JPH0618924A - Production of substrate of liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent the breakdown of thin film transistors due to the discharge of electric charges accumulated in a producing process when the substrate of a liq. crystal display device is produced. CONSTITUTION:At the time of producing the substrate of a liq. crystal display device with picture element electrodes 2 arranged on the substrate 1, thin film transistors 3 for intermitting voltage impressed on each of the electrodes 2, scanning bus lines 5 and data bus lines 6 with the inner ends separately connected to the transistors 3 and the outer ends parallel arranged at peripheral parts of the substrate 1 in the form of input terminals 4, the adjacent input terminals 4 are made close to each other so as to attain electric capacity coupling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a substrate of a liquid crystal display device, and when manufacturing a substrate provided with a TFT,
The present invention relates to a method for manufacturing a substrate of a liquid crystal display device in which input terminals of a scan bus line and a data bus line are capacitively coupled to each other to have the same potential and are separated in terms of direct current.

In recent years, the miniaturization of electronic devices has been promoted by the long-term progress of electronic devices centering on semiconductor devices. However, even in a display device, which is one of the element devices for the interface between a machine and a human, the liquid crystal is used. The display device has been attracting attention as a new display device which is a large and heavy-duty and replaces the CRT display device which is not particularly suitable for a portable type.

The liquid crystal display device was once evaluated to be not very practical as a large panel type display device because of its slow operation speed, low contrast, difficult colorization, and complicated drive circuit. However, due to recent developments such as the development of new liquid crystal materials and driving methods, and the improvement of the manufacturing technology of liquid crystal display panels, the display device has a display performance comparable to that of the CRT display device.

However, in a liquid crystal display device having a large size and a large display capacity, how to reduce display defects to improve the yield is a major issue, and there is still room for consideration in manufacturing technology.

[0005]

2. Description of the Related Art A liquid crystal display panel is one in which a large molecule is moved in a viscous liquid crystal sandwiched between two glass plates to obtain a display device by utilizing optical effects such as polarization. , Generally, the response is slow. Therefore, it has been said that the liquid crystal display device is not suitable for a fast-moving display such as a moving image.

However, a new liquid crystal material called TN (twisted nematic) liquid crystal or STN (super twisted nematic) liquid crystal and its alignment method have been developed, or a so-called active matrix method in which TFTs (thin film transistors) are arranged in each pixel is developed. For example, the function of the liquid crystal display device is approaching that of the CRT display device.

By the way, the basic structure of a liquid crystal display device is that a liquid crystal is sandwiched between two substrates to interrupt a voltage and change the orientation of liquid crystal molecules to transmit or block light. FIG. 3 is a plan view of an example of a substrate provided with a TFT of a liquid crystal display device, in which 1 is a substrate, 2 is a pixel electrode, and 3 is a TF.
T and 3a are sources, 3b is a gate, 3c is a drain, 4 is an input terminal, 4c is a short-circuit portion, 5 is a scan bus line, and 6 is a data bus line.

In an active matrix type liquid crystal display device using a TFT, one substrate 1 has a pixel electrode which is a dot-like pixel formed of a transparent ITO (Indium Tin Oxide) film on the surface of a glass plate. 2 is provided and the pixel electrode 2 is switched by the TFT 3. Although not shown here, the other substrate has a structure of a common electrode in which a transparent electrode is provided on the entire surface of the glass plate.

At least one TFT 3 is provided for each of tens of thousands to hundreds of thousands of pixel electrodes 2 arranged in a grid corresponding to a pixel, and the pixel electrode 2 is a source.
The gate 3b is connected to the scan bus line 5, and the drain 3c is connected to the data bus line 6, respectively. Depending on the driving method of the liquid crystal, the source 3a and the drain 3c may be connected in reverse.

Scan bus line 5 and data bus line 6
Are drawn out to the peripheral portion of the substrate 1 while being orthogonal to each other between the pixel electrodes 2 and serve as input terminals 4 for connecting to a drive circuit (not shown).

[0011]

The substrate 1 is formed through various manufacturing processes such as film formation and photolithography. After each process, the substrate 1 is always cleaned. It is kept. Therefore, the substrate 1 has a high insulating property, and is inevitably charged by various actions such as friction, contact, and peeling during various manufacturing processes.

This charge is accumulated as static charge on the pixel electrode 2, the scanning bus line 5, the data bus line 6 and the like which are formed on the insulating substrate 1 in an electrically floating state, and the charging potential is changed. Going up. The scanning bus line 5 and the data bus line 6 having particularly long patterns in the adjacent portions
When the potential difference between the charged potentials reaches the discharge breakdown voltage,
Electric discharge occurs between the bus lines 5 and 6. As a result, T
Occasionally, the FT3 is destroyed or the bus lines 5 and 6 are broken.

Therefore, the tip of the input terminal 4 is short-circuited so that the scanning bus line 5 and the data bus line 6 have the same potential.
4c is connected in common to prevent such a defective discharge. Then, when a series of manufacturing processes for producing the substrate 1 is completed, the short circuit portion 4c is cut to separate the bus lines 5 and 6 individually.

However, when the scan bus line 5 and the data bus line 6 are commonly connected in this way, it is not possible to perform a disconnection inspection of the bus lines 5 and 6 or a characteristic inspection of the TFT 3 during the manufacturing process of the substrate 1. There was a problem.

Therefore, according to the present invention, when the substrate is manufactured, the input terminals of the scan bus line and the data bus line are capacitively coupled to generate a low discharge that does not destroy the TFT, and the bus lines have the same potential. It is an object of the present invention to provide a method of manufacturing a substrate of a liquid crystal display device which is separated in terms of direct current.

[0016]

Means for Solving the Problems The above-mentioned problems include a pixel electrode provided on a substrate, a TFT (thin film transistor) for intermittently applying a voltage applied to each pixel electrode,
In the method for manufacturing a substrate of a liquid crystal display device having one end connected to each of the TFTs and the other end forming an input terminal and having a scanning bus line and a data bus line juxtaposed in the peripheral portion of the substrate, This is solved by a method of manufacturing a substrate of a liquid crystal display device configured to capacitively couple adjacent input terminals close to each other.

[0017]

In the substrate for forming the TFT of the active matrix type liquid crystal display device using the TFT, the bus lines are commonly connected in the conventional manufacturing method. However, in the present invention, each bus line is connected in common. I try to be insulated.

That is, the input terminals of the adjacent bus lines are arranged close to each other with a gap of several μm between them. Then, the gap serves as an electric capacity so that adjacent input terminals are electrically capacity-coupled. This adjacent portion is cut off after manufacturing the substrate.

Then, in the process of manufacturing the substrate, when the substrate is charged, the TFTs are discharged at such a low voltage that the TFTs are not destroyed and the bus lines have the same potential. Then, it is possible to prevent a strong discharge that would destroy the TFT.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view of a main part of an embodiment of the present invention,
FIG. 2 is a perspective view of the main part of another embodiment of the present invention. In the figure, 1 is a substrate, 2 is a pixel electrode, 3 is a TFT, 4 is an input terminal, 4a is a widened portion, 4b is an electrode gap, 5 is a scanning bus line, 6 is a data bus line, 7 is a coupling electrode, and 7a is The connecting portion, 8 is a cutting line.

The substrate 1 is made of a glass plate on which IT
Transparent pixel electrodes 2 made of an O film are arranged in a grid pattern. A TFT 3 is provided on each pixel electrode 2, and the voltage applied to the pixel electrode 2 is interrupted.

One end of a scanning bus line 5 and one end of a data bus line 6 which are orthogonal to each other are connected to the TFT 3 so as to be driven. Further, the other ends of the two types of bus lines 5 and 6 serve as input terminals 4, which are spread and arranged side by side on the peripheral portion of the substrate 1.

Embodiment 1: In FIG. 1, scan bus line 5 and data bus line 6
Widen the tip of each input terminal 4
Forming 4a. And, for example, 2 to 10μ
They are close to each other with a minute electrode gap 4b of m.

The electrode gap 4b serves as an electric capacity (electrostatic capacity) so that the respective input terminals 4 are capacitively coupled. Then, when a potential difference is generated between the bus lines 5 and 6 to such an extent that dielectric breakdown occurs, the lines are brought to the same potential by the discharge occurring in the electrode gap 4b.

In this way, the electrode gap 4b is blocked in terms of direct current at a low voltage that does not cause a strong discharge such as destruction of the TFT 3, and the respective bus lines 5,
6 is in an insulated state. Therefore, during the manufacturing process of the substrate 1, while driving the respective bus lines 5 and 6,
A disconnection inspection of each line and a characteristic inspection of the TFT 3 can be performed. The portion from the widened portion 4a is cut off along the cutting line 8 after the manufacturing process of the substrate 1 is completed.

Embodiment 2 In FIG. 2, the scan bus line 5 and the data bus line 6 are shown.
A coupling electrode 7 is provided at the tip of each of the input terminals 4. The coupling electrode 7 has a configuration in which the coupling portion 7a projects in a comb shape, and the coupling portion 7a enters into the gaps of the respective input terminals 4 to form an electrode gap 4b between the input terminals 4. The electrode gap 4b serves as an electric capacity.

Thus, as in the first embodiment, the input terminal 4
The adjacent ones are capacitively coupled so that a discharge is generated and the same potential is generated before a strong discharge that destroys the TFT 3 is generated. Therefore, during the manufacturing process of the substrate 1,
While driving the respective bus lines 5 and 6, it is possible to perform a disconnection inspection of each line and a characteristic inspection of the TFT 3. The coupling electrode 7 is cut off along the cutting line 8 after the manufacturing process of the substrate 1 is completed.

[0028]

According to the present invention, the bus lines that drive the TFTs are capacitively coupled, and the bus lines are set to the same potential by a weak discharge that does not damage the TFTs. Then, the TFT is prevented from being destroyed by the strong discharge due to the accumulated electrostatic charge. Moreover, since the respective bus lines are galvanically isolated, electrical inspection can be performed during the process.

As a result, it becomes possible to improve the efficiency of the manufacturing method of the substrate provided with the TFT, and the present invention is applied to the progress of the active matrix type liquid crystal display device, which is expected to be further expanded in the future. It has a great contribution.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of an embodiment of the present invention.

FIG. 2 is a perspective view of a main part of another embodiment of the present invention.

FIG. 3 is a plan view of an example of a substrate provided with a TFT of a liquid crystal display device.

[Explanation of symbols]

1 substrate 2 pixel electrode 3 TFT 4 input terminal 4a widened portion 4b
Electrode gap 5 Scanning bus line 6 Data bus line 7 Coupling electrode 7a Coupling part 8 Cutting line

Claims (3)

[Claims] 1. A pixel electrode (2) disposed on a substrate (1),
A TFT (thin film transistor) (3) for connecting and disconnecting the voltage applied to each of the pixel electrodes (2), and one end of the TFT
(3) Scan bus lines connected to each of the (3) and the other ends of which form input terminals (4) and are arranged in parallel on the peripheral edge of the substrate (1).
In a method of manufacturing a substrate of a liquid crystal display device having (5) and a data bus line (6), adjacent input terminals (4) are closely capacitively coupled to each other. Production method. 2. A widened portion (4a) is provided at a tip portion of the input terminal (4).
2. The liquid crystal display device according to claim 1, wherein the widened portion (4a) is adjacently adjacent to each other to capacitively couple them, and then the widened portion (4a) is cut off after the substrate (1) is manufactured. Substrate manufacturing method. 3. The method of manufacturing a liquid crystal display device according to claim 1, further comprising a coupling electrode (7), wherein the coupling electrode (7) has a comb-shaped protruding portion (7).
a) is provided in each gap of the input terminals (4) to capacitively couple the input terminals (4) adjacent to each other, and then the coupling electrode (7) is cut off after manufacturing the substrate (1). The method for manufacturing a substrate of a liquid crystal display device according to claim 1.