquid crystal display panel is completed. However, in this conventional example, the non-linear element 10 is provided so that the completed liquid crystal display panel is used and electrostatic countermeasures can be taken in the subsequent assembly process. Further, due to the existence of the non-linear element 10, it is possible to perform the assembling process even when the short-circuit bus line is left in the completed product of the liquid crystal display panel.

[0005]

The short-circuited bus line 2 described above is to be solved.
The liquid crystal display panel with No. 5 left is effective as a measure against electrostatic breakdown. However, since the non-linear element 10 has a structure such as a thin film transistor as described above, the manufacturing process is complicated due to formation of through holes, and a leak failure occurs in the non-linear element 10. There was a problem that was invited. The present invention has been made to solve such a problem of the conventional technique. Even if a non-linear element is formed to leave a short-circuit bus line, the number of manufacturing steps does not increase, and the occurrence of defects in the non-linear element is suppressed. It is another object of the present invention to provide an active matrix type liquid crystal panel having a structure capable of improving the defect defect rate of the thin film transistor array.

[0006]

In a liquid crystal display panel of the present invention, one of a pair of insulating substrates, which are opposed to each other with a liquid crystal layer interposed therebetween, has a plurality of scanning wirings and a plurality of scanning wirings in its surface. Signal wiring is formed so as to intersect with each other, and the switching element connected to the vicinity of the intersection of both substrates is connected to the pixel electrode, and the other substrate is connected to the pixel electrode in its plane. In an active matrix type liquid crystal display panel having a structure in which opposed electrodes are formed facing each other, a short circuit bus line partially made of a conductive material at an end of the scanning line and / or an end of a signal line. Is provided, and an insulating thin film formed by anodizing the scanning line end or the shorting bus line is provided between the shorting bus line and the scanning line end at a portion where the shorting bus line and the scanning line end overlap. Formed And / or an insulating thin film formed by anodizing the signal wiring end portion or the short circuit bus line is formed between the short circuit bus line and the signal wiring end portion at a portion where the short circuit bus line and the signal wiring end portion overlap. The above object is achieved by dividing the short-circuited bus line into a plurality of blocks in the terminal areas of the scanning wiring and / or the signal wiring.

[0007]

The short-circuit bus line portion and the scanning wiring end portion, which overlap each other with the insulating thin film sandwiched therebetween, are formed of metal-
An MIM element having an insulating film-metal three-layer structure is formed.
In addition, the short-circuit bus line portion and the signal wiring end portion that overlap with each other with the insulating film interposed therebetween form an MIM element that functions as a non-linear element. The MIM element has a normal driving voltage of 3
When a voltage of about 0 V or less is applied, the resistance value does not affect the drive signal, for example, a high resistance of about 1 MΩ or more. On the other hand, for a high voltage of about 100 V or more generated by static electricity, the resistance becomes lower than, for example, about several 100 kΩ, and the charge of the applied static electricity is diffused. Therefore, this short-circuit bus line does not affect the display characteristics during normal driving, and can be added to the finished panel product, and is effective as a countermeasure against static electricity in the assembly process after the panel is completed. Also, the insulating film of the MIM element is
One of the short-circuit bus line and the wiring that sandwich the insulating thin film as a result is formed by applying the anodic oxidation method. The anodization method has been used in the manufacturing process of a liquid crystal display panel in order to prevent a short circuit defect that occurs at the intersection of the scanning wiring and the signal wiring and the thin film transistor portion.
No new manufacturing steps need to be introduced to form the device.

[0008]

EXAMPLES Examples of the present invention will be described below. FIG. 1 shows an equivalent circuit of the active matrix type liquid crystal display panel of this embodiment. This liquid crystal display panel has an active matrix substrate and a counter substrate which are opposed to each other with a liquid crystal layer as a display medium interposed therebetween. The counter electrode 8 is formed on almost the entire surface of the counter substrate on the display medium side. On one of the active matrix substrates, a gate bus line 1 serving as a scanning wiring and a source bus line 2 serving as a signal wiring are arranged on an insulating substrate 16 serving as a base so as to intersect with each other. The thin film transistor 3 and the pixel electrode 7 are arranged in a region surrounded by. The thin film transistor 3 is connected to the gate bus line 1, the source bus line 2 as a signal line, and the pixel electrode 7, and on / off control is performed by a gate signal sent to the gate bus line 1. When the thin film transistor 3 is on, the source bus line 2 A source signal input through the pixel electrode 7 is applied to the pixel electrode 7. The pixel electrode 7 and the counter electrode 8 formed on the counter substrate side face each other with the liquid crystal layer sandwiched therebetween to form a liquid crystal cell 4 functioning as a capacitor.

Short-circuit bus lines 5 are formed at all end portions of the gate bus line 1 and the source bus line 2 so as to partially overlap all the end portions. The short circuit bus line 5 is provided to prevent the thin film transistor 3 from being destroyed by static electricity generated in the process of manufacturing the liquid crystal display panel. The short-circuit bus lines 5 include a plurality of gate bus lines 1 (for example, a lines each), a plurality of blocks (for example, b lines), and a plurality of source bus lines 2 (for example, c lines). It is arranged so that it is divided equally into blocks. As shown in FIG. 1, each short-circuit bus line 5 has a U-shaped pattern, and electrode terminals 13 are provided at both ends so that they can be connected to the outside like the gate bus line 1 and the source bus line 2. ing. Further, an MIM element 6 is provided which connects the short-circuit bus line 5 and the gate bus line 1 and connects the short-circuit bus line 5 and the source bus line 2 to function as a non-linear element.

As an example, the source bus line 2s is disconnected 3
A case where 0 occurs and a display defect occurs will be described. After the liquid crystal display panel is completed, the input side and non-input side source bus lines 2s and short circuit bus lines 5sa, 5
At the respective intersections 14 and 15 with sb, the metal of the source bus line 2s and the short-circuit bus lines 5sa, 5s
The metal of b is melted by, for example, a laser and short-circuited. Further, by mounting the TCP having the LSI liquid crystal driver mounted on the liquid crystal display panel and the PWB substrate mounting the control circuit, respectively, the source signal on the input side is provided to the short circuit bus line 5sa on the input side, the TCP and the PWB substrate. By inputting the same source signal via the jumper wire and the jumper wire provided on the TCP on the opposite non-input side and the short-circuit bus line 5sb, it becomes possible to apparently correct the defect due to the disconnection. As a result, the yield of the liquid crystal display panel due to defects can be improved.

FIG. 2 is a sectional view showing a portion near the MIM element 6. The MIM element 6 has a gate bus line 1 (or source bus line 2) at the intersection of the gate bus line 1 (or source bus line 2) and the short-circuit bus line 5 wired on the insulating substrate 16. Short circuit bus line 5
It has a structure in which an insulating thin film 9 sandwiched between and is formed. In an actual active matrix substrate, Ta is used as a material for the gate bus line 1 and the source bus line 2 existing below the short bus line 5, and the short bus line 5 is used.
Anodization is performed on the surface portion overlapping with the anodizing method. As a result, an insulating thin film 9 made of a Ta oxide film is formed on the gate bus line 1 portion and the source bus line 2 portion which overlap the short circuit bus line 5, and the short circuit bus line 5 made of Ti is formed on the insulating thin film 9. It is formed so as to be covered with a part thereof. The anodic oxidation need not be partially performed on the gate bus line 1 and the source bus line 2, but may be performed on the entire surface.

As shown in FIG. 5, the MIM element 6 having such a configuration has a resistance value that does not affect the drive signal when a voltage of about 30 V which is a normal drive voltage is applied, for example, a high resistance of about 1 MΩ or more. On the other hand, for a high voltage of about 100 V or higher generated by static electricity or the like, the resistance becomes low, for example, about several hundred KΩ, and the applied static charge is diffused. That is, the MIM element 6 functions as a non-linear element.

Therefore, in the case of the present invention, if the MIM element 6 and the short-circuit bus line 5 are formed and added even in the state of the panel finished product, the gate bus line 1 and the source bus line 2 are statically charged. When a high voltage is generated between the short-circuit bus line 5, the MIM element 6 of the short-circuit bus line 5 has a low resistance, and the gate bus line 1 and the source bus line 2 to which the high voltage is applied and the short-circuit bus line 5 are connected with a low resistance. It becomes a state. As a result, the static charge applied through the gate bus line 1 or the source bus line 2 diffuses to the short-circuit bus line 5 side through the low resistance MIM element 6, so that static electricity causes a thin film transistor of the liquid crystal display panel. Can be prevented from being destroyed. On the contrary, since the MIM element 6 has a high resistance during normal driving and does not affect the display characteristics, the short-circuit bus line 5 can be added to the finished panel product. Further, the liquid crystal display panel having the short circuit bus line 5 and the MIM element 6 described above is effective as a countermeasure against static electricity in the assembly process after the panel is completed.

FIG. 3 shows the electrostatic breakdown rates by the static electricity applied voltage with and without the MIM element of this embodiment. Without the MIM element, the thin-film transistor is destroyed at about 400V, whereas with the MIM element, it withstands up to about 1000V.
The breakdown voltage is improved by about 00V.

Since the insulating thin film of the MIM element 6 is formed by applying the anodic oxidation method, it has few pinholes and is highly uniform. Since this anodization method has been conventionally used for forming an insulating thin film for preventing a short circuit defect occurring at the intersection of the gate bus line 1 and the source bus line 2 and the thin film transistor 3, the MIM element 6 is formed. Therefore, it is not necessary to add a new manufacturing process. Furthermore, since the structure of the MIM element 6 is simple, it is possible to form the short circuit bus line 5 with few defects.

In this embodiment, the gate bus line 1 and the source bus line 2 are anodized to form the MIM element 6. However, the present invention is not limited to this, and the short circuit bus line 5 is anodized to form the short circuit bus line. The gate bus line 1 and the source bus line 2 may be formed on the wiring 5. The shape of the MIM element 6 may be different from that of this embodiment.

Although Ta is used as the material for the gate bus line 1 and the source bus line 2 in the above embodiment, the present invention is not limited to Ta. Further, the gate bus line 1 and the source bus line 2 may be made of different materials. Although Ti is used as the material for one of the short circuit bus lines 5,
The present invention is not limited to Ti. However, the materials of the gate bus line 1 and the source bus line 2 and the material of the short circuit bus line 5 are preferably those capable of effectively ensuring the function of the MIM element 6.

[0018]

As described in detail above, according to the present invention, defects such as line defects due to static electricity generated in the manufacturing process of the liquid crystal display panel and in the assembling process after the liquid crystal display panel is completed are generated. Can be prevented. Further, since the MIM element is formed by using the anodic oxidation method as the non-linear element for connecting the short-circuited bus line to the gate bus line and the source bus line, it is possible to form a highly uniform insulating thin film with few pinholes, the number of manufacturing steps is increased. Without this, it becomes possible to easily form the short-circuit bus line and prevent the occurrence of defects. Further, since the short-circuited bus line is divided on the gate and source sides as shown in FIG. 1, disconnection of the gate bus line or the source bus line can be corrected, and improvement in the yield rate of the liquid crystal display panel can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram showing wiring of an active matrix type liquid crystal display panel of the present invention.

FIG. 2 is a cross-sectional view of an MIM element used in the active matrix type liquid crystal display panel of the present invention.

FIG. 3 is a diagram showing the electrostatic breakdown strength of a liquid crystal display panel.

FIG. 4 is an equivalent circuit diagram of a conventional active matrix type liquid crystal display panel.

FIG. 5 is a diagram showing characteristics of MIM.

[Explanation of symbols]

 1 gate bus line 2 source bus line 2s open source bus line 3 thin film transistor (TFT) 4 liquid crystal cell 5 short circuit bus line 5sa signal input side short circuit bus line 5sb signal non-input side short circuit bus line 6 MIM element 7 pixel electrode 8 counter electrode 9 Insulating film 10 Non-linear element 11 Gate electrode terminal 12 Source electrode terminal 13 Short-circuit bus line electrode terminal 14 Intersection of source bus line and short-circuit bus line 15 Intersection of source bus line and short-circuit bus line 16 Insulating substrate 21 Gate bus line 22 Source bus line 23 Thin film transistor (TFT) 24 Liquid crystal cell 25 Short-circuit bus line 26 Pixel electrode 27 Counter electrode 28 Gate electrode terminal 29 Source electrode terminal 30 Disconnection point

Claims (3)

[Claims] 1. A pair of insulative substrates, which are opposed to each other with a liquid crystal layer interposed therebetween, are arranged such that a plurality of scanning wirings and a plurality of signal wirings intersect each other in the plane thereof. The switching element connected to the vicinity of each intersection of both wirings is connected to the pixel electrode, and the other substrate is formed with an opposite electrode facing the pixel electrode in its surface, and the end portion of the scanning wiring and / or the above A short-circuit bus line made of a conductive material is partially overlapped with the end portion of the signal wiring, and an insulating thin film is formed between a portion where the short-circuit bus line and the scanning wiring end portion overlap with each other, and / Alternatively, in the liquid crystal display panel in which the insulating thin film is formed between the portions where the short-circuit bus line and the end portion of the signal wiring overlap, a plurality of the short-circuit bus lines are provided in the scanning wiring terminal area and / or the signal wiring terminal area. Divided into An active matrix type liquid crystal display panel characterized by being 2. The liquid crystal display according to claim 1, wherein the plurality of scanning wirings and / or the plurality of signal wirings and the short-circuit bus line are electrically coupled to a non-linear element at a predetermined position. panel. 3. A metal-insulating film-metal (MIM) structure in which an insulating thin film formed by anodic oxidation is formed in a portion where the short-circuit bus line and the scanning wiring end portion and / or the signal wiring end portion overlap each other. The liquid crystal display panel according to claim 1, wherein the liquid crystal display panel is provided.