KR102512637B1 - Light Guide Plate, Backlight Unit And Liquid Crystal Display Device Including The Same - Google Patents

Abstract

The present invention relates to a light guide plate including a light absorber, and a backlight unit and a liquid crystal display device including the same, wherein the light absorption layer absorbs light in a wavelength range between red and green. Accordingly, an overlapping region between the red and green wavelength bands of light emitted from the light emitting diode package can be removed, and the color gamut of the liquid crystal display can be improved by realizing pure red and green colors. The light absorber may be variously positioned such as on the upper surface or side surface of the light guide plate.

Description

A light guide plate and a backlight unit and liquid crystal display device including the same {Light Guide Plate, Backlight Unit And Liquid Crystal Display Device Including The Same}

The present invention relates to a liquid crystal display device, and more particularly, to a backlight unit capable of implementing a high color gamut by using a light guide plate including a light absorber absorbing light of a specific wavelength, and to a liquid crystal display device including the same.

A liquid crystal display (LCD) device includes two substrates and a liquid crystal layer formed between the two substrates, and displays an image by transmitting light by adjusting the arrangement of liquid crystal molecules in the liquid crystal layer.

In general, a liquid crystal display device includes a plurality of pixels arranged in a matrix form, and each pixel includes a thin film transistor, a pixel electrode, and a common electrode. By applying a voltage to the pixel electrode and the common electrode of each pixel, an electric field is generated between the pixel electrode and the common electrode, and the liquid crystal molecules of the liquid crystal layer are rearranged by the generated electric field, thereby changing the transmittance of the liquid crystal layer. Therefore, the transmittance of the liquid crystal layer of each pixel can be adjusted to have a value corresponding to the image signal by controlling the voltage applied to the pixel electrode and the common electrode of the liquid crystal display device, and as a result, the liquid crystal display device displays an image.

Since such a liquid crystal display device is not a self-luminous device, light must be supplied separately. Accordingly, the liquid crystal display includes a liquid crystal panel displaying an image and a backlight unit supplying light to the liquid crystal panel.

The backlight unit includes a light source, and a fluorescent lamp such as a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL) has been used as a light source for the backlight unit. .

The backlight unit may be divided into a direct type and an edge type according to a path of light emitted from the lamp. The direct backlight unit is a method of directly supplying light emitted from the lamps to the liquid crystal panel by arranging a plurality of lamps under the liquid crystal panel. The side-type backlight unit is a method of indirectly supplying light emitted from the lamp to the liquid crystal panel by disposing a light guide plate under the liquid crystal panel and disposing the lamp on at least one side of the light guide plate, using refraction and reflection of light in the light guide plate.

Recently, side-type backlight units are widely used according to the trend of thinning and lightening of liquid crystal displays, and light emitting diode (LED) lamps, which have advantages in power consumption, weight, and brightness, are used as light sources of backlight units. are replacing

1 is a schematic cross-sectional view of a liquid crystal display device including a conventional side-type backlight unit.

As shown in FIG. 1, a conventional liquid crystal display device includes a liquid crystal panel 10, a backlight unit 20, a main frame 30, a top frame 40, and a bottom frame 50.

The liquid crystal panel 10 includes a lower substrate 12 and an upper substrate 14, and a liquid crystal layer (not shown) is positioned between the two substrates 12 and 14. A lower polarizing plate 18 is disposed below the lower substrate 12 , and an upper polarizing plate 19 is disposed above the upper substrate 14 .

A driver (not shown) including a driver integrated circuit (driver IC) is connected to one side of the liquid crystal panel 10 to transmit signals to a plurality of pixels (not shown) inside the liquid crystal panel 10. supply

A backlight unit 20 is positioned under the liquid crystal panel 10, and the backlight unit 20 includes a reflective sheet 22, a light guide plate 24, and an optical sheet 26 sequentially disposed from the bottom. Meanwhile, on one side of the light guide plate 24, a light emitting diode (LED) assembly 28 is disposed as a light source. The LED assembly 28 includes an LED printed circuit board 28a and an LED package 28b.

The main frame 30 surrounds the sides of the liquid crystal panel 10 and the backlight unit 20, together with the top frame 40 on the front side of the liquid crystal panel 10 and the bottom frame 50 on the back side of the backlight unit 20. are combined to form modules.

However, since such a conventional liquid crystal display device has a relatively low color gamut and cannot express many colors, it is difficult to display a high-quality image.

2 is a diagram showing the color gamut of a conventional liquid crystal display on a CIE 1976 chromaticity distribution diagram, and also shows the digital cinema initiative (DCI) color standard.

In general, in order to implement a high color gamut, the color gamut of the display device must have an overlap ratio of 95% or more compared to the DCI color standard (DCI). However, as shown in FIG. 2, the color gamut (NCG) of the conventional liquid crystal display has an area smaller than that of the DCI color standard (DCI) and an overlap ratio of about 81.0%. Therefore, it is difficult to implement a high color gamut in the conventional liquid crystal display.

The present invention has been proposed to solve the above problems, and is intended to solve the problem of low color gamut of a liquid crystal display device.

In order to achieve the above object, a liquid crystal display device according to the present invention, a liquid crystal panel including first and second substrates, and first and second polarizing plates respectively positioned on outer surfaces of the first and second substrates, and a backlight unit located below the liquid crystal panel and including a light emitting diode package and a light guide plate. The light emitting diode package includes a blue light emitting diode chip and yellow and red phosphors, and the light guide plate absorbs light in a wavelength range between red and green. It contains a light absorber that

At this time, the light emitting diode package adjusts the total content and mixing ratio of the yellow and red phosphors to relatively lower the intensity of emitted blue light, relatively increase the intensity of yellow and red light, and reduce the amount of light emitted from the light emitting diode package through the light absorbing layer. By eliminating the overlapping region between the red and green wavelength bands, pure red and green colors are achieved.

The light absorber of the present invention may be located on one surface of the light guide plate from which light is emitted or may be located on one surface of the light guide plate from which light is incident.

In the present invention, the total content and mixing ratio of yellow and red phosphors of a light emitting diode package including a blue light emitting diode chip are adjusted, and a light guide plate containing a light absorber absorbing light in a wavelength range between red and green is applied to change parts. It is possible to implement a liquid crystal display device having a high color gamut by minimizing and using a simple method.

Since the light guide plate including the light absorber can be manufactured at a relatively low cost, an increase in manufacturing cost of the liquid crystal display device can be minimized, and thus price competitiveness can be improved.

In addition, the light absorber can be applied in various locations, such as the top or side surface of the light guide plate, and can be manufactured in the form of a laminated film through co-extrusion molding or in the form of a sheet or film containing an adhesive, increasing the degree of freedom in design. can

1 is a schematic cross-sectional view of a liquid crystal display device including a conventional side-type backlight unit.
2 is a diagram showing the color gamut of a conventional liquid crystal display on a CIE 1976 chromaticity distribution chart.
3 is an exploded perspective view schematically illustrating a liquid crystal display device according to a first embodiment of the present invention.
4 is a schematic cross-sectional view of a liquid crystal display device according to a first embodiment of the present invention.
Figure 5a is a perspective view schematically showing the structure of the LED package according to the first embodiment of the present invention, Figure 5b is a cross-sectional view schematically showing the structure of the LED package according to the first embodiment of the present invention.
Figure 6a is a diagram showing the emission spectrum of the LED package of the liquid crystal display according to the first embodiment of the present invention, Figure 6b is the absorption spectrum of the light absorber of the light guide plate in the liquid crystal display according to the first embodiment of the present invention FIG. 6C is a diagram showing the spectrum of light passing through the LED package and the light guide plate of the liquid crystal display device according to the first embodiment of the present invention.
7 is a diagram showing the color gamut of the liquid crystal display according to the first embodiment of the present invention on a CIE 1976 chromaticity distribution chart.
8 is a schematic cross-sectional view of a light guide plate including a light absorber according to a first embodiment of the present invention.
9 is a schematic cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention.
10 is a schematic cross-sectional view of a second layer of a light guide plate including a light absorber according to a second embodiment of the present invention.
11 is a schematic cross-sectional view of a second layer of a light guide plate including another example of a light absorber according to a second embodiment of the present invention.

The liquid crystal display device of the present invention includes a liquid crystal panel for displaying an image, and a backlight unit located under the liquid crystal panel and including a light source and a light guide plate, wherein the light source includes a first light emitting body having a first peak wavelength, A second light emitting body having a second peak wavelength greater than the first peak wavelength, and a third light emitting body having a third peak wavelength greater than the second peak wavelength, wherein the light guide plate comprises a first layer and one surface of the first layer. and a second layer positioned on the second layer, and the second layer includes a light absorber having an absorption peak between the second peak wavelength and the third peak wavelength.

Weight mixing ratios of the second light-emitting body and the third light-emitting body may be 55% and 45%, respectively.

The light source may further include a resin layer, the second luminous body and the third luminous body are located in the resin layer, and a total content of the second luminous body and the third luminous body may be 5.8 wt% of the content of the resin layer. .

The second layer may be located between the first layer and the liquid crystal panel or between the light source and the first layer.

Meanwhile, the backlight unit of the present invention includes a light source and a light guide plate having one side facing the light source, wherein the light source includes a first light emitting body having a first peak wavelength and a second peak wavelength greater than the first peak wavelength. A second light emitting body having a and a third light emitting body having a third peak wavelength greater than the second peak wavelength, wherein the light guide plate includes a first layer and a second layer positioned on one surface of the first layer, The second layer includes a light absorber having an absorption peak between the second peak wavelength and the third peak wavelength.

The first light emitting body may include a light emitting diode chip, the second light emitting body may include a first phosphor, and the third light emitting body may include a second phosphor.

The weight mixing ratio of the first phosphor and the second phosphor may be 55% and 45%, respectively.

The light source may further include a resin layer, the first phosphor and the second phosphor may be located in the resin layer, and a total content of the first phosphor and the second phosphor may be 5.8 wt% of the content of the resin layer. .

The light emitting diode chip may be a blue light emitting diode chip, the first phosphor may be a yellow phosphor, and the second phosphor may be a red phosphor.

The backlight unit may further include an optical sheet positioned above the light guide plate, and the second layer may be positioned between the first layer and the optical sheet or between the light source and the first layer.

The light absorber includes a metal coordination-tetraazapophyrin compound of the following formula, M is Ni, Mg, Mn, CO, Cu, Ru, or V, or Mn coordinated with at least one ligand selected from ammonia, water, and a halogen atom. or Ru, each of R1, R2, R3, and R4 is independently selected from a C1-C10 alkyl group or a C6-C30 aromatic group, and each of a, b, c, and d may be 1 or 2.

chemical formula

Meanwhile, the light guide plate for a backlight unit of the present invention includes a first layer and a second layer disposed on one surface of the first layer and including a light absorber absorbing light in a wavelength range between red and green, wherein the light absorber is It includes the metal coordination-tetraazapoporphyrin compound of the above-mentioned chemical formula.

The second layer may further include a binder, and the content of the metal coordination-tetraazapophyrin compound may be 0.6 to 1.2 wt% based on the binder.

One surface of the first layer may be a light emission surface. Alternatively, one surface of the first layer may be an incident surface of light.

Hereinafter, a liquid crystal display device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

-First Embodiment-

3 is an exploded perspective view schematically illustrating a liquid crystal display according to a first embodiment of the present invention, and FIG. 4 is a cross-sectional view schematically illustrating a liquid crystal display according to the first embodiment of the present invention.

3 and 4, the liquid crystal display device according to the first embodiment of the present invention includes a liquid crystal panel 110, a backlight unit 120, a main frame 130, a top frame 140, And a bottom frame 150 is included.

The liquid crystal panel 110 displays an image, and includes a first substrate 112 at the bottom, a second substrate 114 at the top, and a liquid crystal layer (not shown) positioned between the two substrates 112 and 114. , First and second polarizers 118 and 119 positioned outside the first substrate 112 and the second substrate 114, respectively.

Although not shown, the first substrate 112 includes a plurality of gate lines and data lines on an inner surface, and the gate lines and data lines intersect to define a plurality of pixel areas. In each pixel area, a thin film transistor connected to a gate line and a data line and a pixel electrode connected to the thin film transistor are positioned. This first substrate 112 is referred to as a lower substrate or an array substrate.

Also, although not shown, the second substrate 114 includes a black matrix and a color filter layer on an inner surface. The black matrix has openings corresponding to pixel areas, and red, green, and blue color filter patterns of the color filter layer are sequentially positioned corresponding to the openings of the black matrix. This second substrate 114 is referred to as an upper substrate or a color filter substrate.

Meanwhile, a common electrode is formed on the first substrate 112 or the second substrate 114 to form a liquid crystal capacitor together with the pixel electrode and the liquid crystal layer. For example, the common electrode may be formed in the pixel region of the first substrate 114 together with the pixel electrode, and in this case, the common electrode and the pixel electrode may be patterned in a bar shape and positioned alternately.

The first and second polarizers 118 and 119 are attached to outer surfaces of the first substrate 112 and the second substrate 114 to selectively transmit specific light. The first and second polarizers 118 and 119 transmit only linearly polarized light parallel to each light transmission axis and absorb linearly polarized light perpendicular thereto, and the light transmission axis of the first polarizer 118 and the second polarizer ( 119) are disposed perpendicular to each other.

A driver integrated circuit (driver IC) 116 is attached to at least one edge of the liquid crystal panel 110 via a connecting member such as a tape carrier package (TCP). ) is connected to a printed circuit board (PCB) 117. The printed circuit board 117 is bent during the modularization process and placed on the side of the main frame 130 or the rear surface of the bottom frame 150 .

A backlight unit 120 is disposed below the liquid crystal panel 110 , and the backlight unit 120 supplies light to the liquid crystal panel 110 . The backlight unit 120 includes a reflective sheet 122 , a light guide plate 124 , an optical sheet 126 , and a light emitting diode (LED) assembly 128 .

The LED assembly 128 is a light source of the backlight unit 120, and the LED assembly 128 includes an LED printed circuit board 128a and a plurality of LED packages 128b. The LED package 128b is mounted on one surface of the LED printed circuit board 128a and is positioned at regular intervals along the length direction of the LED printed circuit board 128a. Although a structure in which the LED packages 128b are arranged in one line is presented here, the LED packages 128b may be arranged in two lines or more.

The LED package 128b according to the first embodiment of the present invention includes a blue (B) LED chip, a yellow (Y) phosphor, and a red (R) phosphor to emit white light, which will be described in detail later.

The LED assembly 128 is disposed on one side of the light guide plate 124 and may be positioned corresponding to a short side of the light guide plate 124 . The light guide plate 124 transfers the light emitted from each of the plurality of LED packages 128a and incident to the inside through one side of the light guide plate 124 to the front surface through reflection and refraction, thereby increasing the efficiency of the LED package 128a. It plays a role in realizing the light from the surface light source. Here, one side of the light guide plate 124 on which light is incident is referred to as a light incident surface.

The light guide plate 124 includes a first layer 124a and a second layer 124b over the first layer 124a.

The first layer 124a of the light guide plate 124 may include a pattern having a specific shape on the rear surface to supply a uniform surface light source, and the second layer 124b of the light guide plate 124 is red and green. It includes a light absorber that absorbs light in the wavelength range between, which will be described in detail later.

The reflective sheet 122 is positioned on the rear surface of the light guide plate 124 and reflects light passing through the rear surface of the light guide plate 124 toward the liquid crystal panel 110 to improve the luminance of light.

An optical sheet 126 is positioned above the light guide plate 124 . The optical sheet 126 includes a diffusion sheet and at least one light collecting sheet, and diffuses or concentrates the light passing through the light guide plate 124 so that a more uniform surface light source is incident on the liquid crystal panel 110 . The optical sheet 126 may include first to third optical sheets 126a, 126b, and 126c sequentially disposed on the light guide plate 124 .

For example, each of the first and second optical sheets 126a and 126b may be a light collecting sheet, and the third optical sheet 126c may be a diffusion sheet. The light collecting sheet may include a prism pattern or a lenticular pattern. The first optical sheet 126a may include a lenticular pattern, and the second optical sheet 126b may include a prism pattern.

Meanwhile, the third optical sheet 126c may be a luminance enhancing film. The brightness enhancement film may have a structure in which layers having different refractive indices are alternately stacked.

The liquid crystal panel 110 and the backlight unit 120 are modularized through the main frame 130 , the top frame 140 , and the bottom frame 150 .

The main frame 130 is formed in a quadrangular frame shape and includes a vertical portion and a horizontal portion. The liquid crystal panel 110 is positioned above the horizontal portion of the main frame 130 , the backlight unit 120 is positioned below, and the vertical portion of the main frame 130 surrounds the side of the liquid crystal panel 110 .

The bottom frame 150 includes a horizontal surface on which the backlight unit 120 is seated and a side surface perpendicular thereto. An LED assembly 128 is positioned on the side of the bottom frame 150 .

In addition, the top frame 140 has a square frame shape and has a cross section of an “L” shape to cover the front edge and side surface of the liquid crystal panel 110 . The top frame 140 includes an opening at the center of the front surface so that an image implemented in the liquid crystal panel 110 is displayed outside through the opening.

The top frame 140, the main frame 130, and the bottom frame 150 are assembled and fastened to each other, so that the liquid crystal display device of the present invention is modularized. In this case, the top frame 140 may be omitted.

Here, the top frame 140 is also referred to as a case top, top case, or top cover, the main frame 130 is also referred to as a guide panel or a main support, and the bottom frame 150 is referred to as a cover bottom or bottom cover. also lose

As mentioned above, the liquid crystal display device according to the first embodiment of the present invention includes a blue (B) LED chip, and an LED package 128b including a yellow (Y) phosphor and a red (R) phosphor, This LED package 128b will be described in more detail below.

Figure 5a is a perspective view schematically showing the structure of the LED package according to the first embodiment of the present invention, Figure 5b is a cross-sectional view schematically showing the structure of the LED package according to the first embodiment of the present invention.

5A and 5B, the LED package 128b according to the first embodiment of the present invention includes an LED chip 210, a resin layer 220 including a phosphor, and a mold frame 230. do.

The LED chip 210 may include first and second chips 210a and 210b, each of which emits blue light. Each of the first and second chips 210a and 210b is electrically connected to the LED printed circuit board ( 128a in FIG. 3 ) through wire bonding. Although the case where the first and second chips 210a and 210b are used is described here, the number of chips is not limited thereto.

The mold frame 230 has a cavity therein, and the first and second chips 210a and 210b are positioned in the cavity. More specifically, the first and second chips 210a and 210b are spaced apart from each other on the bottom surface of the mold frame 230 corresponding to the cavity, and the side surface of the mold frame 230 corresponding to the cavity is an oblique reflective surface 230a to send light from the first and second chips 210a and 210b upward. Here, the cavity may further include concave portions respectively corresponding to the first and second chips 210a and 210b.

Although not shown, the mold frame 230 may include a lower frame and an upper frame separated, and a lead frame may be positioned between the lower frame and the upper frame. The lead frame is connected to the first and second chips 210a and 210b and serves to apply a voltage so that recombination of electrons and holes occurs in each of the first and second chips 210a and 210b.

A resin layer 220 containing a phosphor is formed in the cavity to cover the first and second chips 210a and 210b. For example, the phosphor may be dispersed in a silicone resin. In addition, the phosphor may include a yellow (Y) phosphor and a red (R) phosphor.

Here, each of the first and second chips 210a and 210b has a peak wavelength region of about 444 nanometers (nm), the yellow (Y) phosphor has a peak wavelength region of about 540 nanometers, and the red (R) phosphor has a peak wavelength region of about 540 nanometers. The phosphor has a peak wavelength region of about 650 nanometers.

The LED package 128b according to the first embodiment of the present invention relatively lowers the intensity of blue and increases the intensity of yellow and red, compared to a general LED package. To this end, the total content of the yellow (Y) phosphor and the red (R) phosphor is preferably about 5.8 wt% of the content of the resin layer 220 . At this time, it is preferable that the weight mixing ratio of the yellow (Y) phosphor and the red (R) phosphor is 55% and 45%, respectively.

However, in such an LED package 128b, an overlapping region exists between red and green lights, and thus the color gamut of the liquid crystal display device deteriorates. Therefore, in the liquid crystal display device according to the first embodiment of the present invention including the LED package 128b, the light guide plate 124 includes a light absorber to absorb light in a wavelength range between red and green, so that the liquid crystal display device can increase the color gamut.

In this case, the light absorber may include a material having an absorption peak in a wavelength region of 590 nanometers. For example, the light absorber includes a metal coordination-tetra-azaporphyrin compound represented by Chemical Formula 1 below.

chemical formula 1

Here, M is Ni, Mg, Mn, CO, Cu, Ru, or V, or Mn or Ru coordinated with one or more ligands selected from ammonia, water, and halogen atoms. In addition, each of R1, R2, R3, R4 may be independently selected from a C1-C10 alkyl group or a C6-C30 aromatic group, and each of a, b, c, and d is It can be 1 or 2. For example, the alkyl group may be a methyl, ethyl, propyl, or butyl group, and the aromatic group may be a phenyl group.

Figure 6a is a diagram showing the emission spectrum of the LED package of the liquid crystal display according to the first embodiment of the present invention, Figure 6b is the absorption spectrum of the light absorber of the light guide plate in the liquid crystal display according to the first embodiment of the present invention FIG. 6C is a diagram showing the spectrum of light passing through the LED package and the light guide plate of the liquid crystal display device according to the first embodiment of the present invention.

As shown in FIG. 6A, light emitted from the LED package of the liquid crystal display according to the first embodiment of the present invention has a blue peak wavelength, and an overlapping region exists in a wavelength band between red and green.

On the other hand, as shown in FIG. 6B, in the liquid crystal display according to the first embodiment of the present invention, the light absorber of the light guide plate has a strong absorption peak in a wavelength band between red and green.

Therefore, when the light emitted from the LED package of the liquid crystal display according to the first embodiment of the present invention passes through the light guide plate including the light absorber, as shown in FIG. can be removed, and pure red and green colors can be implemented.

The color gamut of the liquid crystal display including the LED package and the light guide plate is shown in FIG. 7 . FIG. 7 is a diagram showing the color gamut of the liquid crystal display according to the first embodiment of the present invention on a CIE 1976 chromaticity distribution chart, and also shows the digital cinema initiative (DCI) color standard.

The CIE 1976 chromaticity distribution diagram is a chromaticity coordinate system proposed to improve the problem of the uniformity of the isochromatic intervals on the visual and the isochromatic intervals on the coordinates, which are the disadvantages of the XYZ chromaticity coordinates. It shows human color perception with u' and v'. Similar distances on this CIE 1976 chromaticity distribution represent similar perceived color differences.

As shown in FIG. 7, the color gamut (LAS) of the liquid crystal display including the LED package and the light guide plate according to the first embodiment of the present invention has a high color gamut with an overlap ratio of 95% with the DCI color standard (DCI). can be implemented

As such, the liquid crystal display device according to the first embodiment of the present invention adjusts the total content and mixing ratio of yellow (Y) and red (R) phosphors of the LED package including the blue (B) LED chip, and red and green High color reproduction can be implemented at a relatively low cost by using a light guide plate including a light absorber that absorbs light in an inter-wavelength range.

On the other hand, the white condition of the liquid crystal display used in the TV requires the CIE 1931 standard (Wx, Wy) = (0.278, 0.288) color coordinates and a color temperature of 10,000K. The white color condition according to the DCI color standard can be satisfied within the error range of ±0.015 by using the light guide plate.

In addition, the relative light efficiency of light emitted from the LED package and passing through the light guide plate containing the light absorber is about 70% or more, and the decrease in luminance is relatively low, thereby preventing an increase in power consumption.

8 is a schematic cross-sectional view of a light guide plate including a light absorber according to a first embodiment of the present invention.

As shown in FIG. 8 , the light guide plate 124 according to the first embodiment of the present invention includes a first layer 124a and a second layer 124b over the first layer 124a.

Here, the first layer 124a may include a pattern having a specific shape on the rear surface to supply a uniform surface light source. For example, in order to guide light incident into the light guide plate 124, the first layer 124a of the light guide plate 124 may have an elliptical pattern, a polygon pattern, or a hologram pattern ( hologram pattern), etc., and such a pattern may be formed on the lower surface of the first layer 124a of the light guide plate 124 by a printing method or an injection method.

In addition, the second layer 124b of the light guide plate 124 includes a light absorber 100 that absorbs light in a wavelength range between red and green, and the light absorber 100 may be distributed in a binder. The light absorber 100 may include a metal coordination-tetraazapoporphyrin compound of Chemical Formula 1.

In this case, the binder may be made of acrylic, and the metal coordination-tetraazapophyrin compound may be included in an amount of 0.6 to 1.2 wt% based on the acrylic binder.

When the content of the metal coordination-tetraazapophyrin compound is greater than 1.2 wt%, the intensity of the absorption spectrum in the 590 nanometer wavelength region increases, thereby increasing the light absorption rate in the 590 nanometer wavelength region. Accordingly, the color reproducibility is improved, but the luminance is lowered.

On the other hand, when the content of the metal coordination-tetraazapophyrin compound is less than 0.6 wt%, the intensity of the absorption spectrum in the 590 nanometer wavelength region is reduced, resulting in a decrease in light absorption in the 590 nanometer wavelength region. Accordingly, the luminance increases, but the color reproducibility decreases.

Here, preferably, the metal coordination-tetraazapophyrin compound may be included in an amount of 0.8 to 1.1 wt% based on the acrylic binder, and more preferably, it may be included in an amount of about 1.0 wt%.

The second layer 124b of the light guide plate 124 may have a thickness smaller than that of the first layer 124a. Alternatively, the first layer 124a and the second layer 124b may have the same thickness.

The first layer 124a and the second layer 124b of the light guide plate 124 may be made of the same material. For example, the first layer 124a and the second layer 124b of the light guide plate 124 may be made of polymethyl methacrylate (PMMA), and the polymethyl methacrylate that does not include the light absorber 100 The first layer 124a and the second layer 124b may be formed by simultaneously extruding methacrylate and polymethyl methacrylate containing the light absorber 100, respectively. Therefore, no adhesive or adhesive is located between the first layer 124a and the second layer 124b, and the first layer 124a and the second layer 124b are in direct contact.

Alternatively, the first layer 124a and the second layer 124b of the light guide plate 124 may be made of polycarbonate (PC), and the material of the light guide plate 124 is not limited thereto.

Meanwhile, the first layer 124a and the second layer 124b of the light guide plate 124 may be formed of different materials.

As described above, the light guide plate 124 according to the first embodiment of the present invention includes a second layer 124b including a light absorber on the upper surface of the first layer 124a, so that red and green light from the LED package are included. The color reproduction rate of the liquid crystal display device can be increased by removing the overlapping region of the wavelength band between the two regions.

-Second Embodiment-

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

As shown in FIG. 9, the liquid crystal display device according to the second embodiment of the present invention includes a liquid crystal panel 310, a backlight unit 320, a main frame 330, a top frame 340, and a bottom frame 350. ).

The liquid crystal panel 310 includes a lower first substrate 312 and an upper second substrate 314, and a liquid crystal layer (not shown) is positioned between the two substrates 312 and 314.

A first polarizer 318 and a second polarizer 319 are attached to the outside of the liquid crystal panel 310, that is, to the lower portion of the first substrate 312 and the upper portion of the second substrate 314, respectively. Light transmission axes of the first polarizer 318 and the second polarizer 319 are disposed perpendicular to each other.

A backlight unit 320 is positioned under the liquid crystal panel 310 to supply light to the liquid crystal panel 310 . The backlight unit 320 includes a reflective sheet 322 , a light guide plate 324 , an optical sheet 326 , and an LED assembly 328 .

The LED assembly 328 is disposed at one side of the light guide plate 324 and is spaced apart from the light guide plate 324, and the LED assembly 328 includes an LED printed circuit board 328a and an LED package 328b. The LED package 328b is mounted on one side of the LED printed circuit board 328a and faces one side of the light guide plate 324 .

The LED package 328b includes a blue (B) LED chip having a peak wavelength of about 444 nanometers, a yellow (Y) phosphor having a peak wavelength of about 540 nanometers, and a peak wavelength of about 650 nanometers. It may include a red (R) phosphor having

The LED package 328b according to the second embodiment of the present invention relatively lowers the intensity of blue and increases the intensity of yellow and red, compared to a general LED package. To this end, the total content of the yellow (Y) phosphor and the red (R) phosphor is preferably about 5.8 wt% of the resin layer content. At this time, it is preferable that the weight mixing ratio of the yellow (Y) phosphor and the red (R) phosphor is 55% and 45%, respectively.

The LED package 328b according to the second embodiment of the present invention may have the same structure as the LED package 128b shown in FIGS. 5A and 5B.

The light guide plate 324 serves to realize the light from the LED package 328a as a surface light source. The light guide plate 324 includes a first layer 324a and a second layer 324b. At this time, the second layer (324b) is located on one side of the first layer (324a), that is, the side facing the LED assembly (328). Accordingly, the second layer 324b is positioned between the LED assembly 328 and the first layer 324a of the light guide plate 324 .

In order to supply a uniform surface light source, a plurality of patterns (not shown) may be formed on the rear surface, ie, the lower surface, of the first layer 324a of the light guide plate 324 . In addition, the second layer 324b of the light guide plate 324 includes a light absorber that absorbs light in a wavelength band between red and green, which will be described in detail later.

The reflective sheet 322 is positioned under the light guide plate 324 to reflect light passing through the rear surface of the light guide plate 324 toward the liquid crystal panel 310, thereby improving the luminance of the light.

An optical sheet 326 is positioned above the light guide plate 324, and the optical sheet 326 may include first to third optical sheets 326a, 326b, and 326c sequentially disposed on the light guide plate 324. . The first to third optical sheets 326a, 326b, and 326c diffuse or condense the light from the light guide plate 324.

The first and second optical sheets 326a and 326b may include light collecting sheets, and the third optical sheet 326c may include a dual luminance enhancement film. The light collecting sheet may include a prism pattern or a lenticular pattern, and the dual brightness enhancement film may have a structure in which layers having different refractive indices are alternately stacked.

Next, the side of the backlight unit 320 is surrounded by a square main frame 330 , and the edge of the liquid crystal panel 310 is placed on the main frame 330 .

The top frame 340 has a -shaped cross section including the front and side surfaces, and has an opening at the center of the front surface, covering the front edge and side surface of the liquid crystal panel 310 .

The bottom frame 350 is located on the rear surface of the backlight unit 320 and is combined with the top frame 340 via the main frame 330 to form a module.

10 is a schematic cross-sectional view of a second layer of a light guide plate including a light absorber according to a second embodiment of the present invention.

As shown in FIG. 10, the second layer 324b of the light guide plate according to the second embodiment of the present invention includes a light absorbing layer 410, a base film 420, and an adhesive layer 430. This second layer 324b may be in the form of a sheet or film.

The base film 420 may be made of polyethylene terephthalate or polycarbonate.

The light absorption layer 410 is positioned on the first surface of the base film 420, that is, the surface facing the LED assembly (328 in FIG. 9). The light absorbing layer 410 includes a binder and the light absorbing agent 100 distributed in the binder. The binder may be made of acrylic, and the light absorber 400 includes a material that absorbs light in a wavelength band between red and green. The light absorber 400 has an absorption peak in a wavelength region of 590 nanometers, and may include a metal coordination-tetraazapophyrin compound of Chemical Formula 1.

The adhesive layer 430 is positioned on the second surface of the base film 420, that is, the surface facing the first layer (324a in FIG. 9) of the light guide plate, and the second layer 324b of the light guide plate is the adhesive layer 430. It is attached to one side of the first layer (324a in FIG. 10) of the light guide plate by The adhesive layer 430 may include pressure sensitive adhesive (PSA).

As such, in the liquid crystal display device according to the second embodiment of the present invention, the second layer 324b including the light absorber 100 is attached to one side of the first layer (324a in FIG. 9) of the light guide plate, thereby increasing the color gamut. can increase

At this time, the second layer 324b of the light guide plate including the light absorber 100 according to the second embodiment of the present invention has a smaller area and have volume Therefore, in order to obtain an effect similar to that of the first embodiment, the amount of the light absorber 100 included in the second layer 324b of the light guide plate according to the second embodiment of the present invention for the same area and volume is The amount of the light absorber 100 included in the second layer ( 124b of FIG. 8 ) of the light guide plate according to the example is preferably larger than that.

11 is a cross-sectional view schematically illustrating a second layer of a light guide plate including another example of a light absorber according to a second embodiment of the present invention.

As shown in FIG. 11 , the second layer 324b of the light guide plate according to the second embodiment of the present invention includes a light absorption layer 510 and a base film 520 .

The base film 520 may be made of polyethylene terephthalate or polycarbonate.

The light absorption layer 510 is positioned on one side of the base film 520, that is, on the side facing the first layer (324a in FIG. 9) of the light guide plate. The light absorbing layer 510 includes a binder and the light absorbing agent 100 distributed in the binder. The binder may be made of acrylic, and the light absorber 100 includes a material that absorbs light in a wavelength band between red and green. The light absorber 800a has an absorption peak in a wavelength region of 590 nanometers, and may include a metal coordination-tetraazaporphyrin compound of Chemical Formula 1.

Here, the light absorption layer 510 may have adhesiveness, and the second layer 324b of the light guide plate is attached to one side of the first layer (324a in FIG. 9 ) of the light guide plate by the light absorption layer 510 . The light absorbing layer 510 may include pressure sensitive adhesive (PSA).

In this way, in the liquid crystal display device including the light guide plate of another example according to the second embodiment of the present invention, the second layer 324b including the light absorber 100 is formed of the first layer (324a in FIG. 9) of the light guide plate. By attaching to one side, the color reproduction rate can be increased. At this time, the light absorbing layer 520 of the second layer 324b is also used as an adhesive layer, thereby reducing materials and simplifying the manufacturing process.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention within the scope not departing from the technical spirit and scope of the present invention described in the claims below. You will understand that it can be done.

110: liquid crystal panel 112: first substrate
114: second substrate 118: first polarizing plate
119: second polarizing plate 120: backlight unit
122: reflective sheet 124: light guide plate
124a: first layer 124b: second layer
126: optical sheet 128: LED assembly
130: main frame 140: top frame
150: bottom frame 210: LED chip
220: resin layer 230: mold frame

Claims (19)

a liquid crystal panel displaying an image;
A backlight unit located under the liquid crystal panel and including a light source and a light guide plate
including,
The light source includes a first luminous material having a first peak wavelength, a second luminous material having a second peak wavelength greater than the first peak wavelength, and a third luminous material having a third peak wavelength greater than the second peak wavelength. and
The light guide plate includes a first layer and a second layer positioned on one surface of the first layer, the second layer includes a light absorber having an absorption peak between the second peak wavelength and the third peak wavelength, ,
The first luminous body includes a light emitting diode chip, the second luminous body includes a first phosphor, and the third luminous body includes a second phosphor,
The light emitting diode chip is a blue light emitting diode chip, the first phosphor is a yellow phosphor, the second phosphor is a red phosphor,
The weight blending ratio of the first phosphor and the second phosphor is 55% and 45%, respectively,
A liquid crystal display having an overlap ratio of 95% with the digital cinema initiative (DCI) color standard on the CIE 1976 chromaticity distribution.
delete According to claim 1,
The light source further includes a resin layer, the second luminous body and the third luminous body are located in the resin layer, and the total content of the second luminous body and the third luminous body is 5.8 wt% of the content of the resin layer. Device.
According to any one of claims 1 and 3,
The light absorber includes a metal coordination-tetraazapoporphyrin compound of the following formula,
chemical formula

M is Ni, Mg, Mn, CO, Cu, Ru, or V, or Mn or Ru coordinated with one or more ligands selected from ammonia, water, and halogen atoms, and each of R1, R2, R3, and R4 is independently C1~ A liquid crystal display device selected from a C10 alkyl group or a C6-C30 aromatic group, and each of a, b, c, and d is 1 or 2.
According to claim 4,
The second layer further includes a binder, and the content of the metal coordination-tetraazapophyrin compound is 0.6 to 1.2 wt% based on the binder.
According to claim 4,
The second layer is positioned between the first layer and the liquid crystal panel.
According to claim 4,
The second layer is positioned between the light source and the first layer.
According to claim 7,
The second layer includes a light absorption layer, a base film, and an adhesive layer,
The base film is located between the light absorption layer and the adhesive layer, and the adhesive layer is located between the base film and the first layer,
The light absorbing layer includes the light absorbing agent.
According to claim 7,
The second layer includes a light absorption layer and a base film,
The light absorbing layer is located between the base film and the first layer, includes the light absorbing agent, and has adhesiveness.
According to claim 1,
Wherein the first layer and the second layer are made of the same material.
According to claim 10,
The liquid crystal display device in which the first layer and the second layer are in direct contact.
According to claim 1,
The liquid crystal display device wherein the first layer and the second layer have the same thickness. delete delete delete delete delete delete delete

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