Patent Application
20070246778
1. Field of the Invention
The present invention relates to an electrostatic discharge (ESD) protection structure, and more particularly, to an electrostatic discharge protection structure for avoiding a feedback electrostatic discharge.
2. Description of the Prior Art
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When the data line 104 of the display area accumulates electrostatic charge, the threshold voltage of the TFT 122 will be reached. The electrostatic charge in the data line 104 passes through the TFT 122 to the short ring 128 by a path 134. When the electrostatic charge passes into the short ring 128, it also passes into the peripheral electrostatic discharge protection structures e.g. electrostatic discharge protection structures 110, and 150 by the paths 118, and 158 respectively. This means the electrostatic charge passes into data lines 102, and 106 from the wires 116, and 156, and the TFTs 114, and 154 respectively. The electrostatic charge spreads in each data line of the display area, so the function of electrostatic discharge protection is achieved. If the electrostatic discharge protection structure 120 has the same voltage difference across the paths, the paths 134, 144 will have the same resistances. The electrostatic charge accumulated in the data line 104 passes into the short ring 128 by the path 134 of the electrostatic discharge protection structure 120. Then, the electrostatic charge is fed back into the data line 104 through the path 144 of the electrostatic discharge protection structure 120. This causes a feedback electrostatic discharge.
Other patents, such as Japan patent JP10-123574, mention forming nonlinear resistance structures on the data line and the scan line to improve the electrostatic discharge. They do not mention any way to solve the problem of the feedback electrostatic discharge, however. Therefore, pursuing a more effective electrostatic discharge protection structure is important.
The present invention provides an electrostatic discharge protection structure to solve the above-mentioned problems.
The embodiment of the present invention provides an electrostatic discharge protection structure in a peripheral area of a display panel is electrical connected to a wire of a display area of the display panel and a short ring of the peripheral area. The electrostatic discharge protection structure comprises a first path having a first resistance, and a second path having a second resistance. The second path and the first path are parallel connection between the wire and the short ring, wherein the first resistance is lower than the second resistance.
Another embodiment of the present invention provides an electrostatic discharge protection structure in a peripheral area of a TFT liquid crystal display panel. The electrostatic discharge protection structure is electrical connected to a wire of a display area of the TFT LCD and a short ring of the peripheral area. The electrostatic discharge protection structure comprises a first TFT having a first resistance, and a second TFT having a second resistance. And the second TFT and the first TFT are parallel connection between the wire and the short ring, wherein the first resistance is lower than the second resistance.
Another embodiment of the present invention provides an thin film transistor liquid crystal display panel comprises a display area having a plurality of data lines and a plurality of scan lines, and the data lines and the scan lines are interlocking, and a peripheral area having a short ring and a plurality of electrostatic discharge protection structures. And the electrostatic discharge protection structure is electrical connected to the data line and the short ring and to the scan line and the short ring. And the electrostatic discharge protection structure comprises a first TFT having a first resistance, and a second TFT having a second resistance. And the second TFT and the first TFT are parallel connection, wherein the first resistance is lower than the second resistance.
The resistance of the path passing the electrostatic charge from the data line or the scan line into the short ring is smaller than the resistance of the path passing the electrostatic charge from the short ring into the data line or the scan line in the electrostatic discharge protection structure of the present invention. Thus, the present invention makes the electrostatic charge unable to feed back into the data line or the scan line, avoiding the feedback electrostatic discharge, and thereby increasing the yield of the LCD panel.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
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In other words, the TFTs 222, 224 can replace two diodes in other embodiment, as
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Please pay attention to that when the electrostatic discharge protection structure applies to TFT LCD panel, the layout of the TFTs 222, 224 can be changed, and the resistance of the TFT 222 is lower than the TFT 224. And the resistance of path 234 is lower than the resistance of path 244. If the value of the transistor channel width/length of the TFT 222 is higher than the value of the transistor channel width/length of the TFT 224, the resistance of the path 234 is lower than the path 244. For example, the length of the TFTs 222, 224 are the same, but the channel width of the TFT 222 is bigger, for example the transistor channel width/length of the TFT 222 is 80/5, and the transistor channel width/length of the TFT 224 is 30/5. Similarly, the channel width of the TFTs 222, 224 are the same, but the channel length of the TFT 222 is lower, for example the transistor channel width/length of the TFT 222 is 50/4, and the transistor channel width/length of the TFT 224 is 50/7. All of them make the resistance of the TFT 222 is lower than the resistance of the TFT 224.
In this embodiment, the electrostatic discharge protection structures 210, 220, 250 are connected to the data lines 202, 204 of the LCD panel. In fact, the electrostatic discharge protection structure can also be connected to the scan line (not shown). The data line and the corresponding scan line can control a pixel unit to turn on or off. In this embodiment, the electrostatic charge from the data line 204 passes into the short ring 228 through the electrostatic discharge protection structure 220, and the whole pixel unit in the data line 204 cannot be electrostatically discharged. Moreover, the electrostatic charge in the short ring 228 cannot be fed back to the data line 204, so the electrostatic charge spreads to several electrostatic discharge protection structures surrounding the electrostatic discharge protection structure 220. Please note that not only the electrostatic discharge protection structures 210, 250 in
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Compare with the prior art. The resistance of the path passing the electrostatic charge from the data line or the scan line into the short ring is smaller than the resistance of the path passing the electrostatic charge from the short ring into the data line or the scan line in the electrostatic discharge protection structure of the present invention. The Japan patent JP10-123574 does not have different nonlinear resistances, so it cannot limit the feedback electrostatic discharge. In comparison, the present invention makes the electrostatic charge unable to be fed back into the data line or the scan line, avoiding the feedback electrostatic discharge, and thereby increasing the yield of the LCD. Moreover, the present invention only changes the channel width or length of the TFT, to change the resistance of the TFT. The present invention does not need to change the driver circuits, and does not need to add PEP. So, it can be easily utilized in current display panel manufacturing.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
