KR101956055B1 - Display device - Google Patents

Abstract

A display device is started. The display device includes a light source; A light conversion member on which light from the light source is incident; And a display panel on which light from the light conversion member is incident, wherein the light source comprises: a first light source for generating blue light; And a second light source for generating white light.

Description

Display device {DISPLAY DEVICE}

The embodiment relates to a display device.

Among display devices, there is a device that requires a backlight unit capable of generating light in order to display an image. The backlight unit is a device for supplying light to a display panel including a liquid crystal or the like and includes a light emitting device and means for effectively transmitting the light output from the light emitting device to the liquid crystal side.

As a light source of such a display device, an LED (Light Emitted Diode) or the like can be applied. Further, in order that the light output from the light source is effectively transmitted to the display panel side, a light guide plate and an optical sheet may be laminated and used.

At this time, an optical member that changes the wavelength of light generated from the light source and causes white light to enter the light guide plate or the display panel can be applied to such a display device. Particularly, in order to change the wavelength of light, a quantum dot or the like can be used.

The quantum dot has a particle size of 10 nm or less and has unique electrical and optical characteristics depending on its size. For example, when the approximate size is 55 to 65 Å, it can emit red, 40 to 50 Å to green, and 20 to 35 Å to blue. Yellow has medium size of red and green quantum dots. As the spectrum of light changes from red to blue, the size of the quantum dots varies from 65 Å to 20 Å, which may be slightly different.

In order to form the optical member including the quantum dots, the quantum dots emitting RGB or RYGB, which are three primary colors of light, can be formed by spin coating or printing on a transparent substrate such as glass. Here, when a quantum dot emitting yellow (Y) is further included, white light closer to natural light can be obtained. The matrix (medium) in which the quantum dots are dispersed can apply an inorganic substance or a polymer having excellent transmittance with respect to light in the visible light region and the ultraviolet region (including Far UV) or in the visible light region. For example, it may be inorganic silica, polymethylmethacrylate (PMMA), polydimethylsiloxane (PDMS), poly lactic acid (PLA), silicon polymer or YAG.

A display device to which such a quantum dot is applied is disclosed in Korean Patent Laid-Open Publication No. 10-2011-0012246.

The embodiment intends to provide a display device having an improved color reproduction ratio and luminance.

A display device according to an embodiment includes a light source; A light conversion member on which light from the light source is incident; And a display panel on which light from the light conversion member is incident, wherein the light source comprises: a first light source for generating blue light; And a second light source for generating white light.

The display device according to the embodiment displays an image using blue light and white light. That is, the display device according to the embodiment can improve color reproducibility as a whole by using the second light source as an auxiliary light source. Accordingly, the second light source emits white light, and the optical characteristics can be complemented as a whole.

In particular, the second light source may include a yellow phosphor. Accordingly, the green light and the red light can be complemented by the light emitted from the second light source.

Therefore, the display device according to the embodiment can have improved color reproducibility.

1 is an exploded perspective view showing a liquid crystal display device according to a first embodiment.
2 is a sectional view showing a second light emitting diode.
FIG. 3 is a perspective view showing the light conversion member according to the first embodiment. FIG.
Fig. 4 is a cross-sectional view showing a section cut along AA 'in Fig. 3; Fig.
5 is an exploded perspective view showing a liquid crystal display device according to a second embodiment.
FIG. 6 is a perspective view showing the light conversion member according to the second embodiment. FIG.
FIG. 7 is a cross-sectional view showing a section cut along BB 'in FIG. 6; FIG.
8 is a cross-sectional view illustrating one side of a light guide plate, a light emitting diode, and a light conversion member according to the second embodiment.
9 is an exploded perspective view showing a liquid crystal display device according to a third embodiment.
FIG. 10 is a perspective view showing a photo-conversion member according to the third embodiment. FIG.
FIG. 11 is a cross-sectional view showing a section cut along CC 'in FIG. 10; FIG.
12 is a cross-sectional view illustrating one side of a light guide plate, a light emitting diode, and a light conversion member according to the third embodiment.

In the description of the embodiments, it is described that each substrate, frame, sheet, layer or pattern is formed "on" or "under" each substrate, frame, sheet, In this case, "on" and "under " all include being formed either directly or indirectly through another element. In addition, the upper or lower reference of each component is described with reference to the drawings. The size of each component in the drawings may be exaggerated for the sake of explanation and does not mean the size actually applied.

1 is an exploded perspective view showing a liquid crystal display device according to a first embodiment. 2 is a sectional view showing a second light emitting diode. FIG. 3 is a perspective view showing the light conversion member according to the first embodiment. FIG. 4 is a cross-sectional view showing a section cut along the line A-A in Fig.

1 to 3, a liquid crystal display device according to an embodiment includes a backlight unit 10 and a liquid crystal panel 20.

The backlight unit 10 emits light to the liquid crystal panel 20. The backlight unit 10 is a surface light source and can uniformly irradiate the bottom surface of the liquid crystal panel 20 with light.

The backlight unit 10 is disposed under the liquid crystal panel 20. The backlight unit 10 includes a bottom cover 100, a light guide plate 200, a reflective sheet 300, a light source, a printed circuit board 401, and a plurality of optical sheets 500.

The bottom cover 100 has a top opened shape. The bottom cover 100 accommodates the light guide plate 200, the light emitting diodes 410 and 420, the printed circuit board 401, the reflection sheet 300, and the optical sheets 500.

The light guide plate 200 is disposed in the bottom cover 100. The light guide plate 200 is disposed on the reflective sheet 300. The light guide plate 200 emits light upward from the light emitting diodes 410 and 420 through total reflection, refraction and scattering.

The reflective sheet 300 is disposed under the light guide plate 200. More specifically, the reflective sheet 300 is disposed between the light guide plate 200 and the bottom surface of the bottom cover 100. The reflective sheet 300 reflects light emitted from the lower surface of the light guide plate 200 upward.

The light source generates light. The light source includes a plurality of light emitting diodes (410, 420). The light emitting diodes 410 and 420 are disposed on one side of the light guide plate 200. The light emitting diodes 410 and 420 generate light to be incident on the light guide plate 200 through the side surface of the light guide plate 200.

More specifically, the light source includes a plurality of first light emitting diodes 410 and a plurality of second light emitting diodes 420.

The first light emitting diodes 410 generate blue light. The first light emitting diodes 410 may be blue light emitting diodes. The first light emitting diodes 410 and 420 may generate blue light having a wavelength range of about 430 nm to about 470 nm.

Referring to FIG. 2, the second light emitting diodes 420 generate white light. The second light emitting diodes 420 may include a blue light emitting diode chip 422 and a yellow phosphor 424.

The blue light emitting diode chip 422 is disposed in the cavity of the body portion 421. The blue light emitting diode chip 422 may emit blue light having a wavelength range of about 430 nm to about 470 nm.

The yellow phosphor 424 converts the blue light from the blue light emitting diode chip 422 into yellow light. Examples of the yellow phosphor 424 include a YAG fluorescent substance. The yellow phosphor 424 can be uniformly dispersed in the filling portion 423 in the cavity.

The light emitting diodes 410 and 420 are mounted on the printed circuit board 401. The light emitting diodes 410 and 420 are disposed under the printed circuit board 401. The light emitting diodes 410 and 420 are driven by receiving a driving signal through the printed circuit board 401.

The first light emitting diodes 410 and the second light emitting diodes 420 may be alternately arranged. The first light emitting diodes 410 and the second light emitting diodes 420 may be alternately arranged one by one. Alternatively, each of the first light emitting diodes 410 and the second light emitting diodes 420 may be alternately arranged.

The number of the first light emitting diodes 410 and the number of the second light emitting diodes 420 may be 2: 1 to 4: 1.

The printed circuit board 401 is electrically connected to the light emitting diodes 410 and 420. The printed circuit board 401 may mount the light emitting diodes 410 and 420. The printed circuit board (401) is disposed inside the bottom cover (100).

The optical sheets 500 are disposed on the light guide plate 200. The optical sheets 500 change or enhance the characteristics of light emitted from the upper surface of the light guide plate 200 and supply the light to the liquid crystal panel 20. [

The optical sheets 500 may be a light conversion member 501, a diffusion sheet 502, a first prism sheet 503, and a second prism sheet 504. [

The light conversion member 501 may be disposed on the light path between the light source 300 and the liquid crystal panel 20. For example, the light conversion member 501 may be disposed on the light guide plate 200. More specifically, the light conversion member 501 may be interposed between the light guide plate 200 and the diffusion sheet 502. The light conversion member 501 can convert the wavelength of the incident light and emit the light upward.

For example, when the light emitting diodes 410 and 420 are blue light emitting diodes, the light converting member 501 may convert blue light emitted upward from the light guide plate 200 into green light and red light. That is, the light conversion member 501 converts a part of the blue light into green light having a wavelength band of about 500 nm to about 600 nm, and converts the other part of the blue light to a light having a wavelength range of about 600 nm to about 700 nm It can be converted into red light.

Accordingly, light passing through the light conversion member 501 without conversion and light converted by the light conversion member 501 can form white light. That is, the blue light, the green light, and the red light may be combined, and the white light may be incident on the liquid crystal panel 20.

That is, the photo-conversion member 501 is an optical member that converts the characteristics of the incident light. The photo-conversion member 501 has a sheet shape. That is, the photo-conversion member 501 may be an optical sheet.

2 and 3, the light conversion member 501 includes a lower substrate 510, an upper substrate 520, a light conversion layer 530, and a sealing portion 540.

The lower substrate 510 is disposed under the light conversion layer 530. The lower substrate 510 is transparent and flexible. The lower substrate 510 may be in close contact with the lower surface of the light conversion layer 530.

Examples of the material used for the lower substrate 510 include transparent polymers such as polyethylene terephthalate (PET) and the like.

The upper substrate 520 is disposed on the light conversion layer 530. The upper substrate 520 is transparent and flexible. The upper substrate 520 may be in close contact with the upper surface of the light conversion layer 530.

Examples of materials used for the upper substrate 520 include transparent polymers such as polyethylene terephthalate.

The lower substrate 510 and the upper substrate 520 sandwich the light conversion layer 530. The lower substrate 510 and the upper substrate 520 support the light conversion layer 530. The lower substrate 510 and the upper substrate 520 protect the light conversion layer 530 from external physical impacts. The lower substrate 510 and the upper substrate 520 may be in direct contact with the light conversion layer 530.

In addition, the lower substrate 510 and the upper substrate 520 have low oxygen permeability and moisture permeability. Accordingly, the lower substrate 510 and the upper substrate 520 can protect the light conversion layer 530 from external chemical impacts such as moisture and / or oxygen.

The light conversion layer 530 is interposed between the lower substrate 510 and the upper substrate 520. The light conversion layer 530 may be in close contact with the upper surface of the lower substrate 510 and may be in close contact with the lower surface of the upper substrate 520.

The light conversion layer 530 includes a matrix 531 and a plurality of light conversion particles 532.

The matrix 531 surrounds the light conversion particles 532. That is, the matrix 531 uniformly disperses the light conversion particles 532 therein. The matrix 531 is transparent. That is, the matrix 531 may be formed of a transparent polymer.

The matrix 531 is disposed between the lower substrate 510 and the upper substrate 520. The matrix 531 may be in close contact with the upper surface of the lower substrate 510 and the lower surface of the upper substrate 520.

The matrix 531 may include a silicone resin, an acrylic resin, or an epoxy resin.

The photo-conversion particles 532 are disposed between the lower substrate 510 and the upper substrate 520. More specifically, the light conversion particles 532 may be uniformly dispersed in the matrix 531, and the matrix 531 may be disposed between the lower substrate 510 and the upper substrate 520. The photo-conversion particles may be dispersed in the host at a concentration of about 0.5 wt% to about 5 wt%.

The photo-conversion particles 532 are disposed between the lower substrate 510 and the upper substrate 520. More specifically, the light conversion particles 532 are uniformly dispersed in the matrix 531, and the matrix 531 is disposed between the lower substrate 510 and the upper substrate 520.

The photoconversion particles 532 convert the wavelength of the light emitted from the light emitting diodes 410 and 420. The light conversion particles 532 receive light emitted from the light emitting diodes 410 and 420 and convert wavelengths. For example, the photoconversion particles 532 may convert blue light emitted from the light emitting diodes 410 and 420 into green light and red light. That is, some of the light conversion particles 532 convert the blue light into green light having a wavelength range of about 520 nm to about 560 nm, and another part of the light conversion particles 532 converts the blue light to about 630 And can be converted into red light having a wavelength band of from about nm to about 660 nm.

Alternatively, the photoconversion particles 532 may convert ultraviolet rays emitted from the light emitting diodes 410 and 420 into blue light, green light, and red light. That is, some of the light conversion particles 532 convert the ultraviolet light into blue light having a wavelength range of about 430 nm to about 470 nm, and another part of the light conversion particles 532 converts the ultraviolet light to about 520 Can be converted into green light having a wavelength band between nm and 560 nm. Further, another part of the light conversion particles 532 may convert the ultraviolet light into red light having a wavelength range of about 630 nm to about 660 nm.

That is, when the light emitting diodes 410 and 420 are blue light emitting diodes that generate blue light, the light conversion particles 532 that convert blue light into green light and red light, respectively, may be used. Alternatively, when the light emitting diodes 410 and 420 are UV light emitting diodes that emit ultraviolet light, photo-conversion particles 532 that convert ultraviolet light into blue light, green light, and red light, respectively, may be used.

The photo-conversion particles 532 may be a plurality of quantum dots (QDs). The quantum dot may include core nanocrystals and shell nanocrystals surrounding the core nanocrystals. In addition, the quantum dot may include an organic ligand bound to the shell nanocrystal. In addition, the quantum dot may include an organic coating layer surrounding the shell nanocrystals.

The shell nanocrystals may be formed of two or more layers. The shell nanocrystals are formed on the surface of the core nanocrystals. The quantum dot may convert the wavelength of the light incident on the core core crystal into a long wavelength through the shell nanocrystals forming the shell layer and increase the light efficiency.

The quantum dot may include at least one of a group II compound semiconductor, a group III compound semiconductor, a group V compound semiconductor, and a group VI compound semiconductor. More specifically, the core nanocrystals may include Cdse, InGaP, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe or HgS. The shell nanocrystals may include CuZnS, CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe or HgS. The diameter of the quantum dot may be 1 nm to 10 nm.

The wavelength of light emitted from the quantum dots can be controlled by the size of the quantum dots or the molar ratio of the molecular cluster compound and the nanoparticle precursor in the synthesis process. The organic ligand may include pyridine, mercapto alcohol, thiol, phosphine, phosphine oxide, and the like. The organic ligands serve to stabilize unstable quantum dots after synthesis. After synthesis, a dangling bond is formed on the outer periphery, and the quantum dots may become unstable due to the dangling bonds. However, one end of the organic ligand is in an unbonded state, and one end of the unbound organic ligand bonds with the dangling bond, thereby stabilizing the quantum dot.

Particularly, when the quantum dot has a size smaller than the Bohr radius of an exciton formed by electrons and holes excited by light, electricity or the like, a quantum confinement effect is generated to have a staggering energy level and an energy gap The size of the image is changed. Further, the charge is confined within the quantum dots, so that it has a high luminous efficiency.

Unlike general fluorescent dyes, the quantum dots vary in fluorescence wavelength depending on the particle size. That is, as the size of the particle becomes smaller, it emits light having a shorter wavelength, and the particle size can be adjusted to produce fluorescence in a visible light region of a desired wavelength. In addition, since the extinction coefficient is 100 to 1000 times higher than that of a general dye, and the quantum yield is also high, it produces very high fluorescence.

The quantum dot can be synthesized by a chemical wet process. Here, the chemical wet method is a method of growing particles by adding a precursor material to an organic solvent, and the quantum dots can be synthesized by a chemical wet method.

The sealing portion 540 is disposed on the side of the light conversion layer 530. More specifically, the sealing portion 540 covers the side surface of the light conversion layer 530. More specifically, the sealing portion 540 is disposed on the side surfaces of the lower substrate 510 and the upper substrate 520. More specifically, the sealing portion 540 covers the side surfaces of the lower substrate 510 and the upper substrate 520.

The sealing portion 540 may be adhered to the side surfaces of the light conversion layer 530, the lower substrate 510, and the upper substrate 520. The sealing portion 540 is in close contact with the side surfaces of the light conversion layer 530, the lower substrate 510, and the upper substrate 520.

Accordingly, the sealing portion 540 can seal the side surface of the light conversion layer 530. That is, the sealing portion 540 is a protecting portion that protects the light conversion layer 530 from external chemical impact.

Further, the light conversion member 501 may further include a first inorganic protective film and a second inorganic protective film. The first inorganic protective film may be coated on the lower surface of the lower substrate 510 and the second inorganic protective film may be coated on the upper surface of the upper substrate 520. Examples of the material used as the first inorganic protective film and the second inorganic protective film include silicon oxide and the like.

The diffusion sheet 502 is disposed on the light conversion member 501. The diffusion sheet 502 improves the uniformity of light passing therethrough. The diffusion sheet 502 may include a plurality of beads.

The first prism sheet 503 is disposed on the diffusion sheet 502. The second prism sheet 504 is disposed on the first prism sheet 503. The first prism sheet 503 and the second prism sheet 504 increase the straightness of light passing therethrough.

The liquid crystal panel 20 is disposed on the optical sheets 500. Further, the liquid crystal panel 20 is disposed on the panel guide 23. The liquid crystal panel 20 may be guided by the panel guide 23.

The liquid crystal panel 20 displays an image by adjusting the intensity of light passing through the liquid crystal panel 20. That is, the liquid crystal panel 20 is a display panel for displaying an image using light emitted from the backlight unit 10. [ The liquid crystal panel 20 includes a TFT substrate 21, a color filter substrate 22, and a liquid crystal layer interposed between the two substrates. In addition, the liquid crystal panel 20 includes polarizing filters.

Although not shown in detail in the drawings, the TFT substrate 21 and the color filter substrate 22 will be described in detail. The TFT substrate 21 defines pixels by intersecting a plurality of gate lines and data lines, A thin film transistor (TFT) is provided for each region and is connected in a one-to-one correspondence with the pixel electrodes mounted on the respective pixels. The color filter substrate 22 includes color filters of R, G and B colors corresponding to the respective pixels, a black matrix 531 for covering the gate lines, the data lines and the thin film transistors, etc., And includes a common electrode.

A driving PCB 25 for supplying a driving signal to the gate line and the data line is provided at the edge of the liquid crystal panel 20.

The drive PCB 25 is electrically connected to the liquid crystal panel 20 by a chip on film (COF) 24. Here, the COF 24 may be changed to a TCP (Tape Carrier Package).

As described above, the liquid crystal display according to the embodiment displays an image using blue light and white light. That is, the liquid crystal display according to the embodiment can improve the color reproducibility as a whole by using the second light emitting diodes 420 as an auxiliary light source. Accordingly, the second light emitting diodes 420 emit white light and can complement the optical characteristics as a whole.

In particular, the second light emitting diodes 420 may include a yellow phosphor 424. Accordingly, green light and red light can be complemented by the light emitted from the second light emitting diodes 420.

Therefore, the liquid crystal display according to the embodiment can have improved color reproducibility.

Therefore, the liquid crystal display according to the embodiment can have improved color reproducibility.

In addition, the features, structures, effects and the like described in the embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects and the like illustrated in the embodiments can be combined and modified by other persons skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (7)

A light guide plate;
A light source disposed on a side surface of the light guide plate;
A light conversion member on which light from the light source is incident, and disposed between the light guide plate and the light source; And
And a display panel on which light from the photo-conversion member is incident,
The light source
A first light source for generating blue light; And
And a second light source for generating white light,
Wherein the first light source and the second light source are plural,
Wherein the number of the first light sources is larger than the number of the second light sources,
The ratio of the number of the first light sources to the number of the second light sources is 2: 1 to 4: 1,
Wherein the first light source and the second light source are disposed apart from each other,
Wherein the photo-
A lower substrate;
An upper substrate on the lower substrate; And
And a light conversion layer between the lower substrate and the upper substrate,
The light conversion layer comprises a matrix; And a plurality of light conversion particles dispersed in the matrix,
Wherein said photo-conversion particles comprise quantum dots. The method of claim 1, wherein the light conversion particles
A plurality of first light conversion particles converting at least a portion of light from the light source into green light; And
And a plurality of second light conversion particles for converting at least a part of light from the light source into red light. 3. The phosphor according to claim 2, wherein the first photoconversion particles comprise a green phosphor,
Wherein the second light conversion particles comprise red quantum dots. delete delete The display device according to claim 1, wherein the second light source comprises a yellow phosphor. The display device according to claim 6, wherein the second light source includes a light emitting portion for emitting blue light to the yellow phosphor.

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