KR20000002542A - Liquid crystal display(lcd) - Google Patents

Abstract

PURPOSE: Provided is a liquid crystal display with a reduced high pixel defect. CONSTITUTION: Normally block mode LCD(Liquid Crystal Display) comprises a gate line for delivering an injection signal, a connection part connected to the gate line, a capacity maintaining electrode connected to the connection part, an insulated data line intersecting the gate line and delivering a picture signal, and an insulated pixel electrode in a pixel area where the gate line and the data line intersect and overlapping the capacity maintaining electrode, wherein high pixel defect is changed into off pixel defect by cutting a connection between the gate line and the capacity maintaining line with a laser when the pixel electrode and the capacity maintaining electrode are short.

Description

Liquid crystal display

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device operating in a normally black mode.

In general, a liquid crystal display device has a structure in which a liquid crystal is injected between two substrates on which an electrode is formed, and a light transmission amount is controlled by adjusting the intensity of a voltage applied to the electrode.

The twisted-nematic (TN) type liquid crystal display device according to the prior art includes a pair of transparent glass substrates each having a transparent electrode formed on an inner surface thereof, and a liquid crystal layer between the two glass substrates. Two polarizing plates for polarizing light are attached to the outer surface of the glass substrate.

When no electric field is applied, the liquid crystal molecules of the liquid crystal layer filled between the two substrates are arranged in parallel in the long axis direction of the two substrates, and have a spirally twisted structure from one substrate to the other substrate. When a power field is connected to two electrodes to form an electric field of sufficient size in the liquid crystal layer, the long axes of the liquid crystal molecules are arranged in a direction parallel to the direction of the electric field and perpendicular to the substrate.

At this time, the polarizing plates attached to the outer surface of the substrate are arranged so that their transmission axes are perpendicular to each other. Then, in a state where no voltage is applied to the liquid crystal layer, light incident through the polarizing plate passes through the liquid crystal layer twisted in a spiral, and its polarization direction is changed to pass through the opposite polarizing plate, thereby showing a white state. On the contrary, when a voltage is applied to the liquid crystal layer, the light incident through the polarizer passes through the liquid crystal layer arranged perpendicular to the substrate, and its polarization direction is maintained as it is and is blocked by the opposite polarizer to show a dark state. This method is called normally white mode.

On the other hand, in order to overcome the problems of the narrow viewing angle and gray level inversion of the TN-LCD, a newly presented vertically aligned liquid crystal display device has a long axis of the liquid crystal molecules arranged perpendicular to the substrate in a state in which no voltage is applied as opposed to a general TN-LCD. When the voltage is applied, it is changed into a spirally twisted arrangement in parallel with the substrate. In this case, the light passing characteristics between two orthogonal polarizing plates are reversed, indicating a dark state when no voltage is applied, and a bright state when voltage is applied. This is called normally black mode.

On the other hand, the liquid crystal display is composed of a plurality of pixels arranged in a matrix form to display an image, the pixel defect occurs due to short circuit or disconnection between the wiring in the process of manufacturing the liquid crystal display.

A pixel defect and a repair method of a general TN-LCD will be described. 1 is a plan view showing one pixel in a TN-LCD according to the prior art.

As shown in FIG. 1, a gate line 2 for transmitting a scan signal is formed in a horizontal direction on the substrate, and a data line 6 for insulated from and intersecting with the gate line 2 in a vertical direction for transmitting an image signal 6. ) Is formed. A transparent pixel electrode 8 is formed in the pixel region defined by the intersection of the gate line 2 and the data line 6. In each pixel area, a thin film transistor, which is a switching element for switching the pixel electrode 8, is formed. The source electrode 61, the drain electrode 62, and the gate electrode 21 of the thin film transistor are respectively a data line 6. The semiconductor layer 4 is connected to the pixel electrode 8 and the gate line 2, and is insulated from and overlaps the gate electrode 21 between the gate electrode 21 and the source and drain electrodes 61 and 62. Formed. On the other hand, the gate line 2 is formed to have a branch 22 extending toward the pixel region so that the branch 22 overlaps the pixel electrode 8 to form a storage capacitor.

In the liquid crystal display as shown in FIG. 1, when a disconnection occurs in a portion of the gate line 2, the data line 6, or a portion of the thin film transistor, the signal is not always supplied to the pixel electrode 8. The voltage is not applied and thus always remains bright. This is referred to as a high pixel defect. When a dark image is to be displayed, when a defective pixel is bright, the defective pixel is easily visible and seriously affects image quality.

In this case, the defect repair method is to short the branch 22 and the pixel electrode 8 of the overlapping gate line 2 with a laser or the like. In this way, a signal is always applied to the bad pixel so that it always remains dark. This is called an off pixel defect, and a pixel that is always dark is not easily noticeable so that the defect is not easily recognized.

However, in the vertically aligned liquid crystal display device having a normally black mode, since the dark state and the bright state are opposite to the normally white mode, the off-pixel defects in the TN-LCD appear as high pixel defects. Can't use it.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a pixel defect repair method in a normally black mode liquid crystal display.

1 is a plan view of a liquid crystal display according to the prior art;

2 is a plan view of a liquid crystal display according to an exemplary embodiment of the present invention;

3 is a plan view of a liquid crystal display according to another exemplary embodiment of the present invention.

In order to solve the above problems, in the present invention, the gate line and the sustain electrode are connected to each other through a connection part, and when a high pixel defect occurs, the connection part between the gate line and the sustain electrode is cut using a laser to be replaced with an off pixel defect.

The liquid crystal display according to the present invention includes a gate line for transmitting a scan signal, a connection portion connected to the gate line, a storage capacitor electrode connected to the connection portion, a data line for insulated from and intersecting the gate line, and for transmitting an image signal. The pixel electrode may be formed in a pixel region defined as an intersection and include a pixel electrode insulated from and overlapped with the storage capacitor electrode, and may operate in a normally black mode.

The thin film transistor may further include a thin film transistor for switching the pixel electrode, and the gate terminal, the source terminal, and the drain terminal of the thin film transistor are connected to the gate line, the data line, and the pixel electrode, respectively.

In this case, when the storage capacitor electrode and the pixel electrode are short-circuited, the connection part is cut to separate the connection between the gate line and the pixel electrode, and the connection part may be cut using a laser.

As such, when the pixel line and the storage capacitor electrode are short-circuited and the pixel line and the storage capacitor electrode are shorted, the high pixel defect of the liquid crystal display device is cut off by using a laser. Can be changed to

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

2 is a plan view of a liquid crystal display according to an exemplary embodiment of the present invention.

As illustrated in FIG. 2, a gate line 20 that transmits a scan signal is formed in a horizontal direction on a substrate (not shown), and a gate electrode 210 that is a branch of the gate line 20 is formed. The storage capacitor electrode 220 is formed in parallel with the gate line 20, and the storage capacitor electrode 220 is connected to the gate line 20 through the connection unit 230. A gate insulating film (not shown) covers the gate line 20, the gate electrode 210, the storage capacitor electrode 220, and the connection portion 230, and is formed of amorphous silicon or the like on the gate insulating film on the gate electrode 210. The channel layer 40 of the formed thin film transistor is formed.

In the longitudinal direction, a data line 60 is formed which is insulated from and crosses the gate line 20 and transmits an image signal, and faces a source electrode 610 and a source electrode 610 which are branches of the data line 60. The drain electrode 620 is formed on the channel layer 40, respectively.

A transparent pixel electrode 80 is formed in the pixel area defined by the intersection of the gate line 20 and the data line 60. The pixel electrode 80 overlaps the storage capacitor electrode 220 with an insulating layer therebetween to form the storage capacitor.

In the liquid crystal display as shown in FIG. 2, when the storage capacitor electrode 220 and the pixel electrode 80 are short-circuited, a voltage is always applied to the defective pixel, resulting in a high pixel defect.

At this time, when the connection portion 230 shown in part (A) of FIG. 2 connecting the gate line 20 and the storage capacitor electrode 220 is cut by using a laser or the like, the gate line 20 and the connection portion 230. The signal can be prevented from being transmitted to the storage capacitor electrode 220 and the pixel electrode 80 shorted thereto, so that the high pixel defect is changed to an off pixel defect.

The method for repairing pixel defects as in the embodiment of the present invention can be applied to an independent wiring type liquid crystal display device in which a storage capacitor wiring for forming a storage capacitor is separately formed.

3 is a plan view of a liquid crystal display having a storage capacitor of an independent wiring method according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the storage electrode line 10 transmitting the common signal for forming the storage capacitor is formed in parallel with the gate line 20, and in parallel with the storage electrode line 10 and the gate line 20. The storage capacitor electrode 120 is formed, and the storage capacitor electrode 120 is connected to the storage electrode line 10 through the connection unit 130. The storage capacitor electrode 120 overlaps the pixel electrode 80 to form a storage capacitor. The rest of the structure is similar to the liquid crystal display according to the embodiment of the present invention shown in FIG.

In the liquid crystal display of the independent wiring method as shown in FIG. 3, when the pixel electrode 80 and the storage capacitor electrode 120 are short-circuited to generate a high pixel defect, the portion (B) of FIG. 3 is cut by a laser or the like. The defect can be replaced with an off pixel defect.

As in the exemplary embodiment of the present invention, the connection between the gate line and the storage capacitor electrode is connected through a connecting portion, and when the pixel electrode and the storage capacitor electrode are short-circuited, the connection portion between the gate line and the storage capacitor electrode is cut by using a laser to fix the high pixel. The defect can be replaced with an off pixel defect, thereby improving the image quality of the liquid crystal display.

Claims (12)

A gate line for transmitting a scan signal, A connection part connected to the gate line; A storage capacitor electrode connected to the connection part; A data line insulated from and intersecting the gate line and transferring an image signal; And a pixel electrode formed in a pixel region defined by the intersection of the gate line and the data line, and insulated from and overlapping the storage capacitor electrode. In claim 1, The liquid crystal display device operates in a normally black mode. In claim 2, And a thin film transistor for switching the pixel electrode. In claim 3, And a gate terminal, a source terminal, and a drain terminal of the thin film transistor are connected to the gate line, the data line, and the pixel electrode, respectively. The method according to any one of claims 1 to 4, And the cutting part is cut when the storage capacitor electrode and the pixel electrode are shorted. In claim 5, The liquid crystal display device for cutting the connection using a laser. A gate line for transmitting a scan signal, Sustain electrode wire for transmitting a common signal, A connection part connected to the storage electrode line; A storage capacitor electrode connected to the connection part; A data line insulated from and intersecting the gate line and transferring an image signal; And a pixel electrode formed in a pixel region defined by the intersection of the gate line and the data line, and insulated from and overlapping the storage capacitor electrode. In claim 7, The liquid crystal display device operates in a normally black mode. In claim 8, And a thin film transistor for switching the pixel electrode. In claim 9, And a gate terminal, a source terminal, and a drain terminal of the thin film transistor are connected to the gate line, the data line, and the pixel electrode, respectively. The method according to any one of claims 7 to 10, And the cutting part is cut when the storage capacitor electrode and the pixel electrode are shorted. In claim 11, The liquid crystal display device for cutting the connection using a laser.