KR20170025728A - Liquid crystal display panel and liquid crystal display device having the same - Google Patents

Abstract

The present invention relates to a liquid crystal display device for preventing a light leakage and improving a contrast ratio. The liquid crystal display device includes a backlight unit which emits ultraviolet rays and visible rays, pixels composed of R, U, G, and B sub pixels, respectively, and a timing controller which includes a data conversion unit which converts RGB data inputted from the outside to RUGB data. The liquid crystal display device controls the discoloration of a photochromic layer at each pixel area.

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal display panel and a liquid crystal display device having the liquid crystal display panel.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display (LCD), and more particularly, to a liquid crystal display (LCD) panel and a liquid crystal display having the same that can improve light leakage and improve contrast ratio in displaying black image data.

A liquid crystal display (LCD), which is attracting attention as a next-generation display device, generally has no backlight, and displays an image by adjusting the light transmittance of the liquid crystal using an electric field.

The liquid crystal display device has advantages such as lightness, thinness and low power consumption compared with a conventional cathode ray tube (CRT), but has a disadvantage that the viewing angle is narrow.

In order to solve the problem of a narrow viewing angle, a liquid crystal display device of a horizontal electric field (IPS) type in which a pixel electrode and a common electrode are arranged on the same substrate and a horizontal electric field is formed between the electrodes appears.

However, since the electric fields in the liquid crystal are not uniform, the transmissivity of the liquid crystal can not be perfectly controlled, and there is a light leakage problem in which some light leaks when displaying black image data. Also, there is a problem that the contrast of the image is lowered because the light leakage does not completely express the black.

It is an object of the present invention to provide a liquid crystal display panel and a liquid crystal display device having the liquid crystal display panel for solving the light leakage problem and improving the contrast ratio in displaying black image data .

According to an aspect of the present invention, there is provided a liquid crystal display panel including a backlight unit for emitting ultraviolet rays and visible rays, R, G, and B sub-pixels for displaying colors, The unit pixels constituted by U subpixels to be transmitted and the data converter for converting RGB data input from the outside into RUGB data are used to control the color change of the photochromic layer in each unit pixel area .

According to an aspect of the present invention, there is provided a liquid crystal display panel comprising: a lower substrate on which a plurality of gate lines and data lines are arranged to form a thin film transistor array defining a plurality of subpixels; An upper substrate on which a color filter array is formed in which color filter layers are arranged corresponding to the subpixels; A photochromic layer disposed between the upper substrate and the color filter array and discolored when irradiated with ultraviolet light; The LCD includes a liquid crystal layer filled between the upper substrate and the lower substrate. The unit pixel includes a plurality of sub-pixels for displaying hue and a U-sub pixel for transmitting ultraviolet light.

Here, the lower substrate may further include a lower polarizer, and the upper polarizer may further include an upper polarizer between the photochromic layer and the color filter array. And an ultraviolet shielding film for shielding ultraviolet rays of ultraviolet rays.

In addition, the photochromic layer may be configured to be separated from each other for each unit pixel.

According to another aspect of the present invention, there is provided a liquid crystal display device including a lower substrate on which a plurality of gate lines and data lines are arranged to form a thin film transistor array defining a plurality of subpixels, And a photochromic layer disposed between the upper substrate and the color filter array, the photochromic layer discolored when ultraviolet light is irradiated to the color filter array; And a liquid crystal layer filled between the upper substrate and the lower substrate, wherein the unit pixel includes a plurality of sub-pixels for displaying hue and a U-sub pixel for transmitting ultraviolet light; A data driver for supplying a data voltage to the plurality of data lines; A gate driver for supplying a scan pulse to the plurality of gate lines; A timing controller for controlling the data driver and the gate driver; And a backlight unit for emitting ultraviolet rays and visible rays to the liquid crystal display panel.

When the RGB data input from the outside is black, the timing controller sets the data corresponding to the U subpixel to one of 1 to 255, converts the RGB data into RUGB data, and outputs RGB And converting the RGB data into RUGB data by setting the data corresponding to the U subpixel to 0 when the data is not black.

The liquid crystal display panel according to the present invention and the liquid crystal display device having the liquid crystal display panel have the following effects.

That is, when the image data input from the outside is black, the photochromic layer is irradiated with ultraviolet rays to discolor the photochromic layer in the corresponding pixel region, thereby blocking the light leakage and improving the contrast ratio of the black image data.

1 is a cross-sectional view showing the overall structure of a liquid crystal display device according to an embodiment of the present invention.
2 is a cross-sectional view of a unit pixel of a liquid crystal display panel according to an embodiment of the present invention.
3A is an operational state diagram when RGB data input from the outside is not black in the liquid crystal display panel according to the embodiment of the present invention.
FIG. 3B is an operational state diagram when RGB data input from the outside in the liquid crystal display panel according to the embodiment of the present invention is black.
4 is an operational state diagram of four unit pixels adjacent to each other and corresponding photochromic layers according to an embodiment of the present invention.

The liquid crystal display panel according to the present invention having the above-described objects and features and a liquid crystal display device having the same will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a plan view showing the overall structure of a liquid crystal display according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a unit pixel of a liquid crystal display panel according to an embodiment of the present invention.

1, a liquid crystal display according to an embodiment of the present invention includes a liquid crystal display panel 100, a data driver 600, a gate driver 700, a data driver 600, and a gate driver 700 And a backlight unit 500 for emitting ultraviolet rays and visible rays to the liquid crystal display panel.

The liquid crystal display panel 100 includes a lower substrate 110, an upper substrate 120, and a liquid crystal layer 130 filled between the upper and lower substrates 110 and 120.

The lower substrate 110 includes a first substrate 112 and a plurality of data lines DL and a plurality of data lines DL that are arranged on the first substrate 112 to define sub- A thin film transistor array including lines GL and thin film transistors (TFTs) formed on the respective sub pixels 113 and a lower polarizer 111 formed on a lower surface of the first substrate 112 .

The gate electrode of the thin film transistor TFT is connected to the gate line GL and the source electrode of the thin film transistor TFT is connected to the data line DL And the drain electrode of the thin film transistor TFT is connected to the pixel electrode of the liquid crystal cell Clc. Each thin film transistor TFT supplies a data voltage from the data line DL to a pixel electrode of the liquid crystal cell Clc in response to a scan pulse supplied through the gate line GL. The liquid crystal cell Clc displays gradations according to the potential difference between the data voltage supplied to the pixel electrode and the common voltage Vcom. The pixel electrode is provided with a storage capacitor Cst for holding a charged voltage.

The subpixels 113 include R subpixels representing red, G subpixels representing green, B subpixels representing blue, and U subpixels transmitting ultraviolet light, and each of R, G , B, and U subpixels are assembled into one unit pixel.

The lower polarizer 111 polarizes and passes light from the backlight unit in one direction.

The upper substrate 130 includes a second substrate 124 and a photochromic layer 123, an upper polarizer 122, a color filter array 121, And an ultraviolet blocking film 125 formed on the second substrate.

The photochromic layer 123 is discolored when exposed to ultraviolet rays in a wavelength range of 110 nm to 380 nm, and returns to its original transparent color when ultraviolet light is removed.

The photochromic layer 123 may be formed of a diarylethene compound, a naphthopyran compound, a polyurethane compound, a spirobenzopyran compound, a fulgide compound, a spirooxazine-based compound, or a compound in which at least two of these are combined.

The photochromic layer 123 may be formed separately on a unit pixel area basis. The reason is that the photochromic layer 123 in the unit pixel region adjacent to each other is not affected or influenced. The photochromic layer 123 may be formed by a coating method or a printing method in order to separate and form a unit pixel. The unit pixel regions are separated from each other by separating the photochromic layers 123 from each other or by coating them with a black matrix. Therefore, it is possible to make the photochromic layer 123 different in color by unit pixel area unit.

The UV blocking film 125 is disposed on the second substrate 124 and transmits visible light emitted from the backlight unit 500 to block ultraviolet rays. The ultraviolet rays emitted from the backlight unit 500 are absorbed by the photochromic layer 123 but a part of the ultraviolet rays can be transmitted through the photochromic layer 123, Is attached to the upper part of the upper substrate (120).

In addition, the ultraviolet protection film 125 may function to prevent discoloration of the photochromic layer 123 due to ultraviolet rays from the outside. Specifically, external light such as a lighting lamp or sunlight may include ultraviolet rays as well as visible light. Therefore, if ultraviolet rays from the outside can not be blocked, ultraviolet rays are incident from the outside into the liquid crystal display panel 100 and the photochromic layer 123 may be discolored. When the photochromic layer 123 is discolored by external light, the image quality of the liquid crystal display device may be deteriorated. Therefore, the ultraviolet ray blocking film 125 is attached to the upper portion of the second substrate 124, .

The color filter array 121 is provided between the liquid crystal layer 130 and the upper polarizer 122 in a portion corresponding to the subpixel and includes red, green and blue color filter layers RC and GC , BC) and an ultraviolet color filter layer (UC), and selectively transmits light. That is, the red color filter layer (RC) passes only the red light and cuts off the remaining light. The green color filter layer (GC) passes only the green light and cuts off the remaining light. The blue color filter layer , And blocks the remaining light. The ultraviolet color filter layer (UC) passes only ultraviolet light and blocks the remaining light.

Although the color filter layers RC, UC, GC and BC are provided at the portions corresponding to the subpixels, the black matrix corresponds to the gate lines GL, the data lines DL and the thin film transistors TFT And a portion corresponding to the spacing space between each sub-pixel.

The upper polarizer 122 blocks light when the R, G, and B image data are black data (0, 0, 0). Since the data voltage is not applied to the source electrode of the thin film transistor TFT of the sub pixel when the image data is 0, the light transmission direction is not changed so that the liquid crystal layer 130 can pass through the upper polarizer 122 to be.

The upper substrate 120 and the lower substrate 110 are bonded together such that the subpixels 113 of the lower substrate 110 and the color filter array 121 of the upper substrate 120 face each other A liquid crystal layer 130 is formed between the upper substrate 120 and the lower substrate 110.

The timing controller 400 generates a data control signal DCS and a gate control signal GCS using a horizontal synchronizing signal Hsync, a vertical synchronizing signal Vsync and a clock signal CLK. The data control signal DCS includes a dot clock signal, a source shift clock signal, a source enable signal, a polarity reversal signal, etc. The gate control signal GCS includes a gate start pulse, a gate shift clock, a gate output enable signal, .

The timing controller 400 includes an image data converter 410 for converting R, G, and B RGB data, which are image data input from the outside, into R, G, and B sub-pixels.

The image data conversion unit 410 generates U data using RGB data input from the outside and converts the U data into RUGB data.

RGB data representing black is defined as (0, 0, 0), RGB data representing white is defined as (255, 255, 255) RGB data representing green is defined as (0, 255, 0), and RGB data representing blue is defined as (0, 0, 255). By adjusting each of the above values, various colors can be expressed.

 Specifically, when the RGB data corresponding to one pixel input from the outside is (0, 0, 0) and the pixel represents Black, the U data is generated with a preset value. In this case, ultraviolet rays in the U-sub pixel region pass through the upper polarizer 122 and reach the photochromic layer 123. The predetermined value is 1 to 255 except 0, and may be set differently depending on the property of the photochromic layer 123. [ 3A to 4, a preset value is assumed to be 255 in the image data conversion unit.

On the other hand, when RGB data corresponding to a pixel is not black, that is, when any one of R data, G data and B data has a value of 1 or more, U data is set to 0 to convert RGB data into RUGB data . In this case, ultraviolet rays in the U-sub pixel region are blocked in the upper polarizer.

If the RGB data input from the outside is black, the image data converter 410 generates the U data to have a non-zero value in order to transmit ultraviolet rays. If the RGB data is not black, the U data is set to 0 And converts the input RGB data into RUGB data.

The timing controller 400 supplies the RUGB data output from the image data converter 410 to the data driver together with the data control signal DCS and supplies the gate control signal GCS to the gate driver 700 Supply.

The data driver 600 converts RUGB data input from the timing controller 400 into data voltages of polarity / negative polarity according to the data control signal DCS to prevent deterioration of the liquid crystal, .

The gate driver 700 includes a shift register (not shown) and a level shifter (not shown). The shift register generates a scan pulse in response to a gate start pulse of the gate control signal GCS input from the timing controller 400. The level shifter converts the voltage of the gate pulse into a voltage level for driving each pixel. The gate driver 700 supplies a scan pulse to the gate line GL according to the gate control signal GCS.

The gate driver 700 sequentially outputs a scan pulse to the gate line GL under the control of the timing controller 400. Each thin film transistor TFT included in the sub pixel 113 is turned on in response to a gate pulse from the gate line GL to supply a data voltage from the data line DL to the pixel electrode of the liquid crystal cell Clc.

The backlight unit 500 is disposed under the liquid crystal display panel 100 and arranges a plurality of light sources to irradiate visible light and ultraviolet light to the entire surface of the liquid crystal display panel. The backlight unit is disposed on a side surface of the light guide plate and is provided with a light-measuring type system for emitting light to the liquid crystal display panel through the light guide plate, a direct light type system for arranging a plurality of light sources under the liquid crystal display panel, .

The light source may be a CCFL, HCFL, or a light emitting diode (LED). In the case of a light emitting diode, an ultraviolet LED may be mixed with an existing LED for supplying visible light.

FIG. 3A is an operational state diagram when RGB data input from the outside in the liquid crystal display panel according to the embodiment of the present invention is not black, FIG. 3B is a diagram illustrating an RGB data input from the outside in the liquid crystal display panel according to the embodiment of the present invention, Is black.

3A and 3B, an operation state in a unit pixel region according to an RGB data signal input from the outside will be described. The operation state is divided into two cases: RGB data from the outside is black, and the case where the RGB data is not black.

In Fig. 3A, white is taken as an example when RGB data inputted from outside is not black. Except for the input RGB data in black, the driving method that expresses white is the same in the driving method in accordance with the RGB data.

Since the RGB data input from the outside is not black (0, 0, 0), the image data conversion unit 410 converts the RGB data into RUGB data of (255,0,255,255) by setting U data to 0.

The ultraviolet light in the U sub pixel area is blocked by the upper polarizer 122, and the visible light in the U sub pixel area is blocked in the color filter layer UC.

The ultraviolet light in the R, G, and B subpixel regions is blocked in the color filter layers RC, GC, BC in the respective R, G, and B subpixel regions and the visible light having red, green, Lt; / RTI > Accordingly, when RGB data is not black, ultraviolet rays do not reach the photochromic layer 123, and the photochromic layer 121 is not discolored.

Referring to FIG. 3B, RGB data input from the outside expresses black as (0, 0, 0). Since the RGB data input from the outside is black (0, 0, 0), the image data converter 410 generates U data as 255, which is a preset value, and outputs RGB data (0, 0, 0) as RUGB data 255, 0, 0).

The ultraviolet light in the U sub pixel area passes through the upper polarizer 122 and reaches the photochromic layer 123 to discolor the photochromic layer 123. Ultraviolet rays are partially absorbed by the photochromic layer and blocked by the photochromic layer, but ultraviolet rays partially leaking from the photochromic layer 123 are blocked by the ultraviolet blocking film 125 and can not reach the user. Then, the visible light in the U sub-pixel region is cut off at the color filter array 121.

Ultraviolet rays in the R, G, and B sub pixel areas are cut off in the color filter layers RC, GC, and BC. Then, the visible light in the R, G, and B sub-pixel regions are all blocked by the upper polarizer 122, and a part of the visible light leaking from the upper polarizer 122 is blocked by the discolored photochromic layer 123.

4 is an operational state diagram of four adjacent unit pixels and their corresponding photochromic layers according to an embodiment of the present invention.

There are four unit pixels adjacent to each other, and a photochromic layer 123 formed separately from each unit pixel region is located. Each unit pixel consists of R, U, G, and B sub-pixels.

First, a unit pixel composed of an R subpixel 1011, a U subpixel 1012, a G subpixel 1013, and a B subpixel 1014 and a unit pixel composed of a unit pixel and an operation state of the photochromic layer 1010 Learn about.

Assuming that the RGB data corresponding to the unit pixel is (0, 0, 0), that is, it is assumed to be black, if the preset value of the image data conversion unit 141 is 255 as shown in FIG. 3B, The image data conversion unit 141 receiving the data (0, 0, 0) generates U data corresponding to the U subpixel 1012 as 255 and outputs RGB data (0, 0, 0) as RUGB data 255, 0, 0).

The ultraviolet light in the U sub-pixel area irradiated from the back light unit 500 reaches the photochromic layer 123 to discolor the photochromic layer 123 and is absorbed by the photochromic layer 123 to be blocked, Blocking film 250 to prevent the user from reaching. In addition, ultraviolet rays in the R, G, and B sub-pixel regions are blocked in the color filter layers RC, GC, and BC.

Visible light in the R, G, and B sub-pixel regions of the visible light emitted from the backlight unit 500 is blocked by the upper polarizer 122. Even if a part of the light is leaked from the upper polarizer 122, the photochromic layer 123 is blocked by the discolored photochromic layer 123. The visible light in the U sub-pixel region of the visible light emitted from the backlight unit 500 is blocked at the color filter array 121. [

As described above, the photochromic layer 123 is discolored by ultraviolet rays. The visible light is blocked by the upper polarizer 122, and the discolored photochromic layer 123 blocks some visible light leaking from the upper polarizer 122.

A unit pixel adjacent to the right side of the unit pixel includes a R subpixel 1021, a U subpixel 1022, a G subpixel 1023, and a B subpixel 1024. The RGB data corresponding to the unit pixel is not black (0, 0, 0). For example, when the RGB data is (100,100,255), since it is not black, the image data converting unit 141 generates U data to be applied to the U pixel to 0, and outputs the RGB data 100, 100, 255 as RUGB data 100, ).

The ultraviolet light in the U sub-pixel region of the ultraviolet light irradiated from the backlight unit 500 is blocked by the upper polarizer 122, and R of the ultraviolet light irradiated from the backlight unit 500 is 0 , G, and B sub-pixel regions are blocked at the color filter layers (RC, GC, BC).

The visible light in the R, G, B sub-pixel areas of the visible light emitted from the backlight unit 500 reaches the user and the visible light in the U sub-pixel area of the visible light emitted from the back light unit 500, Is blocked in the filter layer (UC).

The unit pixel composed of the subpixels 1031, 1032, 1033 and 1034 operates in the same manner as the unit pixel composed of the subpixels 1021, 1022, 1023 and 1024 so that the photochromic layer 123 is not discolored Do not.

The unit pixels constituted by the subpixels 1041, 1042, 1043 and 1044 operate in the same manner as the unit pixels constituted by the subpixels 1011, 1012, 1013 and 1014 so that the photochromic layer 123 is discolored do.

As described above, since the presence or absence of discoloration of the photochromic layer 123 differs for each unit pixel, light leakage phenomenon can be prevented. In addition, the black having the RGB data (0, 0, 0) can be completely expressed, and the contrast ratio can be improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. Will be clear to those who have knowledge of.

100: liquid crystal display panel 111: lower polarizer plate
112: first substrate 113: sub pixel
121: Color filter array 122: Upper polarizer plate
123: photochromic layer 124: second substrate
125: ultraviolet shielding film 130: liquid crystal layer
400: timing controller 410: image data conversion section
500: backlight unit 600: data driver
700: gate driver

Claims (11)

A lower substrate on which a plurality of gate lines and data lines are arranged to form a thin film transistor array defining a plurality of subpixels;
An upper substrate on which a color filter array is formed in which color filter layers are arranged corresponding to the subpixels;
A photochromic layer disposed between the upper substrate and the color filter array and discolored when irradiated with ultraviolet light; And,
And a liquid crystal layer filled between the upper substrate and the lower substrate,
Wherein the unit pixel includes a plurality of subpixels that display a color and a U subpixel that transmits ultraviolet light. The method according to claim 1,
And a top polarizer plate between the photochromic layer and the color filter array. The method according to claim 1,
The liquid crystal display panel according to claim 1, further comprising an ultraviolet blocking film on the upper substrate to block ultraviolet rays from the inside and the outside of the liquid crystal display panel. The method according to claim 1,
Wherein the photochromic layer is separately provided for each unit pixel. The method according to claim 1,
The subpixels for displaying the color are composed of R subpixels for displaying red, G subpixels for displaying green, and B subpixels for displaying blue,
The color filter array includes an R color filter layer through which red light corresponding to the R, G, B, and U sub pixels respectively pass, a G color filter layer through which green light passes, a B color filter layer through which blue light passes, A liquid crystal display panel comprising a color filter layer. A lower substrate on which a plurality of gate lines and data lines are arranged to form a thin film transistor array defining a plurality of subpixels,
An upper substrate on which a color filter array is formed in which color filter layers are arranged corresponding to the sub pixels,
A photochromic layer disposed between the upper substrate and the color filter array and discolored when irradiated with ultraviolet light; And
A liquid crystal display panel including a liquid crystal layer filled between the upper substrate and the lower substrate, the unit pixel including a plurality of sub pixels displaying hue and a U sub pixel transmitting ultraviolet light;
A data driver for supplying a data voltage to the plurality of data lines;
A gate driver for supplying a scan pulse to the plurality of gate lines;
A timing controller for controlling the data driver and the gate driver; And
And a backlight unit for emitting ultraviolet rays and visible rays to the liquid crystal display panel. The method according to claim 6,
Wherein the timing controller converts the RGB data into RUGB data by setting the data corresponding to the U subpixel to one of 1 to 255 when the RGB data input from the outside is black, And converting the RGB data into RUGB data by setting the data corresponding to the U subpixel to 0 when the color data is not black. The method according to claim 6,
And an upper polarizer plate between the photochromic layer and the color filter array. The method according to claim 6,
Further comprising an ultraviolet blocking film on the upper substrate to block ultraviolet rays from the inside and the outside of the liquid crystal display panel. The method according to claim 6,
Wherein the photochromic layer is separately provided for each unit pixel. The method according to claim 6,
The subpixels for displaying the color are composed of R subpixels for displaying red, G subpixels for displaying green, and B subpixels for displaying blue,
The color filter array includes an R color filter layer through which red light corresponding to the R, G, B, and U sub pixels respectively pass, a G color filter layer through which green light passes, a B color filter layer through which blue light passes, A liquid crystal display device comprising a color filter layer.

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