JPH06230416A - Active matrix display device - Google Patents

Abstract

PURPOSE:To provide the active matrix display device capable of easily and exactly correcting the display defects of pixels and the automating a display inspection stage. CONSTITUTION:Pixel electrodes 15 are divided to additive capacity regions 15b and non-additive capacity regions 15a. Both regions 15b, 15a are connected by conductive parts 15c. Markers 50 of, for example, titanium (Ti), etc., are provided near the conductive parts 15c. The conductive part 15c is cut by, for example, a laser beam to separate both regions 15b, 15a with the marker 50 as an earmark in the state of operating the display device if the pixel defect arises in the additive capacity region 15b. The driving of the non-additive capacity region 15a of the pixel electrode 15 only by the scanning line 2 and signal line 4 is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display element using a thin film transistor as a switching element for a display pixel, and more particularly to an active matrix display device used for a terminal display device such as a portable word processor and a personal computer.

[0002]

2. Description of the Related Art In a matrix type display device, a display pattern is formed on a screen by selecting display picture elements arranged in a matrix. As a display pixel selection method, an active matrix method is known in which individual picture elements are arranged by independent picture element electrodes, and the picture element electrodes are selectively driven through switching elements connected to the respective picture element electrodes. There is. The active matrix system is capable of high-contrast display, and has been put to practical use in display devices such as liquid crystal televisions, word processors, and computers.

[0003]

2. Description of the Related Art FIGS. 4 and 5 show an example of an active matrix substrate constituting a conventional active matrix type display device.

In this active matrix substrate 30, a plurality of scanning lines 2, 2, ... Are arranged in parallel with each other on a glass substrate 1 serving as a base, and a plurality of signal lines are arranged in a direction orthogonal to these scanning lines 2, 2 ,. 4, 4, ... Are arranged.

Near the intersection of each scanning line 2 and each signal line 4, a gate electrode 3 is branched from the scanning line 2 in a direction orthogonal to the scanning line 2. Further, above the gate electrode 3, the thin film transistor 20 as a switching element intersecting the gate electrode 3 (hereinafter abbreviated as TFT 20) is provided.
Are formed. At the position where the TFT 20 is formed, the source electrode 5 branches off from the signal line 4 in a direction orthogonal to the signal line 4 to form a part of the TFT 20.

In each of the regions surrounded by the two adjacent signal lines 4 and 4 and the adjacent two scanning lines 2 and 2, the region except the TFT 20 forming portion of this region is substantially filled. The picture element electrode 15 is formed. TFT 20
The drain electrode 1 on the TFT 20 on the pixel electrode 15 side of
One end of 4 overlaps. The protruding portion of the picture element electrode 15 covers the drain electrode 14, and the picture element electrode 15 and the TFT 20 are electrically connected via the drain electrode 14.

Of the scanning lines 2 and 2 forming each area, the scanning line 2 on the opposite side of the scanning line 2 to which the TFT 20 is connected is adjacent to the scanning line 2, An additional capacitance electrode 16 is arranged in parallel with the scanning line 2. The picture element electrode 15 in the corresponding region extends over the additional capacitance electrode 16, and the additional capacitance electrode 16 and the picture element electrode 15
An additional film is formed by sandwiching an insulating film (not shown) between the additional capacitor and the overhang portion.

FIG. 4 is a cross section taken along the line BB 'of FIG. The structure of a portion of the active matrix substrate 30 including the TFT 20 will be described with reference to FIG. A gate electrode 3 is formed on a glass substrate 1 that serves as a base.
An oxide insulating film 6 is formed so as to cover the gate electrode 3. A gate insulating film 7 is formed on the entire surface of the substrate so as to cover the gate electrode 3 covered with the oxide insulating film 6. A portion of the gate insulating film 7 that covers the gate electrode 3 projects upward and is inclined along each side surface of the gate electrode 3.

A semiconductor layer 8 is patterned on the gate insulating film 7 so as to intersect with the gate electrode 3. The central portion of the semiconductor layer 8 becomes the semiconductor layer of the TFT 20. One side of both sides of the central part of the semiconductor layer 8 is a source 10 of the semiconductor layer, and the other side is a drain 11 of the semiconductor layer. The source 10 of the semiconductor layer is a TFT
Covered with sauce 12. The drain 11 of the semiconductor layer is covered with the drain 13 of the TFT.

The source 12 of the TFT covers the source 10 of the semiconductor layer and reaches the gate insulating film 7. The source 12 of this TFT is covered with the signal line 4 and the source electrode 5 branched from the signal line 4.

The drain 13 of the TFT covers the drain 11 of the semiconductor layer and reaches the gate insulating film 7.
The drain 13 of the TFT is a pixel electrode 15 formed on the same gate insulating film 7 from the place where it reaches the gate insulating film 7.
To the end and overlap the end of the pixel electrode 15.
The drain 13 of the TFT is covered with the drain electrode 14.

The additional capacitance electrode 16 is provided on the glass substrate 1 at the same time as the scanning line 2 and the gate electrode 3, and forms an additional capacitance with the projection portion of the pixel electrode 15 via the gate insulating film 7.

In such an active matrix type display device, when one scanning line 2 is selected and a scanning signal is applied to this scanning line 2, all the TFTs 20 connected to this scanning line 2 are selected. The data signal which is turned on and applied to the signal line 4 at the same time as the application of the scanning signal is transmitted to the pixel electrode 15 via the source electrode 5, the TFT source 12, the semiconductor layer 8, the TFT drain 13 and the drain electrode 14. Is applied. At the same time as the voltage is applied to the pixel electrode 15, a voltage is also applied to the counter electrode on the counter substrate (not shown), and the voltage of the potential difference between the pixel electrode 15 and the counter electrode is applied to the liquid crystal in the corresponding pixel region. Is applied. Even if the TFT 20 is turned off, T
During the period until the scan signal is applied at the beginning of the next frame, the charge accumulated in the additional capacitance when the FT 20 is on,
Applied to liquid crystal.

[0014]

In order to manufacture the above-mentioned active matrix substrate, it is necessary to go through extremely complicated steps such as forming many thin films and etching.
In addition, since the TFT as a switching element and the electrode for additional capacitance are provided in all of a huge number of picture element electrodes ranging from 100,000 to 500,000 or more, the electric characteristics of each of them are To secure it, precise process control is required.

Therefore, even if the manufacturing process is sufficiently controlled, leakage occurs between the additional capacitance electrode and the pixel electrode,
A pixel defect may occur. Such pixel defects are found and corrected at the quality inspection stage. This correction is performed by disconnecting the additional capacitance portion and the non-additional capacitance portion of the pixel electrode where the leak has occurred. The pixel electrode is cut by a laser or the like, but since the pixel electrode is formed using a substance having a light-transmitting property, it may be cut without being able to accurately recognize the cut portion. In such a case, the following problems occur.

The non-added capacitance portion of the picture element electrode disappears, and the display quality is significantly impaired.

The above cutting portion cannot be cut by a single laser irradiation, resulting in a decrease in working efficiency.

Foreign matter is mixed into the display medium due to laser breakage in portions other than the cut portion, resulting in deterioration of display quality.

The present invention has been made to solve such a problem, and in an active matrix display device, a pixel defect is caused by a defective insulation between the pixel electrode and the additional capacitance electrode. To provide an active matrix display device capable of easily and accurately correcting a pixel defect in a short time when it occurs and further automating the correction of the pixel defect in a state where the display device is configured. To aim.

[0020]

An active matrix display device of the present invention includes a pair of substrates, at least one of which has a light-transmitting property, and a plurality of pixel electrodes formed in a matrix on one of the pair of substrates. , A display medium sandwiched between the pair of substrates, and an additional capacitance electrode formed by sandwiching an insulating film between a part of each pixel electrode, and each pixel electrode is provided with the additional capacitance. An active matrix display in which an additional capacitance region and a non-additional capacitance region facing an electrode are divided by a narrow conductive portion, and a marker serving as a mark for cutting the conductive portion when a pixel defect is repaired is provided. A device, which achieves the above objectives.

[0021]

As described above, the pixel electrode is divided into the additional capacitance region and the non-additional capacitance region, and both regions are connected by the narrow conductive portion. Titanium (T
When a marker is provided by i) or the like and insulation failure occurs in the additional capacitance area, this marker is used as a mark, and the conductive portion is cut by laser light or the like to separate the two areas. This way
It is possible to drive the non-added capacitance area of the pixel electrode only by the scanning line and the signal line.

[0022]

EXAMPLES Examples of the present invention will be described below. FIG. 1 shows a plan configuration of an active matrix substrate in an embodiment of the present invention. Since the active matrix substrate 1 according to the present embodiment has a substrate structure similar to that of the conventional example, description of the same parts as those of the conventional example will be omitted, and only different parts will be described below. The same elements as those of the conventional example will be described with the same numbers.

The active matrix substrate 30 of this embodiment
In this case, each pixel electrode 15 is divided into an additional capacitance region 15b and a non-additional capacitance region 15a.
b and the non-added capacity region 15a are connected by the conducting portion 15c. Then, titanium (Ti) is provided near the conducting portion 15c
Is provided with a marker 50. The other substrate structure is the same as that of the conventional active matrix substrate.

The conductive portion 15c is formed with a width smaller than the width of the picture element electrode 15 in the scanning line direction, and is easy to cut. Markers 50, which serve as marks at the time of cutting, are provided on the respective gate insulating films 7 on both sides of the conductive portion 15c in the width direction. A material having a high reflectance such as titanium (Ti) is used for the marker 50. As a result, when the conductive portion 15c is cut with laser light, the laser light is reflected by the marker 50,
It is possible to minimize the inclusion of debris at the time of cutting into the display medium.

Further, FIG. 2 shows a case where the markers 50 are provided at both ends of the conducting portion 15c in the longitudinal direction.

FIG. 3 shows a cross section taken along the line AA ′ of the active matrix display device having the active matrix substrate 30 shown in FIG. 1 or 2. In this display device, a protective film 17 made of SiN _x or the like is formed on the entire surface of the substrate so as to cover the substrate elements on the active matrix substrate 30. Further, an alignment film 18 made of polyimide or the like is formed on and in contact with the protective film 17.

Such an active matrix substrate is manufactured as follows.

First, Ta of a refractory metal is laminated on the entire surface of the glass substrate 1 by the sputtering method, and the scanning lines 2, 2 ... And the scanning lines 2, 2 are formed by the photolithography method.
The gate electrodes 3, 3 ... Branched from are patterned.

Next, the scan lines 2 and 2 are formed by the anodic oxidation method.
. And the gate electrodes 3, 3, ..., An oxide insulating film 6 is formed.

Then, silicon nitride (SiN _x ) is formed on the entire surface of the substrate by plasma CVD while covering the scanning lines 2, 2 ... And the gate electrodes 3, 3 covered with the oxide insulating film 6.
Are laminated to form a gate insulating film 7.

Subsequently, amorphous silicon (a) is formed on the gate insulating film 7 at a position crossing the gate electrode 3.
-Si) is laminated to form the semiconductor layer 8. Both sides of the amorphous silicon (a-Si) semiconductor layer 8 correspond to the source 10 of the semiconductor layer and the drain 11 of the semiconductor layer.

Next, n ⁺ -amorphous silicon (n ⁺ -a-Si) is laminated on the semiconductor layer 8 by the plasma CVD method. n ⁺ -amorphous silicon (n ⁺ -a
-Si) is laminated, the n ⁺ -amorphous silicon is patterned by photolithography to form a TFT source 12 on the semiconductor layer source 10 and a TFT drain 13 on the semiconductor layer drain 11. To do.

Next, indium oxide (ITO) which is a transparent conductive film is laminated by the sputtering method, and the picture element electrode 15 and the additional capacitance electrode 16 are formed by the photolithography method. Next, titanium (Ti), which is a refractory metal, is stacked by a sputtering method and patterned by a photolithography method to obtain the signal line 4, the source electrode 5, and the drain electrode 14.
And a marker 50 is formed.

Finally, a protective film 17 is laminated over the entire surface of the glass substrate 1 so as to cover all of the above substrate elements, and an active matrix substrate according to the present invention is obtained.

On the other hand, the counter substrate 40 facing the active matrix substrate 30 is a transparent insulating substrate 41 such as glass.
Are arranged in a matrix so as to face each pixel electrode 15 on the active matrix substrate 30. Further, a black stripe 42 is formed so as to surround each of the color filters 43, 43 ... These color filters 4
A counter electrode 34 is formed on the entire surface of the counter substrate 40 by using a conductive thin film so as to cover 3, 43 ... And the black stripes 42, 42. Covering the counter electrode 44,
An alignment film 45 is formed on the entire surface of the substrate using polyimide or the like.

The above-mentioned counter substrate 40 and the above-mentioned active matrix substrate 30 are sealed by sandwiching the display medium 19 between the electrodes forming surfaces facing each other, and the active matrix display device is constituted. A voltage is applied to the display medium 19 between the counter electrode 44 and the pixel electrode 15 on the active matrix substrate 30 side, and the display medium 19 between the substrates 30 and 40 is optically modulated to perform display.

In the active matrix display device of this embodiment as described above, since the base substrates of both substrates 30 and 40 are translucent substrates such as glass, the optical device such as CCD is operated while the display device is operated. Depending on the device, the marker 50
Can be used to recognize the conducting portion 15c. Therefore,
The additional capacitance area 15b of the pixel electrode 15 and the additional capacitance electrode 1
When a picture element defect occurs due to the insulation failure between the display device 6 and the device 6, laser light or the like is emitted from the outside of the display device through the translucent substrate to disconnect the conductive portion 15c. In this way, the picture element electrode 15 is operated only in the non-added capacity area to correct the picture element defect.

[0038]

As described above, in the active matrix display device of the present invention, each pixel electrode on the active matrix substrate is divided into an additional capacitance region and a non-additional capacitance region,
Since a structure is used in which a conductive portion having a width smaller than the width dimension of the pixel electrode is connected between them, when repairing a pixel defect generated in the additional region, the conductive portion is cut by irradiation with laser light or the like, It is easy to separate the additional capacitance area and the non-additional capacitance area.

The pixel defect can be corrected while the display device is assembled and the device is operated. Since a marker is provided near the conductive part as a means for identifying the conductive part of the pixel in which the pixel defect is occurring, the marker can be used as a clue to recognize the conductive part, and quick and efficient correction can be performed. . When a material having a high reflectance is used for the marker, it is possible to reflect the laser light, and thus it is possible to minimize the inclusion of debris at the time of cutting into the display medium.

If an image recognition device such as a CCD camera is used for the optical recognition of the marker, the automation can be easily performed, so that the inspection process of the pixel defect and the correction process thereof can be automated. Therefore, it is possible to contribute to mass production and cost reduction of the active matrix display device.

[Brief description of drawings]

FIG. 1 is a plan view showing a part of an active matrix substrate of the present invention.

FIG. 2 is a plan view showing a part of an active matrix substrate of the present invention.

FIG. 3 is a cross-sectional view taken along the line A-A ′ of FIG. 1 or 2.

FIG. 4 is a plan view showing a part of a conventional active matrix substrate.

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

[Explanation of symbols]

 1, 41 Glass substrate 2 Scan line 3 Gate electrode 4 Signal line 5 Source electrode 6 Oxide insulating film 7 Gate insulating film 8 Semiconductor layer 10 Semiconductor layer source 11 Semiconductor layer drain 12 TFT source 13 TFT drain 14 Drain electrode 15 Pixel electrode 15a Non-added capacity area 15b Added capacity area 15c Conducting part 16 Added capacity electrode 17 Protective film 18 Alignment film 19 Display medium 20 TFT 50 Marker

Claims (1)

[Claims] 1. A pair of substrates, at least one of which has translucency, a plurality of pixel electrodes formed in a matrix on one of the pair of substrates, and a display medium sandwiched between the pair of substrates. And an additional capacitance electrode formed by sandwiching an insulating film between each pixel electrode and a part of each pixel electrode, each pixel electrode facing the additional capacitance electrode and an additional capacitance region and a non-additional capacitance. An active matrix display device, which is divided into a region and a conductive portion having a narrow width, and is provided with a marker serving as a mark for cutting the conductive portion when a pixel defect is repaired.