KR101350430B1 - An array substrate for IPS-LCD with color-filter on array - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an array substrate for a transverse electric field type liquid crystal display device. In particular, an array for a transverse electric field type liquid crystal display device having a color filter on array structure (COA) having an array portion and a color filter formed on one substrate. It relates to a substrate.

According to the present invention, due to the different dielectric constant values of the red color filter, the green color filter, and the blue color filter, in order to compensate for the poor image quality due to the difference in the pixel voltage by the dielectric constant value according to the pixel corresponding to each color filter, An array substrate structure capable of applying different levels of common voltage for each color is proposed.

Description

An array substrate for IPS-LCD with color-filter on array}

1 is a perspective view schematically showing a liquid crystal display according to the related art,

2 is an enlarged cross-sectional view schematically showing the configuration of a liquid crystal display device having a COA structure according to a first example of the prior art;

3 is a cross-sectional view schematically showing the configuration of an array substrate of a COA-IPS according to a second conventional example.

4 is a view for explaining the dielectric constant characteristics of the color filter,

5 is a plan view showing a part of an equivalent circuit of the transverse electric field type liquid crystal display device according to the first embodiment of the present invention;

6 is an enlarged plan view of a unit pixel of an array substrate for a transverse electric field type liquid crystal display device;

FIG. 7 is a plan view illustrating a partial equivalent circuit of a transverse electric field type liquid crystal display device according to a second exemplary embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

100: substrate 108a to 108c: first to third common wiring

G1 to Gn: Gate wiring D1 to Dn: Data wiring

130a ~ 130c: Color filter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a structure of a COA transverse field array substrate for solving a poor image quality caused by different dielectric constants for each color.

In general, a liquid crystal display device displays an image by using optical anisotropy and birefringence characteristics of liquid crystal molecules. When an electric field is applied, the alignment of liquid crystals is changed, and the characteristics of light transmission vary according to the arrangement direction of the changed liquid crystals.

In general, a liquid crystal display device arranges two substrates on which the field generating electrodes are formed so that the surfaces on which the two electrodes are formed face each other, injects a liquid crystal material between the two substrates, and then applies voltage to the two electrodes. By moving the liquid crystal molecules by the generated electric field, the device expresses the image by the transmittance of light that varies accordingly.

1 is a schematic view of a general liquid crystal display device.

As shown in the drawing, a general color liquid crystal display device 11 includes a red, green, and blue color filter 34a to 34c sequentially formed in a plurality of pixel areas P and a black formed between the color filters 34a to 34c. The matrix 32, the upper substrate 30 having the common electrode 36 formed on the front surface of the substrate 30 on which the color filters 34a to 34c and the black matrix 32 are formed, and the pixel region P are defined. In the pixel region P, the pixel electrode 17 and the switching element T are formed, and the array substrate B1 having the array wirings 12 and 20 formed around the pixel region P, and the color filter substrate ( Liquid crystals (not shown) are filled between B2) and the array substrate B1.

The array substrate B1 has a thin film transistor T which is a switching element on a transparent substrate 10 in a matrix type, and has a gate wiring 12 passing through the plurality of thin film transistors TFT. The data wiring 20 is formed.

In this case, the pixel area P is an area defined by the gate line 12 and the data line 20 crossing each other, and a transparent pixel electrode 22 is formed on the pixel area P as described above.

The pixel electrode 22 uses a transparent conductive metal having excellent light transmittance such as indium-tin-oxide (ITO).

However, when the liquid crystal panel is manufactured by bonding the color filter substrate B2 and the array substrate B1 as described above, light leakage defects due to the bonding error between the color filter substrate B2 and the array substrate B1 are caused. The probability of this occurring is very high.

In addition, in order to prevent light leakage defects, the opening area is reduced by the process margin when the black matrix 32 is formed.

Accordingly, in order to solve such a problem, a liquid crystal display (COA) structure having a color filter on array (COA) structure is proposed.

2 is an enlarged cross-sectional view schematically illustrating a configuration of a liquid crystal display device having a COA structure according to a first example of the related art.

As shown in the drawings, a conventional array substrate for a liquid crystal display (LC) having a COA structure has a gate electrode 54, an active layer, an ohmic contact layer 58, 60, and a source electrode (S) on a transparent insulating substrate 50. Although the thin film transistor T including the 62 and the drain electrode 64 is configured and not illustrated, the gate wiring and the data wiring defining the pixel region P by vertically crossing the thin film transistor T vertically. 52,66).

Red, green, and blue color filters (72a, 72b, not shown) and a black matrix (BM) are formed on the entire surface of the substrate 50 including the thin film transistor T, the gate lines, and the data lines 52 and 66. The color filters 72a and 72b are configured to correspond to the pixel region P, and the black matrix BM is configured to correspond to the active layer 58 of the thin film transistor T. .

A transparent pixel electrode 76 in contact with the drain electrode 64 is formed on the red, green, and blue color filters 72a, 72b (not shown).

Since the above-described configuration has a structure in which the color filter is formed in the array substrate, a design in which alignment errors are not required is required unlike in the prior art.

Therefore, it can be said that it is a preferable structure to further secure an opening area.

However, since the above-described structure is a general vertical electric field type structure, a wide viewing angle characteristic is remarkably inferior as it is known. In order to solve this problem, a COA-IPS structure having a common electrode and a pixel electrode formed on the same layer has been proposed.

3 is a cross-sectional view schematically illustrating a configuration of an array substrate of a COA-IPS according to a second example of the related art, and FIG. 4 is a diagram for describing dielectric constant characteristics of a color filter.

As illustrated, a plurality of pixel areas P are defined on the insulating substrate 80, and the thin film transistor T, the color filters 96a to 96c, and the color filter P are formed for each pixel area P. The common electrode 98b and the pixel electrode 98a are uniformly spaced apart from each other on the upper portion 96a to 96c.

The pixel electrode 98a is configured to be connected to the thin film transistor T formed in each pixel region P, and configured to receive signals individually according to the driving of the thin film transistor T, but the common electrode 98b The same common signal is received for the front surface of the liquid crystal panel.

In general, the common voltage applied through the common electrode is a DC voltage of about 5V.

In this case, the thin film transistor T includes a gate electrode 84, an active layer, and an ohmic contact layer 88a and 88b, a source electrode 90, and a drain electrode 92. One side and the other side of the pixel region P include a gate line 82 in contact with the gate electrode 84 and a data line 94 in contact with the source electrode 90.

The color filters 96a, 96b, and 96c are formed on the substrate 100 including the thin film transistor T, the gate lines, and the data lines 82 and 94, and the common electrode 98b and the pixel electrode 98a. Is formed on top of the color filters 96a, 96b and 96c.

In this case, the color filters 96a, 96b, and 96c are stripe types in which color filters of the same color are formed in the adjacent pixel areas P.

In the above-described configuration, the color filters 96a, 96b, and 96c are generally formed of pigment dispersed color resists, and are coated with a photosensitive material in which pigments are dispersed and manufactured through a photolithography process.

At this time, the pigment is used as a colorant of the color filter and excellent in light resistance heat resistance, and at the same time helps to simplify the manufacturing process of the color filter relatively.

Specifically, the color filters 96a to 96c are red, green, and blue color filters 96a to 96c in which red, green, and blue pigments are dispersed, and the thickness of the green color filter 96a is shown in FIG. The thickness was made to uniformly match the color purity of the green color filter 96a with the red and blue color purity.

The COA-IPS structure configured as described above not only can realize a wide viewing angle, but also has an advantage of further securing an opening area, but there is a problem that a band stain occurs for each color filter.

In detail, as illustrated in FIG. 4, in the case of the transverse electric field structure in which the common electrode 98b and the pixel electrode 98a are simultaneously disposed on the color filter, the two electrodes 98a and 98b are generated. The flow of the electric field is influenced by the dielectric constant value of the liquid crystal at the top and the dielectric constant value of the color filter at the bottom.

Accordingly, a first capacitor C _LC is generated by the two electrodes and the liquid crystal, and a second capacitor C _CR , C _CG , C _CB is generated by the two electrodes and each color fill.

However, the first capacitor C _LC has a uniform value with respect to the entire surface of the liquid crystal panel, but the second capacitors C _CR , C _CG , and C _CB appear differently for each color filter.

This is because the dielectric constant value (ε = 5 ㅁ 1) of the green color filter is different from the dielectric constant value (ε = 4 ㅁ 1) of the blue or red color filter.

As a result, the electric field response dielectric characteristics of the red, green, and blue pixels according to the IPS driving voltage are not uniform, so that the refresh of charges induced in the dielectric (color filter) may not proceed smoothly.

As a result, band unevenness occurs due to afterimages or red, green, and blue colors, thereby degrading the image quality of the liquid crystal panel.

The present invention has been proposed for the purpose of solving the above problems,

It is an object of the present invention to propose a transverse electric field type liquid crystal display device which realizes a uniform image quality by proposing a refresh structure for each color considering the difference in dielectric constant values of the red, green, and blue color filters.

An array substrate for a transverse electric field type liquid crystal display device according to the present invention for achieving the above object is a substrate; A plurality of gate wires extending in one direction on the substrate; A plurality of data lines defining a plurality of pixel regions crossing the plurality of gate lines; A thin film transistor configured at each intersection point of the plurality of gate lines and data lines; Red, green, and blue color filters sequentially formed in the plurality of pixel areas; First, second, and third common wirings arranged in parallel with the gate wirings and configured to be applied to pixels corresponding to the red, green, and blue color filters, and to have different common voltages; And a common electrode disposed on the color filter, the common electrode spaced apart from the pixel electrode, and in contact with the first, second, and third common lines.

The first, second, and third common wires may be connected to different common power sources.

The thin film transistor includes a gate electrode connected to the gate wiring, an active layer formed on the gate electrode, and a source electrode and a drain electrode spaced apart from the upper portion of the active layer.

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A storage capacitor is further configured in parallel with the gate wiring, and an extension portion is further configured from the drain electrode to the storage wiring, so that the storage wiring is a first electrode and the extension portion of the drain electrode is a second electrode. Characterized in that further configured.

The first, second, and third common wires may be connected to the common electrode, respectively, to uniformly correct a difference in pixel voltage according to dielectric constant values of the red, green, and blue color filters. Therefore, a separate common voltage is applied.

According to another aspect of the present invention, an array substrate for a transverse electric field type liquid crystal display device includes a substrate; A plurality of gate wires extending in one direction on the substrate; A plurality of data lines defining a plurality of pixel regions crossing the plurality of gate lines; A thin film transistor configured at each intersection point of the plurality of gate lines and the plurality of data lines; Red, green, and blue color filters sequentially formed in the plurality of pixel areas; First common wirings arranged in parallel with the gate wirings, the green color filters configured in corresponding pixels, and second common wirings configured in the red and blue pixels; It includes a common electrode and a pixel electrode formed on the color filter.

The first and second common wires may be connected to different common power sources.

The storage wiring is further configured in parallel with the gate wiring.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

- Example -

An embodiment of the present invention is characterized by configuring a common electrode connected to a separate power supply to a pixel corresponding to the red, green, and blue color filters.

5 is a plan view showing a part of an equivalent circuit of the transverse electric field type liquid crystal display device according to the first embodiment of the present invention.

As illustrated, a plurality of gate lines G1 to Gn and one or more gate lines G1 to Gn intersect with one surface of the substrate 110 to define the pixel region P to cross the gate lines G1 to Gn. The data wirings D1 to Dn are formed.

The pixel region P includes a liquid crystal capacitor C _LC and a storage capacitor C _ST connected in parallel thereto.

In this case, a color filter is configured correspondingly to each pixel area P. As shown in FIG. 2, a stripe having the same color filter (red, green, blue) is positioned with respect to neighboring pixel areas P. It consists of a stripe type.

In the above configuration, the liquid crystal capacitor Clc receives a common voltage and a data voltage from the common wires 108a, 108b, and 108c and the data wires D1 to Dn, respectively, and the storage capacitor Cst receives the data. The data voltage and the storage voltage are received from the wirings D1 to Dn and the storage wiring 106, respectively.

In this case, the common voltage input from the common wirings 108a, 108b, and 108c is a DC voltage, and is a reference voltage of a data signal input through the data wiring and inversion driving.

The pixel voltage has inversion driving (AC driving) with positive polarity and negative polarity based on the common voltage.

Since the storage capacitor value C _ST is constant with respect to the front surface of the liquid crystal panel, the storage voltage applied to the front surface of the liquid crystal panel is constant for each pixel region P. As shown in FIG. The structure in which the storage wiring 106 is integrally formed can be formed.

On the other hand, in the pixel area P corresponding to the red color filter 130a, the green color filter 130b, and the blue color filter 130c, the first to third common wires connected to a separate common power source (not shown) ( 108a, 108b, 108c.

Different common voltages are applied to the pixel areas P connected to the first to third common wires 108a, 108b, and 108c to compensate for differences in pixel voltages due to differences in dielectric constant values for each color.

That is, when inversion driving is performed based on the same common voltage in a situation where a difference occurs in the pixel voltage, a nonuniformity is generated between the positive and negative polarities, and thus a difference occurs in the pixel voltage applied between the pixel regions. The same band stains will occur.

However, if the level of the common voltage is applied differently according to the change of the pixel voltage, the above problem can be prevented.

The structure of the array substrate corresponding to the unit pixel of the liquid crystal display device configured as described above can be designed as shown in FIG.

6 is an enlarged plan view of a unit pixel of an array substrate for a transverse electric field type liquid crystal display device.

As illustrated, the array substrate for a transverse electric field type liquid crystal display device has a gate line 102 extending in one direction on the substrate 100, and a pixel region P intersecting with the gate line 102 to define the pixel region P. As shown in FIG. A data line 120 and a gate electrode 102 and an intersection of the data line 120 and a gate electrode 104, an active layer 112, a source electrode 118, and a drain electrode 118. The thin film transistor T is configured.

At this time, the storage wiring 106 is formed close to the gate wiring 102, and the common wiring 108 is formed in a region spaced in parallel with the storage wiring 106.

The red color filter (130a of FIG. 5), the green color filter 130b, and the blue color filter (130c of FIG. 5) are formed in each pixel region P in which the gate line 102, the data line, and the thin film transistors 120 and T are formed. ) Sequentially.

Pixel electrodes 132a and 132b and common electrodes 134a and 134b are spaced apart from each other on the color filters 130a to 130c of FIG. 5, and the pixel electrodes 132a and 132b are the drain electrodes 118. Contact with the first horizontal portion 132a extending above the storage wiring 106 and the plurality of first vertical portions 132b vertically extending from the first horizontal portion 132a to the pixel region P. The common electrodes 134a and 134b may include a second horizontal portion 134a in contact with the common wiring 106 and a first horizontal portion 132a of the pixel electrode in the second horizontal portion 134a. And a plurality of second vertical portions 134b extending therebetween.

In this case, the common wire 102 connected to the common electrodes 134a and 134b is connected to different power sources for each pixel corresponding to the red, green, and blue color filters (not shown, 130b, not shown), and the colors are different from each other. Different levels of common voltage are applied.

As described above, the difference in the pixel voltage due to the dielectric constant value different for each color can be corrected for each pixel corresponding to each color, thereby providing a uniform image quality.

-Second Embodiment--

7 is a plan view illustrating some equivalent circuits of a transverse electric field type liquid crystal display device according to a second exemplary embodiment of the present invention.

As illustrated, the transverse electric field type liquid crystal display device according to the present invention crosses a plurality of gate lines G1 to Gn configured to be spaced apart in one direction, and intersects the pixel region P by crossing the gate lines G1 to Gn. A plurality of data lines D1 to Dn are defined and configured.

The liquid crystal capacitor C _LC and the storage capacitor C _ST , which is an auxiliary capacitor, are connected to the pixel region P in parallel.

In this case, color filters 230a to 230c are configured to correspond to each pixel area P. As illustrated, the same color filters 230a to 230c are positioned with respect to the pixel areas P adjacent to each other. The stripe pattern is formed into a stripe shape.

Since the storage capacitor value is constant with respect to the front surface of the liquid crystal panel, the storage voltage applied to the front surface of the liquid crystal panel is constant for each pixel region P, which, as shown, integrates the storage electrode with respect to the front surface of the liquid crystal panel. It is possible to form a structure.

On the other hand, in the pixel areas corresponding to the red color filter 230a, the green color filter 230b, and the blue color filter 230c, first and second common wirings 208a and 208b connected to a separate common power source are formed.

In detail, the red and blue color filters 230a and 230c form a first common line 208a connected to a first common power source (not shown), and the pixel region P corresponding to the green color filter 230b. ) Configures a second common wire 208b connected to a second common power source (not shown).

Unlike the first exemplary embodiment, the same common voltage may be applied to the pixel region P corresponding to the red and blue color filters 230a and 230c having a small difference in dielectric constant.

Therefore, when the array substrate is designed according to the first and second embodiments of the present invention, in the configuration of the array substrate having the common electrode and the pixel electrode formed on the color filters 230a to 230c, the pixel voltage is low. Since the green and blue color filters are not affected by the difference in dielectric constant values, in particular, a uniform image quality can be realized.

Since the COA-IPS structure according to the present invention manufactured as described above is not affected by the difference in the dielectric constant values of the red, green, and blue color filters, in particular, a uniform image quality can be realized.

Claims (12)

A substrate; A plurality of gate wires extending in one direction on the substrate; A plurality of data lines defining a plurality of pixel regions crossing the plurality of gate lines; A thin film transistor configured at each intersection point of the plurality of gate lines and data lines; Red, green, and blue color filters sequentially formed in the plurality of pixel areas; First, second, and third common wirings arranged in parallel with the gate wirings and configured to be applied to pixels corresponding to the red, green, and blue color filters, and to have different common voltages;  A pixel electrode disposed on the color filter and a common electrode spaced apart from the pixel electrode and in contact with the first, second, and third common wires And a plurality of pixel electrodes formed on the substrate. The method of claim 1, And said first, said second and said third common wirings are connected to different common power sources. delete The method of claim 1, And the thin film transistor includes a gate electrode connected to the gate wiring, an active layer formed on the gate electrode, and a source electrode and a drain electrode spaced apart from the active layer. 5. The method of claim 4, A storage capacitor is further configured in parallel with the gate wiring, and an extension portion is further configured from the drain electrode to the storage wiring, so that the storage wiring is a first electrode and the extension portion of the drain electrode is a second electrode. An array substrate for a transverse electric field type liquid crystal display device further comprises. The method of claim 1, The first, the second and the third common wires are connected to the common electrode, respectively, to uniformly correct the difference in pixel voltage according to the dielectric constant values of the red, green, and blue color filters. And a separate common voltage is applied to the array substrate for a transverse electric field type liquid crystal display device. A substrate; A plurality of gate wires extending in one direction on the substrate; A plurality of data lines defining a plurality of pixel regions crossing the plurality of gate lines; A thin film transistor configured at each intersection point of the plurality of gate lines and the plurality of data lines; Red, green, and blue color filters sequentially formed in the plurality of pixel areas; First common wirings arranged in parallel with the gate wirings, the green color filters configured in corresponding pixels, and second common wirings configured in the red and blue pixels; The common electrode and the pixel electrode formed on the color filter And a plurality of pixel electrodes formed on the substrate. The method of claim 7, wherein And the first and second common lines are connected to different common power sources. delete The method of claim 7, wherein And the thin film transistor includes a gate electrode connected to the gate wiring, an active layer formed on the gate electrode, and a source electrode and a drain electrode spaced apart from the active layer. 11. The method of claim 10, The storage wiring is further configured in parallel with the gate wiring, and an extension portion is further configured from the drain electrode to the storage wiring, so that the storage wiring is a first electrode, and the extension portion of the drain electrode is a second electrode. An array substrate for a transverse electric field type liquid crystal display device further comprising a storage capacitor having an insulating film interposed between the first and second electrodes as a dielectric. The method of claim 7, wherein The first and second common wires are respectively connected to the common electrode, and separately common to each color filter so as to uniformly correct a difference in pixel voltage according to dielectric constant values of the red, green, and blue color filters. An array substrate for a transverse electric field type liquid crystal display device, characterized in that a voltage is applied.

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