KR100907421B1 - Liquid Crystal Display Device - Google Patents

Abstract

A liquid crystal display device according to the present invention includes an upper substrate and a lower substrate; A plurality of gate lines formed on the lower substrate, a plurality of data lines crossing the gate lines to define a plurality of pixel regions, a thin film transistor positioned at an intersection of the gate line and the data line, and the thin film transistor; A red, green, and blue conductive polymer pixel electrode electrically connected to each other and disposed on the pixel area for each pixel; A common electrode formed on the front surface of the upper substrate; It is configured to include a liquid crystal layer interposed between the upper substrate and the lower substrate.

According to the present invention, the sub color filter formed on the upper substrate of the conventional liquid crystal display device is removed, thereby reducing the cost of manufacturing the liquid crystal display device, and the manufacturing process is simplified.

Description

Liquid Crystal Display Device

1 is an exploded perspective view showing a part of a conventional liquid crystal display device.

2A to 2B are plan views showing some regions of the liquid crystal display shown in FIG. 1 and cross-sectional views of specific portions A-A ';

3A to 3B are a plan view showing a partial region of the liquid crystal display according to the present invention and a sectional view of a specific portion B-B '.

<Explanation of symbols for the main parts of the drawings>

5, 5 ': Upper substrate 6, 6': Black matrix

8: sub color filter 13: gate line

15 data line 17 pixel electrode

18: common electrode 19: conductive polymer pixel electrode

22, 22 ': lower substrate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device in which a conductive polymer is used as the pixel electrode, and the conductive polymer as the pixel electrode is red, green, and blue, respectively.

Recently, liquid crystal displays (LCDs) have been widely used as devices for displaying various images including still and moving images. This is due to the characteristics such as light weight, thinness, low consumption driving, and the like, the image quality is being accelerated by the improvement of the liquid crystal material and the development of the fine pixel processing technology, and the application range is gradually increasing.

In general, the driving principle of the liquid crystal display device uses the optical anisotropy and polarization of the liquid crystal. Since the liquid crystal is thin and long in structure, the liquid crystal has directivity in the arrangement of molecules, and the direction of the molecular arrangement can be controlled by artificially applying an electric field to the liquid crystal.

Accordingly, if the molecular arrangement direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and light polarized by optical anisotropy may be arbitrarily modulated to express image information.

Currently, an active matrix LCD in which a thin film transistor and pixel electrodes connected to the thin film transistor are arranged in a matrix manner is generally used because of its excellent resolution and video performance.

The structure of the liquid crystal panel, which is a basic component of the liquid crystal display, is as follows.

1 is an exploded perspective view showing a part of a conventional liquid crystal display device.

Referring to FIG. 1, a conventional color liquid crystal display device includes a color filter 7 including a black matrix 6 and a subcolor filter (red, green, blue) 8, and a common electrode 18 transparent on the color filter. ) Is formed of an upper substrate 5 formed with the upper substrate 5 and a lower substrate 22 having an array wiring including a pixel region P, a pixel electrode 17 formed on the pixel region, and a switching element T. The liquid crystal 14 described above is filled between the substrate 5 and the lower substrate 22.

In this case, the upper substrate 5 is also referred to as a color filter substrate, and in particular, the black matrix 6 serves to distinguish between the sub color filters 8 and to block light.

In addition, the lower substrate 22 may also be referred to as an array substrate, and the thin film transistor T, which is a switching element, may be disposed in a matrix, and the gate line 13 and the data line 15 passing through the plurality of thin film transistors may be formed. do.

In addition, the pixel area P is a region where the gate line 13 and the data line 15 cross each other. The pixel electrode 17 formed on the pixel region P uses a transparent conductive metal having a relatively high transmittance of light, such as indium tin oxide (ITO).

In the liquid crystal display device 11 configured as described above, the liquid crystal layer 14 positioned on the pixel electrode 17 is oriented by a signal applied from the thin film transistor, and the liquid crystal layer depends on the degree of alignment of the liquid crystal layer. The image can be expressed by controlling the amount of light passing through the image.

2A to 2B are plan views illustrating a partial region of the liquid crystal display shown in FIG. 1 and cross-sectional views of a specific portion A-A '.

Referring to FIG. 2A, a plurality of gate lines 13 and data lines 15 cross each other to define a pixel region P on a lower substrate of the liquid crystal display, and the gate line 13 and the data line may be formed. The thin film transistor T composed of the gate electrode 31, the source electrode 33, and the drain electrode 35 is formed at the intersection point of 15. In this case, the pixel region P is arranged on the lower substrate in a matrix form, and the pixel electrode 17 formed on each pixel region P is formed of light such as indium tin oxide (ITO). A transparent conductive metal having a relatively high transmittance of is used.

Here, the source electrode 33 and the drain electrode 35 are configured to be spaced apart from each other by a predetermined interval on the gate electrode 31, and the active channel 37a of the semiconductor layer 37 is exposed between them. In addition, the drain electrode 35 and the pixel electrode 17 are electrically connected by contact holes.

When a predetermined scanning pulse is applied to the gate electrode 31 of the thin film transistor, the voltage of the gate electrode 31 is increased accordingly, and the thin film transistor is turned on. At this time, the liquid crystal driving voltage is applied from the data line 15 to the pixel electrode 17 via the source and drain electrodes 33 and 35 of the thin film transistor T, and the liquid crystal capacitor Clc and the holding capacitor are applied. The pixel capacity combined with (Cst) is charged.

By repeating this operation, a voltage corresponding to the image signal is repeatedly applied every frame time to the pixel capacitance on the front of the panel, and eventually any pixel switched when the arbitrary pixel electrode 17 is switched by the thin film transistor T. The electrode 17 may transmit light of the lower light source.

In addition, the upper substrate is bonded to the lower substrate configured as described above, and as described above, the black matrix 6 is formed in other regions so that only the light passing through the pixel electrode 17 can pass through the upper substrate. The light transmitted to the outside of the pixel electrode 17 is blocked.

In this case, the black matrix 6 is generally formed to overlap a portion of the pixel electrode 17 in consideration of a bonding margin between the lower substrate and the upper substrate.

2B is a cross-sectional view of the specific area A-A 'of FIG. 2A. Referring to FIGS. 2A and 2B, light transmitted through the pixel electrode 17 of the lower substrate 22 by the lower light source is a liquid crystal ( By passing through the plurality of sub-color filters (red, green, blue) 8 formed on the upper substrate 5 through 14), various images including still and moving images are displayed.

In addition, the upper substrate 5 has a common electrode 18 formed on the front surface of the lower substrate 22 to form an electric field with the plurality of pixel electrodes 17 formed on the lower substrate 22. The black matrix 6 is formed to block light leakage that occurs in a region other than the pixel electrode 17 of FIG.

 The black matrix 6 generally includes a thin film transistor region T of a lower substrate and a portion of the pixel electrode 17 adjacent to the data / gate lines 13 and 15 and the data / gate lines 13 and 15. It is formed in the included area.

That is, the black matrix 6 plays a role of distinguishing and blocking the light between the sub color filters 8. In general, the black matrix 6 takes the margin of bonding between the lower substrate 22 and the upper substrate 5 into consideration. The electrode 17 is formed so as to overlap some regions.

 The present invention uses a conductive polymer as the pixel electrode of the liquid crystal display device, and also by dispersing red, green, and blue pigments in the conductive polymer, thereby forming a layer capable of simultaneously serving as a pixel electrode and a color filter, thereby costing It is an object of the present invention to provide a liquid crystal display that reduces the cost.

In order to achieve the above object, the liquid crystal display device according to the present invention,

An upper substrate and a lower substrate; A plurality of gate lines formed on the lower substrate, a plurality of data lines crossing the gate lines to define a plurality of pixel regions, a thin film transistor positioned at an intersection of the gate line and the data line, and the thin film transistor; A red, green, and blue conductive polymer pixel electrode electrically connected to the pixel region; A common electrode formed on the front surface of the upper substrate; It is configured to include a liquid crystal layer interposed between the upper substrate and the lower substrate.

In addition, the red, green, and blue conductive polymer pixel electrodes are formed in each of the pixel regions, and three adjacent pixel regions including each of the red, green and blue conductive polymer pixel electrodes form one pixel. do.

In addition, the red, green, and blue conductive polymer pixel electrodes are formed by dispersing red, green, and blue pigments in a colorless conductive polymer material, respectively.

In addition, a black matrix is formed on the upper substrate so that the conductive polymer pixel electrodes of red, green, and blue formed on the lower substrate are distinguished from each other.

Prior to the description of the present invention, the components of the thin film transistor, which is a component of the conventional liquid crystal display, and the problems thereof will be briefly described.

In the conventional liquid crystal display, a metal material is used for a gate line, a data line, and a pixel electrode.

For example, Al, AlNd, Mo, Cr, etc. are frequently used for the gate line and the gate electrode, Cr, Mo, Cu, AlNd, etc. are used for the source / drain electrode and the data line, and ITO is used as the pixel electrode. And metal such as IZO were used.

However, in recent years, a lot of researches have been conducted on organic TFTs manufactured using conductive organic films instead of conventional metal materials.

As described above, in the case of an organic thin film transistor in which an electrode is formed using an organic film instead of a metal electrode, the organic thin film transistor is formed by using a relatively easy spin coating or ink-jet printing by a conventional sputtering method. The cost can be reduced by using a polymer organic film instead of a metal. In addition, since it can be applied to various substrates, it is advantageous to manufacture a flexible display device as compared to the conventional liquid crystal display device process.

Currently, the gate and source / drain electrodes are formed by using a conductive conjugated polymer (eg, polyethylene dioxy thiophene) and when the pixel electrode is formed, the conductive polymer is used instead of the conventional ITO. Research to form is in progress.

However, in the case of forming the pixel electrode using a conductive polymer, reducing the thickness thereof increases the resistance, whereas increasing the thickness thereof decreases the transparency.

Accordingly, the present invention can overcome the problem of transparency decrease caused by increasing the thickness of the conductive polymer by using a conductive polymer as the pixel electrode and dispersing red, green and blue pigments in the conductive polymer. .

That is, the conductive polymer as the pixel electrode is formed of a layer capable of performing the role of the pixel electrode and the color filter at the same time, thereby removing the sub color filter formed on the upper substrate of the conventional liquid crystal display device, thereby liquid crystal display The cost of manufacturing the device can be reduced.

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

3A to 3B are plan views showing a partial region of the liquid crystal display according to the present invention and a cross sectional view of a specific portion B-B '. Referring to FIG. 3A, a lower substrate of a liquid crystal display according to the present invention is formed by crossing a plurality of gate lines 13 and data lines 15 to define a pixel region P, and the gate line 13. The thin film transistor T including the gate electrode 31, the source electrode 33, and the drain electrode 35 is formed at the intersection of the data line 15 and the data line 15. In this case, the pixel region P is arranged on the lower substrate in a matrix form, and the pixel electrode 19 formed on each of the pixel regions P is formed of the conductive polymer material, unlike in the prior art. .

Here, the source electrode 33 and the drain electrode 35 are configured to be spaced apart from each other by a predetermined interval on the gate electrode 31, and the active channel 37a of the semiconductor layer 37 is exposed therebetween. The drain electrode 35 is in electrical contact with the pixel electrode 19 formed in the pixel region P so that a predetermined signal applied to the data line 15 is applied to the pixel electrode 19.

In more detail, when a predetermined scanning pulse is applied to the gate electrode 31 of the thin film transistor, the voltage of the gate electrode 31 is increased accordingly, and the thin film transistor is turned on. At this time, a liquid crystal driving voltage is applied to the pixel electrode 19 from the data line 15 via the source and drain electrodes 33 and 35 of the thin film transistor T, which is formed on the front surface of the upper substrate. A predetermined electric field is formed with an electrode (not shown) and applied to the liquid crystal, which eventually charges the pixel capacitance in which the liquid crystal capacitor Clc and the holding capacitor Cst are combined. By repeating this operation, a voltage corresponding to an image signal is repeatedly applied every frame time to the pixel capacitance on the front of the panel. When the arbitrary pixel electrode 19 is switched by the thin film transistor, the switched arbitrary pixel electrode is lowered. It will be able to transmit the light of the light source.

According to the present invention, the pixel electrode 19 is formed of a conductive polymer material, and in particular, red, green, and blue pigments are dispersed in the conductive polymer material so that each pixel electrode 19 is red, green, and blue. It is characterized by.

That is, the colored color formed by dispersing red, green, and blue pigments used in the sub color filter (8 in FIG. 2B) of the conventional upper substrate with respect to each pixel electrode 19 formed in each pixel region P of the lower substrate. It is to use a conductive polymer material.                     

As a result, one of the red, green, and blue conductive polymer pixel electrodes 19 is formed in each of the pixel regions P, and three red, green, and blue conductive polymer pixel electrodes 19 are included. The adjacent pixel region P forms one pixel.

In this case, the red, green, and blue conductive polymer pixel electrodes 19 are used in a colorless conductive polymer material (eg, PEDOT (polyethylene dioxy thiophene)) used in a sub color filter (8 in FIG. 2B) of a conventional upper substrate. It is obtained by disperse | distributing red, green, and blue pigment. In this case, the conductive polymer material binds the pigment.

3B is a cross-sectional view of a specific portion B-B ', and referring to FIGS. 3A and 3B, the upper substrate 5' according to the present invention has a sub color filter (unlike the conventional upper substrate 5). 8) of FIG. 2B is not formed. This is because each pixel electrode 19 formed on the lower substrate 22 ′ according to the present invention has a red, green, and blue pigment in its own color, as described above with reference to FIG. 3A. In addition, a liquid crystal layer (not shown) is interposed between the upper substrate 5 'and the lower substrate 22'.

Accordingly, the light transmitted through the pixel electrode 19 of the lower substrate 22 by the lower light source passes through the liquid crystal (not shown) and passes through the upper substrate 5 'as it is to display various images including still or moving images. Will be displayed.

However, in the upper substrate 5 'according to the present invention, a plurality of pixel electrodes 19 formed on the lower substrate 22' and a common electrode 18 'which serves to form an electric field are formed on the front substrate 5'. The black matrix 6 'is formed to block light leakage generated in a region other than the pixel electrode 19 of the lower substrate 22'. That is, a black matrix 6 ′ is formed on the upper substrate so that the conductive polymer pixel electrodes 19 formed on the lower substrate are separated from each other.

In this case, the black matrix 6 'is formed to overlap a portion of the pixel electrode 17 in consideration of a bonding margin between the lower substrate 22' and the upper substrate 5 '.

In this case, when the black matrix 6 ′ is formed on the lower substrate 22, it is not necessary to consider the bonding margin of the lower substrate 22 and the upper substrate 5 as described above. 17) and some regions do not need to overlap, but the material of the black matrix 6 'should be made of resin.

According to the liquid crystal display device according to the present invention according to the above description, by removing the sub-color filter formed on the upper substrate of the conventional liquid crystal display device, the cost of manufacturing the liquid crystal display device is reduced, and the manufacturing process is simplified. have.

Claims (5)

An upper substrate and a lower substrate; A plurality of gate lines formed on the lower substrate, a plurality of data lines crossing the gate lines to define a plurality of pixel regions, a thin film transistor positioned at an intersection of the gate line and the data line, and the thin film transistor; A red, green, and blue conductive polymer pixel electrode electrically connected to the pixel region; A common electrode formed on the front surface of the upper substrate; And a liquid crystal layer interposed between the upper substrate and the lower substrate. The method of claim 1, And one red, green, and blue conductive polymer pixel electrode is formed in each pixel area. The method of claim 2, And three adjacent pixel regions including each of the red, green, and blue conductive polymer pixel electrodes form one pixel. The method of claim 1, The red, green, and blue conductive polymer pixel electrodes are formed by dispersing red, green, and blue pigments in a colorless conductive polymer material, respectively. The method according to claim 1 or 2, And a black matrix formed on the upper substrate so that the conductive polymer pixel electrodes of the red, green, and blue colors formed on the lower substrate are separated from each other.

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