JP3326674B2 - Liquid crystal display - 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 type liquid crystal display (hereinafter, LCD) using thin film transistors (hereinafter, referred to as TFTs).

[0002]

2. Description of the Related Art Conventionally, in a TFT-LCD using a pixel electrode substrate formed by combining switching elements such as TFTs and bus lines such as signal lines and scanning lines on a light-transmitting insulating substrate such as glass, Since the pixel electrode substrate has a complicated manufacturing process and is formed in a large area, it is not easy to form all the bus lines without disconnection defects, and this disconnection defect lowers the production yield of the pixel electrode substrate. It has contributed. Therefore, in order to improve the yield of the pixel electrode substrate, it is important to repair the disconnection defect.

FIG. 3 is a circuit diagram schematically showing a surface structure of a pixel electrode substrate which can easily correct a disconnection defect described in Japanese Patent Application Laid-Open No. 2-156227. In FIG. 3, source bus lines X1, X2,.
.., Xm-1, Xm (m is the number of pixels in the horizontal direction of the display screen of the liquid crystal display device, r is an integer of 1 ≦ r ≦ m. Represented by
Denotes a bus line serving as a signal line, and a gate bus line Y
1, Y2,..., Yn-1, Yn (n is the number of pixels in the vertical direction of the display screen of the liquid crystal display device, hereinafter, an arbitrary gate bus line is represented by a symbol Y) is a bus serving as a scanning line. Line. Source bus line X and gate bus line Y
Are arranged at right angles to each other and on a three-dimensional intersection on an insulating substrate. TFT1
Is a switch element of the pixel electrode substrate.
T1 and the pixel electrode 2 are formed in a matrix so as to correspond to the intersections of the source bus line X and the gate bus line Y, respectively. Bus line Y
In addition, the drain electrodes are connected to the pixel electrodes 2 respectively.

Outside the regions where the source bus line X, the gate bus line Y, the TFT 1, the pixel electrode 2 and the like are formed, repair wirings 3a and 3b are provided at the respective edges of the source bus line X and the gate line. It is formed so as to three-dimensionally intersect each edge of Y via an insulating film. Here, the repair wiring 3a is formed for repairing a source bus line located on the left side from the center of the display screen, and the repair wiring 3b is formed for repairing a source bus line located on the right side from the center of the display screen. . The repair wiring 3a corresponding to the area on the left side from the center of the display screen and the repair wiring 3 corresponding to the area on the right side from the center of the display screen
b is separated at the center of the display screen. In driving a TFT-LCD completed by combining the pixel electrode substrate configured as described above with a liquid crystal material, a gate voltage for controlling ON / OFF of the TFT 1 and a source electrode of the TFT 1 as a display signal are selectively provided. The applied source voltage is applied from one defined edge of the gate bus line Y and the source bus line X, respectively.

Therefore, as shown in FIG. 3, when there is a break in the middle part D of the source bus line Xr, the TFT 1 connected from the edge to which the source voltage is applied to the break point D is connected. No source voltage is applied, and the pixels corresponding to these TFTs 1 are not driven.

Therefore, in the pixel electrode substrate having such a disconnection defect, the source bus line Xr and the repair wiring 3a are connected at the portions A and B where the source bus line Xr and the repair wiring 3a cross each other three-dimensionally. , The disconnection defect is repaired. That is, at this time, the source voltage is applied to the portion from the disconnection point D of the source bus line Xr to the edge on the side where the source signal is not applied via the repair wiring 3a.

FIG. 4 is a cross-sectional view of a T-type pixel in which the pixel electrode substrate is incorporated.
FIG. 5 is an enlarged cross-sectional view of the TFT portion of the FT-LCD. FIG. 5 shows a portion N where the repair wiring 3a and the bus lines X and Y in the TFT-LCD of FIG. 3 cross three-dimensionally (in FIG. 5, the bus line is a source bus line). X is an enlarged cross-sectional view. In FIG. 4, an insulating substrate 4 is made of, for example, glass, and a gate electrode 5 of the TFT 1 is formed of a metal such as Cr on the insulating substrate 4, and SiNx is formed thereon.
A film (silicon nitride, for example, Si ₃ N ₄ , SiN, etc.) is formed as the gate insulating film 6. On the gate insulating film 6, an a-Si (amorphous silicon) layer 7 and an a-Si (n) (n-type semiconductor amorphous silicon) layer 8
Are formed, and the source electrode 9 and the drain electrode 10 are further formed thereon, thereby forming the TFT 1 made of the a-Si layer.

The pixel electrode 11 is made of an ITO (indium tin oxide) film, and a part of the pixel electrode 11 is overlaid on the drain electrode 10. TFT comprising the a-Si layer described above
1, pixel electrode 11, gate bus line Y serving as a scanning line
(Not shown), and a source bus line X which is a signal line
A SiNx film is formed as a protective film 12 on the entire surface of
Further, an alignment film 13a is formed on the entire surface of the protective film 12, and a display electrode substrate 14 is formed therefrom.

The pixel electrode substrate 1 thus formed
A counter electrode substrate 15 is arranged to face the liquid crystal material 1 between the pixel electrode substrate 14 and the counter electrode substrate 15.
6 is enclosed. In the counter electrode substrate 15, a color filter 18 is formed in a portion of the insulating substrate 17 made of glass facing the pixel electrode substrate 14 on a surface facing the pixel electrode substrate 14, and in other portions, A light non-transmissive film 19 is formed, a counter electrode 20 made of an ITO film is formed on the surface thereof, and an alignment film 13b is formed thereon.

In FIG. 5, a repair wiring 3a formed on the pixel electrode substrate 14 is three-dimensionally crossed over a source bus line X, a gate bus line Y and the like via an insulating film 21.

[0011]

As described above, the repair wirings 3a and 3b both cross the source bus line X and the gate bus line Y three-dimensionally via the insulating film, and the repair wirings 3a and 3b float at these intersections. While the capacitance is generated, the liquid crystal material 16 and the alignment films 13a, 13 interposed between the repair wirings 3a, 3b and the counter electrode 20 are interposed between them.
Since a stray capacitance due to dielectric properties such as b and the protective film 12 is present, a signal delay occurs according to a time constant given by a product of the resistances of the repair wirings 3a and 3b. In other words, a difference occurs between the input signal of the bus line where the broken line is repaired and the input signal of another normal bus line, and the display by the pixels arranged in the bus line has a thin line shape as compared with the normal part, There is a problem that display quality is reduced.

In order to improve such a problem, for example,
As shown in FIG. 6, the line width of the intersection N between the repair wiring 3a and the source bus line X and the line width of the intersection N between the repair wiring 3b and the gate bus line Y are smaller than the line width of the non-intersection W. Then, the intersection N between the repair wiring 3a and the source bus line X, and the repair wiring 3b and the gate bus line Y
A method of reducing the stray capacitance generated at the intersection N between the two has been considered. However, the repair wiring 3
a and source bus line X, and repair wiring 3
In order to make the connection between the gate bus line Y and the gate bus line Y, the line widths of the repair wirings 3a and 3b are determined in view of the size of the laser spot diameter by the laser repair, the connection resistance by the laser connection, and the reliability of the disconnection. It is necessary to secure a certain threshold or more, for example, 30 μm or more. Therefore, there is a limit in reducing the stray capacitance.

On the other hand, TFT-LCDs have been improved in definition, and XGA (1024 × 768 pixels), EWS
(High-definition LCDs with a pixel count of 1280 × 1024) have been put to practical use. In such a high-definition LCD, the number of source bus lines and gate bus lines is the same as that of the conventional VG.
Since the number of pixels significantly increases as compared with A (640 × 480 pixels), the stray capacitance at the intersection of the repair wirings 3a and 3b with the source bus line X and the gate bus line Y also increases. Furthermore, these high definition L
In the CD, since the charge / discharge time of the TFT 1 decreases with an increase in the number of pixels, the above-described deterioration in display quality due to the influence of the input signal delay becomes remarkable, and the repair wirings 3a and 3b are reduced by the laser repairable amount. If the line width is secured, there is a problem that even if the broken bus line is repaired, it is recognized as a thin linear defect.

The present invention solves such a problem, stray capacitance generated in the repair wiring and each bus line (source bus line and gate bus line) is suppressed, and the disconnection defect of the bus line is corrected by the repair wiring. It is an object of the present invention to provide a liquid crystal display device in which a signal supplied via a repair wiring sometimes does not cause a delay.

[0015]

According to the liquid crystal display device of the present invention, a plurality of signal lines and scanning lines as bus lines can be connected to any one of the bus lines on an insulating substrate. And an active matrix type liquid crystal display device having a plurality of repair wirings for correcting disconnection formed by three-dimensionally crossing any one of the bus lines, wherein: (a) an intersection between the repair wiring and the bus line; The line width of the repair wiring in the portion is narrower than the line width other than the intersection, and the first line width capable of laser repair, and
One of the second line widths which are even smaller than the first line width and cannot be repaired by laser, and (b) the signal line as the bus line intersects with the scanning line.
The display area to be displayed is divided into three or more areas parallel to the signal lines or scanning lines.
Area and divide the plurality of repair wires into groups.
Dedicated to each of the divided display areas by
Each group of paired wiring has a corresponding display area
Only the repair target area, and repair within the repair target area.
Repair wiring line width at the intersection of the pair wiring and bus line
Is the first line width, and the intersection outside the repair target area is
The line width of the repair wiring in the portion was defined as the second line width .

In the liquid crystal display device of the present invention, the first line width portion of the repair wiring is biased to one side in a width direction perpendicular to the wiring direction, and the edge of the biased side is straightened. It may be formed.

In the liquid crystal display device according to the present invention, the second line width portion of the repair wiring is offset to one side in a width direction perpendicular to the wiring direction, and the edge of the offset side is straightened. It is preferable that the wiring is formed for preventing disconnection of the repair wiring.

In the liquid crystal display device according to the present invention, when the second line width is 10 to 30 μm, the stray capacitance between the bus line and the repair wiring is reduced, and the resistance of the repair wiring is increased. Is preferable because it suppresses

In the liquid crystal display device according to the present invention, the repair line having the second line width is divided into two lines in parallel with the wiring direction, and the total of the divided line widths is equal to the second line width. The repair wires having a width equal to each other and being divided may be formed at intervals from each other.

In the liquid crystal display device according to the present invention, it is preferable that the line width in a region other than the corresponding repair region of the repair wiring is equal to the second line width, between the bus line and the repair wiring other than the repair region. This is preferable for reducing stray capacitance.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the liquid crystal display of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory view of a wiring portion according to an embodiment of the liquid crystal display device of the present invention, and FIG. 2 is a schematic explanatory view of a surface structure of a pixel electrode substrate of the liquid crystal display device of the present invention. In the present embodiment, the display region of the TFT-LCD is divided into a plurality of regions (eight regions in FIG. 2), and a repair wiring for repairing a disconnection of the source bus line is dedicated to each region. That is, the disconnection defect of the source bus line generated in the area A1 is repaired using the repair wiring RW1, and the disconnection defect of the source bus line generated in the area A2 is repaired using the repair wiring RW2. In this way, the repair wirings used for the regions A1 to A8 correspond to the repair wirings RW1 to RW8, respectively.

FIG. 1 is an enlarged view of a repair wiring portion. As shown in FIG. 1, the line width of the repair wirings RW1 to RW8 is determined based on the source bus line X or the gate bus line Y.
Non-intersecting portions W which do not cross three-dimensionally with repair wirings RW1 to RW
8 is made wider to reduce the wiring resistance, the intersections N1 and N2 of the repair wirings RW1 to RW8 with the source bus line X and the gate bus line Y are repaired. Wiring RW1 to RW8
In order to reduce the stray capacitance generated between the non-intersecting portion W and the source bus line X and the gate bus line Y, the line width is formed narrower than the non-intersecting portion W. Further, as described above, for example, since the repair wiring RW2 is a wiring dedicated to repairing a source bus line disconnection defect in the area A2, the line width of the intersection N1 between the repair wiring RW2 and the source bus line X in the area A2 (the 1 line width) is the width where laser repair is possible,
That is, about 30 to 50 μm is secured. On the other hand, the line width (second line width) of the intersection N2 between the repair wiring RW2 and the source bus line X and the gate bus line Y in the area A1 is floating because the area A1 is not the area to repair the repair wiring RW2. In order to further reduce the capacitance, the line width is so small that laser repair is impossible, that is, about 10 to 30 μm. In a conventional liquid crystal display device,
Although the line width was not reduced to 50 μm or less because the repair wiring resistance was suppressed to be sufficiently small,
In the liquid crystal display device of the present invention, since the display device has a high resolution of the XGA level, the area of the intersection between the bus line and the repair wiring increases. Therefore, in order to reduce the stray capacitance due to the increase in the area of the intersection, the intersection N1
And the line width of the portion of N2 was formed narrower than W.

Next, a case where the liquid crystal display device of the present invention is applied to a liquid crystal display device having a resolution XGA (1024 × 768 pixels) of a diagonal 12-inch class in the effective display area of the liquid crystal display device will be described. . The display region is divided into eight regions as shown in FIG. 2, and repair wirings RW1 to RW8 for repairing source bus line disconnection defects in each region are provided in two regions.
Each book is provided. This enables disconnection repair of up to two of the 384 source bus lines in each area.

By the way, in the liquid crystal display device of this class, the line width of the repair wirings RW1 to RW8 is about 50 μm. In the present invention, the line width of the non-intersection portion W with the source bus line X is about 50 μm, and the line width of the repair wirings RW1 to RW8 with the intersection N1 with the source bus line X in the repairable region is about 45 μm. The line width of the intersection N2 of the repair wirings RW1 to RW8 with the source bus line X and the gate bus line Y in the unrepairable region was set to about 20 μm. The signal time constant τ due to the repair wiring in the liquid crystal display device of the present invention is compared with the case where the line width of the conventional repair wiring is constant at about 50 μm in any part.

Consider the repair wirings RW4 and RW5 in which the resistance R of the repair wiring and the stray capacitance C between the repair wiring and the bus line are both maximum. In the case of the conventional repair wiring, the repair wiring resistance R1 is about 790Ω, and the stray capacitance C1 is about 600 pF. On the other hand, according to the present embodiment, the resistance R2 of the repair wiring is 1300Ω and the stray capacitance C
2 is 250 pF. Here, the time constant τ1 of the conventional repair wiring is compared with the time constant τ2 of the repair wiring of the present embodiment.

Τ2 / τ1 = (R2 · C2) / (R1 · C
1) = 0.69, and the time constant of the repair wiring in this embodiment can be reduced to 70% or less as compared with the conventional one.
In addition, when a disconnection defect of a source bus line was repaired using a conventional repair wiring, a linear display defect that a pixel corresponding to the repaired source bus line became brighter than other pixels was observed. It was confirmed that repairing a disconnection defect of a source bus line using the repair wiring according to the example did not cause a linear display defect.

Further, in this embodiment, an example in which two repair wires are provided in each region has been described, but it is sufficient that at least one repair wire is provided. However, when there is one repair wiring, one source bus line can be repaired, and when there are two repair wirings, two source bus lines can be repaired. Also, the portion of the intersection N2 where laser repair is not possible does not necessarily have to be one,
For example, the portion of the intersection N2 is divided into two parallel to the wiring portion, and the total of the divided line widths is formed to be equal to the width of the intersection N2.
It may be formed with a space between books. In short, it is only necessary that the stray capacitance of the entire divided intersection portion N2 is sufficiently small and that the line width of each of the divided portions is a width that cannot be repaired by laser.

As shown in FIG. 1A, the portion having the second line width of the repair wiring, that is, the intersection N2 in FIG. Even if it is not formed at the center of W, as shown in FIG. 1B, it is offset to one side in the width direction perpendicular to the wiring direction, and the offset edge is formed in a straight line. You may. That is, as shown in FIG. 1B, if the wiring direction is the horizontal direction, the width direction of the non-intersecting portion W (FIG.
A portion N2 having a second line width is provided at either the upper edge or the lower edge (the lower side in FIG.
May be biased so that their edges coincide, and the lower side may be formed in a straight line. The reason is the second
When the portion N2 having the second line width is offset to the non-intersection W, the portion N2 having the second line width is formed at the center in the width direction of the non-intersection W. This is because the wiring resistance is the same. Further, similarly to the second line width portion N2, the first line width portion N1 is shifted to one side of W in the width direction perpendicular to the wiring direction, and the shifted edge is straight. May be formed. In this case, the reason is also the same because the repair wiring resistance is the same as when the portion N1 having the first line width is formed at the center of the non-intersecting portion W in the width direction.

[0030]

According to the present invention, the line width of the repair wiring at the intersection of the repair wiring and the bus line is smaller than the line width other than the intersection, and the first line width at which laser repair is possible. And (b) associating each of the plurality of repair wirings with a different repair area on the insulating substrate, and Is formed so that the intersection with the bus line in the corresponding repair area has a first line width, and the intersection with the bus line outside the repair area has a second line width. Therefore, the stray capacitance generated in the repair wiring and each bus line (source bus line and gate bus line) is suppressed to a small value, and when the disconnection defect of the bus line is corrected by the repair wiring, the repair is performed. It does not occur a delay in the signal supplied via the wiring.

[Brief description of the drawings]

FIG. 1 is an explanatory plan view of a wiring portion according to an embodiment of a liquid crystal display device of the present invention.

FIG. 2 is a schematic explanatory view of a surface structure of a pixel electrode substrate according to the liquid crystal display device of the present invention.

FIG. 3 is a circuit diagram schematically illustrating a surface structure of a conventional pixel electrode substrate.

FIG. 4 shows a TFT-L in which a conventional pixel electrode substrate is incorporated.
FIG. 2 is a partially enlarged cross-sectional view of the structure of the CD.

FIG. 5 is an enlarged cross-sectional view of a portion where a repair wiring and a source bus line cross three-dimensionally in a TFT-LCD.

FIG. 6 is an explanatory plan view of a wiring portion according to an example of a conventional liquid crystal display device.

[Explanation of symbols]

 A1 to A8 area RW1 to RW8 Repair wiring

Continuation of the front page (56) References JP-A-2-156227 (JP, A) JP-A-2-212,811 (JP, A) JP-A-6-67189 (JP, A) JP-A-4-179930 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/1345 G02F 1/1343 G02F 1/1362 G02F 1/13 101

Claims (5)

(57) [Claims] 1. A plurality of signal lines and scanning lines as bus lines, each of which can be connected to any one of the bus lines, and three-dimensionally crossing any one of the bus lines on an insulating substrate. An active matrix type liquid crystal display device having a plurality of repair wires for repairing a disconnection to be formed, wherein: (a) a line width of the repair wire at an intersection of the repair wire and the bus line is an intersection portion; A first line width narrower than the other line widths and capable of laser repair, and
One of the second line widths which are even smaller than the first line width and cannot be repaired by laser, and (b) the signal line as the bus line intersects with the scanning line.
The display area to be displayed is divided into three or more areas parallel to the signal lines or scanning lines.
Area and divide the plurality of repair wires into groups.
Dedicated to each of the divided display areas by
Each group of paired wiring has a corresponding display area
Only the repair target area, and repair within the repair target area.
Repair wiring line width at the intersection of the pair wiring and bus line
Is the first line width, and the intersection outside the repair target area is
A liquid crystal display device wherein the line width of the repair wiring in the section is the second line width . 2. The repair wiring according to claim 1, wherein a portion having a first line width is shifted to one side in a width direction perpendicular to a wiring direction, and an edge of the shifted side is formed in a straight line. 2. The liquid crystal display device according to 1. 3. The repair wiring according to claim 2, wherein a portion having a second line width is shifted to one side in a width direction perpendicular to a wiring direction, and an edge of the shifted side is formed in a straight line. 2. The liquid crystal display device according to 1. 4. The liquid crystal display device according to claim 1, wherein said second line width is 10 to 30 μm. 5. The repair wiring of a second line width portion is divided into two parallel to the wiring direction, and the total of the divided line widths is equal to the second line width, and 2. The liquid crystal display device according to claim 1, wherein the divided repair wirings are formed at an interval from each other.