JPH09152620A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the yield, and to make the screen large and to reduce the weight by preventing the electrostatic breakdown of an LCD panel and preventing wires from being short-circuited by a conductive spacer. SOLUTION: At the periphery of an LCD display part (TFT element 5), a common electrode 4 to which a shunt transistor 11 for electrostatic breakdown prevention is connected is formed on the top surface of a TFT substrate 1 where the element is formed. Then a conductive spacer containing seal material 3 is arranged between a TFT substrate 1 and a CF substrate 2 at the position corresponding to the common electrode 4 and a liquid crystal material 7 is sandwiched between those substrates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a sealing material containing a conductive spacer on a common electrode having a shunt transistor for preventing static electricity connected to an element side surface around a display portion of a TFT substrate. And a liquid crystal display device having the same.

[0002]

2. Description of the Related Art A conventional TFT (Thin film t)
ransistor) -LCD (Liquid cry)
stal display) is 3 to 1 in screen size
The 3 type class is generally used. In pursuit of thinness, light weight and low power consumption, OA (O
office, FA (Fact)
Widely used in all fields of ory automation. Now, these conventional TFT-LC
D usually has a configuration as shown in FIG. FIG.
(A) is a sectional view showing a conventional liquid crystal display element. A liquid crystal material 7 is interposed between a CF (Color filter) substrate 2 provided with a counter electrode 6 and a TFT substrate 1 provided with a TFT element 5.
Are held at an interval of 10 μm, and the periphery of the liquid crystal material is adhered with a sealing material 8 to form a TAB (Tape au).
A configuration is adopted in which a driving device that applies a voltage to a tomated bonding (terminal) 10 is provided.

At this time, in order to keep the distance between the TFT substrate 1 and the CF substrate 2 constant, spacer materials 12 such as plastic beads and glass fibers are uniformly arranged in the screen display portion and the seal material 8, respectively. Generally, the spacer material 12 to be mixed with the liquid crystal material and the sealing material 8 often has a different diameter in consideration of the pattern step of the TFT element 5 and the like. The application of a voltage to the counter electrode 6 formed on the CF substrate 2 is performed from the TFT substrate 1 through the transfer 9. For this reason, a silver paste is often used as a material of the transfer 9. Also,
FIG. 2B is a top view showing a state in which elements, wiring, and the like are formed on the conventional TFT substrate 1. The drain lines 13 and the gate lines 14 are arranged in a grid pattern, and the TF is arranged inside the grid pattern.
T elements 5 and pixels are arranged. Further, the common pad 16 is provided at an appropriate position which does not belong to the display screen, and the transfer 9 is arranged.

[0004] In recent LCDs, FIG.
As shown in FIG. 2B, a method of forming the transfer electrode 38 (common pad 16) on a part of the peripheral sealing material 44 at a position not overlapping with other electrodes and terminals to obtain a compact structure (Japanese Patent Laid-Open No. −153625) and FIG.
(A) to (d), a method of combining the sealing and electrical bonding of the upper and lower electrode substrates (Japanese Utility Model Application Laid-Open No. 61-89819)
In addition, as shown in FIGS. 5A to 5C, the elastic conductive particles 10 constituting a part of the sealing material 7 and having a larger elasticity than the substrate interval are used to generate electricity at an appropriate position between the upper and lower electrode substrates. (Japanese Unexamined Patent Publication No. 62-21893)
7).

Here, in the conventional LCD, a silver paste is provided as a transfer for connecting the CF substrate 2 and the TFT substrate 1, but ionic impurities contained in the silver paste are generated in a display portion on the surface of the substrate. There was a problem that display failure was caused by forming a double layer or the like. This problem is described in
The transfer electrode is formed together with the peripheral seal as shown in FIG. 3 of 153625, or the upper and lower electrode substrates are electrically connected by a sealing material including a conductive spacer as shown in FIG. 4 of Japanese Utility Model Application Laid-Open No. 61-89819. We are trying to solve it.

[0006]

However, in the recent method, several electrodes for transfer have to be individually formed. In addition, for example, if the wiring of the transfer electrode is inside or outside the sealing material, the screen size occupying the substrate is reduced accordingly, which hinders the increase in screen size and weight. In addition, JP-A-4-15
Even when a transfer electrode (common pad) is formed in a part of the sealing material and a conductive spacer is used as shown in FIG. 3 of 3625, if the transfer electrode forming pattern is a part of the sealing material, the transfer electrode does not relate to the transfer electrode. There is also a problem that the conductive spacer in the sealing material causes a short circuit between the wiring of the drain line or the gate line and the counter electrode, or between the drain line and the gate line. In this case, an insulating film such as a thin passivation film having a thickness of about 200 nm is usually formed on the wiring, but the reliability with respect to the mechanical pressure between the spacer and the wiring-counter electrode is not ensured.
Therefore, at present, it is inevitable to cause an interlayer short circuit.

[0007] In addition, in the step of screen printing on the TFT substrate 1 on which the elements are formed, or in the step of superposing the TFT substrate and the CF substrate, the sealing material mixed with the conductive spacer is reduced in the number of conductive spacers to the sealing material. The greater the mixing ratio, the more inconvenience that the TFT element 5, which has not been a problem with the conventional sealing material and spacer, causes electrostatic breakdown. In the experiment, the mixing ratio of the conductive spacer to the sealing material was 0.5 wt%.
As a result, the electrostatic breakdown failure of the TFT element after the manufacture of the TFT-LCD increased by 6.2%.

According to the present invention, a shunt transistor connected to a common common electrode is used to prevent a TFT element from being electrostatically damaged and to prevent a short circuit between a conductive spacer and a wiring-opposite electrode and between wirings. By forming a common common electrode connected to a shunt transistor for preventing static electricity on the element side surface around the screen and forming a sealing material containing a conductive spacer along this formation pattern, the yield is improved, and Another object of the present invention is to maximize the screen display area occupying the substrate and reduce the weight of the liquid crystal display element.

[0009]

The liquid crystal display device of the present invention comprises a liquid crystal material between a TFT substrate and a CF substrate on which electrodes are respectively arranged, and is sandwiched by a sealing material while maintaining a uniform gap by a spacer material. In liquid crystal display devices,
A common common electrode to which a shunt transistor for preventing static electricity is connected is formed on an element side surface around a surface portion of the TFT substrate, and a sealing material contains a conductive spacer having a transfer function. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described with reference to the drawings. FIG. 1A is a cross-sectional view of a liquid crystal display device according to a first embodiment of the present invention, and FIG. 1B is a conceptual top view of the liquid crystal display device of the first embodiment on the TFT substrate side. is there. In manufacturing this liquid crystal display element, first, TF
On the T substrate 1, ITO (Intim tin oxid)
e), the TFT element 5 and the shunt transistor 11 are formed by repeating sputtering, exposure, development and peeling with Al (aluminum), α-Si (amorphous silicon) or the like, and the gate line 1 is similarly formed with Al or Cr (chromium).
4, the drain line 13 and the TAB terminal 10 are formed.
Then, the common common electrode 4 is patterned on the outer surface of the display unit by sputtering of Al or Cr on the outermost surface of the TFT substrate. In addition, C having the counter electrode 6
On the F substrate 2, a sealing material 3 containing a conductive spacer is formed on the TFT substrate 1 at a position corresponding to the common common electrode 4 by screen printing. At this time, an organic adhesive made of an epoxy resin is used for the sealing material 3, and conductive particles obtained by depositing gold on plastic beads are used for the conductive spacer.

Next, the TFT substrate 1 on which wirings, elements, etc. are formed, and the CF substrate 2 on which the sealing material 3 containing a conductive spacer is printed, are subjected to high-temperature press bonding at 150 to 230 ° C. after alignment. And overlap. The liquid crystal material 7 is vacuum-injected into the superposed LCD panel from the injection hole, sealed with a UV curable resin, and a peripheral driving device is assembled to complete a liquid crystal display element.

Here, as the organic adhesive used for the sealing material 3, a silicone resin is also used. Further, glass fibers can be used for the particles of the conductive spacer, and silver may be used for the metal deposition film attached to the surface.

Since the liquid crystal display device manufactured in this manner does not have the conventional silver paste, it is possible to control the gap with high precision and eliminate the gap defect in the display surface. The conductive spacers uniformly arranged around the display surface increased the ground area related to conduction, so that ionic impurities were not eluted into the panel, thereby reducing display stains. Further, by forming the conductive spacer-containing sealing material 3 on the common common electrode 4 on the surface to which the shunt transistor 11 is connected, for example, during production of an LCD panel, when cutting a substrate, transporting a substrate, or handling the substrate. Static electricity charged to the TFT substrate element due to friction, etc., or LCD
After the panel is manufactured, the static electricity charged on the element portion of the TFT substrate in the repair work of replacing the polarizing plate is transferred to the gate line 1.
4 or drain line 13 to shunt transistor 11
As a result, the TFT element 5 can be prevented from being destroyed. In addition, when a conductive spacer is used in the related art, a short circuit between the counter electrode and between the wirings can be prevented by disposing the conductive spacer on the common common electrode 4. Since the common common electrode 4 and the conductive spacer-containing sealing material 3 are located at the same position in the LCD panel surface, the display area occupied in the surface can be maximized, and the weight of the liquid crystal display element can be reduced accordingly. Was. Table 1 shows the ratio of occurrence of electrostatic breakdown and short circuit, and Table 2 shows a comparison of the occupation ratio of the effective display area.

[0014]

[Table 1]

[0015]

[Table 2]

As a second embodiment of the present invention, TF
It is not necessary that the common common electrode 4 formed on the surface of the T-substrate 1 and the sealing material 3 containing a conductive spacer correspond to 1: 1 in the entire area, and the area (width) of the common common electrode 4 is larger. May be. In this case, for example, if only the width of the common common electrode 4 is increased by 0.2 mm, the manufacturing margin for the seal displacement at the time of printing the seal can be maintained at 20% larger than that of the first embodiment.

[0017]

As described above, according to the present invention, the conductive spacer-containing sealing material is arranged on the common electrode to which the shunt transistor is connected. It has become possible to prevent a short circuit between wirings. Further, the effective display area occupying the substrate was improved by about 5% as compared with the conventional product.

[Brief description of the drawings]

FIGS. 1A to 1C are a sectional view, a top view on a TFT substrate side, and a detailed sectional view of a TFT substrate, respectively, showing a first embodiment of the present invention.

FIGS. 2A to 2C are a cross-sectional view showing a conventional example, a top view on the TFT substrate side, and a detailed cross-sectional view of the TFT substrate, respectively.

FIGS. 3A and 3B are diagrams showing a conventional example of Japanese Patent Application Laid-Open No. 4-153625.

FIGS. 4A to 4D are views showing a conventional example of Japanese Utility Model Application Laid-Open No. 61-89819.

FIGS. 5A to 5C are diagrams showing a conventional example of JP-A-62-218937.

[Explanation of symbols]

 Reference Signs List 1 TFT substrate 2 CF substrate 3 Sealing material containing conductive spacer 4 Common common electrode 5 TFT element 11 Shunt transistor

Claims (1)

[Claims] In a liquid crystal display element in which a liquid crystal material is filled in a gap between a TFT substrate and a CF substrate which are opposed to each other and sandwiched by a sealing material, a surface of the TFT substrate on which the sealing material is formed is provided with an antistatic film. A liquid crystal display element, wherein a common common electrode to which a shunt transistor is connected is formed, and the sealing material has a conductive spacer having a transfer function.