KR100318538B1 - liquid crystal display - Google Patents

Abstract

A plurality of gate lines and data lines intersecting with each other are formed on the thin film transistor substrate, and pixel electrodes are formed in each pixel defined by the intersections thereof. Each pixel is formed with a thin film transistor including a gate electrode connected to a gate line, a source electrode connected to a data line, and a drain electrode connected to a pixel electrode. On the other hand, red, green, and blue color filters are formed in the pixels of the color filter substrate facing the thin film transistor substrate, and a black matrix is formed around the outside of the active region in which the image is displayed. In addition, one or two or more repair lines overlapping the gate line and the data line are formed in a ring or ring shape around the thin film transistor substrate not covered by the black matrix. Here, not covering the repair line with the black matrix means that the repair line and the black matrix do not overlap each other. Such a structure can be applied to a twisted nematic method or a planar drive type liquid crystal display device in which a common electrode and a pixel electrode are formed on one substrate to form an electric field almost parallel to the substrate. In the case of manufacturing with a black matrix can be formed so as not to overlap the repair line without adding a new mask.

Description

Liquid crystal display

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display, and more particularly, to a flat panel display having a repair line formed around the outside of the display area in order to prevent wiring defects occurring in a plurality of signal lines.

Among flat panel displays, a liquid crystal display using a liquid crystal material is composed of two substrates facing each other and a liquid crystal material layer injected between the two substrates, and is a common electrode that is two electrodes formed on each of the two substrates or on one substrate. A device for displaying an image in a manner of changing the arrangement of liquid crystals to adjust the transmittance of light by changing the voltage applied between the electrode and the pixel electrode.

In general, a plurality of gate lines and data lines that cross each other are formed on one substrate, and a plurality of thin film transistors and pixel electrodes are formed in a matrix form on a pixel in which data lines and gate lines are defined as intersections, and face one substrate. In another substrate, a color filter is formed at a portion corresponding to the pixel. Here, an area in which an image is displayed by being a set of pixels is called an active area, and a black matrix is formed on another substrate to prevent light from leaking around the active area. In this case, when the common electrode is formed on another substrate, the black matrix is in a state of being electrically connected to the common electrode. When the common electrode is formed on the same substrate as the pixel electrode, the black matrix is in a floating state. In addition, a plurality of gate pads and data pads connected to a plurality of gate lines and data lines outside the active area to receive signals from the outside are formed.

The manufacturing method of the thin film transistor liquid crystal display device may include various causes of defects in reducing the process yield, but the source terminal of each thin film transistor may be output from an output terminal of a data driving integrated circuit that transmits an image signal through a data pad. This is an open defect of the data line connected to the circuit, which is expensive to repair.

Specifically, there are various methods for repairing disconnection defects. However, a repair line intersecting each data line and gate line is formed around the outer circumference of the active area, which becomes a display area, on the substrate so that each data line and gate line can be repaired. When an open occurs, there is a method of transmitting a signal by using a repair line to bypass the outside of the active area.

However, since the repair line overlaps a plurality of gate lines, data lines, and the black matrix, a signal that is bypassed and transmitted to the repair line causes a delay due to an increase in capacitance.

The present invention is to solve this problem, and to minimize the load capacity generated in the repair ship.

1 is a view schematically showing a path of a signal transmitted through a repair line in a conventional twisted nematic liquid crystal display device;

2 and 3A to 3C are diagrams for explaining a change in parasitic capacitance formed between the floated black matrix and the repair line.

4 is a diagram schematically illustrating a path of a signal transmitted through a repair line in a liquid crystal display according to an exemplary embodiment of the present invention.

5 is a layout view illustrating a structure of a liquid crystal display according to an exemplary embodiment of the present invention.

In the liquid crystal display according to the present invention, one or more repair lines are formed so as not to overlap the black matrix.

Here, the black matrix may be electrically connected to the common electrode, may be floated, and the repair line may be passed through the PCB substrate for the gate of the liquid crystal panel or the PCB substrate for data in order to reduce the resistance.

In the liquid crystal display of the present invention, since the repair line does not overlap the black matrix, the load capacity generated by the repair line is reduced.

Next, embodiments of the liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice the present invention.

FIG. 1 is a view schematically illustrating a path of a signal transmitted through a repair line in a conventional twisted nematic liquid crystal display device.

The twisted nematic method of the liquid crystal display device is a structure in which liquid crystal molecules are aligned in parallel with the substrate and are continuously twisted from the lower substrate to the upper substrate. The common electrode facing the pixel electrode formed in each pixel is entirely formed, and the black matrix is connected to the common electrode.

Here, there are 768 gate lines and 1024 x 3 data lines.

As shown in FIG. 1, in the center of the liquid crystal panel 12, there is an active area or display area A formed of a set of pixels, and a black matrix is formed around the active area A to block leakage of light. There is an area B.

At this time, if the load on the signal transmitted through the repair line is calculated, the capacitive load due to the overlap of the gate line, the data line and the repair line in the path (1) is about 60pF, and the capacitive load due to the overlap with the black matrix is almost also. Similar to the load capacity formed by overlapping the gate line and the data line, it was measured at about 60pF, and the resistance of the repair line was measured at about 2kΩ. In the path 2, the resistance of the data line was measured about 40 kΩ, and the capacitive load was measured about 80 pF. Due to this load capacity or resistance, the delay for the signal transmitted through the repair ship was measured to be about 4.2 μm.

On the other hand, even when the common electrode and the pixel electrode are formed on the lower substrate and the black matrix formed on the upper substrate is floating, if the capacitance generated between the peripheral gate line or data line and the floating black matrix is large, the twisted nematic It looks similar to the method. This will be described in detail.

2 and 3A to 3C are diagrams for explaining a change in parasitic capacitance formed between the floated black matrix and the repair line. Here, the black matrix is made of a conductive material.

2 and 3A to 3C, reference numeral 80 denotes a floating black matrix, reference numeral 70 denotes a repair line, 20 denotes a peripheral wire formed around the repair line 70, and 90 denotes an electrical connection. That is an arbitrary electrode. In addition, the capacity of the A capacitor is a, the capacity of the B capacitor is b, and the capacity of the C capacitor is c.

As shown in Fig. 2, the A capacitor and the B + C capacitors connected in parallel with each other are connected in series with each other. Here, when calculating the total parasitic capacity generated,

[a × (b + c)] / (a + b + c)

Becomes

At this time, if (b + c) is very large compared to a,

[a × (b + c)] / (a + b + c) ≒ a

to be.

That is, a capacity similar to the case where the floated black matrix 80 is electrically connected and used as one electrode of the A capacitor is accumulated in the A capacitor.

In fact, as shown in FIG. 3A, the repair line 70 has a width of 10 μm, a length of 3,000 μm, and a capacity of about 0.55 pF when the electrode 90 made of ITO is formed.

On the contrary, as shown in FIG. 3B, when the peripheral line 20 is additionally formed and the floating black matrix 80 is formed, parasitic capacitance of about 0.52 pF was measured similarly to FIG. 3A.

On the other hand, as shown in FIG. 3C, when the repair line 70 is formed so as not to overlap the black matrix 80, parasitic capacitance of about 0.01 pF was measured.

Therefore, if the repair line 70 is formed so as not to overlap the black matrix 80, the parasitic capacitance generated between the repair line 70 and the black matrix 80 can be significantly reduced.

In addition, in the twisted nematic liquid crystal display device, since both the pain electrode and the black matrix are formed on the upper plate, the common electrode as well as the black matrix should be formed so as not to overlap with the repair line.

4 is a diagram schematically illustrating a path of a signal transmitted through a repair line in a liquid crystal display according to an exemplary embodiment of the present invention.

In fact, as shown in FIG. 4, when a repair line is formed outside the region B in which the black matrix is formed to bypass the signal transmitted through the repair line outside the black matrix region B, the gate in the path 1 is blocked. The load capacity generated by overlapping with the line and data line was measured at 74pF, and the load capacity generated by the black matrix was measured at 1.4pF and decreased significantly. Thus, the resistance of the repair line was measured at 2.5kΩ. In the path (2), the parasitic capacitance was about 250 pF and the resistance of the data line was about 8 kΩ.

Through this calculation, the delay for the signal transmitted through the repair line is about 1.7 μ.

On the other hand, the load capacity generated due to the overlap of the black matrix and the repair line is 74pF, and the delay for the signal is calculated to be about 2.1 μm.

As you can see, the signal delay is reduced by about 25%.

Next, a structure of a liquid crystal display according to an exemplary embodiment of the present invention, in which a black matrix and a repair line do not overlap, will be described in detail.

5 is a layout view illustrating a structure of a liquid crystal display according to an exemplary embodiment of the present invention.

As shown in FIG. 5, the liquid crystal display according to the exemplary embodiment of the present invention includes two substrates 100 and 200 facing each other. A plurality of gate lines 30 and data lines 40 are formed on the first substrate 100 to cross each other, and pixel electrodes (not shown) are formed in each pixel defined by the intersections of 30 and 40. Is formed. Each pixel is formed with a thin film transistor (not shown) including a gate electrode connected to the gate line 30, a source electrode connected to the data line 40, and a drain electrode connected to the pixel electrode. The first substrate 100 is also called a thin film transistor substrate. On the other hand, red, green, and blue color filters are formed in the pixels of the second substrate 200, so that the color filter substrate may be used. Here, the center of the liquid crystal panel 120 is composed of a set of pixels, and an image is displayed, which is called an active region A. The black matrix 80 is formed on the color filter substrate 200 outside the active region A. Is formed. In addition, one or more repair lines 70 overlapping the gate line 30 and the data line 40 are formed in a ring or ring shape around the thin film transistor substrate 100 not covered by the black matrix 80. It is. Here, not covering the repair line 70 with the black matrix 80 means that the repair line 70 and the black matrix 80 do not overlap each other. The gate pad 30 is connected to the gate line 30 and the data line 40 at an edge of the thin film transistor substrate 100 that is not covered by the color filter substrate 200, and receives a scan signal or a data signal from the outside. ) And a data pad 41 are formed.

Such a liquid crystal display device may take a twisted nematic method as described above, and may be applied to a liquid crystal display device of a planar driving method. Here, at least one linear common electrode and a pixel electrode facing each other are formed on the same substrate in order to form an electric field almost parallel to the substrate, and the liquid crystal molecules are oriented parallel to the substrate. Take the structure that is.

In particular, in the case of manufacturing a flat panel type liquid crystal display, the black matrix 80 may be formed so as not to overlap the repair line 70 without adding a new mask.

Here, although not shown in the drawings, a printed circuit board or data printed for the gate for outputting an electrical signal to the liquid crystal panel 120 to minimize the resistance of the repair line 70 or to not overlap with the black matrix 80 It may also be formed via a circuit board.

Therefore, in the liquid crystal display according to the present invention, since one or a plurality of repair lines and a black matrix are formed so as not to overlap each other, a delay for a signal bypassing the repair lines can be reduced. In addition, the resistance of the repair line can be reduced by allowing the repair line to pass through the data PCB board and the gate PCB board.

Claims (6)

A plurality of gate lines to which a (correction) scan signal is applied and formed in a horizontal direction, In the active region in which an image is displayed, data lines are formed in a vertical direction to define pixels by crossing the gate lines, A conductive black matrix formed around the outside of the active region, At least one repair line formed around the black matrix and intersecting the gate line and the data line Liquid crystal display comprising a. In claim 1, And the repair line passes through a PCB substrate that outputs a scan signal or a data signal to the liquid crystal display. In claim 2, And a common electrode and a pixel electrode formed on the same substrate of the liquid crystal display and linearly facing each other. In claim 3, And the black matrix is floating. In claim 2, And a common electrode and a pixel electrode respectively formed on different substrates of the liquid crystal display. In claim 5, And the black matrix is connected to the common electrode, and the common electrode is formed so as not to overlap the repair line.