KR20050096368A - Lcd and method for manufacturing lcd - Google Patents

Abstract

The present invention discloses a liquid crystal display device and a method of manufacturing the same that can improve the brightness of the liquid crystal display device and simplify the manufacturing process of the color filter substrate. The present invention disclosed is a substrate; A white color filter layer formed of a red, green, and blue color filter layers and transparent metals alternately formed on the substrate; A black matrix disposed between the color filter layers to block light leakage; And a common electrode disposed on the substrate on which the respective color filter layers are formed, and serving as the white color filter layer.

Here, the white color filter layer includes an overcoat layer and a common electrode, and a cell gap of the white color filter layer region is greater than a cell gap of the red, green and blue color filter layer regions, and the white color filter layer region and the red, green and blue layers. The gamma voltage applied to the white color filter region to compensate for the cell gap difference of the color filter layer region is different from the gamma voltage applied to the red, green, and blue color filter layers.

Description

Liquid crystal display and its manufacturing method {LCD AND METHOD FOR MANUFACTURING LCD}

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 and a method of manufacturing the same, which improve luminance of a liquid crystal display device and simplify a manufacturing process of a color filter substrate.

In general, as the modern society changes to the information socialization, the importance of the liquid crystal display module, which is one of the information display devices, is gradually increasing. The CRT (Cathode Ray Tube), which is widely used so far, has many advantages in terms of performance and cost, but has many disadvantages in terms of miniaturization or portability.

On the other hand, although the LCD is somewhat expensive in terms of price, it has advantages such as miniaturization, light weight, thinness, low power, and consumption, and thus has been attracting attention as an alternative means to overcome the disadvantages of the CRT.

The liquid crystal display device has a structure in which an array substrate on which thin film transistors are arranged, and a color filter substrate on which red, green, and blue color filter layers are formed are bonded to each other with a liquid crystal interposed therebetween.

Liquid crystal displays are one of the fastest growing flat panel display devices and are expected to lead the display device market in the future. For high quality and high contrast display of the liquid crystal display, a black matrix (BM: Black Matrix) having excellent light blocking property among the pixels of the red (R), green (G), and blue (B) color filters Formation is necessary.

In particular, in the case of an active matrix driving type TFT-LCD using a thin film transistor, high light shielding property is required. In general, a black matrix is formed on a substrate using a vacuum deposition process, such as chromium (Cr), coated with a photoresist and then patterned using a photolithography method, Chromium is etched along the patterned photosensitive resin.

In general, a method of forming a black matrix using a resin material between color filter layers of red, green, and blue on a color filter substrate may be manufactured by dyeing, printing, pigment dispersion, electrodeposition, or the like, but currently color The filter layer and the black matrix are mainly produced by the pigment dispersion method.

The pigment spraying method for forming the color filter layer of red, green, and blue is composed of a photopolymerizable photosensitive composition such as a photopolymerization initiator, a monomer, a binder, and an organic pigment having a red, green, blue, or similar color. .

In the method for producing a color filter layer formed on the color filter substrate, first, chromium or a synthetic resin is deposited or coated on the substrate, and a photo process is performed to form a black matrix having a lattice structure.

On the substrate on which the black matrix is formed, a photosensitive resin having a red color is applied to the entire region of the substrate and then selectively exposed to form a red color filter layer in a desired region.

Then, a photosensitive resin having a green color is applied on the entire area of the substrate on which the red color filter layer is formed, and selectively exposed to light to form a green color filter layer in a desired area.

Subsequently, a photosensitive resin having a blue color is applied to all regions of the substrate on which the red color filter layer and the green color filter layer are formed, and are selectively exposed to form a blue color filter layer.

When the color filter layer is formed as described above, in the case of a liquid crystal display having a twist nematic (TN) or vertical alignment (VA) mode, a transparent electrode is formed on the color filter layer to complete the color filter substrate.

1 is a plan view schematically illustrating a pixel structure of a liquid crystal display according to the related art.

As illustrated in FIG. 1, an array substrate of a liquid crystal display device such as a twist nematic (TN) mode or a vertical alignment (VA) mode includes a gate bus line 20 and a plurality of data bus lines 10 vertically arranged in a cross. The pixel region is defined by.

On the pixel region, a pixel electrode 15 formed of an ITO transparent metal is disposed in a direction parallel to the data bus line 10.

In addition, a thin film transistor, which is a switching element, is disposed in an area where the data bus line 10 and the gate bus line 20 are vertically arranged to be transferred through the data bus line 10. It transmits a data signal to the pixel electrode 15.

In this case, the thin film transistor TFT is turned on by a scan or gate signal applied to the gate bus line 20.

In FIG. 1, R, G, and B displayed on the pixel electrode 15 represent red, green, and blue color filters, and the color corresponds to the pixel electrode 15. R, G, B color filters are formed on the filter substrate in the form of a matrix.

 2 is a cross-sectional view showing the structure of a liquid crystal display device completed according to the prior art.

As shown in FIG. 2, the lower substrate 30a on which the pixel electrode 18 is formed and the upper substrate 30b on which the color filter layers 25a, 25b, and 25c are formed are bonded to each other with the liquid crystal layer 50 interposed therebetween. Is doing.

Pixel electrodes 18 are formed on the unit pixel region formed by vertically crossing the data bus line 10 and the gate bus line on the lower substrate 30a.

In addition, R, G, and B color filter layers 25a, 25b, and 25c are disposed on the upper substrate so as to correspond to the pixel electrodes 18 so as to correspond 1: 1 with the pixel electrodes 18. .

In the TN mode and the VA mode, unlike the IPS mode (In Plane Switching), the common electrode 22 is formed on the upper substrate 30b, and the pixel electrode 18 and the common electrode formed on the lower substrate 30a By displacing the liquid crystal by the electric field generated between 22), the light transmittance is adjusted.

Therefore, as shown in the drawing, the common electrode 22 made of a transparent metal is formed on the color filter layers 25a, 25b, and 25c of the upper substrate 30b.

In addition, a black matrix 27 (blocking layer) made of chromium metal is formed between the color filter layers 25a, 25b, and 25c formed on the upper substrate 30b to block light transmitted from the lower substrate 30a. Formed.

The black matrix 27 has an advantage of increasing the color clarity between the R, G, and B color filter layers 25a, 25b, and 25c to enhance the displayed image quality.

In addition, in order to improve image quality, it is important to keep cell gaps A and B constant between the upper substrate 30b and the lower substrate 30a. The upper substrate 30b and the lower substrate 30a are important. In order to maintain the cell gap, the spacer balls are spread on the upper or lower substrate and then bonded.

In the liquid crystal display fabricated as described above, the sal gap difference between each of the R, G, and B color filter layers 25a, 25b, and 25c is maintained within a maximum of 0.5 μm.

 However, in the liquid crystal display device having the above structure, the R, G, and B color filter layers are partitioned in advance, and the transmittance of the light transmitted through each color filter layer is predetermined according to the transmittance curve.

Due to the characteristics of the liquid crystal display device, there is a problem in that performance of implementing bright colors (high luminance) is inferior to that of CRTs.

In other words, in the case of the CRT, bright colors having high luminance can be realized in all areas to be displayed by freely moving the position irradiated to the electron beam, but in the liquid crystal display device, all the areas partitioned in the form of a matrix are the same to implement bright colors. It's hard to do.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device that can realize a high luminance color by forming a filter layer capable of implementing white on a upper substrate of a liquid crystal display device using a common electrode metal.

In addition, by using a white filter layer formed on the upper substrate as a common electrode, another object of the present invention is to provide a method for manufacturing a liquid crystal display device that can simplify the manufacturing process of the color filter substrate having an RGBW structure.

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

Board;

A white color filter layer formed of a red, green, and blue color filter layers and transparent metals alternately formed on the substrate;

A black matrix disposed between the color filter layers to block light leakage; And

And a common electrode disposed on the substrate on which each color filter layer is formed, and serving as the white color filter layer.

Here, the white color filter layer includes an overcoat layer and a common electrode, and a cell gap of the white color filter layer region is greater than a cell gap of the red, green and blue color filter layer regions, and the white color filter layer region and the red, green and blue layers. The gamma voltage applied to the white color filter region to compensate for the cell gap difference of the color filter layer region is different from the gamma voltage applied to the red, green, and blue color filter layers.

In addition, the white color filter layer is formed of a common electrode metal between the black matrix, and has a high transmittance. The white color filter layer generates a gamma voltage voltage independently of the gamma voltage applied to the red, green, and blue color filter layers. It is characterized by driving.

The white color filter layer and the red, green, and blue color filter layers may be driven by a gamma voltage generated from the same gamma voltage generator.

In the liquid crystal display device manufacturing method according to the present invention,

Forming a black matrix on the transparent insulating substrate for light blocking;

Sequentially applying red, green and blue color resins on the substrate on which the black matrix is formed, and exposing and developing the red, green and blue color filter layers; And

And depositing and etching a transparent metal on the substrate on which the red, green, and blue color filter layers are formed, and simultaneously forming a white color filter layer and a common electrode.

The method may further include forming an overcoat layer for planarization on the substrate on which the red, green, and blue color filter layers are formed, wherein the white color filter layer is formed of an overcoat layer and a common electrode.

According to the present invention, by forming a filter layer capable of implementing white on the upper substrate of the liquid crystal display using a common electrode metal, high luminance color can be realized.

By using the white filter layer formed on the upper substrate as a common electrode, the manufacturing process of the color filter substrate having the RGBW structure can be simplified.

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

3 and 4 illustrate pixel structures of a liquid crystal display manufactured according to the present invention.

As illustrated in FIG. 3, a white electrode is further disposed on the lower substrate to correspond to the white color filter layer formed on the upper substrate in order to improve the low luminance characteristic of the conventional LCD.

Therefore, in the lower substrate used in the liquid crystal display of the present invention, the plurality of gate bus lines 102 and the plurality of data bus lines 100 are vertically arranged to define a unit pixel area.

The pixel electrode 105 formed of ITO metal is disposed in the direction parallel to the data bus line 100 on the unit pixel area.

In addition, a thin film transistor (TFT), which is a switching element, is disposed in an area where the data bus line 100 and the gate bus line 102 vertically cross each other, and thus a data signal transmitted through the data bus line 100. To the pixel electrode 105.

In this case, the thin film transistor TFT is turned on by a driving signal applied to the gate bus line 102.

R, G, B, and W displayed on the pixel electrode 105 represent red, green, blue, and white color filter layers, and correspond to the pixel electrode 105. Preferably, R, G, B, and W color filter layers are formed on the upper substrate in a matrix form.

4 illustrates a pixel electrode corresponding to white to have a structure different from that of FIG. 3.

By forming a gate bus line 120 to be additionally divided between the gate bus lines 120 formed on the lower substrate, the pixel electrode is divided into two units based on a unit pixel.

That is, although the unit pixel region defined by the plurality of gate bus lines 120 and the data bus lines 110 are vertically intersected and arranged is reduced to half of FIG. 3, R, G, B, and W are in the same unit pixel space. Since all of the pixel electrodes corresponding to are disposed, the amount of luminance transmitted per unit pixel as a whole increases.

Although the pixel structure illustrated in FIG. 4 is different from the pixel structure illustrated in FIG. 3, the manufacturing process may be performed by going through the same process.

In the present invention, the technique using the common electrode as the white filter layer may be applied to both of FIGS. 3 and 4 in order to realize high luminance of the liquid crystal display having the RGBW four-color filter layer.

Hereinafter, a color filter layer and a liquid crystal display device corresponding to the pixel structure of FIG. 3 will be described as an example.

5A to 5D illustrate a color filter substrate corresponding to the pixel structure of the present invention.

As illustrated in FIG. 5A, an opaque metal having a low reflection property such as chromium (Cr) is deposited and patterned on the upper substrate 200, or a photosensitive black resin is coated and then exposed and etched to form a black matrix 201. ).

When chromium metal is used as the material of the black matrix 201, since chromium metal is a heavy metal material, serious environmental pollution may be caused, and thus patterning may be performed using a non-heavy metal or a synthetic resin-based material.

 When the black matrix 201 is formed on the upper substrate 200 as described above, as illustrated in FIG. 5B, an R (Red) color filter layer 210a is formed.

That is, a red (R) color resin is coated on the upper substrate 200, and exposed and developed to form a color filter layer 210a.

As shown, the red (R) color filter layer 210a is formed in the unit pixel space of the black matrix 201 formed on the upper substrate 200, and is formed in the unit pixel space of the lower substrate. It is preferable that the pixel electrode is formed so as to be opposite to each other.

When the red color filter layer 210a is formed as described above, as shown in FIG. 5C, the green color filter layer 210b and the blue color filter layer 210c are formed. G) After applying the color resin and the blue (B) color resin, the exposure and development processes are performed to form a filter layer.

When the red, green, and blue color filter layers 210a, 210b, and 210c are sequentially formed on the upper substrate 200 as described above, an overcoat layer (not shown) is formed for the planarization process, and then shown in FIG. 5D. As described above, a conductive transparent metal is deposited to form the white color filter layer 210d and the common electrode 220.

When the transparent metal is deposited on the upper substrate 200, a transparent metal is deposited on a space of the black matrix 201 where the color filter layers 210a, 210b, and 210c are not formed, thereby forming a white color filter layer. 210d is formed.

The white (W) color filter layer 210d not only serves as a color filter layer itself but also serves as a common electrode 220.

In this case, an overcoat layer (not shown) applied between the common electrode 220 serving as the white (W) color filter layer 210d and the upper substrate 200 is removed or is common on the overcoat layer. The electrode 220 may be formed.

As described above, in the present invention, unlike the other red (R), green (G), and blue (B) color filter layers 210a, 210b, and 210c, the color filter layer does not exist in the white (W) color filter layer 210d. The light propagated through the liquid crystal layer from the lower substrate may be transmitted without loss, thereby increasing the luminance.

In addition, since the color filter layer manufacturing process does not have to be performed in order to form the white color filter layer 210d, the production process is simplified and manufacturing cost can be reduced.

6 is a cross-sectional view showing the structure of a liquid crystal display according to the present invention.

As shown in FIG. 6, the lower substrate 300 on which the pixel electrode 301 is formed so as to correspond to the R, G, B, and W pixel regions, and the R, G, B, and W color filter layers 210a, 210b, 210c, and 210d. ) Is formed on the upper substrate 200 and is bonded to each other with the liquid crystal layer 250 interposed therebetween.

The pixel electrodes 301 are formed on the lower substrate 300 on the unit pixel region formed by vertically intersecting a data bus line 305 and a gate bus line (not shown).

R, G, B, and W color filter layers 210a, 210b, 210c, and 210d correspond to the pixel electrodes 301 on the upper substrate 200 so as to correspond to the pixel electrodes 301. It is formed to be.

In the present invention, the W (white) color filter layer 210d as well as the RGB color filter layers 210a, 210b, and 210c are further formed on the upper substrate 200 in order to improve the low luminance characteristics of the conventional TN and VA modes. .

Since the W color filter layer 210d is formed of the same transparent metal as the common electrode 220, the W color filter layer 210d serves as the common electrode 220 and serves as the W color filter layer 210d.

Therefore, R, G, B, and W color filter layers 210a, 210b, 210c, and 210d are alternately disposed between the black matrix 201 (blocking layer) on the upper substrate 200, and the R, G, B, The W color filter layers 210a, 210b, 210c, and 210d correspond to the pixel electrodes 301 formed on the lower substrate 300, respectively.

As shown in the figure, since the W color filter layer 210d is replaced by the common electrode 220 between the R, G, and B color filter layers 210a, 210b, and 210c, the luminance characteristic per pixel is improved. You can.

Particularly, in the present invention, the W color filter layer 210d is formed together when the transparent common electrode 220 is formed instead of the transparent resin, thereby obtaining a higher transmittance.

In addition, although the common electrode 220 is formed in the white color filter layer 210d according to the present invention, color characteristics of high luminance can be obtained, but there is a difference in cell gap between the white color filter layer region and the R, G, and B color filter layer regions. Since 0.5 μm or more occurs, a gamma voltage is applied to be independently supplied to the white color filter layer region during driving.

This will be described with reference to FIG. 7.

7 is a view for explaining the transmittance characteristics of the liquid crystal display according to the present invention.

As shown in FIG. 7, the transmittance curve is shown based on the normally white mode or normally black mode used in the TN mode or the VA mode.

D denotes the cell gap of the liquid crystal display device, and Δn denotes the refractive index value of the liquid crystal layer.

1st min and 2nd min represent the first and second minimum transmittances based on the transmittance curves according to the normally black mode.

Since the values of 1st min and 2nd min are the same in normal white, the maximum transmittance is expressed as 1st min in the normal white mode.

Therefore, in the normally white mode, the 1st min value refers to a value corresponding to 100% transmittance for the first time in the transmittance curve, and a value corresponding to 0% transmittance for the first time in normal black mode.

Hereinafter, driving conditions of the liquid crystal display according to the present invention will be described based on the normally white mode, but the same applies to the normally black mode.

According to the present invention, since the W color filter layer of the color filter substrate is formed of a common electrode without using a separate color filter material, the cell gap is larger than that of other R, G, and B color filter layers.

Therefore, based on the curve of the transmittance from 0 to the first transmittance of 100% in FIG. 7, since the d value of the white color filter layer is large, the u value is large, resulting in R, G, B, and W color filter layers. When the same gamma voltage is applied, the transmittance of the W color filter layer is always higher.

This causes a problem in that the image quality is deteriorated because the luminance is higher than that of the R, G, and B color filter layers in the W color filter layer at all times even when displaying a high luminance image or when displaying a dark image.

Therefore, an optimum image can be displayed by applying a gamma voltage independent of the gamma voltages applied to R, G, and B to the W color filter layer.

In other words, based on the normal white mode curve, the transmittance curve up to the 1 min point remains linear, so that the system maintains stabilization and displays an image with improved luminance in the R, G, and B color filter layers. A gamma voltage suitable for the W color filter layer different from the applied gamma voltage should be applied.

In addition, in a system in which the liquid crystal display device can be safely driven even in a curve exceeding 1st min, it is positioned between the 1st min point and the 2nd min point only for the W color filter layer, and also has the same points as the R, G, and B transmittances. If set (adjust the d value and Δn value), the image can be displayed with the existing gamma voltage without having a separate gamma voltage generator.

As described above, in the present invention, the white color filter layer is simultaneously formed at the time of forming the common electrode, thereby improving the transmittance of the white color filter layer to obtain a high luminance value.

As described in detail above, the present invention has an advantage of realizing a color having high luminance by forming a filter layer capable of implementing white on the upper substrate of the liquid crystal display using a common electrode metal.

And by using the white filter layer formed on the upper substrate as a common electrode, there is an effect that can simplify the manufacturing process of the color filter substrate having an RGBW structure.

The present invention is not limited to the above-described embodiments, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the following claims.

1 is a plan view schematically illustrating a liquid crystal display pixel structure according to the related art.

2 is a cross-sectional view showing the structure of a liquid crystal display device completed according to the prior art.

3 and 4 illustrate pixel structures of a liquid crystal display device manufactured according to the present invention.

5A to 5D illustrate a color filter substrate corresponding to the pixel structure of the present invention.

6 is a cross-sectional view showing the structure of a liquid crystal display device according to the present invention;

7 is a view for explaining the transmittance characteristics of the liquid crystal display device according to the present invention.

* Description of the symbols for the main parts of the drawings *

200: upper substrate 201: black matrix (blocking layer)

210a: red color filter layer 210b: green color filter layer

210c: blue color filter layer 210d: white color filter layer

220: common electrode 250: liquid crystal layer

300: lower substrate 301: pixel electrode

305: data bus line

Claims (10)

Board; A white color filter layer formed of a red, green, and blue color filter layers and transparent metals alternately formed on the substrate; A black matrix disposed between the color filter layers to block light leakage; And And a common electrode disposed on the substrate on which the respective color filter layers are formed and serving as the white color filter layer. The method of claim 1, And the white color filter layer comprises an overcoat layer and a common electrode. The method of claim 1, And a cell gap of the white color filter layer region is greater than a cell gap of the red, green and blue color filter layer regions. The method according to claim 1 or 3, The gamma voltage applied to the white color filter area to compensate for the cell gap difference between the white color filter layer area and the red, green and blue color filter layer areas is different from the gamma voltage applied to the red, green and blue color filter layers. A liquid crystal display device. The method of claim 1, And the white color filter layer is made of a common electrode metal between the black matrices and has a high transmittance. The method of claim 1, And the gamma voltage voltage is generated and driven independently of the gamma voltage applied to the red, green, and blue color filter layers with respect to the white color filter layer. The method of claim 1, And the white color filter layer and the red, green, and blue color filter layers are driven by a gamma voltage generated from the same gamma voltage generator. Forming a black matrix on the transparent insulating substrate for light blocking; Sequentially applying red, green and blue color resins on the substrate on which the black matrix is formed, and exposing and developing the red, green and blue color filter layers; And And depositing a transparent metal on the substrate on which the red, green, and blue color filter layers are formed, and etching the same to form a white color filter layer and a common electrode simultaneously. The method of claim 8, And forming an overcoat layer for planarization on the substrate on which the red, green, and blue color filter layers are formed. The method according to claim 8 or 9, The white color filter layer is formed of an overcoat layer and a common electrode.