KR20160081999A - Liquid Crystal Display Device - Google Patents

Abstract

The present invention discloses a liquid crystal display device. (R), green (G), blue (B) and white (W) subpixels SP are partitioned and the red (R) and blue (G) and white (W) sub-pixels of a first pixel and a green (G) and white (W) sub-pixels are defined as a second pixel, The color temperature can be adjusted without reducing the luminance by making the area smaller than the area of the red (R) or blue (B) sub-pixel of the pixel.

Description

[0001] The present invention relates to a liquid crystal display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a liquid crystal display device capable of controlling a white color temperature without diminishing luminance by designing an area of sub pixels asymmetrically.

[0002] A liquid crystal display typically displays an image by adjusting the light transmittance of a liquid crystal having dielectric anisotropy using an electric field. In a liquid crystal display device, a color filter substrate on which a color filter array is formed and a thin film transistor array substrate on which a thin film transistor (TFT) array is formed are bonded together with a liquid crystal therebetween.

Since the liquid crystal display device does not have its own light emitting element, a separate light source is required to display the difference in transmittance as an image. To this end, a backlight unit having a light source is disposed on the back of the liquid crystal display panel .

Such a backlight unit is divided into a direct type and an edge type according to the position of a light source. Fluorescent lamps such as a cold cathode fluorescent lamp (CCFL) and an external electrode fluorescent lamp (EEFL) have been used as a light source of the backlight unit. However, recently, a liquid crystal display has been made thinner and lighter The LED package having a light emitting diode (LED) having advantages in terms of power consumption, weight, and brightness is used as a light source.

In general, the chromaticity of the light source or the reference white can be expressed by the temperature of the nearest region on the radiation curve instead of the coordinate on the two-dimensional color chart, which is called a correlated color temperature (CCT) or color temperature. The color temperature is used as a numerical value indicating the degree to which a white color is close to a certain color.

The higher the color temperature, the higher the blue color, and the lower the color temperature, the more red color is included in the display device. In the color temperature characteristic, the preference varies depending on the country.

FIG. 1A is a diagram illustrating a pixel structure of a conventional liquid crystal display device, and FIG. 1B is a diagram illustrating a pixel structure in which a white (W) sub-pixel is added for securing a transmittance according to the related art.

1A, a liquid crystal display panel of a conventional liquid crystal display device includes red (R), green (G), and blue (B) subpixels SP in a pixel structure, Are provided with a thin film transistor (TFT) as a switching element.

Therefore, the liquid crystal display panel controls the light transmittance of each sub-pixel by the data signal supplied to the red (R), green (G) and blue (B) sub-pixels (SP) It works in a way that implements the desired color.

However, according to recent demands of a high resolution liquid crystal display panel, a sufficient luminance can not be secured by only the pixel structure of FIG. 1A, and a structure in which a white (W) sub pixel SP is added to a pixel P structure as shown in FIG. .

In the liquid crystal display device of FIG. 1B, white W, red R, green G and blue B subpixels SP constitute one pixel, The light transmittance is adjusted to display a full color image.

However, in the conventional liquid crystal display panel having the pixel structure as shown in FIG. 1B, the red (R), green (G) and blue (B) sub- There is a problem that the area of the pixels SP becomes smaller and the luminance of red (R), green (G), and blue (B) deteriorates.

Particularly, since red (R) and blue (B) have a large effect on the color of the displayed image, the image quality is deteriorated due to the decrease in luminance.

Therefore, in the past, a technique of mixing various phosphors with a light source of a backlight unit to prevent luminance deterioration and to adjust a color temperature has been proposed, but the process is complicated and the manufacturing cost is increased.

The present invention relates to a liquid crystal display device in which areas of white (W), red (R), green (G) and blue (B) sub pixels SP are formed asymmetrically, The purpose is to provide.

Another object of the present invention is to provide a liquid crystal display device capable of adjusting the area of white (W) and green (G) sub-pixels to realize a desired color temperature without lowering brightness while using a single phosphor as a light source of a backlight unit. .

According to an aspect of the present invention, there is provided a liquid crystal display device including red (R), green (G), blue (B) and white (W) (G) and white (W) subpixels are defined as a first pixel and a green (G) and a white (W) subpixel as a second pixel, W) sub-pixel is smaller than the area of the red (R) or blue (B) sub-pixel of the first pixel, the color temperature can be adjusted without lowering the luminance.

The liquid crystal display device according to the present invention can form asymmetrically the areas of white (W), red (R), green (G) and blue (B) sub pixels (SP) There is an effect.

Further, the liquid crystal display device according to the present invention has an effect of adjusting the area of white (W) and green (G) sub-pixels to realize a desired color temperature without lowering brightness while using a single phosphor as a light source of the backlight unit .

1A is a diagram showing a pixel structure of a liquid crystal display device according to the related art.
FIG. 1B is a diagram illustrating a pixel structure in which white (W) sub-pixels are added for ensuring transmittance according to the related art.
2 is an exploded perspective view of a liquid crystal display device according to the present invention.
3 is a view showing the structure of an LED assembly of a liquid crystal display according to the present invention.
4A and 4B are diagrams illustrating light wavelength characteristics of the phosphor used in the LED assembly of the backlight unit of the present invention.
5 is a diagram illustrating a pixel structure of a liquid crystal display device according to the first embodiment of the present invention.
6 to 8 are diagrams showing the pixel structure of the liquid crystal display device according to the second to fourth embodiments of the present invention.
9 and 10 are graphs showing color temperature and luminance characteristics according to embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

In the case where the word 'includes', 'having', 'done', etc. are used in this specification, other parts can be added unless '~ only' is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

In the case of a description of a temporal relationship, for example, if a temporal posterior relationship is described by 'after', 'after', 'after', 'before', etc., 'May not be contiguous unless it is used.

The first, second, etc. are used to describe various components, but these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

FIG. 2 is an exploded perspective view of a liquid crystal display device according to the present invention, FIG. 3 is a view illustrating a structure of an LED assembly of a liquid crystal display device according to the present invention, FIGS. 4a and 4b are cross- Fig. 5 is a graph showing the light wavelength characteristics of the phosphor used in Fig.

2 to 4B, a liquid crystal display 100 according to the present invention includes a liquid crystal display panel 110, a backlight unit 120, a support main body 110 for modulating the liquid crystal display panel 110 and the backlight unit 120, (130), a lower cover (150), and a top cover (140).

The liquid crystal display panel 110 and the backlight unit 120 are modularized through a top cover 140, a support main 130 and a bottom cover 150. The top cover 140 is a liquid crystal display In order to cover the top and side edges of the display panel 110, the front surface of the top cover 140 is opened to display an image to be displayed on the liquid crystal display panel 110 .

The lower cover 150, on which the liquid crystal display panel 110 and the backlight unit 120 are mounted and is a basis for assembling the entire structure of the liquid crystal display device, includes a horizontal surface 151 And a side surface 153 whose edge is vertically bent upward.

A square main support main body 130 having a rectangular opening on one side and covering the edges of the liquid crystal display panel 110 and the backlight unit 120 is mounted on the bottom cover 150, And is coupled to the cover 150.

In this case, the top cover 140 may be referred to as a case top or a top case, and the support main 130 may be referred to as a guide panel or a main support or a mold frame. The bottom cover 150 may be a bottom cover, It is also called.

The liquid crystal display panel 110 is a part that plays a key role in image display and includes an array substrate 112 and a color filter substrate 114 which are bonded to each other with a liquid crystal layer interposed therebetween.

At this time, a plurality of gate lines and data lines intersect to define the pixels on the inner surface of the array substrate 112, which is usually referred to as a lower substrate or a thin film transistor substrate, though not shown in the drawing, A thin film transistor (TFT) is provided at each of the intersections and is connected in one-to-one correspondence with the transparent pixel electrodes formed in each pixel.

The inner surface of the color filter substrate 114, which is called an upper substrate, includes a color filter of white (W), red (R), green (G) And a black matrix for covering the gate lines, the data lines, and the thin film transistors is provided. In addition, color filters of white (W), red (R), green (G) and blue (B) color and transparent common electrodes covering the black matrix are provided.

However, in the case of the IPS (In-Plane Switching) mode or the FFS (Fringe Field Switching) mode liquid crystal display, the pixel electrode and the common electrode may be disposed in the array substrate 112.

A polarizing plate (not shown) selectively transmitting only specific light is attached to the outer surfaces of the array substrate and the color filter substrates 112 and 114, respectively.

A printed circuit board 117 is connected to at least one edge of the liquid crystal display panel 110 via a connection member 116 such as a flexible circuit board or a tape carrier package (TCP) And is brought into close contact with the side surface of the support main body 130 or the back surface of the lower cover 150 as appropriate.

In the liquid crystal display panel 110, when the selected thin film transistor is turned on for each gate line by the on / off signal of the gate driving circuit, the signal voltage of the data driving circuit is transmitted to the corresponding pixel electrode through the data line, The alignment direction of the liquid crystal molecules is changed by the electric field between the pixel electrode and the common electrode, resulting in a difference in transmittance.

In addition, the liquid crystal display device according to the present invention includes a backlight unit 120 for supplying light from the backside of the liquid crystal display panel 110 so that the difference in transmittance represented by the liquid crystal display panel 110 is externally expressed.

The backlight unit 120 includes an LED assembly 129, a white or silver reflective plate 125, a light guide plate 123 seated on the reflective plate 125, and an optical sheet 211 interposed therebetween . The optical sheet 211 may include a light conversion sheet including quantum dots.

The LED assembly 129 is disposed on one side of the light guide plate 123 so as to face the light incident surface of the light guide plate 123. The LED assembly 129 includes a plurality of LED packages 129a, And a printed circuit board (PCB) 129b mounted at a predetermined interval.

The LED package 129a includes an LED 200 and a body 201 having a wall structure so that the LED is mounted and a lens unit 202 disposed inside the wall corresponding to the LED 200 do.

The LED 200 is made of a blue LED that emits blue light having a wavelength of about 430 nm to 450 nm, and the lens unit 202 has a phosphor mixed with a silicone material.

In the present invention, a yellow single phosphor of YAG or Silicate is used for the lens portion 202 of the LED package 129a.

As shown in FIGS. 4A and 4B, the YAG fluorescent material and the silylated fluorescent material have a yellow characteristic, but they can emit light in a wavelength band of 430 nm to 480 nm and 500 nm to 630 nm.

As described above, in the present invention, a single phosphor of YAG or Silicate is used for the LED package 129a, but the area of the sub-pixels is implemented asymmetrically to control the desired color temperature (65000K) There is an effect that can be.

5 is a diagram illustrating a pixel structure of a liquid crystal display device according to the first embodiment of the present invention.

Referring to FIG. 5, a liquid crystal display device of the present invention includes a plurality of white W, red R, green G and blue B sub-pixels SP partitioned The red (R) and blue (B) subpixels SP are defined as a first pixel P, a green G and a white W subpixel SP as a second pixel P.

However, this is not fixed, but the red (R) and green (G) sub-pixels may be defined as the first pixel and the blue (B) and white (W) sub-pixels may be defined as the second pixel in the horizontal direction .

In the present invention, red (R) and blue (B) subpixels arranged adjacent to each other in a vertical direction are defined as a first pixel P, green (G) and white ).

In the first embodiment of the present invention, red (R) and blue (B) subpixels (SP) included in a first pixel (P) (SP) of the green (G) subpixel (SP) is equal to the area of the white (W) subpixel (SP) included in the second pixel (P) Respectively.

Therefore, the area ratio of the red (R), green (G), blue (B) and white (W) subpixels SP according to the first embodiment of the present invention is 1: 1: 1: 0.45.

A first thin film transistor TFT1 and a second thin film transistor TFT2 are arranged parallel to the gate line (not shown) below the white (W) subpixel SP, (TFT1) is connected to a white pixel electrode (not shown) of a white (W) sub-pixel SP. The second thin film transistor TFT2 is connected to a red pixel electrode (not shown) adjacent to the white (W) sub-pixel SP.

A third thin film transistor TFT3 and a fourth thin film transistor TFT4 are formed on the upper side of the white (W) sub pixel (SP) as a gate line (not shown) arranged in the green (G) sub pixel And the third thin film transistor TFT3 is connected to a green pixel electrode (not shown) of a green (G) sub-pixel SP. The fourth thin film transistor TFT4 is connected to a blue pixel electrode (not shown) adjacent to the green (G) sub pixel SP.

In the present invention, the area of the white (W) sub pixel (SP) or the green (G) sub pixel is formed smaller than the area of the red (R) and blue In order to prevent the luminance from decreasing, the thin film transistors are arranged along the vertical direction with reference to sub pixels (SP: white sub pixels) having a small area.

Thus, the areas of the red (R) and blue (B) sub-pixels (SP) adjacent to the white (W) and green (G) sub-pixels are sufficiently secured to prevent a decrease in color luminance.

As shown in FIG. 1B, white (W) sub-pixels are added to pixels in order to improve brightness in the prior art, so that areas of red (R), green (G) and blue (B) There is a problem that the luminance of green (G) and blue (B) is lowered. However, in the present invention, the area of white (W) sub-pixels is formed asymmetrically to prevent a decrease in color luminance.

9, even if the area ratio of the red (R), green (G), blue (B) and white (W) subpixels SP is designed to be 1: 1: 1: 0.45 as in the present invention , The color temperature is 6355K or more, and the luminance is 301.1.

As described above, in the liquid crystal display device according to the present invention, areas of white (W), red (R), green (G) and blue (B) subpixels SP are formed asymmetrically with each other, Can be controlled.

FIGS. 6 to 8 are diagrams showing the pixel structure of the liquid crystal display according to the second to fourth embodiments of the present invention. FIG. 9 and FIG. 10 show color temperature and luminance characteristics according to the embodiments of the present invention Fig.

Referring to FIGS. 6 to 10, the red (R) and blue (B) sub pixels SP included in the first pixel P are equal to each other according to the second embodiment of the present invention The area of the green subpixel SP included in the second pixel P is smaller than the area of the red subpixel SP and the area of the white subpixel SP included in the second pixel P is smaller than the area of the red subpixel SP, Pixel is larger than the area of the sub-pixel SP.

Therefore, the area ratio of the red (R), green (G), blue (B) and white (W) subpixels SP according to the second embodiment of the present invention is 1: 0.9: 1: 0.6.

It can be seen that the white color temperature of the second embodiment of the present invention is 6420K and the luminance is 301.4.

In the third embodiment of the present invention, the areas of the red (R) and blue (B) sub pixels (SP) included in the first pixel (P) The area of the red (R) sub-pixel SP is designed to be larger than that of the green (G) sub-pixel SP.

Therefore, the area ratio of the red (R), green (G), blue (B) and white (W) subpixels SP according to the third embodiment of the present invention is 1: 0.7: 1: 0.7.

The white color temperature of the third embodiment of the present invention is 6489K and the luminance is 301.9.

 In the fourth embodiment of the present invention, the areas of the red (R) and blue (B) sub-pixels (SP) included in the first pixel (P) The white (W) sub-pixel has a larger area than the green (G) sub-pixel SP.

The area of the white W subpixel SP is smaller than the area of the red subpixel SP and larger than the area of the green subpixel SP.

Therefore, the area ratio of the red (R), green (G), blue (B) and white (W) subpixels SP according to the fourth embodiment of the present invention is 1: 0.5: 1: 0.8.

It can be seen that the white color temperature of the fourth embodiment of the present invention is 6570K and the luminance is 301.2.

As can be seen from the color temperature coordinates of FIG. 10, the color temperature approaches 6500K from the first embodiment to the fourth embodiment (A to D). As shown in Fig. 9, it can be seen that there is almost no change in luminance with respect to the first to fourth embodiments.

As described above, the liquid crystal display according to the present invention has an effect of adjusting the area of the white (W) and green (G) sub-pixels to realize a desired color temperature without lowering the luminance while using a single phosphor for the light source of the backlight unit have.

100: liquid crystal display
110: liquid crystal display panel
112: first substrate
114: second substrate
120: Backlight unit
SP: sub-pixel

Claims (9)

(R), green (G), blue (B) and white (W) subpixels SP are partitioned and the red (R) and blue And a white (W) sub-pixel as a second pixel,
And the area of the green (G) and white (W) sub-pixels of the second pixel is smaller than the area of the red (R) or blue (B) sub-pixel of the first pixel.
The liquid crystal display of claim 1, wherein an area of the green (G) sub-pixel of the second pixel is larger than an area of the white (W) sub-pixel.
The liquid crystal display of claim 1, wherein areas of the green (G) and white (W) sub-pixels of the second pixel are equal to each other.
The liquid crystal display of claim 1, wherein the area of the white (W) sub-pixel of the second pixel is larger than the area of the green (G) sub-pixel.
The liquid crystal display of claim 1, wherein the red (R) and blue (B) sub-pixels of the first pixel are adjacent to each other in the vertical direction.
The liquid crystal display of claim 1, wherein the green (G) sub-pixel and the white (W) sub-pixel of the second pixel are adjacent in the vertical direction.
The organic light emitting display according to claim 1, wherein the thin film transistors arranged in the red (R), green (G), blue (B) and white (W) subpixels (SP) (W) sub-pixels.
The liquid crystal display device according to claim 1, wherein the liquid crystal display device includes a backlight unit,
Wherein the light source of the backlight unit includes a blue light emitting diode and a lens unit disposed on the blue light emitting diode.
The liquid crystal display of claim 8, wherein the lens unit comprises a single phosphor composed of YAG or silicate.

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