JP2000292803A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] A video signal line can be repaired with an extremely simple configuration. SOLUTION: One of the transparent substrates disposed opposite to each other with a liquid crystal therebetween is disposed in each pixel region on the liquid crystal side of one transparent substrate.
A pixel electrode to which a selected video signal is supplied from a video signal line; and a reference electrode which is arranged at a distance from the pixel electrode and to which a reference signal from a reference signal line is supplied. In a liquid crystal display device which controls the light transmittance of liquid crystal between them by an electric field generated between the pixel signal region and the pixel region, the video signal line may be short-circuited at two separated portions in the pixel region. A conductor layer is formed.

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, and more particularly to a so-called in-plane switching method.

[0002]

2. Description of the Related Art In a liquid crystal display device called a so-called in-plane switching method, one of transparent substrates disposed opposite to each other with a liquid crystal interposed therebetween is connected to a pixel region on the liquid crystal side of one of the transparent substrates. A pixel electrode to which a selected video signal is supplied, and a reference electrode which is arranged at a distance from the pixel electrode and to which a reference signal from a reference signal line is supplied, and is generated between the pixel electrode and the reference electrode. The light transmission of the liquid crystal between them is controlled by the applied electric field. Such a liquid crystal display device can recognize a clear image even when viewed from a large angle field of view with respect to its display surface, and has come to be known as one having an excellent angle field. Such a liquid crystal display device is described in detail in, for example, Japanese Patent Publication No. 5-505247 and Japanese Patent Publication No. 63-21907. In recent years, such a liquid crystal display device has been further increased in size and definition.

[0003]

However, with the increase in size and the increase in definition, a decrease in yield due to disconnection of a signal line occurs in the manufacture thereof. It has been pointed out that there are many disconnections in lines. That is, light use efficiency (aperture ratio)
In order to improve the image quality, the wiring width of each of the scanning signal line, the reference voltage signal line, and the video signal line tends to decrease, but when each pixel has a vertical stripe shape, This is because the signal line has a particularly thinned configuration due to the problem of limitation of the occupied area. When the video signal line is broken, most of the pixels to which the video signal must be supplied via the video signal line are not driven, so that it is wise in terms of production cost to repair the pixel signal line. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a liquid crystal display device capable of repairing a video signal line with an extremely simple configuration.

[0004]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows. That is, a pixel electrode to which a selected video signal from a video signal line is supplied to each pixel region on the liquid crystal side of one of the transparent substrates disposed opposite to each other via the liquid crystal, and the pixel electrode And a reference electrode that is arranged at a distance from the reference signal line and supplied with a reference signal from a reference signal line, and controls the light transmittance of the liquid crystal therebetween by an electric field generated between the pixel electrode and the reference electrode. In the liquid crystal display device, a conductor layer that can be short-circuited at two portions in the pixel region of the video signal line is formed in the pixel region. The liquid crystal display device thus configured is provided with a conductor layer capable of short-circuiting at two portions between the disconnection portions even when a disconnection occurs in the video signal line. Since this conductor layer is formed as a bypass circuit having a relatively short length in the pixel region, it can be formed with a very simple configuration.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the liquid crystal display device according to the present invention will be described below with reference to the drawings. Embodiment 1 FIG. [Equivalent Circuit of Liquid Crystal Display Device] The liquid crystal display device of this embodiment is of a so-called lateral electric field type active matrix type, and its equivalent circuit is as shown in FIG. Although the figure is a circuit diagram, it is drawn corresponding to an actual geometric arrangement. In the figure, one transparent substrate SU of the transparent substrates arranged to face each other via a liquid crystal is shown.
A scanning signal line GL and a reference voltage signal line CL extending in the x direction (row direction) and juxtaposed in the y direction (column direction) are formed on the liquid crystal side surface of B.

In this case, in FIG. 1, the scanning signal line GL, the reference voltage signal line CL relatively separated from the scanning signal line GL, and the reference voltage signal line CL are arranged from above the transparent substrate SUB. The scanning signal line GL, the reference voltage signal line CL relatively separated from the scanning signal line GL,...
And so on. The video signal lines DL which are insulated from the scanning signal lines GL and the reference voltage signal lines CL and extend in the y direction and are arranged in parallel in the x direction.
Are formed.

Here, each of the rectangular regions having a relatively large area surrounded by each of the scanning signal lines GL, the reference voltage signal lines CL, and the video signal lines DL is a region where a unit pixel is formed. The signal line that contributes to the pixel is one of the scanning signal line GL, the reference signal line CL, and one of the video signal lines DL adjacent to each other (the left video signal line DL in the drawing). This is because the other video signal line DL (the right video signal line DL in the drawing) contributes to another pixel adjacent to the right. Each of these unit pixels is arranged in a matrix to form a display surface. The detailed configuration of this pixel will be described below.

The transparent substrate SUB is provided with a vertical scanning circuit GDRV and a video signal driving circuit DDRV as external circuits, and the vertical scanning circuit GDRV sequentially applies a scanning signal (voltage) to each of the scanning signal lines GL. Is supplied from the video signal drive circuit DDRV to the video signal line DL in accordance with the timing.
Is supplied.

Note that power and image information are separately supplied to the vertical scanning circuit GDRV and the video signal driving circuit DDRV from a power supply device / signal conversion device into display data and control signals. The reference voltage signal line CL is supplied with a reference voltage signal from a reference signal drive circuit CDRV in the power supply / signal converter.

In this embodiment, the reference voltage signal is supplied from both ends of each reference voltage signal line CL. When there is one terminal CLIE for supplying a reference voltage signal to each reference voltage signal line CL, a low resistance layer is used as a wiring layer extending from the terminal CLIE to both ends of each reference voltage signal line CL. Although the distortion of the waveform of the reference voltage signal transmitted to each reference voltage signal line CL can be reduced, this embodiment has a configuration necessary for repairing the video signal line DL. Therefore, in this embodiment, the wiring layer extending from the terminal CLIE to both ends of each reference voltage signal line CL does not necessarily have to be a low resistance layer.

[Configuration of Pixel] FIG. 1 is a plan view showing the configuration of the unit pixel. FIG. 3 is a sectional view taken along line III-III in FIG. In FIG. 1, a transparent substrate S
A reference voltage signal line CL extending in the x direction on the main surface of UB
And the scanning signal line GL is formed relatively parallel to the reference voltage signal line CL in the (-) y direction and in parallel with the reference voltage signal line CL. These reference voltage signal lines CL and scanning signal lines GL are formed of, for example, Cr or an alloy thereof.

Here, three reference electrodes CE are integrally formed on the reference voltage signal line CL. That is, two of the reference electrodes CE are in the y-direction side of a pixel region formed by a pair of video signal lines DL described later, that is, in the (-) y direction in proximity to the respective video signal lines DL. It is formed to extend to the vicinity of the scanning signal line GL, and the remaining one is formed between them. Here, in this embodiment, of the reference electrodes CE, one of the reference electrodes CE which is adjacent to the video signal
E (corresponding to the reference electrode on the right side in the figure in each pixel region) is formed so that its end extends in the (+) x direction, and its extending portion is superimposed on the video signal line. Is configured. The surface of the transparent substrate SUB on which the scanning signal lines GL, the reference voltage signal lines CL, and the reference electrodes CE are formed also covers these scanning signal lines GL and the like, and covers the insulating film GI made of, for example, a silicon nitride film. 3) is formed. The insulating film GI serves as an interlayer insulating film for an intersection with the scanning signal line GL and the reference voltage signal line CL for a video signal line DL to be described later, and as a gate insulating film for a region where the thin film transistor TFT is formed. The region for forming the storage capacitor CSTG functions as a dielectric film.

On the surface of the insulating film GI, first, a semiconductor layer AS is formed in a region where the thin film transistor TFT is formed.
Are formed. The semiconductor layer AS is made of, for example, amorphous Si, and is formed on the scanning signal line GL so as to overlap a portion close to the video signal line DL.
Thus, a part of the scanning signal line GL also serves as a gate electrode of the thin film transistor TFT. On the surface of the insulating film GI, as shown in FIG. 1, video signal lines DL extending in the y direction and arranged in parallel in the x direction are formed. This video signal line DL is formed of, for example, Cr or an alloy thereof. The video signal line DL extends to a part of the surface of the semiconductor layer AS of the thin-film transistor TFT.
E is provided integrally.

Further, a pixel electrode PE is formed on the surface of the insulating film GI in the pixel region. This pixel electrode P
E is formed so as to travel between the reference electrodes CE. That is, one end of the pixel electrode PE also serves as the source electrode SE of the thin film transistor TFT, extends in the (+) y direction as it is, further extends in the x direction along the reference signal line CL, and then (-) It has a U-shape extending in the direction and having the other end. In this case, a portion of the pixel electrode PE overlapping the reference voltage signal line CL constitutes a storage capacitor CSTG provided with the insulating film GI as a dielectric film between the pixel electrode PE and the reference voltage signal line CL. For example, the thin film transistor TF
When T is turned off, it has an effect of storing video information in the pixel electrode PE for a long time.

The surface of the semiconductor layer AS corresponding to the interface between the drain electrode DE and the source electrode SE of the thin-film transistor TFT is doped with phosphorus (P) to form a high concentration layer. Ohmic contact at the electrode is achieved. In this case, the semiconductor layer A
The high-concentration layer is formed over the entire surface of S, and after forming each of the electrodes, the high-concentration layer other than the electrode formation region is etched using the electrodes as a mask to form the above-described configuration. be able to.

The thin film transistor TF
T, video signal line DL, pixel electrode PE, and storage capacitor C
On the upper surface of the insulating film GI on which the STG is formed, a protective film PAS (see FIG. 3) made of, for example, a silicon nitride film is formed.

In the liquid crystal display device configured as described above, as is apparent from FIG. 1, in each pixel, the video signal line DL contributing to the pixel is connected to one side (the left side in the figure) of the reference. The electrode CE and the reference voltage signal line CL connected thereto are formed with the possibility that a bypass circuit can be formed. This configuration is based on the extremely simple configuration as described above, and the video signal line DL
This is because, when a disconnection occurs, it can be easily repaired.

[Method of Repairing Video Signal Line] FIG. 4 is a plan view showing a method of repairing the video signal line DL when it is disconnected. When the video signal line DL is disconnected at a location corresponding to DEF in the figure, all the pixels that contribute to the video signal line DL and are arranged in the (−) direction after the disconnection cannot be driven. Become.

In this case, the video signal line DL can be restored by performing the following operations (1) to (4). (1) Reference electrode CE newly formed according to the present embodiment
Is connected to the video signal line DL at the portion LST1 of the extending portion. In this case, for example, by using a laser beam and irradiating the laser beam through the protective film PAS, the insulating film GI that insulates the extension of the video signal line DL from the reference electrode CE is broken. FIG. 5 is a sectional view showing this portion (the line VV in FIG. 4). At this time, the extension of the video signal line DL and the reference electrode CE at the irradiation location is melted, and the deposit LSOL is used to electrically connect the extension of the video signal line DL and the reference electrode CE. Become.

(2) Video signal line DL and this video signal line D
The reference voltage signal line C at a point LST2 where the
L is connected. In this case, as in the case of (1),
For example, this is performed by irradiating a laser beam.

(3) Disconnect the crossing of the reference voltage signal line CL with the video signal line DL on one side LCT1. In this case, for example, using a laser beam,
This is performed by scanning the laser beam at a location where disconnection is to be performed. FIG. 6 shows this part (VI-VI in FIG. 4).
FIG.

(4) Disconnect the crossing of the reference voltage signal line CL with the video signal line DL on the other side. Also in this case, similarly to the case (3), for example, irradiation is performed with a laser beam.

By doing so, the video signal lines DL separated at the disconnection point are connected to each other via the reference voltage signal line CL and the reference electrode CE, and can be repaired. become. In this case, the reference voltage signal line CL is cut off. However, since the reference voltage signal is supplied from both ends of the reference voltage signal line as described above, this does not cause a problem. However, the video signal line DL in each pixel arranged in parallel in the x direction
If the disconnection occurs simultaneously in several places, there is a problem. However, even when such disconnections occur simultaneously at, for example, two locations, it is known from empirical rules that the probability is extremely small, and does not cause much problem as a practical problem. Then, as a result of the restoration, in one pixel adjacent to the target video signal line,
One of the reference electrodes loses its function. However, even in this case, since there is no adverse effect up to the so-called point defect of the pixel, there is no much problem as a practical problem.

[Consideration on restoration] Assuming that the yield of the reconnection by the above-mentioned restoration is 100%, the length l indicated by the arrow in FIG. 4 and the periodic distance p of the pixel in the direction in which the video signal line DL extends are shown in FIG. Is the rescue rate. The rescue rate is calculated as follows using typical products as examples. The rescue rate is 80% for a wide range of liquid crystal display devices from small to large.
The above-described measures against the disconnection failure of the video signal line DL can be taken. In the case of a diagonal 8.4 type VGA standard liquid crystal display device: 81% rescue rate In the case of a 10.4 type SVGA standard liquid crystal display device: 81% diagonal In the case of a 13.3 type diagonal XGA standard liquid crystal display device: Relief rate 81% Diagonal 18.0 type SXGA standard liquid crystal display device: Relief rate 82% [Configuration of scanning signal line terminal] FIG. 7 shows a terminal GLIE for supplying a scanning signal to the scanning signal line GL. 2A is a plan view, and FIG. 2B is a cross-sectional view taken along line bb of FIG. In the figure, a scanning signal line GL extends beyond a display area which is an aggregate of pixels, and a terminal GLIE is formed by, for example, an ITO film superimposed on an end thereof. The reason why the ITO film is used as the terminal GLIE is to prevent so-called electrolytic corrosion since the portion is exposed to the atmosphere. For this reason, the insulating film GI and the protective film PAS include at least the scanning signal line GL and the terminal GL.
It is formed to extend to the overlapping portion of the IE.

[Configuration of Terminal of Video Signal Line] FIG. 8 is a configuration diagram showing a terminal DLIE for supplying a video signal to the video signal line DL, (a) is a plan view, and (b) is (a). B-
It is sectional drawing in a b line. The planar shape is almost the same as the terminal DLIE of the scanning signal line GL. However, since the video signal line DL is formed between the insulating film GI and the protective film PAS, only the layer structure is different.

[Configuration of Terminal of Reference Voltage Signal Line] FIG.
FIGS. 3A and 3B are configuration diagrams illustrating a terminal CLIF for supplying a reference voltage signal to a reference voltage signal line CL, wherein FIG. 3A is a plan view and FIG. Scan signal line G
This is the same as the case of the terminal GLIE of L. This is because the reference voltage signal line CL is formed of the same layer and the same material as the scanning signal line GL.

Embodiment 2 FIG . FIG. 10 is a configuration diagram showing another embodiment of the liquid crystal display device according to the present invention, and is a plan view corresponding to FIG. In the figure, a conductor film NI is superimposed on the video signal line DL and is superimposed on the video signal line DL below the insulating film GI.
L1 is formed. This conductor film NIL1 is formed of the same material together with, for example, a reference voltage signal line CL (reference electrode CE), and is formed in a region between the reference voltage signal line CL and the scanning signal line GL without being connected thereto. Have been. In this case, if a disconnection occurs in the video signal line DL at a location substantially similar to that shown in FIG. 4, connection with the video signal line DL is made at each of both ends of the conductive film (indicated by X in FIG. 4). To obtain the video signal line D
L can be repaired.

Embodiment 3 FIG . FIG. 11 is a configuration diagram showing another embodiment of the liquid crystal display device according to the present invention, and is a plan view corresponding to FIG. In this figure as well, a conductor film NIL2 is formed below the video signal line DL with the insulating film GI interposed therebetween, and the conductor film NIL2 has a significantly narrower overlap region with the video signal line DL. It has a configuration. That is, in the conductor film NIL2, linear conductor films are formed on both sides of the video signal line DL, respectively, in parallel to the running direction of the video signal line DL, and the conductor films are formed at both ends thereof. Are formed by a loop-shaped pattern connected by a linear conductive film crossing the video signal line. The conductor film NIL2 is formed of the same material together with, for example, a reference voltage signal line CL (reference electrode CE), and is formed in a region between the reference voltage signal line CL and the scanning signal line GL without being connected thereto. Have been. In this case, if a disconnection occurs in the video signal line DL at a location substantially similar to that shown in FIG. 4, the video signal line DL is provided at both ends of the conductive film NIL2 (indicated by "x" in FIG. 4).
With this connection, the video signal line DL can be repaired.

Each of the above-described embodiments describes a so-called in-plane switching mode liquid crystal display device. But,
It goes without saying that the present invention can be applied to a vertical electric field type liquid crystal display device. This is because it has been pointed out that even in the case of the vertical electric field type, the video signal line has a narrow line width, and the above-described adverse effects similarly occur. Here, a vertical electric field type liquid crystal display device is a device in which transparent electrodes are formed on the liquid crystal side of each transparent substrate which is disposed to face each other via liquid crystal, and each electrode is generated by an electric field generated between these electrodes. The light transmittance of the liquid crystal during the period is controlled.

[0030]

As is apparent from the above description,
According to the liquid crystal display device of the present invention, a video signal line can be repaired with a very simple configuration.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram showing one embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is an equivalent circuit diagram showing one embodiment of a liquid crystal display device according to the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is an explanatory view showing one embodiment of a method for repairing a liquid crystal display device according to the present invention.

FIG. 5 is a sectional view taken along line VV in FIG. 4;

FIG. 6 is a sectional view taken along line VI-VI of FIG.

FIG. 7 is a configuration diagram showing an embodiment of a portion of a terminal of a scanning signal line of the liquid crystal display device according to the present invention.

FIG. 8 is a configuration diagram showing an embodiment of a terminal portion of a video signal line of the liquid crystal display device according to the present invention.

FIG. 9 is a configuration diagram showing one embodiment of a terminal portion of a reference voltage signal line of the liquid crystal display device according to the present invention.

FIG. 10 is a main part configuration diagram showing another embodiment of the liquid crystal display device according to the present invention.

FIG. 11 is a main part configuration diagram showing another embodiment of the liquid crystal display device according to the present invention.

[Explanation of symbols]

GL: scanning signal line, CL: reference voltage signal line, DL:
... video signal line, AS ... semiconductor layer, CE ... reference electrode,
PE ... pixel electrode, SBAR1 ... extension portion of reference electrode,
CSTG: Storage capacity.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junichi Square 3300 Hayano, Mobara City, Chiba Prefecture Within Hitachi, Ltd. Display Group (72) Inventor Masuyuki Ota 3300 Hayano, Mobara City, Chiba Prefecture, Hitachi, Ltd. 72) Inventor Yoshiaki Nakayoshi 3300 Hayano, Mobara-shi, Chiba Prefecture Within Hitachi, Ltd. Display Group (72) Inventor Masahiro Ishii 3300-Hayano, Mobara-shi, Chiba Prefecture Hitachi Display Group, F-term (reference) 2H092 GA14 GA17 GA20 JA37 JA41 JB61 JB64 JB65 JB71 JB73 KA05 MA47 NA15 NA29 5C094 AA41 AA42 BA03 BA43 CA19 DA13 DA14 EA01 EA04 EA05 EB02 FB14 FB19

Claims (5)

[Claims] 1. A liquid crystal side pixel region of one of the transparent substrates disposed opposite to each other via a liquid crystal,
A pixel electrode to which a selected video signal is supplied from a video signal line; and a reference electrode which is disposed separately from the pixel electrode and to which a reference signal from a reference signal line is supplied, wherein the pixel electrode and the reference electrode are provided. A liquid crystal display device that controls the light transmittance of liquid crystal between them by an electric field generated between the pixel signal region and the video signal line in the pixel region.
A liquid crystal display device, wherein a conductor layer that can be short-circuited is formed at a part separated from each other. 2. The device according to claim 1, wherein the conductor layer is formed of a different layer via a video signal line and an insulating film, and at least both ends thereof are formed so as to overlap the video signal line. Liquid crystal display. 3. The liquid crystal display device according to claim 2, wherein said conductor layer is formed of the same layer as a reference electrode. 4. The liquid crystal display device according to claim 2, wherein said conductor layer also serves as a reference electrode. 5. Each of the reference voltage signal lines is configured to receive a reference signal from both ends thereof, and the conductor layer also serves as a reference electrode and a reference voltage signal line connected to the reference electrode. The liquid crystal display device according to claim 2, wherein: