KR101956058B1 - Display device - Google Patents

Abstract

A display device is started. The display device includes a light source; A first photo-conversion member through which light from the light source is incident; A light guide plate through which light from the first light conversion member is incident; A second light conversion member through which light from the light guide plate is incident; And a display panel on which light from the second photo-conversion member is incident.

Description

Display device {DISPLAY DEVICE}

The embodiment relates to a display device.

Recently, flat panel display devices such as a liquid crystal display (LCD), a plasma display panel (PDP), and an organic light emitting diode (OLED) have been developed in place of the conventional CRT.

The liquid crystal display device includes a thin film transistor substrate, a color filter substrate, and a liquid crystal display panel in which liquid crystal is injected between both substrates. Since the liquid crystal display panel is a non-light emitting device, a backlight unit for supplying light to the bottom surface of the thin film transistor substrate is positioned. The amount of light irradiated from the backlight unit is adjusted according to the alignment state of the liquid crystal.

The backlight unit is divided into edge type and direct type according to the position of the light source. The edge type is a structure in which a light source is provided on a side surface of the light guide plate.

The direct type is a structure that is mainly developed with the size of a liquid crystal display device being enlarged. One or more light sources are arranged on the lower surface of the liquid crystal display panel to supply light to the liquid crystal display panel.

The direct-type backlight unit has advantages in that it can utilize a larger number of light sources than the edge-type backlight unit and can secure a high luminance, but has a disadvantage that the thickness becomes thicker than the edge type in order to ensure uniformity of brightness have.

In order to overcome this problem, a quantum dot bar in which a plurality of quantum dots dispersed in a red wavelength or a green wavelength is dispersed is provided in front of a blue LED emitting blue light constituting a backlight unit, Thus, light mixed with blue light, red light and green light by a plurality of quantum dots dispersed in the quantum dot bar is incident on the light guide plate to provide white light.

At this time, when white light is provided to the light guide plate using the quantum dot bar, high color reproduction can be realized.

The backlight unit may include an FPCB (Flexible Printed Circuits Board) for transmitting and supplying LEDs and signals to one side of a blue LED emitting blue light, and an adhesive member may be further provided on the lower surface of the FPCB.

As such, when a light emitted from a blue LED is leaked, a display device for displaying an image in various forms using white light provided to the light guide plate through the quantum dot bar is widely used.

A display device to which such a quantum dot is applied is disclosed in Korean Patent Laid-Open Publication No. 10-2011-0068110.

The embodiment intends to provide a display device having improved color reproducibility and brightness.

A display device according to an embodiment includes a light source; A first photo-conversion member through which light from the light source is incident; A light guide plate through which light from the first light conversion member is incident; A second light conversion member through which light from the light guide plate is incident; And a display panel on which light from the second photo-conversion member is incident.

The display device according to the embodiment arranges the first photo-conversion member adjacent to the light source, and disposes the second photo-conversion member on the light guide plate to separate the light source. Accordingly, the light conversion particles having a relatively high heat resistance such as a fluorescent material are disposed on the first light conversion member, and the light conversion particles having a relatively low heat resistance such as a quantum dot can be disposed on the second light conversion member.

Accordingly, the display device according to the embodiment can prevent the phenomenon of deterioration due to heat from the light source, and can have improved reliability and durability.

In addition, the first photo-conversion member may include a green phosphor. Accordingly, a part of light from the light source can be directly converted into green light. Therefore, the green light from the first photo-conversion member can be incident on the second photo-conversion member with high transmittance.

That is, when the light source emits blue light, since blue light has a shorter wavelength than green light, the light loss rate may be higher than that of green light. At this time, the remaining blue light other than blue light necessary for displaying an image on the display panel may be converted into green light, and may be incident on the second light conversion member.

Accordingly, more light can be incident on the second photo-conversion member and converted into red light.

Therefore, the liquid crystal display according to the embodiment can have improved luminance and luminance uniformity.

1 is an exploded perspective view showing a liquid crystal display device according to a first embodiment.
2 is a sectional view showing a light source, a light guide plate, a first light conversion member and a second light conversion member according to the first embodiment.
3 is a perspective view showing a light source, a light guide plate, a first light conversion member, and a second light conversion member according to the second embodiment.
4 is a cross-sectional view showing a light source, a light guide plate, a first light conversion member and a second light conversion member according to the second 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 light source, a light guide plate, a first light conversion member and a second light conversion member according to the first embodiment.

1 and 2, a liquid crystal display 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 reflection sheet 300, a light source such as a plurality of light emitting diodes 400, a printed circuit board 401, A member 600 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 400, 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 400 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 emitting diodes 400 are light sources for generating light. The light emitting diodes 400 are disposed on one side of the light guide plate 200. The light emitting diodes 400 generate light and enter the light guide plate 200 through the side surface of the light guide plate 200.

The light emitting diodes 400 may be a blue light emitting diode for generating blue light or a UV light emitting diode for generating ultraviolet light. That is, the light emitting diodes 400 may generate blue light having a wavelength range of about 430 nm to about 470 nm.

The light emitting diodes 400 are mounted on the printed circuit board 401. The light emitting diodes 400 are disposed under the printed circuit board 401. The light emitting diodes 400 are driven by receiving a drive signal through the printed circuit board 401.

The printed circuit board 401 is electrically connected to the light emitting diodes 400. The printed circuit board 401 may mount the light emitting diodes 400. The printed circuit board (401) is disposed inside the bottom cover (100).

The first light conversion member 600 receives light from the light emitting diodes. As shown in FIGS. 1 and 2, the first light conversion member 600 is interposed between the light emitting diodes and the light guide plate. The first light conversion member 600 is interposed between the exit surface of the light emitting diodes and the incident surface of the light guide plate.

The light-converting member 600 may have a shape elongated in one direction. More specifically, the light conversion member 600 may have a shape extending along one side of the light guide plate 200. More specifically, the light conversion member 600 may have a shape extending along the incident surface of the light guide plate 200.

The first light conversion member 600 may convert blue light from the light emitting diodes 400 into green light. More specifically, the first light conversion member 600 may receive light from the light emitting diode and convert the light into green light having a wavelength range of about 520 nm to about 560 nm.

As shown in FIG. 2, the first photo-conversion member 600 includes a first transparent substrate 610, a second transparent substrate 620, and a first photo-conversion layer 630.

The first transparent substrate 610 and the second transparent substrate 620 may be a polymer substrate. More specifically, the first transparent substrate 610 and the second transparent substrate 620 may be a polyethylene terephthalate substrate.

The first light conversion layer 630 is interposed between the first transparent substrate 610 and the second transparent substrate 620. The first light conversion layer 630 may be in close contact with the first transparent substrate 610 and the second transparent substrate 620.

The first photoconversion layer 630 includes a plurality of first photoconversion particles 631 and a first host 632.

The first photoconversion particles 631 convert the wavelength of the light from the light emitting diodes. More specifically, the first photoconversion particles 631 convert the light from the light emitting diodes into green light. The second photoconversion particles convert light from the light emitting diode into green light having a wavelength band between about 520 nm and about 560 nm.

The first photo-conversion particles 631 include a phosphor. More specifically, the first photo-conversion particles 631 include a green phosphor. Examples of the green phosphor include manganese-doped zinc oxide-based phosphor (for example, Zn2SiO4: Mn), europium-doped strontium gallium sulfide phosphor (for example, SrGa2S4: Eu) or europium-doped barium silicon oxide chloride Based phosphor (for example, Ba5Si2O7Cl4: Eu).

The first host 632 is in close contact with the first transparent substrate 610 and the second transparent substrate 620. The first host 632 is transparent. Examples of the material used for the first host 632 include a silicone resin or an epoxy resin.

The first host 632 receives the first photoconversion particles 631. The first host 632 surrounds the first photoconversion particles 631. The first photoconversion particles 631 are inserted into the first host 632. The first host 632 may disperse the first photoconversion particles 631.

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 second light conversion member 501, a diffusion sheet 502, a first prism sheet 503, and a second prism sheet 504.

The second light-converting member 501 is disposed on the light guide plate 200. More specifically, the second light conversion member 501 may be interposed between the light guide plate 200 and the diffusion sheet 502. The second photo-conversion member 501 can convert the wavelength of incident light and emit upward.

For example, the second light conversion member converts the blue light from the light emitting diodes and the green light converted by the first light conversion member 600 into red light. That is, the second light conversion member converts the green light and the blue light emitted from the upper surface of the light guide plate into red light. More specifically, the second light conversion member can convert light incident from the light guide plate into red light having a wavelength range of about 630 nm to about 660 nm.

Accordingly, the blue light passing through the first photo-conversion member 600 and the photo-conversion member, the green light converted by the first photo-conversion member 600, and the blue light passing through the second photo-conversion member 501 ) Are combined, so that white light can be generated. The white light may be incident on the liquid crystal panel 20.

The first light conversion member 600 and the second light conversion member 501 are optical members that change the characteristics of incident light.

As shown in FIG. 2, the second photo-conversion member 501 includes a lower substrate 510, an upper substrate 520, and a second photo-conversion layer 530.

The lower substrate 510 is disposed below the second 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 second 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 second 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 second 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 second light conversion layer 530. The lower substrate 510 and the upper substrate 520 support the second light conversion layer 530. The lower substrate 510 and the upper substrate 520 protect the second light conversion layer 530 from external physical impacts.

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 second light conversion layer 530 from external chemical impacts such as moisture and / or oxygen.

The second light conversion layer 530 is interposed between the lower substrate 510 and the upper substrate 520. The second 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 second photo-conversion layer 530 includes a plurality of second photo-conversion particles 531 and a second host 532.

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

The second light conversion particles 531 convert the wavelength of the light emitted from the light emitting diodes 400 and the light from the first light conversion member 600. The second light conversion particles 531 receive light emitted from the light emitting diodes 400 and the first light conversion member 600 and convert the wavelength. For example, the second light conversion particles 531 may convert incident light into red light. That is, the second light conversion particles 531 may convert blue light and green light into red light having a wavelength range of about 630 nm to about 660 nm.

The second photoconversion particles 531 may be a plurality of quantum dots (QDs). More specifically, the second photoconversion particles 531 may be red quantum dots. 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 second host 532 surrounds the second light conversion particles 531. That is, the second host 532 uniformly disperses the second light conversion particles 531 therein. The second host 532 may be comprised of a polymer. The second host 532 is transparent. That is, the second host 532 may be formed of a transparent polymer. A silicone resin or an epoxy resin may be used for the second host 532.

The second host 532 is disposed between the lower substrate 510 and the upper substrate 520. The second host 532 may be in close contact with the upper surface of the lower substrate 510 and the lower surface of the upper substrate 520.

Referring again to FIG. 1, the diffusion sheet 502 is disposed on the second 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 for covering the gate lines, the data lines, the thin film transistors, etc., .

And a driving PCB 25 for supplying a driving signal to the gate line and the data line is provided at an edge of the liquid crystal display panel 210.

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, in the liquid crystal display device according to the embodiment, the first light conversion member 600 is disposed adjacent to the light source, the second light conversion member 501 is disposed on the light guide plate, (400). Accordingly, the first photo-conversion particles 631 having relatively high heat resistance such as phosphors are disposed on the first photo-conversion member 600, and the second photo-conversion member 501 has a relatively low The second photo-conversion particles 531 having heat resistance can be disposed.

Accordingly, the liquid crystal display according to the embodiment can prevent a phenomenon of heat deterioration from the light emitting diodes 400, and can have improved reliability and durability.

In addition, the first photo-conversion member 600 may include a green phosphor. Accordingly, a part of light from the light emitting diodes 400 can be directly converted into green light. Therefore, the green light from the first photo-conversion member 600 can be incident on the second photo-conversion member 501 with high transmittance.

That is, since the blue light has a shorter wavelength than the green light, the light loss rate may be higher than that of the green light. At this time, the remaining blue light other than the blue light necessary for displaying an image on the liquid crystal panel 20 may be converted into green light, and may be incident on the second photo-conversion member 501.

Accordingly, more light can be incident on the second photo-conversion member 501 and converted into red light.

Therefore, the liquid crystal display according to the embodiment can have improved luminance and luminance uniformity.

3 is a perspective view showing a light source, a light guide plate, a first light conversion member, and a second light conversion member according to the second embodiment. 4 is a cross-sectional view showing a light source, a light guide plate, a first light conversion member and a second light conversion member according to the second embodiment. In the description of this embodiment, the description of the foregoing embodiment will be made. That is, the description of the above-described liquid crystal display device can be essentially combined with the description of the present liquid crystal display device except for the changed portions.

Referring to FIGS. 3 and 4, the light source according to the present embodiment includes a plurality of first light emitting diodes 410 and a plurality of second light emitting diodes 420. The first light emitting diodes 410 emit blue light and the second light emitting diodes 420 emit ultraviolet light. More specifically, the first light emitting diodes 410 emit blue light having a wavelength range of about 430 nm to about 470 nm, and the second light emitting diodes 420 emit blue light having a wavelength range of about 300 nm to about 400 nm Can be emitted.

The first light emitting diode 410 and the second light emitting diode 420 emit light to the first light converting member 600. The first light conversion member 600 may convert light from the first light emitting diode 410 and the second light emitting diode 420 into blue light and green light.

That is, the first light conversion member 600 can convert blue light from the first light emitting diode 410 into green light.

The first light conversion member 600 may convert ultraviolet light from the second light emitting diode 420 into blue light and green light.

The first photo-conversion member 600 further includes a plurality of third photo-conversion particles 633. The third photoconversion particles 633 are disposed in the first host 632. The third photoconversion particles 633 are uniformly dispersed in the first host 632. The third photoconversion particles 633 are inserted into the first host 632.

The third light conversion particles 633 convert ultraviolet light from the second light emitting diode into blue light. More specifically, the third photoconversion particles 633 can convert ultraviolet light from the second light emitting diode into blue light of a short wavelength. In particular, the third photoconversion particles 633 may convert the ultraviolet light into blue light having a shorter wavelength than the blue light of the first light emitting diode 410.

For example, the third photoconversion particles 633 can convert ultraviolet rays from the second light emitting diode 420 into blue light having a wavelength of about 400 nm to about 430 nm.

Accordingly, the liquid crystal display according to the present embodiment can display an image using blue light, which is difficult to realize by a blue light emitting diode. That is, the liquid crystal display device according to the present embodiment can have an improved color gamut.

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)

Light source;
A first photo-conversion member through which light from the light source is incident;
A light guide plate through which light from the first light conversion member is incident;
A second light conversion member through which light from the light guide plate is incident; And
And a display panel on which light from the second photo-conversion member is incident,
Wherein the first photo-conversion member comprises a phosphor,
Wherein the second photo-conversion member comprises a compound semiconductor. The method according to claim 1,
Wherein the second photo-conversion member comprises a quantum dot. 2. The apparatus according to claim 1, wherein the first light conversion member converts blue light from the light source into green light,
And the second photo-conversion member converts blue light from the light source into red light. The light source according to claim 1,
A first light source for emitting blue light; And
And a second light source for emitting ultraviolet rays. 5. The device of claim 4, wherein the first light conversion member
A first light conversion particle for converting blue light from the first light source into green light; And
And third light conversion particles for converting ultraviolet rays from the two light sources into blue light. The apparatus of claim 4, wherein the first light source and the second light source are a plurality of,
Wherein the first light source and the second light source are alternately arranged. The light guide plate according to claim 1, wherein the light source is disposed on a side surface of the light guide plate,
Wherein the display panel is disposed on an upper surface of the light guide plate,
Wherein the first light conversion member is interposed between the light source and the light guide plate,
And the second light conversion member is interposed between the light guide plate and the display panel.

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