KR102272351B1 - Backlight Unit And Liquid Crystal Display Device Including The Same - Google Patents

Abstract

The present invention relates to a backlight unit including a light absorber and a liquid crystal display including the same, wherein the light absorber absorbs light in a wavelength range between red and green. Accordingly, the overlapping region between the red and green wavelength bands of light emitted from the chip and the phosphor of the light emitting diode package can be removed, and the color gamut of the liquid crystal display can be increased by realizing pure red and green. Such a light absorber may be variously located in the light emitting diode package.

Description

Backlight Unit And Liquid Crystal Display Device Including The Same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a backlight unit having a high color reproducibility including a light absorber absorbing light of a specific wavelength, and 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 controlling 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. Accordingly, by controlling the voltages applied to the pixel electrode and the common electrode of the liquid crystal display, the transmittance of the liquid crystal layer of each pixel can be adjusted to have a value corresponding to the image signal, and as a result, the liquid crystal display 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 device includes a liquid crystal panel for displaying an image and a backlight unit for 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 the light source of 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 backlight unit is a method of indirectly supplying light emitted from the lamp to the liquid crystal panel by arranging a light guide plate under the liquid crystal panel and placing the lamp on at least one side of the light guide plate, using refraction and reflection of light in the light guide plate.

Recently, in accordance with the trend of thinner and lighter liquid crystal display devices, a light emitting diode (LED) lamp having advantages in power consumption, weight, luminance, etc. as a light source of a backlight unit is replacing a fluorescent lamp.

1 is a cross-sectional view schematically illustrating a liquid crystal display including a conventional side-type backlight unit.

As shown in FIG. 1 , the conventional liquid crystal display 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 under 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) in 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 arranged from the bottom. Meanwhile, a light emitting diode (LED) assembly 28 is disposed on one side of the light guide plate 24 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 side surfaces of the liquid crystal panel 10 and the backlight unit 20 , together with the top frame 40 on the front of the liquid crystal panel 10 and the bottom frame 50 on the back of the backlight unit 20 . combined to form a module.

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

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

In general, in order to realize a high color gamut, the color gamut of a display device should 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 a smaller area than the DCI color standard (DCI), and the overlap ratio is about 81.0%. Therefore, it is difficult for the conventional liquid crystal display device to realize a high color reproducibility.

The present invention has been proposed to solve the above problems, and aims 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 includes a liquid crystal panel, a backlight unit located under the liquid crystal panel, the backlight unit including a light emitting diode package, the light emitting diode package including a blue light emitting diode chip and It includes yellow and red phosphors, and the light emitting diode package further includes a light absorber that absorbs light in a wavelength range between red and green.

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, and the intensity of yellow and red light is relatively high. By removing the overlapping region between the red and green wavelength bands of the emitted light, pure red and green are achieved.

The light absorber is located in the resin layer of the light emitting diode package.

Alternatively, the light absorber may be positioned on the resin layer of the light emitting diode package.

In this case, the light emitting diode package further includes a transparent substrate on the resin layer, and the transparent substrate is positioned between the light absorber and the resin layer, or the light absorber is positioned between the transparent substrate and the resin layer .

Meanwhile, a lens covering the light emitting diode package may be positioned on the upper portion.

In the present invention, the total content and mixing ratio of yellow and red phosphors of the LED package including the blue chip are adjusted, and the LED package further includes a light absorber that absorbs light in a wavelength range between red and green, thereby minimizing changes in components. And it is possible to implement a liquid crystal display having a high color gamut in a simple way.

Since the LED package including the light absorber can be manufactured at a relatively low cost, the increase in manufacturing cost of the liquid crystal display can be minimized, and thus price competitiveness can be increased.

In addition, the light absorber can be variously applied to be located in the resin layer of the LED package or located on the resin layer, thereby increasing the degree of freedom in design, and when the light absorber is located on the resin layer, heat resistance can be improved.

1 is a cross-sectional view schematically illustrating a liquid crystal display 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 diagram.
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 cross-sectional view schematically illustrating a liquid crystal display 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.
6A is a view illustrating emission spectra of a blue LED chip and yellow and red phosphors in an LED package of a liquid crystal display according to a first embodiment of the present invention, and FIG. 6B is a liquid crystal display according to the first embodiment of the present invention. It is a view showing the absorption spectrum of the light absorber in the LED package of the device, and FIG. 6C is a view showing the spectrum of light emitted from the LED package of the liquid crystal display according to the first embodiment of the present invention.
7 is a view showing the color gamut of the liquid crystal display according to the first embodiment of the present invention on the CIE 1976 chromaticity distribution diagram.
8 is a cross-sectional view schematically illustrating a structure of an LED package according to a second embodiment of the present invention.
9 is a cross-sectional view schematically illustrating a liquid crystal display device according to a third embodiment of the present invention.
10 is an enlarged cross-sectional view illustrating the structure of an LED assembly of a liquid crystal display according to a third exemplary embodiment of the present invention.
11A is a cross-sectional view schematically illustrating a structure of an LED package according to a third embodiment of the present invention, and FIG. 11B is a cross-sectional view schematically illustrating another structure of an LED package according to a third embodiment of the present invention.

The liquid crystal display device of the present invention includes a liquid crystal panel, a backlight unit positioned below the liquid crystal panel and including a light source, wherein the light source includes a first light emitting body having a first peak wavelength and a greater than the first peak wavelength. a second illuminant having a second peak wavelength, and a third illuminant having a third peak wavelength greater than the second peak wavelength, wherein the light source has an absorption peak between the second peak wavelength and the third peak wavelength. It further includes a light absorber having.

The first light-emitting body includes a light emitting diode chip, the second light-emitting body includes a first phosphor, and the third light-emitting body includes a second phosphor.

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

The light source further includes a resin layer, the first phosphor and the second phosphor are located in the resin layer, and the total content of the first phosphor and the second phosphor is 5.8 wt% of the content of the resin layer.

The light absorber is located in the resin layer.

Alternatively, the light absorber is located on the resin layer.

In this case, the light source further includes a transparent substrate on the resin layer, and the transparent substrate is positioned between the light absorber and the resin layer, or the light absorber is positioned between the transparent substrate and the resin layer.

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

The light absorber includes a metal coordination-tetraazaporphyrin compound of the following formula.

chemical formula

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 a halogen atom, and each of R1, R2, R3, and R4 is independently It is selected from a C1-C10 alkyl group or a C6-C30 aromatic group, and each of a, b, c, and d is 1 or 2.

On the other hand, the backlight unit of the present invention includes a light source and an optical sheet over the light source, wherein the light source includes a first light emitting body having a first peak wavelength and a second light having a second peak wavelength greater than the first peak wavelength. 2 illuminants, and a third illuminant having a third peak wavelength greater than the second peak wavelength, wherein the light source further comprises a light absorber having an absorption peak between the second peak wavelength and the third peak wavelength .

The light source further includes a resin layer, and the light absorber is located in the resin layer.

Alternatively, the light source further includes a resin layer, and the light absorber is positioned on the resin layer.

In this case, the light source further includes a transparent substrate on the resin layer, and the transparent substrate is positioned between the light absorber and the resin layer, or the light absorber is positioned between the transparent substrate and the resin layer.

The backlight unit of the present invention further includes a lens covering the light source.

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 showing a liquid crystal display device according to a first embodiment of the present invention, and FIG. 4 is a cross-sectional view schematically showing a liquid crystal display device according to a first embodiment of the present invention.

3 and 4 , the liquid crystal display 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 .

The liquid crystal panel 110 displays an image, the lower first substrate 112 , the upper second substrate 114 , and a liquid crystal layer (not shown) positioned between the two substrates 112 and 114 , and , and first and second polarizing plates 118 and 119 positioned outside each of the first substrate 112 and the second substrate 114 .

Although not shown, the first substrate 112 includes a plurality of gate lines and data lines on the inner surface, and the gate lines and the data lines cross each other 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.

In addition, although not shown, the second substrate 114 includes a black matrix and a color filter layer on the inner surface. The black matrix has an opening corresponding to the pixel area, and the red, green, and blue color filter patterns of the color filter layer are sequentially positioned corresponding to the opening 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 alternately positioned in a bar shape or the like pattern.

The first and second polarizing plates 118 and 119 are attached to the outer surfaces of each of the first and second substrates 112 and 114 to selectively transmit specific light. The first and second polarizing plates 118 and 119 transmit only linearly polarized light parallel to each light transmission axis, and the light transmission axis of the first polarizing plate 118 and the light transmission axis of the second polarizing plate 119 are perpendicular to each other. are placed

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

A backlight unit 120 is disposed under 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 longitudinal direction of the LED printed circuit board 128a. Although the structure in which the LED packages 128b are arranged in one row is presented here, the LED packages 128b may be arranged in two or more rows.

The LED package 128b according to the first embodiment of the present invention emits white light including a blue (B) LED chip, a yellow (Y) phosphor and a red (R) phosphor, and emits light in a wavelength range between red and green. It contains a light absorbing agent that absorbs, 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 to correspond to a short side of the light guide plate 124 . The light guide plate 124 transmits light emitted from each of the plurality of LED packages 128a and incident inside through one side of the light guide plate 124 to the front through reflection and refraction, thereby 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 may include a pattern having a specific shape on its rear surface in order to supply a uniform surface light source. For example, the light guide plate 124 may include an elliptical pattern, a polygon pattern, a hologram pattern, etc. to guide the light incident into the light guide plate 124 . , this pattern may be formed on the lower surface of the light guide plate 124 by a printing method or an injection method.

The reflective sheet 122 is located on the rear surface of the light guide plate 124 , and reflects the light passing through the rear surface of the light guide plate 124 toward the liquid crystal panel 110 to improve the luminance of the 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 condenses 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 enhancement 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 rectangular frame shape, and includes a vertical portion and a horizontal portion. The liquid crystal panel 110 is positioned on the upper horizontal portion of the main frame 130 , the backlight unit 120 is positioned on the lower portion, and the vertical portion of the main frame 130 surrounds the side surface of the liquid crystal panel 110 .

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

In addition, the top frame 140 has a rectangular frame shape, and has a “L”-shaped cross section to cover the front edge and side surfaces of the liquid crystal panel 110 . The top frame 140 includes an opening in the center of the front 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 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, a top case, or a top cover, the main frame 130 is also referred to as a guide panel or a main support, and the bottom frame 150 is also referred to as a cover bottom or a bottom cover. also lose

As mentioned above, the LED package 128b of the liquid crystal display 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. and a light absorber that absorbs light in a wavelength range between red and green, and 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.

As shown in FIGS. 5A and 5B , the LED package 128b according to the first embodiment of the present invention has a resin layer including an LED chip 210 , a phosphor (not shown), and a light absorber 250 . 220 , and a mold frame 230 .

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. Here, a case in which the first and second chips 210a and 210b are used is described, but 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. In more detail, 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 has an oblique reflective surface. It has a 230a to send light from the first and second chips 210a and 210b upwards. Here, the cavity may further include concave portions corresponding to the first and second chips 210a and 210b, respectively.

Although not shown, the mold frame 230 may include a separate lower frame and an upper frame, 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 to cause recombination of electrons and holes in each of the first and second chips 210a and 210b.

A resin layer 220 including a phosphor and a light absorber 250 is formed in the cavity to cover the first and second chips 210a and 210b. For example, the phosphor and the light absorber 250 may be dispersed in a silicone resin. The phosphor may include a yellow (Y) phosphor and a red (R) phosphor, and the light absorber 250 absorbs light in a wavelength range between red and green.

Here, each of the first and second chips 210a and 210b has about 444 nanometers (nm) as a peak wavelength region, the yellow (Y) phosphor has about 540 nanometers as a peak wavelength region, and red (R) 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 . In this case, the weight mixing ratio of the yellow (Y) phosphor and the red (R) phosphor is preferably 55% and 45%, respectively.

However, in the LED package 128b including the blue LED chip and the yellow and red phosphors, an overlapping region exists between the red and green light, and thus the color gamut of the liquid crystal display is reduced. Therefore, in the LED package 128b according to the first embodiment of the present invention, the resin layer 220 includes the light absorber 250 to absorb light in a wavelength band between red and green, thereby increasing the color gamut of the liquid crystal display. can be raised

In this case, the light absorber 250 may have an absorption peak in a wavelength region of 590 nanometers. For example, the light absorber 250 includes a metal coordination-tetra-azaporphyrin compound of Formula 1 below.

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 a halogen atom. 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, d is It may 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.

The metal coordination-tetraazaporphyrin compound may be included in an amount of 0.05 to 0.15 wt% based on the resin layer 220 .

When the content of the metal coordination-tetraazaporphyrin compound is greater than 0.15 wt%, the intensity of the absorption spectrum in the 590 nm wavelength region increases, thereby increasing the light absorption in the 590 nm wavelength region. Accordingly, the color gamut is improved, but the luminance is lowered.

On the other hand, when the content of the metal coordination-tetraazaporphyrin compound is less than 0.05 wt %, the intensity of the absorption spectrum in the 590 nm wavelength region is reduced, and thus the light absorption in the 590 nm wavelength region is reduced. Accordingly, the luminance is increased, but the color gamut is decreased.

Here, preferably, the metal coordination-tetraazaporphyrin compound may be included in an amount of 0.08 to 0.12 wt% based on the acrylic binder, and more preferably, it may be included in an amount of about 0.1 wt%.

6A is a view illustrating emission spectra of a blue LED chip and yellow and red phosphors in an LED package of a liquid crystal display according to a first embodiment of the present invention, and FIG. 6B is a liquid crystal display according to the first embodiment of the present invention. It is a view showing the absorption spectrum of the light absorber in the LED package of the device, and FIG. 6c is a view showing the spectrum of light emitted from the LED package of the liquid crystal display according to the first embodiment of the present invention.

As shown in FIG. 6A , in the LED package of the liquid crystal display according to the first embodiment of the present invention, light emitted from the blue LED chip and yellow and red phosphors has a peak wavelength of blue, and is in a wavelength range between red and green. An overlapping area exists.

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

Accordingly, in the case of light emitted from the LED package of the liquid crystal display according to the first embodiment of the present invention, as shown in FIG. 6c , the overlapping region between the red and green wavelength bands can be removed by the light absorber, Pure red and green can be realized.

The color gamut of the liquid crystal display including such an LED package is shown in FIG. 7 . 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 diagram, and also shows a digital cinema initiative (DCI) color standard.

CIE 1976 chromaticity distribution diagram is a chromaticity coordinate system proposed to improve the uniformity of the visual isochromatic interval and the coordinated isochromatic interval, which is a disadvantage of XYZ chromaticity coordinates, and shows human color perception with u' and v'. Similar distances on this CIE 1976 chromaticity distribution map indicate similarly perceived differences in colors.

As shown in FIG. 7 , the color gamut (LAS) of the liquid crystal display including the LED package according to the first embodiment of the present invention has an overlap ratio with the DCI color standard (DCI) of 95% to realize high color gamut. have.

As described above, the liquid crystal display device including the LED package according to the first embodiment of the present invention has the total content and mixing ratio of the yellow (Y) and red (R) phosphors of the LED package including the blue (B) LED chip. Control, and the resin layer of the LED package includes a light absorber that absorbs light in a wavelength range between red and green, so that high color reproduction can be achieved at a relatively low cost.

On the other hand, the white condition of the liquid crystal display used in the TV requires a color coordinate of CIE 1931 standard (Wx, Wy) = (0.278, 0.288) and a color temperature of 10,000K, and the LED package according to the first embodiment of the present invention is required. It can satisfy the white condition according to the DCI color standard.

In addition, the relative light efficiency of the light emitted from the LED package including the light absorber with respect to the light emitted from the LED package that does not include the light absorber is about 70% or more, which is a relatively low decrease in luminance, thereby increasing power consumption. can be stopped

-Second embodiment-

8 is a cross-sectional view schematically illustrating a structure of an LED package according to a second embodiment of the present invention.

As shown in FIG. 8 , the LED package 128b according to the second embodiment of the present invention includes an LED chip 310 , a resin layer 320 including a phosphor (not shown), and a mold frame 330 . , a transparent substrate 340 , and a light absorber 350 .

The LED chip 310 may include first and second chips 310a and 310b, each of which emits blue light. Each of the first and second chips 310a and 310b is electrically connected to the LED printed circuit board (128a in FIG. 3) through wire bonding. Here, a case in which the first and second chips 310a and 310b are used is described, but the number of chips is not limited thereto.

The mold frame 330 has a cavity therein, and the first and second chips 310a and 310b are positioned in the cavity. In more detail, the first and second chips 310a and 310b are spaced apart from each other on the bottom surface of the mold frame 330 corresponding to the cavity, and the side surface of the mold frame 330 corresponding to the cavity has an oblique reflective surface. It has a 330a to send light from the first and second chips 310a and 310b upwards. Here, the cavity may further include concave portions corresponding to the first and second chips 310a and 310b, respectively.

Although not shown, the mold frame 330 may include a separate lower frame and an upper frame, 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 310a and 310b, and serves to apply a voltage to cause recombination of electrons and holes in each of the first and second chips 310a and 310b.

A resin layer 320 including a phosphor is formed in the cavity to cover the first and second chips 310a and 310b. For example, the phosphor may be dispersed in a silicone resin. In addition, the phosphor may include a yellow (yellow: Y) phosphor and a red (red: R) phosphor.

A transparent substrate 340 is positioned on the resin layer 320 and the mold frame 330 . The transparent substrate 340 may be made of glass.

A light absorber 350 absorbing light in a wavelength range between red and green is positioned on the transparent substrate 340 . The light absorber 350 has an absorption peak in a wavelength region of 590 nanometers, and may include a metal coordination-tetraazaporphyrin compound of Formula 1 .

The light absorber 350 may be dispersed in a binder and coated on the transparent substrate 340 . For example, the binder may be an acrylic compound.

Here, each of the first and second chips 310a and 310b has a peak wavelength region of about 444 nanometers (nm), the yellow (Y) phosphor has a peak wavelength region of about 540 nm, and the red (R) The phosphor has a peak wavelength region of about 650 nanometers.

The LED package 128b 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 content of the resin layer 320 . In this case, the weight mixing ratio of the yellow (Y) phosphor and the red (R) phosphor is preferably 55% and 45%, respectively.

However, since the LED package 128b including the blue LED chip and the yellow and red phosphors has an overlapping region between the red and green lights, the color gamut of the liquid crystal display is reduced. Accordingly, the LED package 128b according to the second embodiment of the present invention includes the light absorber 350 to absorb light in a wavelength range between red and green, thereby increasing the color gamut of the liquid crystal display.

At this time, since the light absorber 350 is located on the transparent substrate 340 and is spaced apart from the LED chip 310 under the transparent substrate 340 , the light absorber 350 is heated by the heat generated from the LED chip 310 . By preventing deterioration, heat resistance can be ensured. The transparent substrate 340 preferably has a thickness of about 0.5 millimeters (mm) or less in consideration of transmittance and heat resistance.

Alternatively, the light absorber 350 may be positioned on the lower surface of the transparent substrate 340 . In this case, it is possible to prevent damage to the light absorber 350 due to an external impact.

In the LED package 128b shown in FIGS. 5A and 5B , since the light absorber 250 is included in the resin layer 220 together with a phosphor (not shown), the light absorption characteristic may be somewhat deteriorated. That is, light emitted from the phosphor may be emitted from the LED package 128b in a state in which absorption of a specific wavelength region is not made through the light absorber 250 . However, in the LED package 128b of FIG. 8 , since the light absorber 350 is located on the resin layer 320 , such a problem does not occur.

In the previous embodiment, a liquid crystal display including a side backlight unit has been described, but the present invention can also be applied to a liquid crystal display including a direct backlight unit, which will be described with reference to the drawings.

-Third embodiment-

9 is a cross-sectional view schematically showing a liquid crystal display according to a third embodiment of the present invention, and FIG. 10 is an enlarged cross-sectional view showing the structure of an LED assembly of the liquid crystal display according to the third embodiment of the present invention.

As shown in FIG. 9 , the liquid crystal display according to the third embodiment of the present invention includes a liquid crystal panel 410 , a backlight unit 420 , a main frame 430 , a top frame 440 , and a bottom frame 450 . ) is included.

The liquid crystal panel 410 displays an image, and includes a lower first substrate 412 , an upper second substrate 414 , and a liquid crystal layer (not shown) positioned between the two substrates 412 and 414 , and , and first and second polarizing plates 418 and 419 positioned outside each of the first substrate 412 and the second substrate 414 .

Although not shown, the first substrate 412 includes a plurality of gate lines and data lines on the inner surface, and the gate lines and data lines cross each other 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 412 is referred to as a lower substrate or an array substrate.

Also, although not shown, the second substrate 414 includes a black matrix and a color filter layer on the inner surface. The black matrix has an opening corresponding to the pixel area, and the red, green, and blue color filter patterns of the color filter layer are sequentially positioned corresponding to the opening of the black matrix. This second substrate 414 is referred to as an upper substrate or a color filter substrate.

Meanwhile, a common electrode is formed on the first substrate 412 or the second substrate 414 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 414 together with the pixel electrode, and in this case, the common electrode and the pixel electrode may be alternately positioned in a bar shape or the like pattern.

The first and second polarizing plates 418 and 419 are attached to the outer surfaces of the first and second substrates 412 and 414, respectively, and selectively transmit only specific light. The first and second polarizers 418 and 419 transmit only linearly polarized light parallel to each light transmission axis, and the light transmission axis of the first polarizer 418 and the light transmission axis of the second polarizer 419 are perpendicular to each other. are placed

A backlight unit 420 is disposed under the liquid crystal panel 410 , and the backlight unit 420 supplies light to the liquid crystal panel 410 . The backlight unit 420 includes a reflective sheet 422 , a diffusion plate 424 , an optical sheet 426 , and a light emitting diode (LED) assembly 428 .

The LED assembly 428 includes an LED printed circuit board 428a, an LED package 428b, and a lens 428c.

A plurality of LED packages 428b and a plurality of lenses 428c are positioned at regular intervals along the longitudinal direction of the LED printed circuit board 428a. In the drawings, the LED package 428b and the lens 428c are presented as being arranged in one row, but the LED package 428b and the lens 428c may be arranged in two or more rows.

In addition, although not shown, the LED assembly 428 may include a plurality of LED printed circuit boards 428a, and the plurality of LED printed circuit boards 428a are placed side by side on the bottom frame 450, and LED printing. A plurality of LED packages 428b and a plurality of lenses 428c may be positioned on each of the circuit boards 428a.

Referring to FIG. 10 , an LED package 428b is mounted on the upper surface of the LED printed circuit board 428a, and a lens 428c is positioned on the LED package 428b to cover the LED package 428b.

The LED printed circuit board 428a applies a voltage to the LED package 428b, and the LED package 428b emits light by the applied voltage. Light emitted from the LED package 428b is emitted through the lens 428c.

The LED package 428b of the liquid crystal display according to the third embodiment of the present invention includes a blue (B) LED chip, a yellow (Y) phosphor, and a red (R) phosphor, and emits white light, and emits white light between red and green. It includes a light absorber that absorbs light in a wavelength band, which will be described in detail later.

The lens 428c has an inner space, and the LED package 428b is located in the inner space of the lens 428c. The lens 428c has an inner surface and an outer surface of a predetermined curved surface to diffuse light emitted from the LED package 428b.

The lens 428c may be made of poly(methyl methacrylate) (PMMA) or polycarbonate (PC).

Referring back to FIG. 9 , the reflective sheet 422 is positioned on the exposed LED printed circuit board 428a between the adjacent LED packages 428b. The reflective sheet 422 reflects the light directed downward from the LED package 428b toward the liquid crystal panel 410 to improve the luminance of the light.

A diffusion plate 424 is positioned on the LED assembly 428 and the reflective sheet 422 and spaced apart from each other by a predetermined distance. The diffuser plate 424 uniformly diffuses the light from the LED package 428b.

An optical sheet 426 is positioned on the diffusion plate 424 . The optical sheet 426 includes a diffusion sheet and at least one light collecting sheet, and diffuses or condenses the light passing through the diffusion plate 424 so that a more uniform surface light source is incident on the liquid crystal panel 410 . The optical sheet 426 may include first to third optical sheets 426a, 426b, and 426c sequentially disposed on the diffusion plate 424 .

For example, each of the first and second optical sheets 426a and 426b may be a light collecting sheet, and the third optical sheet 426c may be a diffusion sheet. The light collecting sheet may include a prism pattern or a lenticular pattern. The first optical sheet 426a may include a lenticular pattern, and the second optical sheet 426b may include a prism pattern.

Meanwhile, the third optical sheet 426c may be a luminance enhancement film. The brightness enhancement film may have a structure in which layers having different refractive indices are alternately stacked.

The liquid crystal panel 410 and the backlight unit 420 are modularized through the main frame 430 , the top frame 440 , and the bottom frame 450 .

The main frame 430 has a rectangular frame shape, and includes a vertical portion and a horizontal portion. The liquid crystal panel 410 is positioned on the upper horizontal portion of the main frame 430 , the backlight unit 420 is positioned on the lower portion, and the vertical portion of the main frame 430 is the liquid crystal panel 410 and the side surfaces of the backlight unit 420 . surrounds

The bottom frame 450 includes a horizontal plane and a side surface, and the backlight unit 420 is mounted on the horizontal plane. A side surface of the bottom frame 450 surrounds the backlight unit 420 , and one end of the side surface may be positioned between the main frame 430 and the backlight unit 420 .

In addition, the top frame 440 has a rectangular frame shape, and has a cross-section in the shape of an “L” to cover the front edge and side surfaces of the liquid crystal panel 410 . The top frame 440 includes an opening in the center of the front so that an image implemented in the liquid crystal panel 410 is displayed outside through the opening.

The top frame 440, the main frame 430, and the bottom frame 450 are assembled and fastened to each other, so that the liquid crystal display of the present invention is modularized. In this case, the top frame 440 may be omitted.

Here, the top frame 440 is also referred to as a case top, top case, or top cover, the main frame 430 is also referred to as a guide panel or a main support, and the bottom frame 450 is also referred to as a cover bottom or bottom cover. also lose

As mentioned above, the LED package 428b of the liquid crystal display according to the third embodiment of the present invention includes a blue (B) LED chip, a yellow (Y) phosphor, and a red (R) phosphor to emit white light. and a light absorber that absorbs light in a wavelength band between red and green, and this LED package 428b will be described in more detail below.

11A is a cross-sectional view schematically illustrating a structure of an LED package according to a third embodiment of the present invention, and FIG. 11B is a cross-sectional view schematically illustrating another structure of an LED package according to a third embodiment of the present invention.

11A and 11B, the LED package 428b according to the third embodiment of the present invention includes an LED chip 510, a resin layer 520 including a phosphor (not shown), and a mold frame. 530 , and a light absorber 550 .

The LED chip 510 emits blue light and is electrically connected to the LED printed circuit board 428a through wire bonding. Here, the case in which the LED package 428b includes a single LED chip 510 is described, but the number of chips is not limited thereto.

The mold frame 530 has a cavity therein, and the LED chip 510 is positioned in the cavity. In more detail, the LED chip 510 is positioned on the bottom surface of the mold frame 530 corresponding to the cavity, and the side surface of the mold frame 530 corresponding to the cavity has an oblique reflective surface 530a ( 510) is sent upwards. Although not shown, the cavity may further include a recess corresponding to the LED chip 510 .

Also, although not shown, the mold frame 530 may include a separate lower frame and an upper frame, and a lead frame may be positioned between the lower frame and the upper frame. The lead frame is connected to the LED chip 510 and serves to apply a voltage to cause recombination of electrons and holes in the LED chip 510 .

A resin layer 520 including a phosphor is formed in the cavity to cover the LED chip 510 . For example, the phosphor may be dispersed in a silicone resin. In addition, the phosphor may include a yellow (yellow: Y) phosphor and a red (red: R) phosphor.

Here, the LED chip 510 has about 444 nanometers (nm) as a peak wavelength range, the yellow (Y) phosphor has about 540 nanometers as a peak wavelength range, and the red (R) phosphor has about 650 nanometers. It has a peak wavelength region.

The LED package 428b according to the third 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. For this, 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 520 . In this case, the weight mixing ratio of the yellow (Y) phosphor and the red (R) phosphor is preferably 55% and 45%, respectively.

However, in the LED package 428b including the blue LED chip and the yellow and red phosphors, an overlapping region exists between the red and green light, and thus the color gamut of the liquid crystal display is reduced.

Accordingly, the LED package 428b according to the third embodiment of the present invention includes the light absorber 550 to absorb light in a wavelength range between red and green, thereby increasing the color gamut of the liquid crystal display.

At this time, as shown in FIG. 11A , the resin layer 520 may include the light absorber 550 , or as shown in FIG. 11B , the light absorber 550 may be formed on the resin layer 520 .

The light absorber 520a has an absorption peak in a wavelength region of 590 nanometers, and may include a metal coordination-tetraazaporphyrin compound of Formula 1.

Meanwhile, the LED package 428b of FIG. 11B preferably further includes a transparent substrate 540 between the resin layer 520 and the light absorber 550 . The transparent substrate 540 may be made of glass, and the light absorber 550 may be dispersed in a binder and coated on the transparent substrate 540 . For example, the binder may be an acrylic compound.

In the LED package 428b of FIG. 11b , the light absorber 550 is located on the transparent substrate 540 and is spaced apart from the LED chip 510 under the transparent substrate 540 , resulting from the LED chip 510 . Heat resistance can be ensured by preventing the light absorber 550 from being deteriorated by the heat. The transparent substrate 540 preferably has a thickness of about 0.5 millimeters (mm) or less in consideration of transmittance and heat resistance.

Alternatively, the light absorber 550 may be positioned on the lower surface of the transparent substrate 540 . In this case, it is possible to prevent damage to the light absorber 550 due to an external impact.

In the LED package 428b shown in FIG. 11A , since the light absorber 550 is included in the resin layer 520 together with the phosphor (not shown), the light absorption characteristic may be somewhat deteriorated. That is, light emitted from the phosphor may be emitted from the LED package 428b without being absorbed in a specific wavelength region through the light absorber 550 . However, in the LED package 428b of FIG. 11B , since the light absorber 550 is located on the resin layer 520 , such a problem does not occur.

As described above, in the liquid crystal display including the direct backlight unit according to the third embodiment of the present invention, the total content of yellow (Y) and red (R) phosphors in the LED package including the blue (B) LED chip and By controlling the mixing ratio, the resin layer of the LED package includes a light absorber that absorbs light in a wavelength range between red and green, and high color reproduction can be realized at a relatively low cost.

Although the above has been described with reference to the preferred embodiment of the present invention, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention described in the claims below. You will understand that it can be done.

110, 410: liquid crystal panel 112, 412: first substrate
114, 414: second substrate 118, 418: first polarizing plate
119, 418: second polarizer 120, 420: backlight unit
122, 422: reflective sheet 124: light guide plate
126, 426: optical sheet 128, 428: LED assembly
130, 430: main frame 140, 440: top frame
150, 450: bottom frame 210, 310, 510: LED chip
220, 320, 520: resin layer 230, 330, 530: mold frame
340, 540: transparent substrate 250, 350, 550: light absorber

Claims (14)

a liquid crystal panel;
A backlight unit located under the liquid crystal panel and including a light source
includes,
The light source includes a first illuminant having a first peak wavelength, a second illuminant having a second peak wavelength greater than the first peak wavelength, and a third illuminant having a third peak wavelength greater than the second peak wavelength and,
The light source further comprises a light absorber having an absorption peak between the second peak wavelength and the third peak wavelength,
The first light-emitting body includes a light emitting diode chip, the second light-emitting body includes a first phosphor, and the third light-emitting body includes a second phosphor,
The light emitting diode chip is a blue light emitting diode chip, the first phosphor is a yellow phosphor, and the second phosphor is a red phosphor,
The weight mixing 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 diagram.
delete delete According to claim 1,
The light source further includes a resin layer, the first phosphor and the second phosphor are located in the resin layer, and the total content of the first phosphor and the second phosphor is 5.8 wt% of the resin layer. display device.
5. The method of claim 4,
The light absorbing agent is a liquid crystal display located in the resin layer.
5. The method of claim 4,
The light absorber is a liquid crystal display positioned on the resin layer.
7. The method of claim 6,
The light source further includes a transparent substrate on the resin layer, wherein the transparent substrate is positioned between the light absorber and the resin layer, or the light absorber is positioned between the transparent substrate and the resin layer.
8. The method of claim 7,
The thickness of the transparent substrate is 0.5 mm or less liquid crystal display.
9. The method of any one of claims 1 and 4 to 8,
The light absorber includes a metal coordination-tetraazaporphyrin 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 a halogen atom, and each of R1, R2, R3, R4 is independently C1~ A liquid crystal display device selected from an alkyl group of C10 or an aromatic group of C6 to C30, and each of a, b, c, and d is 1 or 2.
light source;
the optical sheet on the light source
includes,
The light source includes a first illuminant having a first peak wavelength, a second illuminant having a second peak wavelength greater than the first peak wavelength, and a third illuminant having a third peak wavelength greater than the second peak wavelength and,
The light source further comprises a light absorber having an absorption peak between the second peak wavelength and the third peak wavelength,
The light source further includes a resin layer, and the light absorber is located on the resin layer,
The light source further includes a transparent substrate on the resin layer, and the transparent substrate is positioned between the light absorber and the resin layer.
11. The method of claim 10,
The thickness of the transparent substrate is 0.5 mm or less in the backlight unit.
11. The method of claim 10,
The first light-emitting body includes a light emitting diode chip, the second light-emitting body includes a first phosphor, and the third light-emitting body includes a second phosphor,
The light emitting diode chip is a blue light emitting diode chip, the first phosphor is a yellow phosphor, and the second phosphor is a red phosphor.
13. The method of claim 12,
The weight mixing ratio of the first phosphor and the second phosphor is 55% and 45%, respectively.
14. The method according to any one of claims 10 to 13,
The backlight unit further comprising a lens covering the light source.

Images