KR100438967B1 - Liquid crystal display device - Google Patents

Abstract

The present invention is to improve the brightness and color reproducibility of the liquid crystal display device, an upper polarizing plate for converting the polarization characteristics of the light beam, a color filter substrate disposed on the upper polarizing plate formed with a color filter and a common electrode, a color filter A liquid crystal layer provided under the substrate, a thin film transistor disposed under the liquid crystal layer to apply a signal to control the amount of light beam transmission, and a lower substrate provided in a matrix form, and disposed under the upper substrate to provide polarization characteristics of the light beam. The lower polarizing plate to be converted, and the red (R) and green (G) which are disposed under the lower polarizing plate and correspond to the red (R), green (G) and blue (B) color filters formed in each pixel. The backlight unit includes a blue (B) light emitting device.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

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 having improved luminance and color reproducibility.

In general, liquid crystal display devices have tended to be gradually widened due to their light weight, thinness, and low power consumption. According to this trend, LCD is being used for office automation equipment, audio / video equipment, and the like. On the other hand, the LCD is controlled to display the desired image on the screen by adjusting the transmission amount of the light beam according to the image signal applied to the plurality of control switches arranged in a matrix form.

In general, the liquid crystal display includes a backlight unit 10 that generates a light beam and uniformly supplies the light beam as shown in FIG. 1, and is disposed on the backlight unit 10 to improve polarization characteristics of the light beam. A lower substrate 24 disposed on the lower polarizing plate 22 to convert the lower polarizing plate 22 and having a thin film transistor 38 having a matrix to apply a signal to control a transmission amount of the light beam; The liquid crystal layer 28 provided on the lower substrate 24, the common electrode 30 formed on the liquid crystal layer 28, and the upper portion of the common electrode 30 are formed of red (R) and green ( G), a color filter 36 of a resin film containing dyes or pigments of three basic colors of blue (B), an upper substrate 32 disposed above the color filter 36, and an upper portion An upper polarizer 34 is disposed on the substrate 32 to convert polarization characteristics of the light beam. The backlight unit 10 reflects a light source for generating a light beam, a light guide plate for uniformly guiding the light beam generated by the light source toward the liquid crystal panel, and a light beam positioned below the light guide plate and traveling toward the bottom or side of the light guide plate in the direction of the liquid crystal panel. It is composed of a reflector. By this configuration, the light beam of the backlight unit 10 proceeds uniformly toward the liquid crystal panel.

As described above, the liquid crystal display does not emit light by itself, and has a characteristic of displaying an image by adjusting light transmittance, so that a backlight unit provided separately for irradiating light onto the liquid crystal panel has a light source disposed on the bottom of the liquid crystal display. Disposed directly so that light is transmitted directly to the front side of the liquid crystal panel, and disposed on one or both sides of the light guide plate such that the light is reflected, diffused and collected through the light guide plate, the reflecting plate and the sheets, thereby It is divided into the edge (edge) method to be transmitted to the front surface, and currently the edge method is mainly used.

However, since the edge method has a lower luminance than the direct method, an attempt is made to condense light by using a prism sheet to compensate for this.

Referring to the drawings of Figure 2 will be described in detail with respect to the structure and its role of the edge-type backlight unit.

The edge unit backlight unit includes a light guide plate 42 for guiding light generated from the lamp 41; It is provided with a lamp housing 43 which is installed on the side of the light guide plate 42 to surround the lamp 41. Here, the cold cathode tube is mainly used for the lamp 41.

The light generated by the lamp 41 is incident toward the side of the light guide plate 42, and the inner surface of the lamp housing 43 is processed to reflect the light, so that light generated from the lamp 41 may be reflected by the light guide plate ( By reflecting toward the side of 42, the utilization of the light generated in the lamp 41 is improved.

On the other hand, the light guide plate 42 is formed of a plastic-based transparent material such as PMMA to have a panel form of the inclined lower surface and the horizontal upper surface (or, the inclined upper surface and the horizontal lower surface), the slope of the light guide plate 42 As the photograph surface is provided with a plurality of dots or V-shaped grooves to uniformly reflect the light, the light generated from the lamp 41 is uniformly advanced upwards through the upper surface.

In addition, a reflecting plate 44 is disposed below the light guide plate 42, and a diffusion plate 45, first and second prism sheets 46a and 46b, and a protective sheet 48 are sequentially installed above. do. Here, the reflecting plate 44 reflects the light transmitted downward through the lower surface of the light guide plate 42 toward the light guide plate 42, thereby reducing the loss of light and improving the uniformity of the light transmitted above the light guide plate 42. Contribute to improvement.

Therefore, the light guide plate 42 guides the light generated from the lamp 41 along with the reflecting plate 44 upward.

In addition, the diffusion plate 45 disposed between the light guide plate 42 and the first prism sheet 46a disperses the light incident from the light guide plate 42, so that spots due to partial concentration of light may not be generated. In addition, the diffusion plate 45 also plays a role of vertically raising the direction of the light traveling toward the first prism sheet 46a.

In addition, the first prism sheet 46a has a flat lower surface and a corrugated surface corrugated in the front and rear directions, while the second prism sheet 47 has a flat lower surface and a corrugated surface corrugated in the left and right directions. Accordingly, the first prism sheet 46a condenses the light traveling toward the second prism sheet 47 in the front and rear directions, and the second prism sheet 47 condenses the light traveling toward the protective sheet 48 in the left and right directions. As a result, the light propagating toward the protective sheet 48 from the diffusion plate 45 is raised so that it can proceed vertically.

Accordingly, the light passing through the first and second prism sheets 46a and 46b is vertically distributed and uniformly distributed with respect to the entire surface of the protective sheet 48, thereby improving luminance.

In addition, the protective sheet 48 is formed on the top layer of the backlight assembly to protect the lower sheets sensitive to dust or scratches, and to prevent the flow of the lower sheets when only the backlight assembly is transported. In addition, the light distribution may have a property of diffusing light to make the distribution of light more uniform.

The main support 49 may include the lamp 41, the light guide plate 42, the lamp housing 43, the reflecting plate 44, the diffusion plate 45, the first and second prism sheets 46a and 46b, In addition, the protective sheet 48 is supported and serves to seat each member.

In addition, a top case 21 is installed to press and fix the entire upper edge of the liquid crystal panel 50.

The direct type backlight is mainly used for a large screen liquid crystal display device requiring high brightness because the light utilization efficiency is higher than that of the edge method.

The direct light type backlight unit includes a lamp unit for generating light, a reflecting plate for reflecting light under the lamp unit, and is installed on the lamp unit at a predetermined distance from the lamp unit to diffuse light emitted from the lamp into the liquid crystal panel. It consists of a sending diffuser, a main support for supporting the lamp unit, the reflecting plate, and the diffusing plates, and for seating the members.

On the other hand, the white light beam traveling from the backlight unit configured as described above toward the liquid crystal panel 50 shown in FIG. 1 is polarized by the lower polarizer 22. As the polarized light beam passes through the liquid crystal controlled by the thin film transistor 38, the polarization state is changed. In detail, when the thin film transistor 38 is turned on, an image signal is applied to the pixel electrode 26 via the thin film transistor 38. At this time, the arrangement of the liquid crystals is changed in response to the potential between the pixel electrode 26 and the common electrode 30.

The light beam whose polarization state is changed by the liquid crystal layer 28 has a wavelength of a color corresponding to each color filter via the color filter 36. In this case, the spectral characteristics of the light beam transmitted through the color filter are shown in FIG. In addition, one pixel is provided with sub-pixels corresponding to red (R), green (G), and blue (B), respectively. That is, three subpixels including red (R), green (G), and blue (B) form one pixel.

As such, the light beam implemented in the predetermined color by the color filter 36 passes through the upper substrate 32 and then proceeds to the upper polarizing plate 34 to display an image corresponding to the image signal.

However, since the white light incident from the backlight unit 10 passes through the red (R), green (G), and blue (B) color filters, the color is realized, thereby degrading the purity of the color.

In addition, in order to improve the purity of the color to form a thick color filter consisting of a photopolymerization photosensitive composition, such as a photoinitiator, a monomer, a binder and an organic pigment that implements color, the amount of light transmitted decreases. This causes a problem of decreasing luminance.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to correspond to the color filters of red (R), green (G), and blue (B) formed on the upper substrate of the liquid crystal panel. ) And a green (G) and blue (B) light emitting diode (Light Emitting Diode) to be used as a light source, to provide a liquid crystal display device having a wide color reproduction range and improved brightness.

1 is a diagram illustrating a configuration of a general liquid crystal display device.

2 is a view showing the edge unit of the backlight unit.

3 shows the spectral characteristics of a light beam passing through a color filter.

Figure 4 is a red (R), green (G), blue (B) color of the red (R), green (G), blue (B) color light emitting elements arranged in the same manner as the light source is configured as a light source Fig. 2 shows a liquid crystal display device.

5A to 5C are diagrams illustrating an arrangement structure of a light emitting device that may be disposed in a light source.

FIG. 6 is a detailed view of the backlight unit of FIG. 4 in detail. FIG.

*** Explanation of symbols for main parts of drawing ***

51: upper polarizing plate 52: color filter

53: common electrode 61: thin film transistor

62: lower polarizer 63: gate line

65 data line 67 pixel electrode

83: light source 85: light source

84: main support 87: reflector

89: diffuser 88: top gay

90: liquid crystal panel

Liquid crystal display device of the present invention for achieving the above object is a color filter substrate having a color filter of red (R), green (G), blue (B) color; The liquid crystal cells of the red (R), green (G), and blue (B) pixels corresponding to the color filters of the red (R), green (G), and blue (B) colors are arranged in an active matrix form. A thin film transistor (TFT) array substrate having a thin film transistor (TFT) in a liquid crystal cell; A liquid crystal layer formed between the color filter substrate and the thin film transistor (TFT) array substrate; And red (R), green (G), and blue (B) light emitting devices disposed under the array substrate of the thin film transistor so as to match the colors of the red (R), green (G), and blue (B) color filters. Consists of a backlight unit composed of a light source.

The apparatus may further include an upper polarizer disposed on the color filter substrate and a lower polarizer disposed below the thin film transistor array substrate.

Hereinafter, a liquid crystal display of the present invention as described above with reference to the accompanying drawings in detail as follows.

Figure 4 is a red (R), green (G), blue (B) color of the red (R), green (G), blue (B) color light emitting elements arranged in the same manner as the light source is configured as a light source Shows a liquid crystal display device.

As shown in the figure, the liquid crystal display of the present invention comprises: an upper substrate 50 provided with color filters 52 of red (R), green (G), and blue (B) colors; The liquid crystal cells of the red (R), green (G), and blue (B) pixels corresponding to the color filters 52 of the red (R), green (G), and blue (B) colors are arranged in an active matrix form. A lower substrate 60 having a thin film transistor (TFT) 61 in each liquid crystal cell; A liquid crystal layer 70 formed between the upper substrate 50 and the lower substrate 60; Red (R), green (G), and blue (B) are disposed under the lower substrate 60 so as to match the colors of the red (R), green (G), and blue (B) color filters (52). The color light emitting device 83 is composed of a backlight unit 80 formed as a light source.

The upper substrate 50 is a color filter 52 of a resin film containing dyes or pigments of three basic colors of red (R), green (G), and blue (B) below the glass substrate, and the color A common electrode 53 made of an overcoat film (not shown) for flattening the filter 52 or for improving adhesion to the ITO, and ITO, a transparent conductor formed to apply a voltage to the liquid crystal cell. And an alignment layer formed for alignment of liquid crystal molecules, and a black matrix (not shown) is further formed between pixels of the color filter 52 to prevent light leakage, and an upper portion of the upper substrate 50. The upper polarizing plate 51 is comprised.

The lower substrate 60 includes pixels in which a plurality of gate lines 63 and data lines 65 cross each other in a matrix form, and the gate lines 63 and data. A thin film transistor 61 formed at a point where the line 65 crosses and including a gate electrode (not shown), a source electrode (not shown), and a drain electrode (not shown), and formed to apply a voltage to the liquid crystal cell And a pixel electrode 67 made of ITO, which is a transparent conductor, and an alignment film (not shown) formed for the alignment of liquid crystal molecules. In the configuration of the thin film transistor 61, a gate electrode is formed at the gate line 63; A predetermined area protrudes in one direction, and the source electrode protrudes from the data line 65 to the upper portion of the gate electrode.

In addition, a lower polarizer 62 is formed on the lower surface of the lower substrate 60.

The backlight unit 80 includes red (R), green (G), and red (R), green (G), and blue (B) color filters 52 that are disposed in the same manner as the color filter 52 formed on the upper substrate 50. A light source unit 85 in which a light emitting element 83 of blue (B) color is disposed is formed.

Hereinafter, the structure and operation of the backlight unit 80 will be described in detail with reference to FIG. 5 showing the backlight unit 80 in detail.

The backlight unit 80 is spaced apart from the light source 83 by a reflecting plate 87 for reflecting a light beam traveling toward the liquid crystal panel while the light source 83 is seated on the lower side or the side of the light source 83. A diffusion plate installed on the light source 83 to diffuse the light emitted from the light source 83 to the liquid crystal panel 90 including an upper substrate 50 having a color filter and a lower substrate 60 having a thin film transistor array; It consists of 89.

At this time, the reflective plate 87 is formed in a periodic "V" bend shape in order to efficiently reflect the light generated from the light source 83, each red "V" of the upper substrate 50 inside the "V" bend ( Red (R), green (G), and blue (B) light emitting elements 83 corresponding to the color filters R, green, and blue (B) 1: 1 are disposed.

In addition, the light source 83, the reflecting plate 87, the diffusion plate 89, and the liquid crystal panel 90 are mounted on the main support 84, and a top case 88 is installed to provide the liquid crystal panel ( Press the entire top edge of 90) to fix it.

Referring to the operation of the backlight unit configured as described above are as follows.

First, the light generated from the light source 83 of the light emitting element disposed inside the “V” shaped bend of the reflecting plate 87 proceeds directly to the diffuser plate 89 formed on the light source 83. A part of the light incident on the diffuser plate 89 passes through the diffuser plate 89 and proceeds upward, and the other part is reflected by the reflector plate 87 provided under the light source 83, and then diffused. The light proceeds through the upper part 89 and proceeds upward. The light traveling through the diffuser plate is incident on the red, green, and blue pixels of the liquid crystal panel. The light emitting devices of green (G) and blue (B) are disposed in one-to-one correspondence with color filters of red (R), green (G) and blue (B) formed on the upper substrate of the liquid crystal panel. Light from the light emitting device proceeds to the color filter of red (R), and light from the light emitting device of green (G) proceeds to the color filter of red (R). Since light is transmitted, the purity of red (R), green (G), and blue (B) colors can be increased as compared with the conventionally transmitted white light color. It can be widened.

5A to 5C illustrate an arrangement structure of a light emitting device in which a light source may be disposed.

In general, the color filter arrangements of red (R), green (G), and blue (B) formed on the upper substrate of the liquid crystal panel are strip array, mosaic array, and delta depending on the purpose of the liquid crystal display. It may consist of a (delta) array. Accordingly, the arrangement of the light emitting devices in which the light emitting devices of red (R), green (G), and blue (B) are formed at the same position as the color filters of red (R), green (G), and blue (B) is illustrated in FIG. 6A, 6B, and 6C may be formed in a strip arrangement, a mosaic arrangement, and a delta arrangement.

The light emitting device applied as the backlight of the present invention may use an EL (electro luminescence) which provides a very thin, light and uniform light, but the brightness is brighter than the EL due to the short lifespan of the EL, the lifetime It is desirable to use this long, low power light emitting diode (LED).

The liquid crystal display according to the present invention as described above can reduce the power consumption by using the EL or LED as a backlight, and the red (R), green (G), blue (B) light emitting element to the upper portion of the liquid crystal panel The red (R), green (G), and blue (B) color filters formed on the substrate correspond to the one-to-one correspondence, and the light emitted from the red (R) light emitting element proceeds to the red (R) color filter, and green Light emitted from the light emitting device (G) proceeds to the color filter of red (R), and light generated from the light emitting device of the blue (B) proceeds to the color filter of blue, whereby red (R) and green ( G), blue (B) has the effect of increasing the color reproduction range by increasing the purity.

Claims (9)

A color filter substrate including red (R), green (G), and blue (B) color filters; A thin film transistor array substrate in which liquid crystal cells of red (R), green (G), and blue (B) pixels corresponding to the color filter are arranged in an active matrix form, and a thin film transistor is provided in each liquid crystal cell; The light source of red (R), green (G), and blue (B) color is disposed under the array substrate of the thin film transistor so as to match the color of the red (R), green (G), and blue (B) color filters. Liquid crystal display comprising a backlight unit. The liquid crystal display device according to claim 1, further comprising a liquid crystal layer formed between the color filter substrate and the thin film transistor array substrate. The method of claim 1, wherein the backlight unit, A reflector formed with periodic "V" bends; A light emitting device disposed inside the “V” bend of the reflector; And a diffuser plate disposed above the light source and spaced apart from the light emitting device by a predetermined distance, and configured to diffuse the light emitted from the light source and send the diffuser plate to the upper portion where the color filter is formed. The liquid crystal display device according to claim 1, wherein the light source is an EL element. The liquid crystal display device according to claim 1, wherein the light emitting element is a strip array. The liquid crystal display device according to claim 1, wherein the light emitting elements have a mosaic arrangement. The liquid crystal display device according to claim 1, wherein the light emitting elements have a delta arrangement. The liquid crystal display of claim 1, wherein the light source is a light emitting diode (LED) element. A color filter substrate having red (R), green (G), and blue (B) color filters; A thin film transistor substrate in which liquid crystal cells of red (R), green (G), and blue (B) pixels corresponding to the color filter are arranged in an active matrix form, and a thin film transistor is provided in each liquid crystal peck; And Red (R), green (G), and blue (B) disposed under the thin film transistor substrate and disposed in a 1: 1 correspondence with the red (R), green (G), and blue (B) color filters. Liquid crystal display comprising a backlight unit consisting of a light source.