JPH08129188A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: To provide a liquid crystal display device of a low cost without degradation in a production yield with simple production processes. CONSTITUTION: This liquid crystal display device is provided with plural image signal wirings 22 and plural scanning signal wirings 23 intersecting with each other via insulating films and is provided with pixel electrodes 24 and switching elements 23 consisting of at least gate electrodes, insulating films, semiconductor films, source electrodes and drain electrodes for supplying image signals to these pixel electrodes in a matrix form at the intersected points of the image signal wiring and the scanning signal wirings. A liquid crystal material is held between the pixel electrodes and the counter electrodes formed to face the pixel electrodes. The device is provided with the pixel electrodes 24 and the drain electrodes of the switching elements 23 on the same side of the insulating films and is provided with the shorting circular wirings 27a, 27b connected via transistors 23 with the plural image signal wirings 22. The gate electrodes and source electrodes or drain electrodes of these TRs 23 are capacitance coupled via the insulating films.

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 panel (hereinafter referred to as a panel) in which a thin film transistor is formed in each pixel.
The present invention relates to an active matrix type liquid crystal display device using a TFT array panel).

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device has a higher contrast than a simple matrix type liquid crystal display device and is excellent in multi-gradation display characteristics, and is therefore an essential technique for a color liquid crystal display device. In particular, an active matrix type liquid crystal display device using a thin film transistor as a switching element has come to obtain an image quality equivalent to that of a CRT.

A conventional liquid crystal display device will be described below with reference to the drawings. 7 is an equivalent circuit diagram of a TFT array panel in the conventional liquid crystal display device, FIG. 8 is a plan view of one pixel of the TFT array panel in the conventional liquid crystal display device, and FIG. 9 is a line AA ′ in FIG. FIG.

In this active matrix type liquid crystal display device, the thin film transistor 3 is switched by the scanning signal supplied from the scanning signal wiring 2, and the signal voltage of the image signal wiring 1 is applied to the pixel electrode 4 connected to the drain electrode 14. By doing so, a voltage is applied to the liquid crystal material (not shown) held between the pixel electrode 4 and the counter electrode (not shown) to display an image.

In this conventional liquid crystal display device, as shown in FIGS. 8 and 9, an image signal wiring 1 and a scanning signal wiring 2 are provided so as to intersect with each other with an insulating film 12 interposed therebetween. A pixel electrode 4 is provided at an intersection with the scanning signal line 2, a thin film transistor 3 including a gate electrode 2a for supplying an image signal to the pixel electrode 4, an insulating film 12, a semiconductor film 13, a source electrode 1a and a drain electrode 14 is provided. It has a structure in which additional capacitors 5 for holding the supplied image signal voltage are provided in a matrix.

Here, the pixel electrode 4 and the thin film transistor 3
The drain electrode 14 and the additional electrode 18 of the insulating film 1 are
It is connected through the contact holes 10a and 10b formed in the No. 2.

In the process of assembling the liquid crystal display device,
The FT array panel is charged with strong static electricity, and a high voltage due to static electricity is applied between the gate electrode 2a and the source electrode 1a of the thin film transistor 3 and between the scanning signal wiring 2a and the image signal wiring 1a, resulting in insulation. Dielectric breakdown of the film 12 often occurred.

Therefore, in the conventional liquid crystal display device, as shown in FIG.
As shown in FIG. 3, a short circuit ring wiring 7 is provided outside the display area X, each scanning signal wiring 2 is connected to the short circuit ring wiring 7, and each image signal is supplied via the transistors 6a and 6b for high voltage protection. The wiring 1 was connected.

The high voltage protection transistors 6a, 6
b is the gate electrode 1 as shown in FIGS.
6a, 16b, the gate insulating film 12, and the source or drain electrodes 19a to 19d. The source or drain electrode 19a of the transistor 6a is connected to the short-circuit ring wiring 7, and the source or drain electrode 1
9b is connected to the image signal wiring 1. The source electrode or drain electrode 19c of the transistor 6b is connected to the image signal wiring 1, and the source electrode or drain electrode 1
9d is connected to the short-circuit ring wiring 7. The gate electrode 16a of the transistor 6a is connected to the short-circuit ring wiring 7 through the contact hole 10c, and the gate electrode 17b of the transistor 6b is connected to the image signal wiring 1 through the contact hole 10d. 1 is a plan view of a thin film transistor for high voltage protection provided in the peripheral portion of a TFT array panel in a conventional liquid crystal display device, and FIG.
1 is a sectional view taken along the line BB ′ of FIG.

Further, as shown in FIGS. 7 and 12, the scanning signal wiring 2 has a contact hole 10e formed in the insulating film 12 connected to the short-circuit ring wiring 7. FIG.
2 is a sectional view of a portion P in FIG.

In this way, the image signal wiring 1 is connected to the short-circuit ring wiring 7 via the high-voltage protection thin film transistors 6a and 6b, and the scanning signal wiring 2 is short-circuited.
It was directly connected to and the electric charge due to static electricity was discharged to the short-circuit ring wiring 7 to prevent dielectric breakdown.

[0012]

In the conventional liquid crystal display device as described above, as shown in FIGS. 8 and 9, the pixel electrode 4 includes the drain electrode 14 and the additional electrode 18 with the insulating film 12 interposed therebetween. Since it is formed on the opposite side, there is a problem that contact holes 10a and 10b for connecting the pixel electrode 4, the drain electrode 14 and the additional electrode 18 must be formed in the insulating film 12.

Further, as shown in FIG. 10 and FIG.
In the thin film transistors 6a and 6b for high voltage protection provided on the periphery other than the display portion, the gate electrodes 16a and 16b are connected to the source or drain electrodes 19a and 19c through the contact holes 10c and 10d. It was necessary to form 10c and 10d on the insulating film 12. (See JP-A-63-220289) Furthermore, as shown in FIG. 12, a contact hole 10e in which the scanning signal wiring 2 and the short-circuit ring wiring 7 are formed in the insulating film 12
Was connected through.

Therefore, in the conventional liquid crystal display device, a photo process for opening the contact holes 10a to 10e in the insulating film 12 is required, which complicates the manufacturing process, lowers the manufacturing yield, and raises the manufacturing cost. It was.

The present invention has been made in view of the above-mentioned problems of the prior art, and reduces the contact holes that must be formed in the insulating film as much as possible to simplify the manufacturing process and reduce the manufacturing yield. It is an object of the present invention to provide a liquid crystal display device that can solve the problems and suppress an increase in manufacturing cost.

[0016]

In order to achieve the above object, in a liquid crystal display device according to the present invention, a plurality of image signal wirings and a plurality of scanning signal wirings are provided so as to cross each other through an insulating film, Pixel electrodes are provided at the intersections of the image signal wirings and the scanning signal wirings, and at least gate electrodes for supplying image signals to the pixel electrodes, switching elements composed of the insulating film, semiconductor film, source electrode, and drain electrode are provided in a matrix. In a liquid crystal display device in which a liquid crystal material is held between the pixel electrode and a counter electrode provided so as to face the pixel electrode, the pixel electrode and the drain electrode of the switching element are provided on the same side of the insulating film. A short circuit ring wiring is provided in which the plurality of image signal wirings are connected via a transistor, and the gate electrode and the source electrode or the drain electrode of the transistor are provided. There is capacitive coupling through the insulating film.

[0017]

With the above structure, the pixel electrode and the switching element can be connected to each other, or the additional electrode can be formed or formed without forming a contact hole in the insulating film. A low-cost liquid crystal display device can be provided without lowering the manufacturing yield. Further, when a plurality of image signal wirings and short circuit wirings are pseudo-connected, they can be connected without forming a contact hole in the insulating film, the manufacturing process is simple, the manufacturing yield is not reduced, and the cost is low. The liquid crystal display device can be provided.

[0018]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIGS. 1, 2 and 3 are views showing an embodiment of the present invention. FIG. 1 shows a TF in a liquid crystal display device.
2 is an equivalent circuit diagram of the T array panel, FIG. 2 is a plan view of one pixel, and FIG. 3 is a sectional view taken along the line AA ′ of FIG.

As shown in FIG. 1, in the image display area X, the image signal wiring 21 and the scanning signal wiring 22 are provided so as to intersect with each other, and switching is performed at each intersection of the image signal wiring 21 and the scanning signal wiring 22. The element 23 and the pixel electrode 24 connected to the switching element 23 are provided. Further, the additional capacitor 25 is formed between the pixel electrode 24 and the scanning signal wiring 22 in the previous stage or the subsequent stage.

As shown in FIGS. 2 and 3, the switching element 21 includes a gate electrode 22a formed on a substrate 31, an insulating film 32, a semiconductor film 33, and the semiconductor film 33.
It is mainly composed of a source electrode 21a and a drain electrode 34 which are formed from above to the insulating film 32.
A pixel electrode 24 is formed on the side of the insulating film 32 where the drain electrode 34 is formed so as to cover the adjacent scanning signal line 22b. Therefore, the drain electrode 34 and the pixel electrode 24 of the switching element 23 are connected to the insulating film 32.
Can be connected without forming a contact hole. Further, since the pixel electrode 24 itself also serves as an additional electrode, a contact hole for connecting the pixel electrode and the additional electrode is unnecessary.

The switching element 23 shown in FIG.
Is a transistor having an inverted stagger structure in which the source electrode 21a and the drain electrode 34 are formed on the surface side of the insulating film 32, but a transistor having a stagger structure in which the insulating film 32 is sandwiched may be used. When the switching element 23 is formed of a staggered transistor, the semiconductor film 32, the source electrode 21a, the drain electrode 34, and the pixel electrode 24 are arranged on the back surface side of the insulating film 32, and the gate electrode 22a and the additional electrode 22b are insulated. It may be arranged on the surface side of the film 32. In this case, the image signal wiring 21 is located on the back surface side of the insulating film 32, and the scanning signal wiring 22 is located on the front surface side of the insulating film 32.

As shown in FIG. 1, a short circuit ring wiring 27b is provided outside the image display area X, and a plurality of image signal wirings 21 are provided on the short circuit ring wiring 27b via two transistors 26a and 26b. Connected. Further, a second short-circuit ring wiring 27a for connecting the plurality of scanning signal wirings 22 is provided, and the second short-circuit ring wiring 27 is provided.
The a and the short circuit ring wiring 27b are connected via a capacitor 38.

As shown in FIGS. 4 and 5, the transistor 26a is formed such that the gate electrode 36a and the source or drain electrode 39a partially overlap with each other with the insulating film 32 in between, and the capacitance is formed at this overlapping portion. They are combined to form the capacitor 30a. Also, the transistor 26b is
The gate electrode 36b and the source or drain electrode 39c are formed so as to partially overlap each other with the insulating film 32 interposed therebetween, and the overlapping portion capacitively couples to form a capacitor 30b. That is, unlike the conventional TFT array panel, the gate electrode and the source electrode or the drain electrode are not connected via the contact hole.

Even if the positive or negative high voltage due to static electricity or the like charges the image signal wiring 21, the transistor 26a,
Short circuit ring wiring 2 in which gate electrodes 36a and 36b of 26b also serve as source or drain electrodes 39a and 39c
7b or the image signal wiring 21 is capacitively coupled with the capacitances 30a and 30b, so that for pulse voltage such as static electricity, this capacitive coupling portion is apparently short-circuited, and the transistor 26a or 26b is turned on and the short-circuit ring wiring 27.
It is possible to discharge the electric charge to the electrostatic absorption capacitor 38 through b and prevent dielectric breakdown.

The high voltage protection transistors 26a, 2
6b may be formed simultaneously with the switching element 23 in the display area X shown in FIG.

In order to prevent contact holes from being formed in the insulating film 32 as much as possible, when the short circuit ring wiring 27b and the second short circuit ring wiring 27a are connected, it is desirable to connect them via the capacitor 38. However, as long as the invention described in claim 2 is implemented, the short-circuit ring wiring 27b and the second short-circuit ring wiring 27a may be directly connected instead of capacitive coupling.

1 and 6 are views showing another embodiment. In the present invention, as shown in FIG. 1, a plurality of image signal wirings 21 are provided with short circuit ring wirings 27b connected through two transistors 26a and 26b, and a plurality of scanning signal wirings 22 are connected to a second circuit. Short circuit ring wiring 27a
The short-circuit ring wiring 27b and the second short-circuit ring wiring 27 are provided.
In this example, a is capacitively coupled via the capacitor 38. That is, as shown in FIG. 8, the second short-circuit ring wiring 27 a and the short-circuit ring wiring 27 b are formed so as to partially overlap with each other through the insulating film 32, and the capacitor 38 is formed in this insulating film 32. Therefore, the second short-circuit ring wiring 27 a and the second short-circuit ring wiring 27 b are capacitively coupled by the capacitance 38, and the static electricity generated between the image signal wiring 21 and the scanning signal wiring 22 is absorbed by the capacitance 38.

In order to prevent contact holes from being formed in the insulating film 32 as much as possible, the gate electrodes and source electrodes or drain electrodes of the transistors 26a and 26b connecting the plurality of image signal wirings 21 and the short-circuit ring wirings 27b. Is preferably formed so as to partially overlap with each other and capacitively coupled. However, as long as the invention described in claim 3 is implemented, the gate electrodes and the source or drain electrodes of the transistors 26a and 26b are capacitively coupled. You may connect directly instead. In this case, the second short-circuit ring wiring 27a and the short-circuit ring wiring 27b may be provided so as to intersect with each other, and the intersecting portion may be irradiated with laser light to electrically short-circuit.

In this embodiment, a second short-circuit ring wiring to which a plurality of scanning signal wirings are connected is provided, and the second short-circuit ring wiring and a plurality of image signal wirings are connected via a transistor. Since the wiring is capacitively coupled, when a plurality of scanning signal wirings and the short-circuit ring wiring are pseudo-connected,
A liquid crystal display device can be provided which can be connected without forming a contact hole in the insulating film, has a simple manufacturing process, does not reduce the manufacturing yield, and is low in cost.

Further, the short-circuit ring wiring 27b and the second short-circuit ring wiring 27 of the TFT array panel of the liquid crystal display device shown in FIG.
a is for preventing electrostatic breakdown of the insulating film during the manufacturing process, and when actually used as a display device, the short circuit ring wiring 27b and the second short circuit ring wiring 27a are separated.

[0032]

As described above, in the liquid crystal display device according to the present invention, the pixel electrode and the drain electrode of the switching element are provided on the same side of the insulating film, and a plurality of image signal wirings are connected through the transistor. Since the gate electrode and the source electrode or drain electrode of this transistor are capacitively coupled through the insulating film by providing a short circuit ring wiring, when connecting the pixel electrode and the switching element or forming the additional electrode, It is possible to provide a low-cost liquid crystal display device that can be connected or formed without forming contact holes, has a simple manufacturing process, does not reduce the manufacturing yield, and has a plurality of image signal wirings and short-circuit ring wirings. When making a pseudo connection, it can be connected without forming a contact hole in the insulating film, the manufacturing process is simple, and the manufacturing yield is high. Without causing made, it is possible to provide a liquid crystal display device of low cost.

[Brief description of drawings]

FIG. 1 shows a liquid crystal display device according to an embodiment of the present invention.
It is an equivalent circuit schematic of an FT array panel.

FIG. 2 shows a liquid crystal display device according to an embodiment of the present invention.
It is a top view of one pixel of an FT array panel.

3 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 4 is a plan view of a transistor portion showing an embodiment of a liquid crystal display device according to the present invention.

5 is a sectional view taken along line B-B ′ of FIG.

FIG. 6 is a cross-sectional view showing a capacitive coupling portion of a short-circuit ring wiring showing another embodiment of the liquid crystal display device according to the present invention.

FIG. 7 is an equivalent circuit diagram of a TFT array panel in a conventional liquid crystal display device.

FIG. 8 is a plan view of one pixel of a TFT array panel in a conventional liquid crystal display device.

9 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 10 is a plan view of a high voltage protection transistor portion in a conventional liquid crystal display device.

11 is a cross-sectional view taken along the line B-B ′ of FIG.

FIG. 12 is a cross-sectional view showing a capacitive coupling portion of a short-circuit ring wiring in a conventional liquid crystal display device.

[Explanation of symbols]

1, 1a, 1b, 21, 21a, 21b ... Image signal wiring and source electrodes, 2, 2a, 2b, 22, 22
a, 22b ... Scan signal wiring and gate electrodes, 3,
23 ... Thin film transistor for pixel switching, 4,
24 ... Pixel electrode, 5, 25 ... Additional capacitance, 6a,
6b, 26a, 26b ... Thin film transistor for high voltage protection, semiconductor film, 7, 27a, 27b ... Short circuit ring wiring, 8, 28 ... Inspection pad, 9, 29 ... Driving circuit connecting terminal, 10, 10a, 10b, 10c, 10d,
10e ... Contact hole, 11 ... Transparent glass substrate, 12, 32 ... Interlayer insulating film, 13, 17a, 1
7b, 33, 37a, 37b ... Semiconductor film, 14, 3
4 ... Drain electrode contact hole, 15 ... Insulating protective film, 16a, 16b, 36a, 36b ... Gate electrode of high voltage protection transistor, 17a, 17
b, 37a, 37b ... Semiconductor film of high voltage protection transistor, 18 ... Additional electrode, 19a, 19b, 19
c, 19d ... Source or drain electrode of high voltage protection transistor, 30a, 30b ... Gate connection capacitance of high voltage protection transistor, 38 ... Electrostatic absorption capacitance

[Procedure amendment]

[Submission date] February 2, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Further, as shown in FIGS. 7 and 12, the scanning signal wiring 2 is connected to the short-circuit ring wiring 7 through a contact hole 10e formed in the insulating film 12. Note that FIG. 12 is a cross-sectional view of the portion P in FIG. 7.

Claims (3)

[Claims] 1. A plurality of image signal wirings and a plurality of scanning signal wirings are provided so as to intersect with each other through an insulating film, and a pixel electrode is provided at an intersection of the image signal wiring and the scanning signal wiring and an image signal is provided to the pixel electrode. Supplying at least a gate electrode, the insulating film, the semiconductor film, a switching element composed of a source electrode and a drain electrode in a matrix form, and between the pixel electrode and a counter electrode provided so as to face the pixel electrode. In a liquid crystal display device in which a liquid crystal material is held, the pixel electrode and a drain electrode of a switching element are provided on the same side of the insulating film, and a short circuit ring wiring in which the plurality of image signal wirings are connected via a transistor is provided. A liquid crystal display device, wherein a gate electrode and a source electrode or a drain electrode of this transistor are capacitively coupled via the insulating film. 2. A second short-circuit ring wiring to which the plurality of scanning signal wirings are connected is provided, and the second short-circuit ring wiring and the plurality of image signal wirings are connected via a transistor. The liquid crystal display device according to claim 1, wherein and are capacitively coupled. 3. The liquid crystal display device according to claim 2, wherein a gate electrode and a source electrode or a drain electrode of the transistor are capacitively coupled via the insulating film.