KR100697367B1 - Liquid crystal display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device. When the polarity occurs, the greenish phenomenon can be prevented by increasing the capacitor formed with the data bus line in the green line to reduce distortion of the common voltage signal. According to an exemplary embodiment of the present invention, a liquid crystal display includes a plurality of gate bus lines and a plurality of data bus lines that are formed orthogonally with a gate insulating layer formed on a lower substrate to define a pixel area, and the plurality of gate bus lines and the plurality of data. A thin film transistor formed on a bus line, the thin film transistor including a gate electrode, a channel layer, and a source and drain electrode, an opposite electrode formed on the lower substrate in a rectangular frame shape on the same plane as the gate electrode in the pixel area, and the gate electrode interposed therebetween; And a pixel electrode arranged on the counter electrode in the form of a letter “I” and electrically connected to any one of the source and drain electrodes, wherein the green signal of the plurality of data bus lines The line width and width of the incoming data bus line Alternatively, the line width of the data bus line into which the blue signal enters is the same, but the line width of the data bus line into which the green signal enters in a portion overlapping the opposite electrode line is twice the line width of the data bus line into which the red or blue signal enters. It is characterized in that it is formed large.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

1 is a structural diagram of a TFT-LCD pixel in the conventional IPS and FFS mode

2 is a view showing the polarity of the voltage applied to the liquid crystal in each field during the dot inversion driving of the conventional TFT-LCD

3 is an explanatory diagram for explaining that a screen is greenish due to distortion of a common voltage signal in a conventional TFT-LCD.

4 is a structural diagram of a TFT-LCD pixel in IPS and FFS mode according to the present invention;

5 is a structural diagram of TFT-LCD pixels in IPS and FFS mode according to another embodiment of the present invention.

6 is a structural diagram of a TFT-LCD pixel in IPS and FFS mode according to another embodiment of the present invention;

Explanation of symbols on the main parts of the drawings

1: counter electrode 2: counter electrode line

3: pixel electrode 4: data bus line

5: gate bus line 6: thin film transistor

7: inner short ring

10: lower substrate 40, 400: green (G) data bus line

42: Red (R) or Blue (B) data bus line

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquid crystal display, and in particular, in an in-plane switching (IPS) which is a wide viewing angle mode liquid crystal display, a liquid crystal display which prevents the screen from being greenish due to distortion of the common voltage signal Vcom. Relates to a device.

1 illustrates a structure of a TFT-LCD pixel in a conventional In-Plane Switching (IPS) mode and a Fringe Field Switching Mode (FFS) mode.

In the liquid crystal display of the conventional IPS mode and FFS mode, the plurality of gate bus lines 5 are arranged in parallel with each other in the first direction, that is, the x direction, on the lower substrate 10 and the plurality of data bus lines 4 ) Are arranged parallel to each other in the second direction, that is, the y direction, forming a matrix arrangement. Each of these matrix arrays defines a unit pixel area.

1 shows a unit cell of an LCD, in which one gate bus line 5 and one data bus line 4 are shown. The gate bus line 5 and the data bus line 4 are insulated with a gate insulating film (not shown) interposed therebetween.

The counter electrodes 1 are formed in the unit pixel space so as to have a rectangular frame shape, for example. The counter electrode 1 is disposed on the surface of the lower substrate like the gate bus line 5.

The pixel electrode 3 is arranged above the counter electrode 1 with a gate insulating film (not shown) interposed therebetween, and is divided into letters “I” so as to divide the area surrounded by the counter electrode 1 having a rectangular frame shape. It is arranged in the form.

The thin film transistor 6 is provided at the intersection of the gate bus line 5 and the data bus line 4. The thin film transistor 6 includes a gate electrode extending from the gate bus line 5, a drain electrode extending from the data bus line 4, a source electrode extending from the pixel electrode 3, and a channel formed on the gate electrode. Layer.

The storage capacitor Cst is formed at a portion where the counter electrode 1 and the pixel electrode 3 overlap each other. Although not shown in FIG. 1, an upper substrate (not shown) having a color filter (not shown) is disposed to face the lower substrate 10 at a predetermined distance. Here, the gate bus line 5, the counter electrode 1, the pixel electrode 3 and the data bus line 4 are formed of at least one metal selected from the group consisting of aluminum, titanium, tantalum, chromium and combination ITO thereof. do.

As described above, in the case of the IPS mode and the FFS mode, the counter electrode 1 is formed on the lower substrate 10 unlike the general TN mode. At this time, the formed counter electrode 1 has a capacitance a due to overlap with the data bus line 4 and a fringe capacitance b generated in parallel with the data bus line 4. .

FIG. 2 is a diagram illustrating polarities of voltages applied to liquid crystals in each field during dot inversion driving of a conventional TFT-LCD, and FIG. 3 shows a greenish screen due to distortion of a common voltage signal in a conventional TFT-LCD. It is explanatory drawing to explain what becomes).

In the case of dot inversion, the red (R) and blue (B) signals always have the same polarity in the red (R), green (G), and blue (B) strip arrays. Has the opposite polarity of red (R) and blue (B). In a normal screen, the polarities of the entire screen are conflicted with each other and become "0".

However, certain patterns, for example, one skip line and two skip dot patterns, have (+) to (-) polarities in n gate bus lines as shown in FIG. 2. This polarity causes the common voltage Vcom signal to be distorted due to the capacitance between the data bus line 4 and the counter electrode 1. At this time, the common voltage Vcom signal is distorted in a direction of increasing the brightness of green G in a direction of decreasing the brightness of red R and blue B as shown in FIG. 3. Due to the distortion of the Vcom, the entire screen appears closer to green.

Accordingly, an object of the present invention is to reduce the distortion of the common voltage signal Vcom by increasing the capacitor formed with the data bus line in the green line when polarity occurs. An object of the present invention is to provide a liquid crystal display device which can prevent greenish phenomenon.

In order to achieve the above object, the liquid crystal display according to the present invention includes a plurality of gate bus lines and a plurality of data bus lines which are formed orthogonal to each other by interposing a gate insulating film formed on a lower substrate to define a pixel area. A thin film transistor disposed on a gate bus line and the plurality of data bus lines, the thin film transistor including a gate electrode, a channel layer, a source and a drain electrode, and formed in a rectangular frame shape on the lower substrate on the same plane as the gate electrode in the pixel area; The liquid crystal display device comprising: an electrode and a pixel electrode arranged in the form of a letter “I” on the counter electrode via the gate electrode and electrically connected to any one of the source and drain electrodes. Of green data bus lines The line width of the data bus line and the line width of the data bus line into which the red or blue signal enters are formed to be the same, and the line width of the data bus line into which the green signal enters in a portion overlapping with the opposite electrode line includes the red or blue signal. It is characterized in that it is formed twice as large as the line width of the data bus line.

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In the liquid crystal display of the present invention, the data bus line into which the green signal enters is formed by dividing a portion overlapping with the counter electrode line in two divisions.

In order to achieve the above object, another liquid crystal display of the present invention includes a plurality of gate bus lines and a plurality of data bus lines which are formed orthogonally with a gate insulating film formed on a lower substrate to define a pixel region, A thin film transistor disposed on a gate bus line and the plurality of data bus lines, the thin film transistor including a gate electrode, a channel layer, a source and a drain electrode, and formed in a rectangular frame shape on the lower substrate on the same plane as the gate electrode in the pixel area; The liquid crystal display device comprising: an electrode and a pixel electrode arranged in the form of a letter “I” on the counter electrode via the gate electrode and electrically connected to any one of the source and drain electrodes. Extend the data bus lines to The greenish is reduced by overlapping the extension line of the data bus line to which the green signal of the plurality of data bus lines enters the portion connected to the panel outer inner short ring on the substrate with the portion formed in the outer panel of the counter electrode line. do.

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Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In addition, in all the drawings for demonstrating an embodiment, the thing with the same function uses the same code | symbol, and the repeated description is abbreviate | omitted.

Fig. 4 shows the structure of a TFT-LCD pixel in IPS and FFS mode according to the present invention.

As shown, the structure of the TFT-LCD pixel of the present invention is vertical so that a plurality of gate bus lines 5 and a plurality of data bus lines 40 and 42 are insulated with a gate insulating film (not shown) interposed therebetween. Formed to define a pixel area. The plurality of data bus lines 40 and 42 may include a green (G) data bus line 40 and a red (R) or blue (B) data bus line 42.
In the pixel area, the counter electrode 1 is formed to have a rectangular frame shape, for example. The counter electrode 1 is disposed on the surface of the lower substrate like the gate bus line 5. In addition, the pixel electrode 3 is arranged above the counter electrode 1 with a gate insulating film (not shown) interposed therebetween, and the letter “I” is divided so as to divide a region surrounded by the counter electrode 1 having a rectangular frame shape. Are arranged in the form of characters.
The thin film transistor 6 is provided at the intersection of the gate bus line 5 and the data bus lines 40 and 42. The thin film transistor 6 includes a gate electrode extending from the gate bus line 5, a source and drain electrode formed together with the data bus lines 40 and 42, and a channel layer formed on the gate electrode. The source electrode is in contact with the pixel electrode 3 and electrically connected.
The storage capacitor Cst is formed at a portion where the counter electrode 1 and the pixel electrode 3 overlap each other. An upper substrate (not shown) provided with a color filter (not shown) is spaced apart from the lower substrate 10 by a predetermined distance so as to face each other. Here, the gate bus line 5 and the counter electrode 1 data bus lines 40 and 42 may be formed of at least one metal selected from the group consisting of aluminum, titanium, tantalum, chromium, and combinations thereof. 3) is formed of a transparent ITO film.
In the structure of the TFT-LCD pixel described above, the data bus line 40 into which the green (G) signal enters and the data bus line 42 into which the red (R) or blue (B) signal enters have substantially the same line width. Is formed. However, the line width of the data bus line 40 into which the green (G) signal overlaps with the counter electrode line 2 is 2 larger than the line width of the data bus line 42 into which the red (R) or blue (B) signal enters. It is formed by forming a large ship.
As a result, the green (G) data bus line 40 and the counter electrode line (without increasing the capacitance due to the overlap of the red (R) or blue (B) data bus line 42 and the counter electrode line 2). Only capacitance due to overlap of 2) is doubled.

In general, the distortion of the common voltage signal Vcom is caused by the influence of the data signal due to the capacitance due to the overlap of the green G data bus line 40 and the counter electrode line 2. At this time, the degree of distortion is expressed as follows.

ΔVcom = ΔVd × Ccom / Ctot

Where Ccom is the capacitance between the opposing electrode line 2 and the data bus line, Ctot is the total pixel capacitance, and ΔVd is Vdh (data 'high' voltage)-Vdl (data 'low' voltage).

In the above formula, if red (R) and blue (B) have the same polarity, only green (G) has the opposite polarity, so that the common voltage signal (Vcom) is distorted toward the polarity of red (R) and blue (B). do. In other words,

ΔVcom = ΔVd × Ccom / Ctot (R)-ΔVd × Ccom / Ctot (G) +

         ΔVd × Ccom / Ctot (B) = ΔVd × Ccom / Ctot

At this time, the capacitance Ccom between the counter electrode line 40 and the data bus line 2 of the green G line may be doubled to make the overall ΔVcom to zero. In other words,

ΔVcom = ΔVd × Ccom / Ctot (R)-ΔVd × 2Ccom / Ctot (G) +

         ΔVd × Ccom / Ctot (B) = 0

By using this principle, the greenish can be reduced by doubling the capacitance between the data bus line 40 and the counter electrode line 2 of the green G.

In the pixel, the overlapping portion between the red (R) or blue (B) data bus line 40 and the counter electrode line 2 is formed in a conventional manner, and the data bus line 40 and the counter electrode line 2 of green (G) are formed as in the related art. ) And the capacitance between the data bus line 40 of the green (G) and the counter electrode line 2 is increased by increasing the line width of the data bus line or forming two data bus lines of the same line width. Decreases.

5 shows the structure of a TFT-LCD pixel in IPS and FFS mode according to another embodiment of the present invention.

As shown, according to the structure of the TFT-LCD pixel of the present invention, the line width of the data bus line 400 into which the green (G) signal in the pixel enters is the data bus line into which the red (R) or blue (B) signal enters. The red bus or the blue bus is formed to have the same line width as that of (42), and the data bus line 400 into which the green (G) signal of the part overlapping with the counter electrode line 2 enters is divided into two wirings. (B) It is formed by forming two times larger than the line width of the data bus line 42 into which the signal enters.

6 shows the structure of a TFT-LCD pixel in an IPS and FFS mode according to another embodiment of the present invention.

As shown, the greenish is reduced by forming an overlap between the data bus line of green (G) and the outer opposing electrode wiring at the data bus line extension of the outside of the panel.

As described above, according to the liquid crystal display according to the present invention, the greenish is obtained by reducing the distortion of the common voltage signal Vcom by increasing the capacitor formed with the data bus line in the green G line when polarity occurs. The image quality can be improved by preventing the phenomenon.

In addition, preferred embodiments of the present invention are disclosed for the purpose of illustration, those skilled in the art will be able to various modifications, changes, additions, etc. within the spirit and scope of the present invention, these modifications and changes should be seen as belonging to the following claims. something to do.

Claims (3)

A plurality of gate bus lines and a plurality of data bus lines formed orthogonal to each other via a gate insulating layer formed on the lower substrate to define a pixel region; A thin film transistor disposed on the plurality of gate bus lines and the plurality of data bus lines, the thin film transistor comprising a gate electrode, a channel layer, and a source and a drain electrode; An opposite electrode formed on the lower substrate in a rectangular frame shape on the same plane as the gate electrode in the pixel area; In the liquid crystal display device including a pixel electrode arranged in the form of the letter "I" on the counter electrode and the electrically connected to any one of the source and drain electrodes through the gate electrode, Among the plurality of data bus lines, the line width of the data bus line into which the green signal enters and the line width of the data bus line into which the red or blue signal enters are formed to be the same, and the data bus line into which the green signal enters in a portion overlapping the opposite electrode line. The line width of the liquid crystal display device is formed to be twice as large as the line width of the data bus line to which the red or blue signal enters. The method of claim 1, The data bus line into which the green signal enters, And a portion overlapping with the counter electrode line is divided into two portions. A plurality of gate bus lines and a plurality of data bus lines formed orthogonal to each other via a gate insulating layer formed on the lower substrate to define a pixel region; A thin film transistor disposed on the plurality of gate bus lines and the plurality of data bus lines, the thin film transistor comprising a gate electrode, a channel layer, and a source and a drain electrode; An opposite electrode formed on the lower substrate in a rectangular frame shape on the same plane as the gate electrode in the pixel area; In the liquid crystal display device including a pixel electrode arranged in the form of the letter "I" on the counter electrode and the electrically connected to any one of the source and drain electrodes through the gate electrode, An extension line of the data bus line to which the green signal of the plurality of data bus lines enters is formed at the outer side of the panel among the opposing electrode lines at a portion that extends the plurality of data bus lines to connect with the panel outer inner short ring on the lower substrate. The liquid crystal display device which overlapped with the part and reduced greenish.

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