KR101713148B1 - Liquid crystal display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display (LCD), and more particularly, to improvement in brightness and color gamut of a liquid crystal display device using an LED as a light source.
A feature of the present invention is that a quantum dot plate is cured by mixing red light emitting nano particles and green light emitting nano particles in front of a blue LED through which blue light is emitted.
Thus, it is possible to realize white light having excellent optical characteristics, thereby improving the color reproduction rate, and thus the color coordinate of BT.709 is satisfied.
In addition, the present invention can prevent a yellow color defect in the light-incident portion of the light guide plate by forming a blue ink layer on one surface of the PCB that covers the light guide plate light-incident portion.

Description

[0001] Liquid crystal display device [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to an improvement in the color gamut of a liquid crystal display device using an LED as a light source.

A liquid crystal display device (LCD), which is advantageous for moving picture display and has a large contrast ratio and is actively used in TVs and monitors, exhibits optical anisotropy and polarization properties of a liquid crystal, And the like.

Such a liquid crystal display device has a liquid crystal panel in which a liquid crystal panel is interposed between two adjacent substrates through a liquid crystal layer as an essential component and changes the alignment direction of the liquid crystal molecules in an electric field in the liquid crystal panel to realize a difference in transmittance do.

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

Here, as a light source of the backlight unit, a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp, a light emitting diode (LED) .

In particular, LEDs are widely used as light sources for displays, having characteristics such as small size, low power consumption, and high reliability.

The LED 29a used as a light source of the liquid crystal display device is composed of a light emitting LED chip and a phosphor. When light is emitted from the LED chip, the emitted light excites the phosphor to emit white light.

A typical white LED device uses a blue LED including a blue LED chip having excellent luminous efficiency and brightness, and uses yttrium aluminum garnet (YAG: Ce) doped with cerium, that is, a yellow phosphor as a phosphor.

Some blue light emitted from the blue LED is transmitted through the phosphor and mixed with the yellow light emitted by the phosphor, thereby realizing white light.

However, the liquid crystal display device using the blue LED as the light source has a problem that the brightness is increased but the color reproduction rate is reduced.

That is, the color reproduction rate realized by transmitting the white light emitted from the blue LED to the red (R), green (G), and blue (B) color filter patterns of the liquid crystal panel 10 is low, The color coordinates of BT.709, which is the color coordinate system indicating the color reproduction ratio of the high definition television (HDTV), is not satisfied.

SUMMARY OF THE INVENTION It is a first object of the present invention to improve the brightness and color gamut of a liquid crystal display device using a blue LED as a light source.

It is also a second object of the present invention to prevent occurrence of a yellow color defect in the light guide plate light-incident portion.

In order to achieve the above-mentioned object, the present invention provides a liquid crystal display comprising: a reflection plate; A light guide plate mounted on the reflection plate; A plurality of blue LEDs arranged along the light incidence surface of the light guide plate and emitting light toward the light incidence surface and a PCB having a plurality of blue LEDs mounted thereon and having a blue ink layer formed on one surface thereof facing the light guide plate, Assembly; A bar-shaped quantum dot plate interposed between the plurality of blue LEDs and the light incident surface of the light guide plate; An optical sheet that is seated on the light guide plate; A liquid crystal panel mounted on the plurality of optical sheets; A support main body covering an edge of the liquid crystal panel; And a cover bottom formed of a bottom surface which is in close contact with the support main back surface and a side surface of the cover bottom. The bar-shaped quantum dot plate is a liquid crystal display device which emits white light by exciting light emitted from the plurality of blue LEDs Lt; / RTI >

At this time, the PCB is in the form of a bar, and a plurality of blue LEDs are arranged along a longitudinal direction on a side of the PCB at a predetermined interval so as to emit light toward the other edge of the PCB, Is disposed on the other edge side of the PCB, the PCB is positioned perpendicular to the light incident surface of the light guide plate, and the other edge of the PCB on which the blue ink layer is formed covers a part of the light incident portion of the light guide plate.

The bar-shaped quantum dot plate is cured by mixing a red light emitting nanoparticle and a green light emitting nanoparticle having a quantum confinement effect, and the bar- The yellow light-emitting nanoparticles having a quantum confinement effect are cured.

The light emitting nanoparticles may be selected from the group consisting of CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, InP, GaP, GaInP2, PbS, ZnO, TiO2, AgI, AgBr, Hg12, PbSe, In2S3, In2Se3, Cd3P2, Cd3As2 or GaAs CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe, ZnSe, ZnSe, ZnSe, ZnSe, ZnSe, HgTe and HgS, and the core comprising any one material selected from the group consisting of CdSe, CdTe, And HgS. ≪ / RTI >

As described above, the present invention has a quantum dot plate cured by mixing red light emitting nano particles and green light emitting nano particles in front of a blue LED emitting blue light, Thus, it is possible to improve the color reproduction rate, and thus the color coordinates of BT.709 can be satisfied.

In addition, a plurality of blue LEDs are mounted, and a blue ink layer is formed on one surface of the PCB that covers the light guide plate light-incident portion, thereby preventing yellow light color defect in the light-guide plate light-

1 is an exploded perspective view of a liquid crystal display device according to an embodiment of the present invention;
2 is a graph showing BT.709 overlap ratio on a color coordinate system of a liquid crystal display device having a backlight unit including a quantum dot plate according to an embodiment of the present invention.
FIG. 3A is a perspective view schematically showing a structure of an LED assembly according to an embodiment of the present invention; FIG.
Figure 3b is a plan view of Figure 3a.
Fig. 4 is a photograph showing a state in which a yellow color defect occurs. Fig.
Fig. 5 is a cross-sectional view schematically showing a partial cross-section of the modular Fig. 1; Fig.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

1 is an exploded perspective view of a liquid crystal display device according to an embodiment of the present invention.

As shown, the liquid crystal display includes a liquid crystal panel 110, a backlight unit 120, a support main body 130 for modulating the liquid crystal panel 110 and the backlight unit 120, a cover bottom 150, (140).

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

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

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

A polarizing plate (not shown) for selectively transmitting only specific light is attached to the outer surfaces of the first and second substrates 112 and 114, respectively.

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

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

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

The backlight unit 120 includes an LED assembly 129, a quantum dot plate 127, a white or silver reflective plate 125, a light guide plate 123 mounted on the reflective plate 125, And an optical sheet 121 interposed therebetween.

The LED assembly 129 is disposed on one side of the light guide plate 123 so as to face the light incident surface of the light guide plate 123. The LED assembly 129 includes a plurality of LEDs 128, And a PCB 200 that is mounted to be spaced apart.

The LED assembly 129 is a side view type in which light emitted from a plurality of LEDs 128 is parallel to the PCB 200.

In this case, a blue ink layer 210 (see FIG. 3A) for guiding light emitted from the LED 128 is formed on the PCB 200 on which the LED 128 is mounted.

3A) reflects light emitted to the upper side of the LED 128 among the light emitted from the LED 128 to the inside of the light guide plate 123, and the blue ink layer 210 210, see FIG. 3A) is formed by coating blue ink using a silk screen technique.

The LED 128 mounted on the PCB 200 is made of a blue LED that emits blue light having a wavelength of about 430 to 450 nm for improving luminous efficiency and luminance.

The backlight unit 120 of the present invention is characterized in that a bar-shaped quantum dot plate 127 is provided in front of the blue LED 128 from which blue light is emitted from the blue LED 128 .

The bar-shaped quantum dot plate 127 corresponds to the length of the PCB 200 of the LED assembly 129 and preferably has a width corresponding to the light incidence plane of the light guide plate 123.

Accordingly, the backlight unit 120 of the present invention realizes white light having excellent optical characteristics. Accordingly, the color reproduction ratio is improved even when the blue LED 128 having a low color reproduction rate is used as the light source of the backlight unit 120. [

When the blue light emitted from the plurality of blue LEDs 128 passes through the quantum dot plate 127 and is realized as excellent white light, the white light is incident into the light guide plate 123, The liquid crystal panel 110 is uniformly distributed over a wide area of the light guide plate 123 to provide a planar light source.

Here, the light guide plate 123 is made of a plastic material such as polymethylmethacrylate (PMMA) or polycarbonate (PC), which is an acrylic transparent resin, which is one of the transparent materials capable of transmitting light, It is made in flat type.

The light guide plate 123 includes a pattern of a specific pattern on its back surface in order to supply a uniform surface light source. The pattern may include an elliptical pattern, an elliptical pattern, A polygon pattern, a hologram pattern, and the like.

 The reflection plate 125 is disposed on the back surface of the light guide plate 123 and reflects light passing through the back surface of the light guide plate 123 toward the liquid crystal panel 110 to improve the brightness of light.

The optical sheet 121 on the light guide plate 123 includes a diffusion sheet and at least one light condensing sheet and diffuses or condenses the light passing through the light guide plate 123 to provide a more uniform surface light source to the liquid crystal panel 110 Let it enter.

The liquid crystal panel 110 and the backlight unit 120 are modularized through a top cover 140, a support main 130 and a cover bottom 150. The top cover 140 is disposed on the upper surface and the side surface of the liquid crystal panel 110, The top cover 140 is opened so that an image formed on the liquid crystal panel 110 is displayed.

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

The support main body 130 having a square shape and having one opened edge which is placed on the cover bottom 150 and covers the edges of the liquid crystal panel 110 and the backlight unit 120 is supported by the top cover 140, Is combined with the bottoms (150).

The support main body 130 is provided with a protrusion 131 for separating the positions of the liquid crystal panel 110 and the backlight unit 120 from each other. The liquid crystal panel 110 is supported on the protrusion 131.

The cover main body 130 may be referred to as a guide panel or a main support or a mold frame. The cover main body 130 may be referred to as a bottom cover or a bottom cover, I will.

In the above-described liquid crystal display device, by placing a bar-shaped quantum dot plate 127 in front of the blue LED 128, white light having excellent optical characteristics can be realized, thereby improving the color reproduction rate compared to the conventional method. Thus, the color reproduction ratio of the liquid crystal cell of the present invention satisfies the color coordinates of BT.709.

The backlight unit 120 of the present invention forms a blue ink layer 210 (see FIG. 3A) for guiding light emitted from the blue LED 128 on the PCB 200, It is possible to prevent the light leakage phenomenon from occurring and also to increase the amount of light incident into the light guide plate 123, thereby improving the light efficiency.

Particularly, it is possible to prevent a yellow color defect from occurring due to the light-incident portion of the light guide plate 123 through the blue ink layer 210 (see Fig. 3A).

Here, the quantum dot plate 200 having the shape of a bar will be described in more detail. The quantum dot plate 200 has a quantum confinement effect in a state in which light emitting nano particles are mixed and cured, , Which is also referred to as a quantum dot.

Luminescent nanoparticles are semiconductor crystals of several nanometers (nm) in size, which are produced by chemical synthesis. They convert the wavelength of light emitted from the light source and emit the light. The emission wavelength varies according to the size of the particles. .

The diameters of these light emitting nanoparticles are in the range of 1 to 10 nm.

The light emitting nanoparticles may be a group II-VI, III-V, or IV-group 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 addition, the light emitting nanoparticles may have a core-shell structure. Wherein the core comprises any one material selected from the group consisting of CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe and HgS and the shell comprises CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe and HgS And the like.

Such a light emitting nanoparticle can easily obtain seven colors of rainbow colors including red, green and blue depending on the light of various wavelengths according to the quantum size effect.

That is, the wavelength of emitted light is changed according to the size of the light emitting nanoparticles.

For example, when CdSe is used as the light emitting nanoparticles, when the light emitting nanoparticles are irradiated with light, the wavelength of the emitted light changes depending on the size of CdSe. When CdSe has a diameter of about 1.7 nm, it emits blue light, emits green light when it has a diameter of 2.3 nm, and emits red light when it has a diameter of 5.0 nm.

Since the light emitting nanoparticles having a quantum confinement effect have excellent color purity, white light having excellent optical characteristics can be obtained. Since various light colors can be realized by controlling the size of the luminescent nanoparticles, various light can be easily obtained by using a single light source according to the luminescent nanoparticles to be used.

Accordingly, the backlight unit 120 of the present invention includes the bar-shaped quantum dot plate 127 cured by mixing the red light emitting nano particles and the green light emitting nano particles in front of the blue LED 128, The blue light emitted from the LED 128 can emit white light having excellent optical characteristics in the process of passing through the bar-shaped quantum dot plate 127.

That is, when blue light is emitted from the blue LED 128, the blue light passes through the bar-shaped quantum dot plate 127, and the red light-emitting nanoparticles of the bar- The wavelength of the blue light is converted into red light by the green light emitting nano particle, and the wavelength of the blue light is converted by the green light emitting nano particle to be converted into the green light.

Accordingly, the blue light emitted from the blue LED 128, the red light realized by the red light emitting nanoparticles, and the green light realized by the green light emitting nanoparticles are mixed with each other to realize a white light having excellent optical characteristics.

2 is a graph showing a BT.709 overlap ratio on a color coordinate system of a liquid crystal display provided with a backlight unit including a bar-shaped quantum dot plate according to an embodiment of the present invention.

As shown, it can be seen that the overlap ratio of BT.709 on the color coordinates of the liquid crystal display according to the embodiment of the present invention is 98%.

1) of the liquid crystal panel (110 in FIG. 1), which is realized when the blue light emitted from the blue LED (128 in FIG. 1) passes through the bar-shaped quantum dot plate The color reproduction ratio realized by transmitting color filter layers of red (R), green (G), and blue (B) colors is substantially similar to the color coordinates of BT.709, which is the color coordinate system of HDTV (High Definition Television) .

Here, the color recall ratio refers to a range of colors that a display device including a liquid crystal display device can express, which measures the color coordinates and luminance of red (R), green (G), and blue (B) Color Reproduction can be obtained for 3 Primary Colors.

The color coordinates are the scientific quantities that are typically displayed to measure the color and then distinguish each, and coordinate values of red (700 nm), green (546.1 nm), and blue (435.8 nm) on Illumination) on the coordinate system specified in 1931.

More specifically, the color reproduction ratio can be calculated by connecting the color coordinates of each of red (R), green (G) and blue (B) determined on the color coordinate system. It can be calculated by comparing with the area of the NTSC (International TV Standards Committee) color coordinate.

That is, the color recall ratio is expressed as a ratio of the relative area when assuming that the value of the color coordinate area of NTSC is 100.

Accordingly, if the color coordinate system of BT.709, which is a color coordinate system showing the color reproduction ratio of the HDTV (High Definition Television), is realized with the area A, the blue light emitted from the blue LED (128 in FIG. 1) The liquid crystal display device in which the white light realized in the process of passing through the bar-shaped quantum dot plate (127 in FIG. 1) is realized as the area of B.

Therefore, the above BT.709 overlapping amount refers to the amount of overlapping with the area of A on the color coordinate system, and it can be seen that the area of A and the area of B almost overlap with each other.

1), the white light realized in the process of passing the blue light emitted from the blue LED (128 in FIG. 1) of the present invention through the bar-shaped quantum dot plate (127 in FIG. 1) The color reproduction ratio realized by passing through the color filter layers of red (R), green (G), and blue (B) colors of the red (R) It is similarly satisfied, and it is understood that the color reproduction rate is further improved.

The backlight unit (120 in FIG. 1) of the present invention forms a blue ink layer 210 (see FIG. 3A) for guiding light emitted from a blue LED (128 in FIG. 1) on a PCB The light leakage phenomenon can be prevented from occurring in response to the light incident portion of the light guide plate 123 and the amount of light incident into the light guide plate 123 is increased to improve the light efficiency.

Particularly, it is possible to prevent a yellow color defect from occurring due to the light-incident portion of the light guide plate 123 through the blue ink layer 210 (see Fig. 3A).

3A is a perspective view schematically showing a structure of an LED assembly according to an embodiment of the present invention, and FIG. 3B is a plan view of FIG. 3A.

4 is a photograph showing a state in which a yellow color defect has occurred.

3A to 3B, the LED assembly 129 includes a plurality of blue LEDs 128 and a plurality of blue LEDs 128 spaced apart from each other by a surface mount technology (SMT) And a printed circuit board (PCB) 200.

The PCB 200 includes a power wiring layer 205 formed with metal wiring lines (not shown), an insulating layer 203 and a PCB base 201. The PCB base 201 includes a power wiring layer 205, The LEDs 203 and other components are mounted and supported on the upper layer, and the heat generated from the plurality of blue LEDs 128 is discharged to the bottom surface side.

The PCB base 201 may be formed of a metal having a high thermal conductivity such as aluminum (Al) or copper (Cu), or may be coated with a heat transfer material to improve the heat releasing function.

Alternatively, a heat sink (not shown) such as a heat sink may be provided on the back surface of the PCB base 201 to receive heat from the respective blue LEDs 128 and to discharge the heat efficiently.

A power supply wiring layer 205 including a plurality of metal wirings (not shown) formed by patterning a conductive material is formed on the PCB base 201. A power supply wiring layer 205 is formed between the PCB base 201 and the power supply wiring layer 205, The layer 203 is positioned to electrically isolate the PCB base 201 from the metal wiring (not shown).

A plurality of LEDs 128 mounted on the PCB 200 are connected in parallel through metal wiring (not shown) of the power wiring layer 205 to receive power.

At this time, on / off of the plurality of LEDs 128 is controlled by an LED driving circuit (not shown). The LED driving circuit (not shown) normally contacts the cover bottom Thereby minimizing the overall size of the liquid crystal display device.

A flexible cable 220 is connected to one side of the PCB 200 so that the LEDs 128 can be connected to an LED driving circuit (not shown) .

The PCB 200 is divided into a region where the blue LED 128 is mounted (hereinafter referred to as region A) and a region that guides light emitted from the blue LED 128 (hereinafter referred to as region B) In other words, the plurality of blue LEDs 128 are mounted adjacent to the edge of the PCB 200 at a predetermined distance. At this time, the blue LEDs 128 emit light toward the other edge facing the one edge, (Not shown).

A blue ink layer 210 is formed on the other edge of the PCB 200 to guide light emitted from the blue LED 128.

The blue ink layer 210 is formed by coating an ink containing a blue pigment using a silk screen technique.

At this time, since the other edge of the PCB 200 on which the blue ink layer 210 is formed is positioned near the light-incident portion of the light guide plate 123 (FIG. 1), light emitted from the plurality of blue LEDs 128 is reflected by the light guide plate 1) 123 in the process of being incident into the light guide plate (123 of FIG. 1) through the light incident surface of the light guide plate (123 of FIG. 1) by reflecting the light emitted toward the upper part of the blue LED 128, So as to be incident inside.

Therefore, light leakage is prevented from occurring in the light-incident portion of the light guide plate 123 (FIG. 1), and the amount of light incident into the light guide plate 123 (FIG. 1) is increased, thereby improving the light efficiency.

Particularly, by forming the ink layer into blue, it is possible to prevent the yellow color defect in the light-incoming portion of the light guide plate (123 in Fig. 1) from occurring.

In more detail, when an ink layer is formed in white, which is the most widely used for reflecting light in the B region of the PCB 200, the white ink layer has a low wavelength band (400 to 480 nm) including a blue wavelength band It has a problem that it can not efficiently reflect light.

Therefore, even if the blue light emitted from the blue LED 128 is realized as white light having good light efficiency in the process of passing through the bar-shaped quantum dot plate (127 in FIG. 1), the white light is emitted from the PCB 200, and is incident into the light guide plate (123 in FIG. 1), only the light of the wavelength band excluding the wavelength band corresponding to the blue light is reflected and incident into the light guide plate 123 of FIG.

That is, only the light in the red and green wavelength ranges is reflected by the white ink layer formed in the B region of the PCB 200 and is incident into the light guide plate (123 in FIG. 1).

Therefore, since the light-incident portion corresponding to the B region of the PCB 200 has a yellow color mixed with red and green, as shown in FIG. 4, the yellow color defect of the light-incident portion of the light guide plate 123 .

However, when the blue ink layer 210 is formed in the B region of the PCB 200 of the present invention, the light reflected by the B region of the PCB 200 in the white light and incident into the light guide plate 123 So that the white light including the light in the wavelength range can be reflected.

In addition, even if only the light except for the blue wavelength band of the white light is reflected and the light incident portion of the light guide plate 123 of FIG. 1 becomes yellow, the yellow color of the light incident portion of the light guide plate The blue color of the blue ink layer 210 formed in the B region of the first and second color filters 200 and 200 may be mixed to make white light appear.

Fig. 5 is a cross-sectional view schematically showing a partial cross-section of the modular Fig.

An LED assembly 129 including a reflective plate 125 and a light guide plate 123 and a PCB 200 on which a blue LED 128 and a blue LED 128 are mounted and a light guide plate 123 on the top of the light guide plate 123, The sheets 121 are laminated to form a backlight unit (120 in FIG. 1).

A liquid crystal panel 110 in which a liquid crystal layer (not shown) is interposed between the first and second substrates 112 and 114 and the backlight unit 120 Polarizers 119a and 119b for selectively transmitting only specific light are attached to the outer surfaces of the two substrates 112 and 114, respectively.

The backlight unit 120 and the liquid crystal panel 110 are surrounded by the support main 130. The cover bottom 150 is coupled to the backside of the backlight unit 120 and the top edge and the side surface of the liquid crystal panel 110 The cover top 140 is coupled to the support main 130 and the cover bottom 150.

The LED assembly 129 is fixed in position by adhesion or the like so that the blue light emitted from the plurality of blue LEDs 128 faces the light incident surface of the light guide plate 123. For this purpose, The LED assembly 129 is attached to the lower surface of the protrusion 131 through an adhesive material (not shown) on the lower surface of the protrusion 131, And is fixed.

This structure is referred to as a side view type.

That is, the LED assembly 129 is configured such that the blue light emitted from the plurality of blue LEDs 128 is parallel to the PCB 200, and the light incidence planes of the PCB 200 and the light guide plate 123 are perpendicular to each other.

Here, the blue LED 128 of the LED assembly 129 is shown as only one of the blue LEDs 128, but a plurality of blue LEDs 128 are mounted on the PCB 200 at a predetermined interval, do.

The PCB 200 is formed to cover a part of the light incident portion of the light guide plate 123. A blue ink layer 210 is formed on one side of the PCB 200 that covers the light incident portion of the light guide plate 123 and faces the light guide plate 123 have.

The backlight unit 120 of FIG. 1 of the present invention diffuses from the blue LED 128 by interposing a bar-shaped quantum dot plate 127 between the blue LED 128 and the light incident surface of the light guide plate 123 The blue light is realized as white light having excellent optical characteristics in the process of passing through the bar-shaped quantum dot plate 127. White light having such excellent optical characteristics is emitted into the light guide plate 123 through the light entrance surface of the light guide plate 123 .

The white light incident into the light guide plate 123 spreads evenly over a wide area of the light guide plate 123 by total reflection several times in the light guide plate 123 and is emitted toward the liquid crystal panel 110. In the course of passing through the optical sheet 121 So that the liquid crystal panel 110 is provided with white light of a surface light source having excellent optical characteristics.

The white light realized in the course of passing through the bar-shaped quadrant dot plate 127 through the blue ink layer 210 formed on the PCB 200 passes through the light guide plate 123 through the light incident surface of the light guide plate 123, The light emitted toward the upper side of the blue LED 128, that is, toward the PCB 200, is reflected to be incident into the light guide plate 123.

Accordingly, light leakage is prevented from occurring in the light-incident portion of the light guide plate 123, and the amount of light incident into the light guide plate 123 is increased, thereby improving the light efficiency.

Particularly, by forming the ink layer to blue, it is possible to prevent the yellow color defect in the light-incident portion of the light guide plate 123 from occurring.

As described above, in the backlight unit of the present invention, a bar-shaped quantum dot plate 127 is formed by mixing red light emitting nano particles and green light emitting nano particles in front of a blue LED 128 to which blue light is emitted The blue light emitted from the blue LED 128 can emit white light having excellent optical characteristics in a process of passing through a bar-shaped quantum dot plate 127 in which red light emitting nano particles and green light emitting nano particles are mixed do.

Therefore, even though the blue LED 128 having a low color reproduction rate is used as the light source of the backlight unit (120 in FIG. 1), the backlight unit of the present invention (120 of FIG. 1) The color reproduction rate realized by transmitting the white light realized by the quantum dot plate 127 through the color filter layers (not shown) of the red (R), green (G) and blue (B) colors of the liquid crystal panel 110 is improved do. Thus, the color coordinate system of BT.709, which is a color coordinate system representing the color reproduction ratio of HDTV (High Definition Television), is satisfied.

A plurality of blue LEDs 128 are mounted and the blue ink layer 210 is formed on one side of the PCB 200 covering the light incident portion of the light guide plate 123 to cause a yellow color defect in the light incident portion of the light guide plate 123 Can be prevented.

Meanwhile, in the above-described structure, the LED 129a as the light source is a blue LED that emits blue light. In this case, the bar-shaped quantum dot plate 127 is formed by mixing the red light emitting nano particles and the green light emitting nano particles, In this case, the bar-shaped quantum dot plate 127 may be formed of a yellow light emitting nanoparticle having a quantum confinement effect.

The backlight unit (120 in FIG. 1) of the above-described structure is generally called a side light system, and a plurality of LEDs 128 may be arranged in a plurality of layers on the PCB 200 according to purposes .

Further, it is also possible to provide a plurality of LED assemblies 129 each in a corresponding manner so as to interpose the cover bottoms 150 along opposite side edges facing each other.

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

110: liquid crystal panel (112, 114: first and second substrates)
119a and 119b: first and second polarizing plates
121: optical sheet, 123: light guide plate, 125: reflector
127: a bar-shaped quantum dot plate
129: LED assembly (129: blue LED, 200: PCB)
130: support main 131 (protruding jaw)
140: Top cover, 150: Cover bottom
210: blue ink layer

Claims (7)

A reflector;
A light guide plate mounted on the reflection plate;
A plurality of blue LEDs arranged along the light incidence surface of the light guide plate and emitting light toward the light incidence surface and a PCB having a plurality of blue LEDs mounted thereon and having a blue ink layer formed on one surface thereof facing the light guide plate, Assembly;
A bar-shaped quantum dot plate interposed between the plurality of blue LEDs and the light incident surface of the light guide plate;
An optical sheet that is seated on the light guide plate;
A liquid crystal panel mounted on the plurality of optical sheets;
A support main body covering an edge of the liquid crystal panel;
A support bottom main body having a bottom surface in contact with the support main back surface and a side surface connected to the bottom surface,
And the bar-shaped quantum dot plate excites light emitted from the plurality of blue LEDs to emit white light.
The method according to claim 1,
The PCB has a bar shape and the blue LEDs are spaced apart from each other by a predetermined distance so as to emit light toward the other edge of the PCB along a longitudinal direction on a side of one side of the PCB, And is formed on the other edge side of the PCB.
The method according to claim 1,
Wherein the PCB is positioned perpendicular to the light incident surface of the light guide plate and the other edge of the PCB on which the blue ink layer is formed covers a part of the light incident portion of the light guide plate.
The method according to claim 1,
The bar-shaped quantum dot plate is cured by mixing a red light emitting nanoparticle and a green light emitting nanoparticle having a quantum confinement effect.
The method according to claim 1,
The bar-shaped quantum dot plate has cured yellow light emitting nanoparticles having a quantum confinement effect.
5. The method according to one of claims 4 and 5,
The light emitting nanoparticles may be made of one selected from the group consisting of CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, InP, GaP, GaInP2, PbS, ZnO, TiO2, AgI, AgBr, Hg12, PbSe, In2S3, In2Se3, Cd3P2, Cd3As2, Liquid crystal display device.
5. The method according to one of claims 4 and 5,
Wherein the light emitting nanoparticles are made of a material selected from the group consisting of CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe and HgS, Wherein the core is a core-shell composed of a shell of a material selected from the group.

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