JP2613979B2 - Active matrix display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix display device using thin film transistors (hereinafter referred to as "TFT").

[0002]

2. Description of the Related Art FIG. 10 is a sectional view of a conventional active matrix display device. FIG. 11 shows an equivalent circuit diagram of the active matrix display device of FIG. In the active matrix substrate 150, as shown in FIG. 10, a TFT 102 and pixel electrodes 103 are provided in a matrix on a first insulating substrate 101 made of glass or the like. T
The FT 102 has a gate bus line 11 for supplying a scanning signal.
4 and a source bus line 115 for supplying a video signal are connected (FIG. 11). Further, an alignment film 104 usually made of a polyimide film is formed on the entire surface of the substrate, and the alignment film 104 is subjected to an alignment treatment (FIG. 10).

In the counter substrate 160, the second insulating substrate 1
An opposing electrode 106 made of a transparent electrode is formed on almost the entire surface of the substrate 05, and an alignment film 107 that has been subjected to an alignment process is formed on the opposing electrode 106. Plastic beads 109 are interposed between the active matrix substrate 150 and the counter substrate 160 as spacers, and the distance between the substrates 150 and 160 is kept constant. As shown in FIG. 9, the active matrix substrate 150 and the opposing substrate 160 are attached to each other so that long sides intersect with each other.
As shown in FIG. 10, the active matrix substrate 150
The liquid crystal 110 is sealed between the counter substrate 160 and the sealing resin 108.

In this active matrix display device,
The liquid crystal layer 1 is interposed between the pixel electrode 103 and the counter electrode 106.
10 and the alignment films 104 and 107, which form a capacitor 111 as shown in FIG. One electrode of the capacitor 111 is a pixel electrode 103, and the other electrode is a counter electrode 106. Picture element electrode 1
03 is connected to the drain electrode 102d of the TFT 102, and the common electrode 112 is connected to the common electrode 106 for the common electrode 106. The source bus line 115 is connected to the source electrode 102 s of the TFT 102. Gate bus wiring 114 and source bus wiring 115
Are connected to electrode terminals on the outside of the sealing resin 108, respectively.

In order to drive the active matrix display device shown in FIG. 11, a scanning pulse signal 116 is sequentially input from the uppermost gate bus line 114 and the gate bus line 1
The respective TFTs 102 connected to 14 are turned on. When a video signal 117 is input from the source bus wiring 115 in synchronization with the scanning pulse signal, each pixel electrode 1
A voltage is applied to the liquid crystal layer between the liquid crystal layer 03 and the counter electrode 106, and display is performed. The counter electrode 106 has a pixel electrode 1
A DC bias voltage 118 for canceling a DC component applied to the power supply circuit 03 is applied.

In the conventional active matrix display device represented by the equivalent circuit diagram of FIG.
In addition, since the source bus wirings 115 intersect with each other via an insulating film on the substrate, a short circuit between these wirings, a disconnection failure at a stepped portion, and the like easily occur, and a display device cannot be obtained at a high yield. There is a point.

As a solution to such a problem,
There is a display device described in Japanese Patent Application No. 2-24902. This display device has a configuration shown in the equivalent circuit diagram of FIG. 12, and an example of an active matrix substrate constituting the display device is shown in a plan view of FIG. In this display device, the gate electrode 2a of the TFT 1 is connected to the gate bus line 2, and the source electrode 15
Is the gate electrode 15 of the TFT1 in the next column of the TFT1.
Is connected via an electrode line 37 to the gate bus line 2 to which the. The electrode line 37 is made of a metal thin film such as Ti, and is connected to the gate bus line 2 via the contact hole 25 formed in the insulating film on the gate bus line 2 as shown in FIG. On the opposing substrate opposite to FIG.
Are formed. Each video signal electrode 4 arranged in a direction intersecting with the gate bus line 2 is connected to a common video signal line 34.
It is connected to the.

[0008]

In this display device, since there is no source bus line for supplying a video signal on the active matrix substrate, the above-described short circuit between the gate bus line and the source bus line, and disconnection at the step portion. The problem that defects and the like easily occur can be solved. But,
In this display device, the area of the pixel electrode 19 cannot be increased because there is an electrode line 37 made of a metal thin film that electrically connects the source electrode 15 of the TFT 1 and the gate bus line 2. Therefore, there is a problem that the aperture ratio of the display screen cannot be increased.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide an active matrix display device having a large aperture ratio without an intersection between a gate bus wiring and a source bus wiring. To provide.

[0010]

According to the present invention, there is provided an active matrix display device comprising: first and second insulating substrates; a liquid crystal layer sealed between the first and second substrates; A pixel electrode provided in a row on the substrate, a thin film transistor connected to each of the pixel electrodes to form a row, a gate bus wiring connected to a gate electrode of the thin film transistor, and A transparent electrode line for connecting a source electrode of the thin film transistor to the gate bus line connected to the thin film transistor of the next column of the column, and a transparent electrode line provided on the second substrate to face each of the pixel electrodes; A video signal electrode, and the picture element electrode is superimposed on the transparent electrode line via an insulating film, whereby the object is achieved.

[0011]

Embodiments of the present invention will be described below.

FIG. 1 is a plan view of an active matrix substrate constituting a display device of the present embodiment. FIG. 2A is a cross-sectional view taken along the line AA of FIG. 1, and FIG.
The sectional views along line -B are shown. 3 to 6 show steps of manufacturing the active matrix substrate shown in FIG. 3A to 6, (a) is a plan view of the active matrix substrate, and (b) is a cross-sectional view taken along line AA of (a). The active matrix display device of the present embodiment will be described according to the manufacturing process. A Ta metal thin film was formed on a first insulating substrate 10 made of a glass substrate or the like by a sputtering method. This Ta metal thin film was patterned into the shapes of the gate bus line 2 and the gate electrode 2a shown in FIG. 3A by photolithography and etching. FIG. 3B is a cross-sectional view taken along the line AA of FIG. 3 as described above.

Next, a silicon nitride film, an amorphous silicon film, and an n ⁺ type amorphous silicon film were sequentially formed on the entire surface of the substrate 10 by a plasma CVD method. This silicon nitride film becomes the gate insulating film 12. The amorphous silicon film and the n ⁺ -type amorphous silicon film were patterned to form a semiconductor layer 13 and a contact layer 14 on the gate electrode 2a as shown in FIGS. 4A and 4B. Next, the gate insulating film 12 is patterned, and the gate insulating film 12 on the gate bus wiring 2 is patterned.
A contact hole 25 was formed in the portion.

Next, a Ti metal thin film was formed on the entire surface of the substrate 10. This Ti metal thin film was patterned to form a source electrode 15 and a drain electrode 16 having the shapes shown in FIG. At this time, the central part of the contact layer 14 is also etched away and divided into a part below the source electrode 15 and a part below the drain electrode 16.
Thus, the TFT 1 is completed.

Next, the entire surface of the substrate 10 is covered with ITO.
(Indium tin oxide) film is formed and patterned, and as shown in FIG.
A transparent electrode line 17 electrically connecting the gate bus line 2 to the gate bus line 2 was formed. One end of the transparent electrode line 17 is a TFT
One of the source electrodes 15 is superimposed on the other (FIG. 6B), and the other end is also formed on the contact hole 25. FIG.
According to the configuration (a), the source electrode 15 of the TFT 1 is electrically connected to the gate bus line 2 connected to the TFT 1 in the next column of the TFT 1. Although not shown in FIG. 6A, each source electrode 1 in the bottom row of TFTs 1
Reference numeral 5 is connected to one pseudo gate bus line having no gate electrode. TFT for pseudo gate bus wiring
Is not connected.

A silicon nitride film is formed on the entire surface of the substrate 10 on which the transparent electrode lines 17 are formed by using the plasma CVD method, and only the portion covering the TFT 1 and the transparent electrode lines 17 is left, so that the protective film 18 is formed. (FIGS. 1A and 1B). The protective film 18 may be formed using a polyimide resin. In this case, polyimide is applied by a spinner, baked, and then patterned to form the protective film 18.
Is formed.

Next, an ITO film is formed on the entire surface of the substrate and patterned to form a pixel electrode 1 having a shape shown in FIG.
9 was formed. The pixel electrodes 19 are also formed on the transparent electrode lines 17 with the protective film 18 interposed therebetween. Further, an alignment film (not shown) is formed on the entire surface of the substrate 10, and the active matrix substrate 30 is completed.

FIG. 7 is a plan view of a counter substrate 31 constituting the active matrix display device of the present embodiment. On a second insulating substrate made of a glass substrate or the like, a thin film is formed using a black resin such as a color mosaic CK manufactured by Fuji Hunt Electronics Technology, for example, and is patterned into a shape shown by oblique lines in FIG. The light shielding film 22 was formed. The window-like portion 23 surrounded by the light-shielding film 22 is formed on the pixel electrode 1 on the active matrix substrate 30 to be bonded later.
9 is supported. The size of the window 23 is set smaller than that of the pixel electrode 19, and is set so as to cover the periphery of the pixel electrode 19 when the window 23 is bonded to the active matrix substrate 30.

Next, an ITO film is formed on the entire surface of the substrate 10 by a sputtering method, and a portion of the gap region 24 shown by a dashed line in FIG. 7 is removed to form a pattern of the video signal electrode 4. . The gap region 24 is a continuous region connecting the gap between the pixel electrodes 19 on the active matrix substrate 31 and the portion on the gate bus line 2. Further, an alignment film (not shown) is formed on the entire surface of the substrate, and the opposing substrate 31 is completed.

The active matrix substrate 30 and the counter substrate 31 manufactured as described above are bonded together in the same manner as in FIG. 9 described above, and the liquid crystal is sealed, thereby completing the active matrix display device.

The equivalent circuit of the active matrix display device of this embodiment is the same as that of FIG. The capacitor 6 is formed between the picture element electrode 19 connected to the drain electrode 16 of the TFT 1 and the video signal electrode 4, and a liquid crystal layer and an alignment film are sandwiched as a dielectric.

A driving method of the active matrix display device will be described. The scanning pulse signal S shown in FIG. 8 is applied to the gate bus wiring terminals G _n−1 , G _n , G _n−1 .
_n-1 , _Sn , _Sn-1 ... are sequentially input. Here, description will be focused on the scanning signal S _n to be input to G _{n. Sn} is TF
It comprises an ON signal 71 for turning on T1, an OFF signal 72 for turning off TFT1, and a correction signal 73.
When the TFT connected to the gate bus wiring terminal G _n-1 at the previous stage is turned on, the correction signal 73 is supplied to the source electrode of the TFT connected to the gate bus wiring terminal G _n-1 and the OFF signal 72. Are provided to give different potentials. Such a scanning signal is input to each gate bus line 2 in the scanning direction indicated by the arrow in FIG. Thereby, the ON signal 7 is applied to G _n.
When 1 is input, the correction signal 73 is input to G _{n + 1,} and the correction signal 73 is input to the source electrode of the TFT connected to G _n .

The video signal electrode terminals P _{m- 1} , P _m , P _{m + 1} ... Electrically connected to the video signal electrode 4 on the opposite substrate 31 have video signals V _m-1 , V _m , V _{m + 1} ... Are input. The video signals V _m−1 , V _m , and V _{m + 1} are inverted in polarity for each field of the television signal in order to drive the liquid crystal layer by AC, and the video signal to be applied to the liquid crystal layer of each picture element is , Each of the video signal electrode terminals P _m−1 , P _m , P _{m + 1} .
Is input to

In the active matrix display device of the present embodiment, since there is no bus line for supplying a video signal on the active matrix substrate 30, no short circuit occurs with the gate bus line 2 for supplying a scanning signal. Further, since there is no intersection of these bus lines, the occurrence of disconnection of the bus lines is reduced. A pixel electrode 19 is also formed on a transparent electrode line 17 that electrically connects the source electrode 15 of the TFT 1 and a gate bus line connected to the gate electrode of the TFT 1 in the next column of the TFT 1. Therefore, the aperture ratio of the display screen can be increased.

[0025]

According to the active matrix display device of the present invention, since the video signal electrode for inputting the video signal is formed on the opposite substrate, it does not cross the gate bus line for supplying the scanning signal. Therefore, no short circuit occurs between the gate bus wiring and the video signal electrode. In addition, since a pixel electrode is also formed on a transparent electrode line which electrically connects a source electrode of the TFT and a gate bus line connected to a gate electrode of a TFT in the next column of the TFT, a display is performed. The aperture ratio of the screen can be increased. Therefore, according to the present invention, an active matrix display device having a bright display screen can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view of an active matrix substrate constituting one embodiment of an active matrix display device of the present invention.

FIGS. 2A and 2B are cross-sectional views taken along lines AA and BB of FIG. 1, respectively.

3A is a plan view showing a manufacturing process of the active matrix substrate of FIG. 1, and FIG. 3B is a cross-sectional view taken along line AA of FIG.

4A is a plan view illustrating a manufacturing process of the active matrix substrate of FIG. 1, and FIG. 4B is a cross-sectional view taken along line AA of FIG.

5A is a plan view illustrating a manufacturing process of the active matrix substrate of FIG. 1, and FIG. 5B is a cross-sectional view taken along line AA of FIG.

6A is a plan view illustrating a manufacturing process of the active matrix substrate of FIG. 1, and FIG. 6B is a cross-sectional view taken along line AA of FIG.

FIG. 7 is a plan view of a counter substrate constituting one embodiment of the active matrix display device of the present invention.

FIG. 8 is a diagram showing a scanning signal and a video signal input to the active matrix display device of the present invention.

FIG. 9 is a diagram showing a state in which an active matrix substrate and a counter substrate which constitute an active matrix display device are bonded to each other.

FIG. 10 is a sectional view of a conventional active matrix display device.

FIG. 11 is an equivalent circuit diagram of a conventional active matrix display device.

FIG. 12 is an equivalent circuit diagram of an embodiment of the active matrix display device of the present invention and an improved example of the conventional device.

FIG. 13 is a plan view of an active matrix substrate used in a display device obtained by improving a conventional active matrix display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 TFT 2 Gate bus wiring 2a Gate electrode 4 Video signal electrode 10 Insulating substrate 12 Gate insulating film 15 Source electrode 16 Drain electrode 17 Transparent electrode line 18 Protective film 19 Picture element electrode 22 Light shielding film 23 Window part 24 Gap area 25 Contact hole

Claims (1)

(57) [Claims] 1. A first and a second insulating substrate, a liquid crystal layer sealed between the first and the second substrate, and picture elements provided in rows on the first substrate. An electrode, a thin film transistor connected to each of the picture element electrodes to form a column, a gate bus line connected to the gate electrode of the thin film transistor, and a thin film transistor of the next column to the source electrode of the thin film transistor. A transparent electrode line for connecting to the gate bus wiring connected to the pixel bus, and a video signal electrode provided on the second substrate so as to face each of the pixel electrodes. Is an active matrix display device overlaid on the transparent electrode line via an insulating film.