KR20120056001A - Backlight unit and liquid crystal display device - Google Patents

Abstract

PURPOSE: A backlight unit and a liquid crystal display device are provided to insert quantum dots into a light guide plate to slim the light guide plate. CONSTITUTION: A light guide plate(123) is formed on a reflecting plate(125). A light source is located on a side of the light guide plate. A plurality of optical sheets(121) are formed on the light guide plate. The light source includes at least one of either blue and/or green LEDs. The light guide plate includes first quantum dots which convert the wavelength of light emitted from the light source. The first quantum dots emit red light by converting the wavelength of light incident from the blue LEDs.

Description

Backlight Unit and Liquid Crystal Display {BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to a backlight unit and a liquid crystal display device for high brightness and high color reproduction.

In general, a liquid crystal display device is driven by using the optical anisotropy and polarization properties of liquid crystals. The liquid crystal molecules have a directional structure because the structure is thin and long, and artificially applies an electric field to the liquid crystals. You can control the direction of the molecular array.

That is, when the arrangement of the liquid crystal molecules is changed using an electric field, light may be refracted in the arrangement direction of the liquid crystal molecules due to optical anisotropy of the liquid crystal, thereby displaying an image.

Such a liquid crystal display includes an array substrate manufacturing process for forming a gate wiring, a data wiring, a thin film transistor (TFT), and a pixel electrode on an array substrate, and forming a black matrix, a color filter, and a common electrode on the color filter substrate. A cell process of forming a unit panel by combining a color filter substrate manufacturing process, an array substrate and a color filter substrate, cutting each cell unit, and injecting liquid crystal between the cell unit array substrate and the color filter substrate; It is completed through a module process of attaching a driving integrated circuit (IC) and a printed circuit board (PCB) to a unit panel and assembling with a backlight unit.

In particular, the backlight unit is a necessary configuration because the liquid crystal molecules of the liquid crystal display do not emit light. The backlight unit includes a light source, and is classified into a direct type and an edge type according to the position of the light source. do.

As a light source, fluorescent lamps such as Cold Cathode Fluorescent Lamps (CCFLs) and External Electrode Fluorescent Lamps (EEFLs) have been widely used, but according to the trend toward thinner and lighter liquid crystal displays, power consumption has recently been reduced. Light Emitting Diodes (LEDs), which have advantages in terms of weight, brightness, and the like, are replacing fluorescent lamps.

The direct type backlight unit is a method of directly supplying light emitted from the lamp or light emitting diode to the liquid crystal panel by arranging a plurality of lamps or light emitting diodes under the liquid crystal panel. The side type backlight unit uses a light guide plate under the liquid crystal panel. By arranging the lamp or the light emitting diode on at least one side of the light guide plate, the light emitted from the lamp or the light emitting diode is indirectly supplied to the liquid crystal panel by using the refraction and reflection of the light guide plate.

1 is a view showing a part of a cross-sectional view of a conventional liquid crystal display device module.

As shown in FIG. 1, the conventional liquid crystal display device module includes a liquid crystal panel 10, a backlight unit 20 for supplying light to the liquid crystal panel 10, a support main 30, and a cover bottom 50. ), And the top cover 40.

The liquid crystal panel 10 is a part that plays a key role in image expression and is composed of first and second substrates 12 and 14 bonded to each other with a liquid crystal layer interposed therebetween.

First and second polarizing plates 19a and 19b for controlling the polarization direction of light are attached to the outer surfaces of the first and second substrates 12 and 14, respectively.

The backlight unit 20 is provided on the rear surface of the liquid crystal panel 10.

The backlight unit 20 includes a light source arranged along at least one edge length direction of the support main 30, a reflector 25 seated on the cover bottom 50, and a light guide plate 23 positioned on the reflector 25. And a plurality of optical sheets 21 interposed on the light guide plate 23.

As a light source of the backlight unit 20, a light emitting diode (LED) 29a is used. In particular, the LED 29a combines features such as small size, low power consumption, and high reliability. It is a trend that is widely used as a light source.

The reflector 25 is positioned on the rear surface of the light guide plate 23 to reflect the light passing through the rear surface of the light guide plate 23 toward the liquid crystal panel 10 to improve the brightness of the light.

The light guide plate 23 allows total reflection of light incident from each of the plurality of LEDs 29a as a light source, and spreads evenly over a wide area of the light guide plate 23 while traveling inside the light guide plate 23 to provide a surface light source to the liquid crystal panel 10. To be provided.

In this case, the light guide plate 23 may include a pattern of a specific shape on the back surface to supply a uniform surface light source. The pattern may be configured in various ways such as an elliptical pattern, a polygon pattern, a hologram pattern, and the like to guide the light incident into the light guide plate 23. The lower surface of 23 is formed by a printing method or an injection method.

The plurality of optical sheets 21 on the light guide plate 23 include a diffusion sheet, at least one prism sheet, and the like, and diffuse or condense the light passing through the light guide plate 23 to make the liquid crystal panel 10 more uniform. Allow the surface light source to be incident.

The liquid crystal panel 10 and the backlight unit 20 cover a top cover 40 surrounding the top edge of the liquid crystal panel and a back surface of the backlight unit 20 while the edge is surrounded by the support main 30 having a rectangular frame shape. The bottom 50 is respectively combined in the front and rear is integrated through the support main 30.

Accordingly, the light emitted from each of the plurality of LEDs 29a of the backlight unit 20 is incident on the light incident surface of the light guide plate 23, and is then refracted toward the liquid crystal panel 10 therein, and the reflecting plate 25 is provided. While passing through the plurality of optical sheets 21 together with the light reflected by the more uniform high-quality surface light source is supplied to the liquid crystal panel 10.

On the other hand, when using the LED 29a as a light source in more detail, each of the plurality of LED (29a) is spaced at a predetermined interval is mounted on a printed circuit board (PCB) (29B) LED assembly 29 ) Is achieved.

The LED assembly 29 is fixed by a method such as adhesion so that the light emitted from the plurality of LEDs 29a faces the light incident surface of the light guide plate 23.

The plurality of LEDs 29a of the LED assembly 29 may be constituted by white LEDs 29a which allow white light to be emitted to the outside of the light guide plate 23, while using a blue chip. A white LED 29a using a phosphor, or a white LED 29a using a red and green phosphor while using a blue chip.

Accordingly, the white light emitted from each of the plurality of white LEDs 29a of the backlight unit 20 is incident on the light incident surface of the light guide plate 23 and then refracted toward the liquid crystal panel 10 therein, and the reflecting plate 25 While passing through the plurality of optical sheets 21 together with the white light reflected by the) is processed into a more uniform high-quality surface light source is supplied to the liquid crystal panel 10.

FIG. 2 is a view showing an emission spectrum of the white LED used in FIG. 1, and FIG. 3 is a view showing color reproduction of the liquid crystal display according to FIG.

As mentioned above, the emission spectra of the three primary colors emitted from the white LED 29a using the yellow phosphor on the blue chip can be seen from the emission intensity of each of the three primary colors. As shown in FIG. It can be seen that the emission intensity of red is significantly lower than that of blue.

In addition, the color reproducibility of the liquid crystal display using the white LED 29a as a light source has three color coordinates as shown in Table 1 below. The color coordinate of the red (R) light has an x value of 0.648, The y value is 0.332, the color coordinate of the green (G) light has x value of 0.304, the y value is 0.602, the color coordinate of the blue (B) light has x value of 0.152, and y value of 0.057.

R 0.648 0.332 G 0.304 0.602 B 0.152 0.057

When such color coordinates are connected, as shown in FIG. 3, the triangle area corresponding to A has a color displayable area (color reproduction range).

This is based on NTSC, when the reference triangle area representing the color display area in the color coordinate system is 100 as NTSC, which is represented in the international standard called NTSC (National Television System Committee), which is the standard for color display in display devices. The triangular area occupied by A has an area of 72.2 inside the triangle represented by NTSC.

That is, the liquid crystal display has a color gamut of about 72.2% based on NTSC.

On the other hand, although not shown in the drawings, the emission intensity of the three primary colors of the white LED using the red and green phosphors and the color reproducibility of the liquid crystal display device using such a white LED as a light source also shows similar results to the white LED of the yellow phosphor.

In other words, a white LED using yellow, or red and green phosphors is difficult to achieve high color reproduction because it is difficult to control the color sum, wavelength control, and some loss.

Accordingly, an object of the present invention is to provide a backlight unit and a liquid crystal display device that can realize high color reproducibility and high brightness using quantum dots.

In addition, another object of the present invention is to provide a slimmer backlight unit and a liquid crystal display device while realizing high color reproducibility and high brightness by inserting a quantum dot into the light guide plate to reduce the thickness of the light guide plate.

In order to achieve the above object, the backlight unit according to the present invention, the reflection plate; A light guide plate formed on the reflecting plate; A light source positioned at a side of the light guide plate; A plurality of optical sheets formed on the light guide plate, wherein the light source includes one or more of a plurality of blue LEDs and a plurality of green LEDs, and the light guide plate comprises a plurality of first quantums for converting wavelengths of light emitted from the light source; It contains a dot.

The first quantum dot is characterized in that the red light is emitted by converting the wavelength of the light incident from the blue LED.

And converting a wavelength of light incident from the blue LED to emit green light.

Each of the plurality of blue LEDs and the plurality of green LEDs may be alternately arranged in a row.

The plurality of blue LEDs and the plurality of green LEDs are the same number, wherein the plurality of blue LEDs are arranged in a line in a first area of the LED printed circuit board and the plurality of green LEDs are in a second area of the LED printed circuit board. It is characterized in that arranged in a line.

The number of the plurality of blue LEDs and the plurality of green LEDs are different from each other, and the blue LEDs and the green LEDs are mixed and arranged at different ratios.

The light guide plate may include a light emission pattern under the light guide plate.

The plurality of optical sheets is characterized in that it comprises at least one of a diffusion sheet, a prism sheet and a protective sheet.

On the other hand, the liquid crystal display device according to the present invention, the reflection plate; A light guide plate formed on the reflecting plate; A light source positioned at a side of the light guide plate; A plurality of optical sheets formed on the light guide plate; And a liquid crystal panel displaying an image formed on the optical sheets, wherein the light source includes one or more of a plurality of blue LEDs and a plurality of green LEDs, and the light guide plate is configured to convert wavelengths of light emitted from the light sources. It includes a plurality of first quantum dots.

In the light guide plate and the liquid crystal display device according to the present invention, by inserting a quantum dot into the light guide plate and using a blue LED or / and green LED as the light source, it is possible to increase the color reproducibility and emission intensity.

In addition, the thickness of the light guide plate may be adjusted by using quantum dots, thereby realizing a slimmer backlight unit, and thus, a liquid crystal display device may be slimmed.

1 is a view showing a portion of a cross-sectional view of a conventional liquid crystal display device module.
2 is a view showing an emission spectrum of the white LED used in FIG.
3 is a view showing color gamut of the liquid crystal display of FIG.
4 is an exploded perspective view schematically showing a liquid crystal display device according to a first embodiment of the present invention;
5 is a cross-sectional view of a portion of a liquid crystal display module according to a first embodiment of the present invention.
6 shows an emission spectrum of white light according to FIG. 5.
FIG. 7 is a view illustrating color gamut of the liquid crystal display of FIG. 5; FIG.
8 is a view showing a portion of a cross-sectional view of a liquid crystal display module according to a second embodiment of the present invention.
FIG. 9 shows an example of the LED assembly used in FIG. 8. FIG.
10 is a view showing another example of a liquid crystal display module according to a second embodiment of the present invention.
FIG. 11 is a view illustrating an emission spectrum of the liquid crystal display module according to FIG. 10.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

4 is an exploded perspective view schematically illustrating a liquid crystal display according to a first embodiment of the present invention.

As shown in FIG. 4, the liquid crystal display device 100 includes a liquid crystal panel 110, a backlight unit 120, and a support main 130 for modularizing the liquid crystal panel 110 and the backlight unit 120. And cover bottom 150 and top cover 140.

The liquid crystal panel 110 plays a key role in image expression. The liquid crystal panel 110 includes first and second substrates 112 and 114 bonded to each other with a liquid crystal layer interposed therebetween.

Although not shown in the drawings, a plurality of gate lines and data lines intersect on the inner surface of the first substrate 112, which is commonly referred to as a lower substrate or an array substrate, under the premise of an active matrix scheme, and pixels are defined at each intersection. A thin film transistor (TFT) is provided to correspond one-to-one with a transparent pixel electrode formed in each pixel.

In addition, the inner surface of the second substrate 114 called the upper substrate or the color substrate may correspond to each pixel, for example, a color filter of red (R), green (G), and blue (B) color and each of them. A black matrix covering the non-display elements such as gate lines, data lines, and thin film transistors is provided. In addition, a transparent common electrode covering them is provided.

In addition, polarizing plates (not shown) for selectively transmitting only specific light are attached to the outer surfaces of the first and second substrates 112 and 114, respectively.

In addition, the printed circuit board 117 is connected through at least one edge of the liquid crystal panel 110 through a connection member 116 such as a flexible circuit board or a tape carrier package (TCP). At the side of the support main 130 or the cover bottom 150 is properly folded to be in close contact.

Accordingly, the liquid crystal panel 110 having the above-described structure may be configured to have a data driving circuit when the thin film transistor selected for each gate line is turned on by an on or off signal of a gate driver circuit transmitted through the printed circuit board 117. The signal voltage is transmitted to the corresponding pixel electrode through the data line, and the arrangement direction of the liquid crystal molecules is changed by the electric field between the pixel electrode and the common electrode, thereby indicating a difference in transmittance.

The back of the liquid crystal panel 110 is provided with a backlight unit 120 for supplying light to display the difference in transmittance as an image.

The backlight unit 120 includes a light source arranged along an edge of the support main 130, a reflector 125, a light guide plate 123 seated on the reflector 125, and a plurality of optical sheets interposed thereon. (121).

As a light source, an LED 129a is used. Each of the plurality of LEDs 129a is spaced at a predetermined interval and mounted on a printed circuit board (PCB) 129b to form an LED assembly 129.

The LED assembly 129 is fixed in a position such as adhesive so that light emitted from the plurality of LEDs 129a faces the light incident surface of the light guide plate 123.

Although the LED assembly 129 is shown to be arranged only at one edge of the light guide plate 123 in the drawing, the LED assembly 129 may be arranged along four side edges or both edges of the light guide plate 123.

Accordingly, light emitted from the plurality of LEDs 129a of the LED assembly 129 is indirectly supplied to the liquid crystal panel 110 by using the refraction and reflection of the light guide plate 123.

Such LEDs 129a of the LED assembly 129, for example, when composed of 63 LEDs, divide the LED assembly 129 into three blocks into one LED string having 21 LEDs. By applying an independent voltage to each LED string, each block can provide light of different luminance. Such a plurality of LED configurations constituting the LED assembly 129 is not limited to this, it is preferable that it can be variously changed.

Although not shown in the drawings, an LED driver integrated circuit (IC) for driving each block of the LED assembly 129 is mounted.

The reflection plate 125 is positioned on the rear surface of the light guide plate 123 to reflect the light passing through the rear surface of the light guide plate 123 toward the liquid crystal panel 110 to improve the brightness of the light.

The light guide plate 123 evenly spreads the light incident from the plurality of LEDs to a wide area of the light guide plate 123 while propagating through the light guide plate 123 by a plurality of total reflections to provide a surface light source to the liquid crystal panel 110.

The light guide plate 123 may include a pattern of a specific shape on the rear surface to supply a uniform surface light source. The pattern may be configured in various ways, such as an elliptical pattern, a polygon pattern, a hologram pattern, and the like to guide the light incident to the light guide plate 123. The lower surface of the 123 is formed by a printing method or an injection method.

The plurality of optical sheets 121 on the light guide plate 123 include a diffusion sheet, one or more prism sheets, a protective sheet, and the like, and diffuse or condense the light passing through the light guide plate 123 to the liquid crystal panel 110. Allow a uniform surface light source to enter.

The liquid crystal panel 110 and the backlight unit 120 have a top cover 140 covering the top edge of the liquid crystal panel 110 in a state where the edge is surrounded by the support main 130 having a rectangular frame shape, and the back of the backlight unit 120. Cover cover 150 to cover each is coupled to the front and rear are integrated through the support main 130 as a medium and modularized.

Accordingly, light emitted from each of the plurality of LEDs 129a of the backlight unit 120 is incident on the light incident surface of the light guide plate 123 and then refracted toward the liquid crystal panel 110 therein, and the reflector plate 125 is disposed therein. While passing through the plurality of optical sheets 121 with the light reflected by the more uniform high-quality surface light source is supplied to the liquid crystal panel 110.

Here, the top cover 140 may be referred to as a case top or a top case, the support main 130 may be referred to as a guide panel or a main support, and a mold frame, and the cover bottom 150 may be referred to as a bottom cover.

5 is a cross-sectional view of a portion of a liquid crystal display module according to a first embodiment of the present invention.

As shown in FIG. 5, the light guide plate 123 according to the present invention includes a plurality of quantum dots 170 therein, and the light source facing the light incident surface of the light guide plate 123 is a blue LED 129a. ).

The quantum dot 170 is a semiconductor crystal of several nanometers (nm) size made through a chemical synthesis process, and converts the wavelength of light injected from the light source. The quantum dot 170 emits all wavelengths of visible light by changing the emission wavelength according to the particle size. You can exit.

Such a quantum dot 170 may be a II-VI, III-V or IV material, specifically, CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, InP, GaP, GaInP2, PbS, ZnO, TiO2 , AgI, AgBr, Hg12, PbSe, In2S3, In2Se3, Cd3P2, Cd3As2 or GaAs.

In general, the quantum dots 170 generate light having a shorter wavelength as the size of particles is smaller, and generate light having a longer wavelength as the size of particles is larger.

Here, the plurality of quantum dots 170 converts wavelengths of light incident from each of the plurality of blue LEDs 129a so that white light is emitted to the outside of the light guide plate 123. For this purpose, the plurality of quantum dots 170 have a size capable of emitting green light. A plurality of first quantum dots 170a and a plurality of second quantum dots 170b having a size capable of emitting red light are inserted into the light guide plate 123. That is, at least two types of first and second quantum dots 170a and 170b having different sizes are inserted into the light guide plate 123.

Accordingly, the plurality of first quantum dots 170a having a first size capable of emitting green light may convert the wavelengths of light injected from the plurality of blue LEDs 129a to emit green light and emit red light. The plurality of second quantum dots 170b having the second size convert the wavelength of the light injected from the plurality of blue LEDs 129a and emit the red light.

As such, as the plurality of first and second quantum dots 170a and 170b are inserted into the light guide plate 123, a part of the light incident from the plurality of blue LEDs 129a passes through the light guide plate 123. The first quantum dot 170a is converted into green light, and a part of the plurality of second quantum dots 170b is converted into red light.

Accordingly, the green light emitted from the first quantum dot 170a, the red light emitted from the second quantum dot 170b, and the blue light emitted from each of the plurality of blue LEDs 129a are evenly distributed in all regions of the light guide plate 123. It spreads to become white light of the surface light source, and the white light is emitted to the outside of the light guide plate 123.

Meanwhile, the plurality of first and second quantum dots 170a and 170b may be arranged in one line in the light guide plate 123 or may be evenly distributed in all areas, and not only the light guide plate 123 but also the light guide plate. The light guide plate 123 may be positioned between the light guide plate 123 and the reflector plate 121 on the upper surface of the 123 or the lower surface thereof.

FIG. 6 is a diagram illustrating an emission spectrum of white light according to FIG. 5, and FIG. 7 is a diagram illustrating a color reproducibility of the liquid crystal display according to FIG. 5.

First, a plurality of blue LEDs 129a are used as light sources, and at least two types of white light emitted through the light guide plate 123 into which the plurality of first and second quantum dots 170a and 170b of different sizes are inserted. The emission spectrum is as shown in Figure 6, blue has an emission intensity corresponding to B1, green has an emission intensity corresponding to G1, red has an emission intensity corresponding to R1.

Here, in comparison with the emission intensity of each of the blue (B), green (G), and red (R) in the emission spectrum of the white LED used in the conventional liquid crystal display module shown together for comparison, according to the present invention, In particular, the green and red light emission in the white light emitted through the first and second quantum dots 170a and 170b and the plurality of blue LEDs are G1 and R1, respectively, compared to the green and red light emission intensity in the conventional white LEDs. It can be seen that the increase significantly.

In addition, the color coordinates of the three primary colors for showing the color reproducibility in the liquid crystal display device 100 including the backlight unit 120 according to the present invention are as shown in Table 2 below, wherein the color coordinates of the red (R) light have an x value of 0.683. The y value is 0.304, the color coordinate of the green (G) light has x value of 0.192 and the y value of 0.725, and the color coordinate of the blue (B) light has x value of 0.151 and y value of 0.043.

R 0.683 0.304 G 0.192 0.725 B 0.151 0.043

When such color coordinates are connected, as illustrated in FIG. 7, the triangular area corresponding to A1 is used as a color displayable area (color reproduction range).

The triangular area of A1 is NTSC 100 when the reference triangular area of the color coordinate system is 100, indicating NTSC (National Television System Committee), which is the standard for color display. It can be seen that the liquid crystal display according to the present invention has an area of 110 as a reference, and has a color reproduction ratio of 110% compared to that of NTSC.

This is a color reproducibility of about 38% as compared with 72.2% of the conventional liquid crystal display, and it can be seen that the color reproducibility is significantly increased.

Accordingly, when the plurality of first quantum dots 170a and the plurality of second quantum dots 170b having different sizes are inserted into the light guide plate 123 and the plurality of blue LEDs 129a are used as light sources, The present invention can provide a liquid crystal display device having a color reproducibility of about 38% higher than that of a conventional liquid crystal display device and having a significantly increased green and red intensity.

Since the color reproducibility may vary depending on the number of first and second quantum dots inserted into the light guide plate, the number of blue LEDs used as a light source, or the light emission characteristics of the blue LEDs, the number of first and second quantum dots may be appropriately adjusted. The maximum color reproducibility may be realized by adjusting the number of blue LEDs or by maximizing the emission characteristics of the blue LEDs.

FIG. 8 is a view illustrating a part of a cross-sectional view of a liquid crystal display module according to a second embodiment of the present invention. Since it has the same structure as FIG. 4 except for the light guide plate, a description thereof will be omitted.

As shown in FIG. 8, the light guide plate 223 according to the present invention includes a plurality of quantum dots 270. The light source facing the light incident surface of the light guide plate 223 includes a plurality of blue LEDs ( 229a-1) and multiple green LEDs 229a-2.

The quantum dot 270 is a semiconductor crystal of several nanometers (nm) size made through a chemical synthesis process and converts the wavelength of light injected from the light source. You can exit.

The quantum dot 270 may be a II-VI, III-V or IV material, and specifically, CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, InP, GaP, GaInP2, PbS, ZnO, TiO2 , AgI, AgBr, Hg12, PbSe, In2S3, In2Se3, Cd3P2, Cd3As2 or GaAs.

In general, the quantum dot 270 generates light having a shorter wavelength as the particle size is smaller, and generates light having a longer wavelength as the particle size is larger.

In this case, the plurality of quantum dots 270 may convert the wavelengths of light incident from the plurality of blue LEDs 229a-1 so that white light is emitted to the outside of the light guide plate 223, where the plurality of blue LEDs 229a are used. One kind of quantum dots 270 having a size capable of converting the wavelength of light incident from -1) to emit red light are inserted into the light guide plate 223.

As such, the plurality of quantum dots 270 are inserted into the light guide plate 223, and the plurality of blue LEDs 229a-1 and the plurality of green LEDs 229a-2 are used as light sources, thereby providing the plurality of blue LEDs 229a. A portion of the light incident from -1) is converted into red light by the plurality of quantum dots 270 while traveling in the light guide plate 223.

Accordingly, the red light emitted from the quantum dot 270, the blue light emitted from each of the plurality of blue LEDs 229a-1, and the green light emitted from each of the plurality of green LEDs 229a-2 are formed in the light guide plate 223. Spread evenly over the entire area to become white light of the surface light source, and the white light is emitted to the outside of the light guide plate 223.

On the other hand, the plurality of quantum dots 270 may be arranged in one line in the light guide plate 223 or evenly distributed in all areas, and may be disposed on the upper surface of the light guide plate 223 as well as inside the light guide plate 223. The light guide plate 223 may be positioned between the light guide plate 223 and the reflector plate 225.

9 is a diagram illustrating the LED assembly of FIG. 8 as an example.

According to the present invention, the plurality of blue LEDs 229a-1 and the plurality of green LEDs 229a-2, which are used as light sources, are spaced apart at regular intervals and mounted on the LED printed circuit board (PCB) 229b. As shown, the LED assembly 229 is formed, and each of the plurality of blue LEDs 229a-1 and the plurality of green LEDs 229a-2 may be configured to be alternately arranged with each other.

Alternatively, although not shown in the drawing, when the number of the plurality of blue LEDs 229a-1 and the plurality of green LEDs 229a-2 are the same, the plurality of blue LEDs 229a-1 may be the LED printed circuit board 229b. Arrange a row on the left side of the LED and arrange the plurality of green LEDs 229a-2 on the right side of the LED printed circuit board 229b, or arrange a plurality of blue LEDs 229a-1 on the LED printed circuit board 229b. The green LEDs 229a-2 may be arranged in a line on the right side of the LED, and the plurality of green LEDs 229a-2 may be arranged in a line on the left side of the LED printed circuit board 229b.

On the other hand, when the number of the plurality of blue LEDs 229a-1 and the plurality of green LEDs 229a-2 are different from each other, the ratios of the numbers of the blue LEDs 229a-1 and the green LEDs 229a-2 are different from each other. The LED assembly 229 may be formed by mixing and arranging on the LED printed circuit board.

This, LED assembly 229 is arranged along the four sides or both edges of the light guide plate 223, from the plurality of blue LEDs 229a-1 and the plurality of green LEDs 229a-2 of the LED assembly 229. The emitted light is supplied to the liquid crystal panel 210 as a surface light source of white light by using the refraction and reflection of the light guide plate 223.

FIG. 10 is a view showing another example of a liquid crystal display module according to a second embodiment of the present invention. Except for the light guide plate, FIG. 10 has the same structure as that of FIG. 8, and the same parts as in FIG. Description is omitted.

The light guide plate 223 according to the present invention includes a plurality of first and second quantum dots 270a and 270b, and the light source for facing the light incident surface of the light guide plate 223 includes a plurality of blue LEDs 229a. -1) and a plurality of green LEDs 229a-2 are used.

In this case, the light guide plate 223 includes a plurality of first quantum dots 270a and a plurality of blue LEDs having a first size for converting wavelengths of light incident from the plurality of blue LEDs 229a-1 to emit green light. A plurality of second quantum dots 270b having a second size capable of converting wavelengths of light incident from 229a-1 to emit red light are inserted.

That is, at least two types of first and second quantum dots 270a and 270b having different sizes are inserted into the light guide plate 223.

As such, as the plurality of first quantum dots 270a and the plurality of second quantum dots 270b are inserted into the light guide plate 223, a part of the light incident from the plurality of blue LEDs 229a-1 may be disposed in the light guide plate 223. As a result, the light is converted into green light by the plurality of first quantum dots 270a, and a part of the light is converted into red light by the plurality of second quantum dots 270b.

Accordingly, the green light emitted from the first quantum dot 270a, the red light emitted from the second quantum dot 270b, the blue light emitted from each of the plurality of blue LEDs 229a-1, and the plurality of green LEDs ( 229a-2) the green light emitted from each of the light guide plate 223 evenly spreads over the entire area of the light guide plate 223 to become white light of the surface light source, and the white light is emitted to the outside of the light guide plate 223.

Here, in particular, the green light is emitted by the plurality of first quantum dots 270a and is also emitted from each of the plurality of green LEDs 229a-2, thereby increasing the emission intensity.

Meanwhile, the plurality of first and second quantum dots 270a and 270b may be arranged in one line in the light guide plate 223 or may be evenly distributed throughout the light guide plate 223. The light guide plate 223 and the reflective plate 225 may be disposed on the upper surface of the 223 or the lower surface of the light guide plate 223.

FIG. 11 is a view illustrating an emission spectrum of the liquid crystal display module according to FIG. 10.

According to the present invention, the light guide plate 223 using the plurality of blue LEDs 229a-1 and the plurality of green LEDs 229a-2 as a light source and inserting the first and second quantum dots 270a and 270b is used. As shown in FIG. 11, the emission spectrum of the white light emitted through the blue light has a light emission intensity corresponding to B1, a green light emission intensity corresponding to G2, and a red light emission intensity corresponding to R1.

Compared with the emission spectrum of the white light emitted according to the first embodiment of the present invention, it can be seen that the emission intensity of blue and red is the same, but the emission intensity of green is significantly increased from G1 to G2.

Therefore, according to the present invention, it is possible to provide a liquid crystal display device having excellent visibility by realizing a high color reproduction rate by remarkably increasing not only the color reproduction rate but also the green light emission intensity having the best visibility.

Meanwhile, the emission intensity of green according to the present invention may vary depending on the number and emission characteristics of the green LEDs 229a-2.

Similarly, since the color reproducibility may vary depending on the number of quantum dots 270 inserted into the light guide plate 223 and the light emission characteristics of the blue LED 229a-1 and the green LED 229a-2 used as the light source, the quantum dots The number of colors 270 may be appropriately adjusted, or the maximum color reproducibility may be realized by maximizing the emission characteristics of the blue LED 229a-1 or the green LED 229a-2.

Meanwhile, according to the present invention, by inserting quantum dots into the light guide plate, it is possible to adjust the thickness of the light guide plate to be thinner than the thickness of the conventional light guide plate while increasing the color reproducibility.

As a result, according to the present invention, the thickness of the light guide plate may be adjusted thinly to implement a slimmer backlight unit and to implement a slimmer liquid crystal display device.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

110, 210: liquid crystal panel 120, 220: backlight unit
125, 225: reflector 123, 223: light guide plate
121, 221: Multiple optical sheets 129a, 229a-1, 229a-2: LED
130: support main 140: top cover
150: covertum 170, 270: quantum dot

Claims (9)

A reflector;
A light guide plate formed on the reflecting plate;
A light source positioned at a side of the light guide plate;
It includes a plurality of optical sheets formed on the light guide plate,
The light source includes one or more of a plurality of blue LEDs and a plurality of green LEDs, and the light guide plate includes a plurality of first quantum dots for converting wavelengths of light emitted from the light source.
The method of claim 1,
And the first quantum dot emits red light by converting a wavelength of light incident from the blue LED.
The method of claim 1,
And a second quantum dot for converting a wavelength of light incident from the blue LED to emit green light.
The method of claim 1,
And the plurality of blue LEDs and the plurality of green LEDs are alternately arranged in a row with each other.
The method of claim 1,
The plurality of blue LEDs and the plurality of green LEDs are the same number, wherein the plurality of blue LEDs are arranged in a line in a first area of the LED printed circuit board and the plurality of green LEDs are in a second area of the LED printed circuit board. The backlight unit, characterized in that arranged in a line.
The method of claim 1.
And the number of the plurality of blue LEDs and the plurality of green LEDs are different from each other, and the blue LEDs and the green LEDs are mixed and arranged in different ratios.
The method of claim 1,
The light guide plate is
The backlight unit, characterized in that it comprises a light emission pattern at the bottom.
The method of claim 1,
The plurality of optical sheets
And at least one of a diffusion sheet, a prism sheet, and a protective sheet.
A reflector;
A light guide plate formed on the reflecting plate;
A light source positioned at a side of the light guide plate;
A plurality of optical sheets formed on the light guide plate; And
A liquid crystal panel displaying an image formed on the optical sheets;
The light source includes one or more of a plurality of blue LEDs and a plurality of green LEDs, and the light guide plate includes a plurality of first quantum dots for converting wavelengths of light emitted from the light source.

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