KR20090081135A - Liquid crystal display device - Google Patents

Abstract

A liquid crystal display device is provided to reduce the difference of luminance and a sense of color. The first color filter(220) is arranged on the second substrate, and realizes the first white color by sub-color filters for filtering different specific wavelengths. The second color filter(230) is arranged on the second substrate, is adjacent to the first color filter as having a black matrix between them, and realizes the second white color. An over-coat layer(240) is arranged on the second substrate including the first and second color filters, comprises a flat surface and a color-sense compensating unit. The flat surface corresponds to the first color filter and the color-sense compensating unit corresponds the second color filter.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of improving color and luminance.

Today, liquid crystal display devices (LCDs) are spotlighted as next generation advanced display devices with low power consumption, good portability, technology intensive, and high added value.

The liquid crystal display device includes a liquid crystal panel and a backlight for providing light to the liquid crystal panel. The liquid crystal panel includes a thin film transistor array substrate, a curly filter array substrate, and a liquid crystal layer interposed between the thin film transistor array substrate and the curly filter array substrate.

In order to provide a variety of images, the liquid crystal display device controls the transmittance of light provided from the backlight by applying an electric field to the liquid crystal of the liquid crystal layer.

Here, the liquid crystal display uses 5% of the light provided from the backlight, and since 50% of the light does not pass through the polarizing plate, there is a problem that the light efficiency is small.

Accordingly, in order to increase the efficiency of the light provided from the backlight, the liquid crystal display device has been developed a technology that further includes a white color filter in the red, green, blue color filter.

However, since the first white implemented through the red, green, and blue color filters and the second white implemented through the white color filter have different color temperatures, the color of the liquid crystal display is degraded. there was. This is because the red, green, and blue color filters each have a high or low light transmittance selectively in a specific wavelength range, whereas the white color filter transmits the light provided from the backlight.

In particular, when the subpixel including the white color filter is turned on or off according to the brightness of the surrounding, the liquid crystal display may generate a color difference with respect to the on / off. In order to correct such a color sense, the liquid crystal display device has been developed to further configure a color correction circuit. However, the luminance is not only reduced by the driving of the color correction circuit, but also a circuit is added.

Therefore, although a white color filter is further included to improve the brightness of the conventional liquid crystal display device, the color of the liquid crystal display device due to the difference in the color temperature of the light passing through the red, green, and blue color filters and the light passing through the white color filter is different. There was a problem of deterioration.

An object of the present invention is to provide a liquid crystal display device that can improve the brightness and color difference.

In order to achieve the above technical problem, an aspect of the present invention provides a liquid crystal display device. The liquid crystal display device may be disposed on the first and second substrates facing each other, the liquid crystal layer interposed between the first and second substrates, the black matrix disposed on the second substrate, and the second substrate. A first color filter implementing a first white color by sub color filters respectively filtering other specific wavelengths, disposed on the second substrate, neighboring the first color filter with the black matrix therebetween, and a second color filter; A second color filter implementing white and a second substrate including the first and second color filters, the flat part corresponding to the first color filter and the second color filter corresponding to the second color filter; And an overcoat layer having a color correcting unit for reducing the color temperature difference between the first and second whites.

The liquid crystal display of the present invention may further include a second color filter for implementing white color in a first color filter including sub color filters for implementing red, green, and blue colors, respectively, to improve brightness. The first cell gap corresponding to the first color filter and the second cell gap corresponding to the second color filter are adjusted to reduce the color temperature difference between the first color filter and the second color filter without the addition of a separate configuration, for example, a color correction circuit. Since it is possible to, the color of the liquid crystal display device can be improved.

In addition, the first and second cell gap control can be easily implemented through the thickness control of the overcoat layer without additional configuration.

In addition, the first and second cell gap control may be easily implemented through the thickness control of the second color filter without additional configuration.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings of the liquid crystal display. The following embodiments are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like numbers refer to like elements throughout.

1 and 2 are diagrams for explaining a liquid crystal display device according to a first embodiment of the present invention.

1 is an enlarged plan view illustrating four subpixels adjacent to each other among a plurality of pixels included in a liquid crystal display according to a first exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II ′ of FIG. 1.

1 and 2, a liquid crystal display according to a first embodiment of the present invention includes a first and second substrates 100 and 200 facing each other and between the first and second substrates 100 and 200. It includes a liquid crystal layer 300 interposed therein.

The first substrate 100 includes a plurality of wires such as a gate wire 101, a data wire 102, a common wire 103, a thin film transistor Tr, a pixel electrode 130, and a common electrode 140. Can be arranged.

In detail, a plurality of gate lines 101 arranged in the first direction are disposed on the first substrate 100. Each end of the plurality of gate wires 101 is electrically connected to a gate pad part (not shown). The gate pad unit applies a gate signal provided from an external driving circuit unit to the gate wiring 101, and the gate wiring 101 applies the gate signal to a thin film transistor Tr, which will be described later, and the thin film transistor Tr. Can be turned on.

The common wiring 103 parallel to the gate wiring 101 is disposed on the first substrate 100.

A plurality of data lines 102 arranged in the second direction crossing the first direction are disposed on the first substrate 100. By the intersection of the plurality of gate lines 101 and the plurality of data lines 102, the first substrate 100 defines a plurality of subpixels. Each end of the plurality of data lines 102 is electrically connected to a data pad unit (not shown). The data pad unit applies a data signal to the data line 102 from an outer driving circuit unit, and the data line 102 applies the data signal to the thin film transistor Tr on which the gate signal is applied. do.

The gate wiring 101 and the data wiring 102 are insulated from each other by the gate insulating film 110 interposed therebetween. The gate insulating layer 110 may be made of silicon oxide or silicon nitride.

Each pixel includes a thin film transistor Tr and a pixel electrode 130 electrically connected to the thin film transistor Tr. The thin film transistor Tr is turned on by the gate signal of the gate line 101 and applies a pixel voltage to the pixel electrode 130 by a data signal applied from the data line 102.

The thin film transistor Tr includes a semiconductor pattern 121 and a semiconductor pattern overlapping the gate electrode 111 with the gate electrode 111 branched from the gate wiring 101, the gate insulating layer 110 interposed therebetween. And a source electrode 141 disposed on 121 and electrically connected to the data line 102 and a drain electrode 141 disposed on the semiconductor pattern 121 and spaced apart from the source electrode 131.

The passivation layer 120 is disposed on the first substrate 100 including the thin film transistor Tr.

The pixel electrode 130 electrically connected to the thin film transistor Tr and the common electrode 140 electrically connected to the common wiring 103 are disposed in each subpixel. The pixel electrode 130 and the common electrode 140 each branch into a plurality and are disposed to cross each other. That is, the pixel electrode 130 and the common electrode 140 are alternately arranged to form a horizontal electric field based on the first substrate 100. As a result, the liquid crystal display may improve the viewing angle. The pixel electrode 130 may be made of a transparent conductive material, for example, ITO or IZO. In addition, the common electrode 140 is made of the same material as the gate electrode 111 and described as being formed on the same layer, but is not limited thereto. That is, the common electrode 140 may be made of the same material as the pixel electrode 130.

Meanwhile, a black matrix 210 is disposed on the second substrate 200 corresponding to the plurality of wires and the thin film transistor Tr to prevent light leakage. That is, the black matrix 210 may have an opening that exposes the second substrate 200 corresponding to an area where the gate line 101 and the data line 102 intersect with each other.

First and second color filters 220 and 230 are respectively disposed on the second substrate 200 to implement the first and second white colors.

The first color filter 220 includes sub color filters 221, 222, and 223 disposed in each subpixel that implements different colors with the black matrix 210 interposed therebetween. The sub color filters 221, 222, and 223 filter different specific wavelengths to implement different colors such as red, green, and blue, respectively. Thus, when the subpixels are driven at the same time, the light passing through the first color filter 220 may display a first white color.

The second color filter 230 is adjacent to the first color filter 220 with the black matrix 210 interposed therebetween. The light provided from the backlight may pass through the second color filter 230 as it is to display the second white color. As a result, the second white has a color temperature larger than that of the first white, resulting in a color difference, resulting in a deterioration in image quality characteristics of the liquid crystal display.

In order to reduce the color temperature difference between the first and the second white, the flat part 240a and the color compensating part 240b on the second substrate 200 including the first and second color filters 220 and 230. An overcoat layer 240 having a is disposed. The overcoat layer 240 may be made of a material capable of transmitting light, for example, an acrylic resin or an imide resin.

The color correction unit 240b lowers the color temperature of the second white and serves to reduce the color temperature difference with the first white.

In order to lower the color temperature of the second white, the color correction unit 240b may have a height D2 of the surface of the color correction unit 240b based on the second substrate 200. It may be smaller than the height (D1). That is, the color correction unit 240b has a smaller step than the flat part 240a. As a result, the second cell gap Cp2 corresponding to the second color filter 230 may be increased compared to the first cell gap Cp1 corresponding to the first color filter 220. The color temperature of the second white color may be reduced compared to the color temperature.

3 is a graph showing a change in transmittance according to transmittance according to a cell gap of a liquid crystal display.

Referring to FIG. 3, when the cell gap of the liquid crystal display device is large, the transmittance of light having a long wavelength, for example, 500 nm or more increases. On the other hand, when the cell gap of the liquid crystal display device is small, the light transmittance becomes large at short wavelengths, for example, 500 nm or less. That is, it can be seen that the light transmittance of the cell gap of the liquid crystal display is changed according to the size of the wavelength. As a result, the color temperature may be adjusted according to the cell gap of the liquid crystal display.

1 and 2, when the second cell gap Cp2 is formed larger than the first cell gap Cp1, the light transmittance of the long wavelength passing through the second color filter 230 is increased. As a result, the light transmittance of the short wavelength is reduced. As a result, the color temperature passing through the second color filter 230 may be lowered. This is because the length of the wavelength is inversely proportional to the color temperature.

In this case, the difference between the color temperature of the first and the second white is within a difference of ± 1000 K, which is not recognizable by the user. And the difference between the second cell gaps Cp1 and Cp2 may be 0.2 to 1.5 μm.

The second color filter 240 and the overcoat layer 240 may be integrally formed. That is, the second color filter 240 and the overcoat layer 240 are formed by coating a composition for forming the overcoat layer 240 on the second substrate 200 on which the first color filter 240 is formed. Can be. At this time, the coating process of the overcoat layer 240, for example, by adjusting the coating thickness, it is possible to form the overcoat layer 240 having a flat portion 240a having a different height and the color correction portion 240b. That is, the second color filter 230, the flat part 240a, and the color compensating part 240b may be integrally formed.

Therefore, in the first embodiment of the present invention, the red, green, blue, and white color filters are provided, whereby the luminance of the liquid crystal display device can be improved.

At the same time, the color sense correction unit capable of reducing the color temperature difference between the white by the red, green, and blue color filters and the white by the white color filter can be improved, thereby improving the color of the liquid crystal display.

In addition, when the overcoat layer is formed, the color compensator and the white color filter may be formed, so that a separate process may not be added to improve the brightness and the color of the liquid crystal display.

In addition, the liquid crystal display device in the first embodiment of the present invention has been described with reference to the IPS mode, but is not limited thereto.

In addition, in the first exemplary embodiment of the present invention, the liquid crystal display device has been described as horizontally arranged red, green, blue, and white sub-color filters, but the present invention is not limited thereto and may be arranged in various forms.

4 is a cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention. Since the second embodiment of the present invention has the same configuration as the first embodiment described above except for the second color filter, the repeated description of the first embodiment will be omitted for convenience of description, and the same configuration is the same. Reference numerals will be given.

4, the first and second substrates 100 and 400 facing each other and the liquid crystal layer 300 interposed between the first and second substrates 100 and 400 are included.

A plurality of wires, a thin film transistor (Tr), a pixel electrode 130 and a common electrode 140 are disposed on the first substrate 200.

The black matrix 410 and the first and second color filters 420 and 430 are disposed on the second substrate 400.

The first color filter 420 includes sub color filters 421, 422, and 423 that respectively filter different specific wavelengths, and the light passing through the sub color filters 421, 422, and 423 is mixed. The first white color can be displayed.

The light transmitted through the second color filter 420 may display a second white color such as light provided from a backlight.

Accordingly, the first and second white may have different color temperatures. In this case, in order to reduce the color temperature difference between the first and second white, the first cell gap corresponding to the first color filter 420 and the second cell gap corresponding to the second color filter 430 may be adjusted.

Since the color temperature of the first white is lower than that of the second white, the color temperature of the second white may be reduced to reduce the difference between the color temperature of the first white and the color temperature of the second white. At this time, in order to lower the color temperature of the second white, the second cell gap is increased.

In order to increase the second cell gap, the thickness of the second color filter 430 is smaller than the thickness of the first color filter 420, and then the first and second color filters 420 and 430 are formed. An overcoat layer 440 is formed on the second substrate 400. Accordingly, the overcoat layer 440 may include a flat portion 440a corresponding to the first color filter 420 and a color correction unit 440b corresponding to the second color filter 430. In other words, since the thickness of the second color filter 430 is smaller than the thickness of the first color filter 420, the flat part 440a and the color compensating part 440b may have a step D1-D2. As a result, the second cell gap is increased compared to the first cell gap. Accordingly, the color temperature of the second white can be lowered, and thus the difference in color temperature of the first and second white can be reduced.

Here, the step between the color compensator 440b and the flat part 440a may be adjusted according to the thickness of the second color filter 430, so that the difference between the color temperatures of the first and second white may be more easily. Can be reduced.

Table 1 shows optical characteristics according to Comparative Examples and Examples. Here, a comparative example is a liquid crystal display device provided with the overcoat layer which has a flat part. An embodiment is a liquid crystal display device having an overcoat layer having a flat portion and a color correction portion. Here, the step between the flat portion and the color correction portion had 0.3 μm.

In Table 1, the first white is implemented by passing through a first color filter, for example, red, green, and blue color filters. The second white color is implemented through the second color filter, for example, the white color filter. The third white color is implemented through the first and second color filters.

5 is a graph illustrating color temperature and color coordinates of a liquid crystal display according to a comparative example.

6 is a graph illustrating color temperature and color coordinates of the liquid crystal display according to the embodiment.

As shown in Table 1, Figure 5 and Figure 6, compared to the comparative example, when the embodiment, that is, provided with an overcoat layer having a flat portion and the color correction portion, the color temperature difference between the first and second white can be significantly reduced It didn't make a big difference in the color coordinates. In addition, it could be seen that the color temperature difference according to the on / off of the subpixel equipped with the white color filter is also significantly reduced. As a result, by adjusting the first cell gap corresponding to the first color filter and the second cell gap corresponding to the second color filter, the color temperature difference between the first and second whites may be reduced. Accordingly, the color reproducibility of the liquid crystal display device is not affected, and luminance and color are improved simultaneously.

7 is a graph illustrating color temperature differences according to steps between the flat part and the color compensation unit.

Referring to FIG. 7, when the level difference between the flat part and the color compensating part is 0.2 to 1.5 μm, it is confirmed that the color temperature difference between the first and second white color has a range that the user cannot recognize, that is, a range of −1000 K to 1000 K. Could.

Therefore, in the exemplary embodiment of the present invention, in addition to improving luminance in a liquid crystal display device having a red, green, blue, and white color filter without a separate configuration, for example, a color correction circuit unit, color difference due to color temperature difference occurs. You can prevent it.

1 is an enlarged plan view illustrating four subpixels adjacent to each other among a plurality of pixels included in a liquid crystal display according to a first exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II ′ of FIG. 1.

3 is a graph showing a change in transmittance according to transmittance according to a cell gap of a liquid crystal display.

4 is a cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention.

5 is a graph illustrating color temperature and color coordinates of a liquid crystal display according to a comparative example.

6 is a graph illustrating color temperature and color coordinates of the liquid crystal display according to the embodiment.

7 is a graph illustrating color temperature differences according to steps between the flat part and the color compensation unit.

 (Explanation of reference numerals for the main parts of the drawings)

 100 first substrate 110 gate insulating film

 120: protective film 130: pixel electrode

 140: common electrode 200, 400: second substrate

 210, 410: Black matrix 220, 420: First color filter

 230, 430: second color filter 240, 440: overcoat layer

 240a, 440a: flat part 240b, 440b: color correction

 300: liquid crystal layer

Claims (7)

First and second substrates facing each other; A liquid crystal layer interposed between the first and second substrates; A black matrix disposed on the second substrate; A first color filter disposed on the second substrate and implementing first white color by sub color filters respectively filtering different specific wavelengths; A second color filter disposed on the second substrate and adjacent to the first color filter with the black matrix therebetween to implement a second white color; And Disposed on a second substrate including the first and second color filters, the flat part corresponding to the first color filter and the color part corresponding to the second color filter and reducing the difference in color temperature between the first and second white filters; Liquid crystal display comprising an overcoat layer having a color correction unit for. The method of claim 1, And the color compensating part has a smaller step than the flat part based on the second substrate. The method of claim 1, And the level difference between the flat part and the color compensating part is 0.2 to 1.5 mu m. The method of claim 1, And the second color filter and the overcoat layer are integrally formed. The method of claim 1, The thickness of the second color filter is smaller than the thickness of the first color filter. The method of claim 1, The sub color filters implement red, green, and blue colors, respectively, and are disposed with the black matrix interposed therebetween. The method of claim 1, And a first cell gap corresponding to the first color filter is smaller than a second cell gap corresponding to the second color filter.

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