Liquid crystal display device and defect repairing method for the same
A liquid crystal display device comprises a pixel electrode, a thin film transistor, a gate line electrically coupled to the pixel through the thin film transistor and a first auxiliary layer having a first connecting portion overlapped with the pixel electrode and a second connecting portion overlapped with the gate line, wherein the pixel electrode is non-overlapped with the gate line and the first auxiliary layer is electrically insulated from the pixel electrode and the gate line. When a white defect occurs, the pixel electrode is electrically connected to the gate line through the first auxiliary layer thereby repairing the white defect as a black defect.
1. Field of the Invention
This invention generally relates to a liquid crystal display device, and more particularly to a liquid crystal display device having a pixel repairing structure.
2. Description of the Related Art
In the manufacturing process of a liquid crystal display (LCD) device, pixel defects are liable to be generated and should be repaired, which causes the manufacturing cost inevitably to be increased. Typically, the pixel defects are divided into white defects and dark defects, wherein the white defects are easily recognized by naked eyes. Therefore, it is preferable that the white defects should be repaired as black defects, which are always dark and not easily recognized by naked eyes.
One of conventional methods for repairing a white defect as a dark defect is widely used in an LCD device 10 as shown in
In addition, some of conventional methods for repairing a white defect as a dark defect are used in an LCD device (not shown), in which a pixel electrode is overlapped with a storage line (also referred to as storage capacitor line) to form a storage capacitor.
U.S. Pat. No. 6,855,955 B2 issued to Jeon et al. (hereinafter Jeon) on Feb. 15, 2005 discloses that a pixel electrode is electrically connected to a storage capacitor conductor through a contact hole, wherein the storage capacitor conductor has a repairing portion overlapped with the gate line. When a white defect occurs, the gate line is short-circuited with the pixel electrode through the repair portion such that the white defect can be repaired as a dark defect.
However, in the above-mentioned conventional methods, at least one connecting portion (e.g. the part 13 in
The present invention provides a liquid crystal display device, which comprises a thin film transistor and a first auxiliary layer having a first portion overlapped with a pixel electrode and a second portion overlapped with a gate line, wherein the pixel electrode is non-overlapped with the gate line and the first auxiliary layer is electrically insulated from the pixel electrode and the gate line.
The present invention further provides a defect repairing method, which is applied to the above-mentioned liquid crystal display device, wherein the defect repairing method comprises a step of making the pixel electrode electrically isolated from the thin film transistor, a step of connecting the first portion of the first auxiliary layer with the pixel electrode and a step of connecting the second portion of the first auxiliary layer with the gate line.
Furthermore, a second auxiliary layer is overlapped with the first portion of the first auxiliary layer thereby facilitating the electrical connection between the first portion and the pixel electrode.
According to the defect repairing method of the present invention, the pixel electrode can be electrically connected to the gate line through the first auxiliary layer thereby repairing a white defect as a black defect without signal delay problem caused by the capacitive load of the gate line.
BRIEF DESCRIPTION OF THE DRAWINGSOther objects, advantages, and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The plurality of pixel regions 102 are arranged in rows and columns to form a matrix, and each pixel region 102 has a pixel electrode 110 and a pixel repairing structure 111 formed thereon. The data line 104 is electrically coupled, through all the thin film transistors 108 at the same column, to all the pixel electrodes 110 of the pixel regions 102 arranged in the same column. The gate line 106 is electrically coupled, through all the thin film transistors 108 in the same row, to all the pixel electrodes 110 of the pixel regions 102 arranged in the same row. The storage capacitor line 107 is formed across the pixel regions 102 arranged in a row and overlapped with the pixel electrodes 110 to form a storage capacitor for enhancing the charge storing capacity between the pixel electrode 110 and a common electrode formed on a counter substrate (not shown) facing the above-mentioned substrate. In the other word, the storage capacitor line 107 is electrically insulated from the pixel electrodes 110 and data lines 104. The thin film transistor 108 is formed close to the intersection of the data line 104 and the gate line 106. The thin film transistor 108 has a source electrode 108a electrically connected to the data line 104, a drain electrode 108b electrically connected to the pixel electrode 110 through a contact hole 109. In this embodiment, the source electrode 108a and the drain electrode 108b are partially overlapped with a section 106a of the gate line 106 so that the section 106a of the gate line 106 can function as a gate electrode of the thin film transistor 108. In addition, it should be noted that the terms “source electrode” and “drain electrode” could be alternatively used in accordance with the direction of the current flow in the thin film transistor 108.
Referring to
Now referring to FIGS. 2 to 4, if a defect occurs at the predetermined channel in one of the thin film transistors 108, e.g. the thin film transistor also denoted by the numeral 208 shown in
In this embodiment, it is assumed that the pixel electrode also denoted by the numeral 210 is found defective and causes a bright dot. In order to repair the white defect, firstly, the electrical path between the pixel electrode 210 and the drain electrode 108b of the thin film transistor 208 should be cut off such that the pixel electrode 210 can be electrically isolated from the drain electrode 108b. The electrical path can be cut by using a laser to cut off the connecting part 113 of the drain electrode 108b and the connecting part 115 of the source electrode 108a as shown in
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According to the method for making the liquid crystal display device 100, the pixel repairing structure 111, together with the thin film transistor 108, is formed using the same masks and patterning processes. For example, the second auxiliary layer 122, together with the gate line 106, is formed on the substrate 112 through the same mask, i.e. the first mask, and the same patterning process. In addition, the first auxiliary layer 120, together with the data line 104, the source electrode 108a and the drain electrode 108b, is formed on the gate insulating layer 114 through the same mask, i.e. the third mask, and the same patterning process. Therefore, the pixel repairing structure 111 can be formed without using any additional mask and patterning process.
In the pixel repairing structure 111 shown in
In the liquid crystal display devices 100 and 200 shown in
Although the invention has been explained in relation to its preferred embodiment, it is not used to limit the invention. It is to be understood that many other possible modifications and variations can be made by those skilled in the art without departing from the spirit and scope of the invention as hereinafter claimed.
Claims
1. A liquid crystal display device, comprising:
- a first gate line for transmitting a first scan signal;
- a second gate line next to the first gate line;
- a pixel electrode formed without overlapping with the first gate line and the second gate line;
- a thin film transistor having a first electrode electrically connected to the pixel electrode, a second electrode for receiving a data signal, and a gate electrode for receiving the first scan signal; and
- a first auxiliary layer having a first connecting portion overlapped with the pixel electrode and a second connecting portion overlapped with one of the first gate line and the second gate line;
- wherein the first auxiliary layer is electrically insulated from the pixel electrode, the first gate line and the second gate line.
2. The liquid crystal display device as claimed in claim 1, wherein the pixel electrode is located between the first gate line and the second gate line.
3. The liquid crystal display device as claimed in claim 1, wherein the first auxiliary layer, the first electrode and the second electrode are formed by same manufacturing processes.
4. The liquid crystal display device as claimed in claim 1, further comprising:
- a second auxiliary layer overlapped with and electrically insulated from the first connecting portion of the first auxiliary layer.
5. The liquid crystal display device as claimed in claim 4, wherein the second auxiliary layer, the first gate line and the second gate line are formed by same manufacturing processes.
6. The liquid crystal display device as claimed in claim 4, wherein the second auxiliary layer is electrically isolated from the first and second gate lines and electrically insulated from the pixel electrode.
7. The liquid crystal display device as claimed in claim 1, further comprising:
- a gate insulating layer covering the first and second gate lines, wherein the first electrode, the second electrode and the first auxiliary layer are formed on the gate insulating layer; and
- a protective layer covering the first electrode, the second electrode and the first auxiliary layer, wherein the pixel electrode is formed on the protective layer.
8. The liquid crystal display device as claimed in claim 7, further comprising:
- a semiconductor layer formed on the gate insulating layer,
- wherein a part of the first electrode and a part of the second electrode are formed on the semiconductor layer.
9. A defect repairing method, applied to the liquid crystal display device of claim 1 while the pixel electrode is defective, comprising:
- connecting the first connecting portion of the first auxiliary layer with the pixel electrode; and
- connecting the second connecting portion of the first auxiliary layer with the one of the first gate line and the second gate line.
10. The defect repairing method as claimed in claim 9, further comprising:
- making the pixel electrode electrically isolated from the thin film transistor.
11. The defect repairing method as claimed in claim 10, wherein the making step is implemented by cutting off the electrical path between the pixel electrode and the thin film transistor.
12. The defect repairing method as claimed in claim 9, wherein the two connecting steps are implemented by a laser.
13. The defect repairing method as claimed in claim 9, wherein the liquid crystal display device further comprises a second auxiliary layer overlapped with the first connecting portion of the first auxiliary layer, and wherein the step of connecting the first connecting portion of the first auxiliary layer with the pixel electrode further comprises:
- connecting the first connecting portion of the first auxiliary layer with the second auxiliary layer.
14. The defect repairing method as claimed in claim 13, wherein the connecting steps are implemented by a laser.
15. A pixel repairing structure for a liquid crystal display device having a first gate line and a pixel electrode adjacent to the first gate line, comprising:
- a first auxiliary layer having a first portion overlapped with the pixel electrode and a second portion overlapped with the first gate line; and
- a second auxiliary layer overlapped with the first portion of the first auxiliary layer;
- wherein the first auxiliary layer is electrically insulated from the pixel electrode, the first gate line and the second auxiliary layer.
16. The pixel repairing structure as claimed in claim 15, further comprising:
- a second gate line next to the first gate line such that the pixel electrode is located between the first gate line and the second gate line.
17. The pixel repairing structure as claimed in claim 16, wherein the second auxiliary layer is electrically isolated from the first and second gate lines and electrically insulated from the pixel electrode.
18. The pixel repairing structure as claimed in claim 16, wherein the second auxiliary layer, the first gate line and the second gate line are formed by same manufacturing processes.
19. The pixel repairing structure as claimed in claim 15, wherein the second auxiliary layer is electrically isolated from the first gate line and electrically insulated from the pixel electrode.
20. The pixel repairing structure as claimed in claim 15, further comprising:
- a gate insulating layer covering the first gate line and the second auxiliary layer, wherein the first auxiliary layer is formed on the gate insulating layer; and
- a protective layer covering the first auxiliary layer, wherein the pixel electrode is formed on the protective layer.
International Classification: H01L 33/00 (20060101);