Liquid Crystal Display Substrate Having Repair Lines

A. Field of the Invention

The present invention relates to a liquid crystal display substrate having repair lines.

B. Description of the Related Art

There are many flat panel displays, such as liquid crystal displays, plasma display panels (PDPs), electroluminescences (ELs) and field emission displays (FEDs). These flat panel displays have wiring structures in matrix type.

LCDs are typical displays representing the flat panel displays, and active matrix type LCDs using thin film transistors (hereinafter referred to as TFTs) as switching elements are commonly used.

A liquid crystal display generally includes two substrates and a liquid crystal material therebetween. The liquid crystal display substrates have a plurality of pixels and signal lines such as gate lines and data lines supplying signals to the pixels via TFTs. In addition, in order to repair the open of the signal lines, repair lines are often added to the substrate.

A conventional liquid crystal display substrate is described with reference to FIG. 1.

As shown in FIG. 1, a plurality of gate lines 12 are arranged in a transverse direction and each gate line 12 has an input pad 10 through which a gate signal is applied to it. A plurality of data lines 22 are arranged in a longitudinal direction and cross the gate lines 12. Each data line 22 has an input pad 20 through which a data signal is applied to it. A gate line 12 and a data line 22 is connected to a pixel (not shown) which has a pixel electrode (not shown) and a switching element (not shown), the pixel is formed in the area defined by the gate lines 12 and the data lines 22. A first and a second repair lines 14 and 16 are formed around the display area comprised of a plurality of pixels. Since each repair line 14 or 16 is closed and encloses the display area, it cross the gate lines 12 and the data lines 22 twice. The first repair line 14 is enclosed by the second repair line 16.

When a data line D1 is opened at an open point OP1, the data line D1 and the first (or the second) repair line 14 are shorted at their two cross points SP1 and SP2. Then, the data signal may flow into the portion of the data line D1 below the open point OP1 along the path P1 and the path P2 in the repair line 14. However, since the path P2 is longer than the path P1, it should be blocked. Therefore, the repair line 14 is cut at the points CP1 and CP2 in the path P2 between the short points SP1 and SP2 and the cross points of the path P2 and the nearest data line D2.

Let us assume that two data lines D1 and D2 are opened at open points OP1 and OP2, respectively, and the data line D2 is closer to the middle portion of the display area than the data line D1. Then, the data line D1 and the first repair line 14 are shorted at their two cross points SP1 and SP2, and the data line D2 and the second repair line 16 are shorted at their two cross points SP3 and SP4. Thereafter, the repair lines 14 and 16 are cut at the points CP1, CP2, CP3 and CP4 between the short points SP1, SP2, SP3 and SP4 and the cross points of the longer paths P2 and P4 and the nearest data lines D2 and D3, respectively. Then, the data signals entered into the data lines D1 and D2 may reach at the portions of the data lines D1 and D2 below the open points OP1 and OP2 along the path P1 and the path P3 in the repair lines 14 and 16.

Compared with the path P1, the RC delay in the signal through the P3 is large since the path P3 is long and has more cross points with the data lines 22. This delay becomes larger as the number of the signal lines increases.

An object of the present invention is to reduce the RC delay when using a repair line.

The present invention has at least two repair lines. A first repair line crosses twice the data lines lying on the center portion of the substrate and once data lines which a second repair line crosses twice among the remainings.

It is preferable that the data lines lying on the center portion have longer length than the remaining data lines. All the data lines crossing the second repair line may be left or right to the data lines lying on the center portion.

The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein:

FIG. 1 shows a conventional liquid crystal display substrate having repair lines and its repair method;

FIG. 2 shows a liquid crystal display substrate according to the embodiment of the present invention; and

FIG. 3 shows a repair method of the liquid crystal display substrate shown in FIG. 2.

Now, the first embodiment according to the present invention will be described.

As shown in FIG. 2, a plurality of gate lines 12 are arranged in a transverse direction and each gate line has an input pad 10 through which a gate signal is applied to it. A plurality of data lines 22 are arranged in a longitudinal direction and cross the gate lines 12. Each data line has an input pad 20 through which a data signal is applied to it. A gate line 12 and a data line 22 are connected to a pixel (not shown) having a pixel electrode (not shown) and a switching element (not shown), and the pixels are formed in the area defined by the gate lines 12 and the data lines. The data lines 22 are grouped into a center block 200 and edge blocks 100. The data lines 22 of the center block 200 have longer lengths than the data lines 22 of the edge blocks 100. A pair of first repair lines 141 and 142 and a pair of second repair lines 161 and 162 are symmetrically arranged around the display area. The first repair lines 141 and 142 cross twice the data lines 22 in edge blocks 100 and cross once the gate lines 12. The second repair lines 141 and 142 cross once the data lines 22 in edge blocks 100 and the gate lines 12 and cross twice the data lines 22 in the center block 200. In FIG. 2, the number of the data lines 22 are twelve, four of them are in the center block 200 and eight of them are in the edge blocks 100. Each second repair line 161 or 162 cross once the two data lines in the center block 200.

A repair method in case that two data lines D1 and D2 are opened at open points OP1 and OP2, respectively, the data line D1 is in the edge block 100 and the data line D2 is in the center block 200. Then, the data line D1 and the first repair line 141 are shorted at their two cross points SP1 and SP2, and the data line D2 and the second repair line 161 are shorted at their two cross points SP3 and SP4. Thereafter, the repair line 161 is cut at the points CP3 and CP4 between the short points SP3 and SP4 and the cross points of the repair line 161 and the nearest data line D3 more closer to the middle portion of the substrate than the opened data line D2. Then, the data signals entered into the data lines D1 and D2 may reach at the portions of the data lines D1 and D2 below the open points OP1 and OP2 along the path P1 of the first repair line 141 and the path P3 of the second repair line 161, respectively.

The path P3 of this embodiment crosses six times the data lines 12, while the path P3 of the conventional method in FIG. 1 crossing ten times. Therefore, the RC delay in the data signal is reduced. In addition, since the path P1 of this embodiment crosses eight times the data lines 12, the RC delay in the signals flowing along the paths P1 and P2 are similar. Hence, the image quality increases.