KR101360638B1 - Display, light conversion member and method of fabricating light conversion member - Google Patents

Abstract

The light conversion member according to the embodiment may include a lower substrate; A wavelength conversion layer located on the lower substrate; And an upper substrate positioned on the wavelength conversion layer, and the lower substrate includes a reflective layer formed on at least one surface of the lower substrate.
A display device according to an embodiment includes a light source; A light conversion member that converts a wavelength of light emitted from the light source; And a display panel to which light converted by the light conversion member is incident, the light conversion member comprising: a lower substrate; A wavelength conversion layer located on the lower substrate; And an upper substrate positioned on the wavelength conversion layer, and the lower substrate includes a reflective layer formed on at least one surface of the lower substrate.

Description

Display device, light conversion member and manufacturing method of light conversion member {DISPLAY, LIGHT CONVERSION MEMBER AND METHOD OF FABRICATING LIGHT CONVERSION MEMBER}

Embodiments relate to a display device, a light conversion member, and a method for manufacturing the light conversion member.

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

Among them, 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 is located on the lower surface of the thin film transistor substrate. The amount of light transmitted from the backlight unit is adjusted according to the arrangement state of the liquid crystal.

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

The direct type is a structure that is mainly developed as the size of a liquid crystal display device is enlarged, and is a structure in which one or more light sources are disposed on a lower surface of the liquid crystal display panel to supply light to the liquid crystal display panel.

The direct type backlight unit has the advantage of being able to use a large number of light sources compared to the edge type backlight unit to secure high luminance, while the thickness of the edge type backlight unit is thicker than that of the edge type to secure uniformity of luminance. have.

To overcome this, when receiving blue light in front of a blue LED that emits blue light constituting a backlight unit, a quantum dot bar in which a plurality of quantum dots are converted into red or green wavelengths is dispersed, and the blue light is irradiated to the quantum dot bar. By doing so, light mixed with blue light, red light and green light is incident on the light guide plate by a plurality of quantum dots dispersed in the quantum dot bar to provide white light.

In this case, when white light is provided to the light guide plate using the quantum dot bar, high color reproduction may be realized.

The backlight unit is provided with an FPCB (Flexible Printed Circuits Board) for transmitting power and supplying an LED and a signal to one side of the blue LED that emits blue light, and an adhesive member may be further provided on the lower surface of the FPCB.

As described above, when light oscillating from the blue LED leaks, a display device that displays an image in various forms using white light provided to the light guide plate through a quantum dot bar is widely used.

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

The embodiments are intended to provide a display device having improved luminance and reliability, a light conversion member, and a method for manufacturing the light conversion member.

The light conversion member according to the embodiment may include a lower substrate; A wavelength conversion layer located on the lower substrate; And an upper substrate positioned on the wavelength conversion layer, and the lower substrate includes a reflective layer formed on at least one surface of the lower substrate.

A method of manufacturing a light conversion member according to an embodiment includes preparing a lower substrate; Forming a reflective layer on the lower substrate; Forming a wavelength conversion layer on the reflective layer; And preparing an upper substrate on the wavelength conversion layer, and the reflective layer includes gold.

A display device according to an embodiment includes a light source; A light conversion member that converts a wavelength of light emitted from the light source; And a display panel to which light converted by the light conversion member is incident, the light conversion member comprising: a lower substrate; A wavelength conversion layer located on the lower substrate; And an upper substrate positioned on the wavelength conversion layer, and the lower substrate includes a reflective layer formed on at least one surface of the lower substrate.

The light conversion member and the display device according to the embodiment include a reflective layer formed on at least one surface of the lower substrate supporting the wavelength conversion layer. Accordingly, light emitted from the light source and converted by the wavelength conversion layer can be effectively incident on the upper substrate.

That is, the reflective layer reflects light passing through the wavelength conversion member and is incident on the upper substrate. In addition, the reflective layer reflects the light converted by the wavelength conversion member, and is incident on the upper substrate.

Accordingly, the reflective layer prevents light from leaking, and more light is incident on the upper substrate. Therefore, the display device according to the embodiment may have improved luminance.

1 is an exploded perspective view showing a liquid crystal display device according to an embodiment.
2 is a perspective view showing a light conversion member according to an embodiment.
3 is a cross-sectional view showing a cross-section taken along AA` in FIG. 2.
4 is a graph showing a transmittance according to a thickness of a reflector according to an embodiment.

In the description of the embodiment, each substrate, frame, sheet, layer or pattern, etc. is described as being formed "on" or "under" of each substrate, frame, sheet, layer or pattern, etc. In some cases, "on" and "under" include both "directly" or "indirectly" formed through other components. In addition, the criteria for the top or bottom of each component is described based on the drawings. The size of each component in the drawings may be exaggerated for explanation, and does not mean the size actually applied.

1 is an exploded perspective view showing a liquid crystal display device according to an embodiment, FIG. 2 is a perspective view showing a light conversion member according to an embodiment, and FIG. 3 is a cross-sectional view of FIG. 2 taken along AA` 4 is a graph showing the reflectance according to the type of the reflector according to the embodiment, and FIG. 5 is a graph showing the transmittance according to the thickness of the reflector according to the embodiment.

Hereinafter, a light conversion member, a method of manufacturing the light conversion member, and a display device according to an embodiment will be described with reference to FIGS. 1 to 5.

1 to 5, 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 may uniformly irradiate light to the lower surface of the liquid crystal panel 20 with a surface light source.

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, for example, a plurality of light emitting diodes 400, a printed circuit board 401, and a plurality of optical sheets Field 500.

The bottom cover 100 has an open top shape. The bottom cover 100 accommodates the light guide plate 200, the light emitting diodes 400, the printed circuit board 401, the reflective 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 incident from the light emitting diodes 400 upward through total reflection, refraction, and scattering.

The reflective sheet 300 is disposed under the light guide plate 200. In more detail, 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 that generate 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 a side surface of the light guide plate 200.

The light emitting diodes 400 may be blue light emitting diodes that generate blue light or UV light emitting diodes that generate ultraviolet light. That is, the light emitting diodes 400 may generate blue light having a wavelength band between about 430 nm and about 470 nm, or ultraviolet light having a wavelength band between about 300 nm and about 400 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 driving 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 optical sheets 500 are disposed on the light guide plate 200. The optical sheets 500 change or improve 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 510, a diffusion sheet 520, a first prism sheet 530 and a second prism sheet 540.

The light conversion member 510 may be disposed on the light path between the light source and the liquid crystal panel 20. For example, the light conversion member 510 may be disposed on the light guide plate 200. In more detail, the light conversion member 510 may be interposed between the light guide plate 200 and the diffusion sheet 520. The light conversion member 510 may convert the wavelength of the incident light and emit it upward.

For example, when the light emitting diodes 400 are blue light emitting diodes, the light conversion member 510 may convert blue light emitted upward from the light guide plate 200 into green light and red light. That is, the light conversion member 510 converts a portion of the blue light into green light having a wavelength range between about 520 nm and about 560 nm, and the other part of the blue light has a wavelength range between about 630 nm and about 660 nm. Can be converted to red light.

In addition, when the light emitting diodes 400 are UV light emitting diodes, the light conversion member 510 may convert ultraviolet light emitted from the top surface of the light guide plate 200 into blue light, green light, and red light. That is, the light conversion member 510 converts a part of the ultraviolet light into blue light having a wavelength range between about 430 nm and about 470 nm, and other parts of the ultraviolet light have a wavelength range between about 520 nm and about 560 nm. It can be converted to green light, and another part of the ultraviolet light can be converted to red light having a wavelength range between about 630 nm and about 660 nm.

Accordingly, light that is not converted and passes through the light conversion member 510 and light converted by the wavelength conversion member 510 may form white light. That is, blue light, green light and red light are combined, and white light may be incident on the liquid crystal panel 20.

That is, the light conversion member 510 is an optical member that converts characteristics of incident light. The light conversion member 510 has a sheet shape. That is, the light conversion member 510 may be an optical sheet.

2 and 3, the light conversion member 510 includes a lower substrate 501, an upper substrate 502, a wavelength conversion layer 503 and a reflective layer 504.

The lower substrate 501 is disposed under the wavelength conversion layer 503. The lower substrate 501 is transparent and can be flexible. The lower substrate 501 may be in close contact with the lower surface of the wavelength conversion layer 503.

 Examples of the material used as the lower substrate 501 include a transparent polymer such as polyethylene terephthalate (PET).

The upper substrate 502 is disposed on the wavelength conversion layer 503. The upper substrate 502 is transparent and may be flexible. The upper substrate 502 may be in close contact with the upper surface of the wavelength conversion layer 503.

Examples of the material used as the upper substrate 520 include a transparent polymer such as polyethylene terephthalate.

The lower substrate 501 and the upper substrate 502 sandwich the wavelength conversion layer 503. The lower substrate 501 and the upper substrate 502 support the wavelength conversion layer 503. The lower substrate 501 and the upper substrate 502 protect the wavelength conversion layer 503 from external physical impact. The lower substrate 501 and the upper substrate 502 may directly contact the wavelength conversion layer 503.

In addition, the lower substrate 501 and the upper substrate 502 have low oxygen permeability and moisture permeability. Accordingly, the lower substrate 501 and the upper substrate 502 may protect the wavelength conversion layer 503 from external chemical impacts such as moisture and/or oxygen.

The wavelength conversion layer 503 is interposed between the lower substrate 501 and the upper substrate 502. Preferably, the wavelength conversion layer 503 may be disposed on a central region with respect to the lower substrate 501 and the upper substrate 502. In addition, the wavelength conversion layer 503 may be in close contact with the upper surface of the lower substrate 501 and may be in close contact with the lower surface of the upper substrate 502.

The wavelength conversion layer 503 includes a plurality of wavelength conversion particles 505 and a host layer 506.

The wavelength conversion particles 505 are disposed between the lower substrate 501 and the upper substrate 502. In more detail, the wavelength conversion particles 505 are uniformly dispersed in the host layer 506, and the host layer 506 is disposed between the lower substrate 501 and the upper substrate 502.

The wavelength conversion particles 505 convert the wavelength of light emitted from the light emitting diodes 400. The wavelength conversion particles 505 receive light emitted from the light emitting diodes 400 and convert the wavelength. For example, the wavelength conversion particles 505 may convert blue light emitted from the light emitting diodes 400 into green light and red light. That is, some of the wavelength converting particles 505 convert the blue light into green light having a wavelength range between about 520 nm and about 560 nm, and some of the wavelength converting particles 505 convert the blue light to about 630 It can be converted into red light having a wavelength range between nm and about 660 nm.

Alternatively, the wavelength conversion particles 505 may convert ultraviolet light emitted from the light emitting diodes 400 into blue light, green light, and red light. That is, some of the wavelength converting particles 505 convert the ultraviolet light into blue light having a wavelength range between about 430 nm and about 470 nm, and some of the wavelength converting particles 505 convert the ultraviolet light to about 520 It can be converted into green light having a wavelength range between nm and about 560 nm. In addition, another part of the wavelength conversion particles 505 may convert the ultraviolet light into red light having a wavelength range between about 630 nm and about 660 nm.

That is, when the light emitting diodes 400 are blue light emitting diodes that generate blue light, wavelength converting particles 505 that convert blue light into green light and red light, respectively, may be used. Alternatively, when the light emitting diodes 400 are UV light emitting diodes that generate ultraviolet light, wavelength converting particles 505 that convert ultraviolet light into blue light, green light, and red light, respectively, may be used.

The wavelength conversion particles 505 may be a plurality of quantum dots (QD). 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 nanocrystals. In addition, the quantum dots may include an organic coating layer surrounding the shell nano crystals.

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 light incident on the core out crystal through the shell nanocrystals forming the shell layer and increase the efficiency of light.

The quantum dot may include at least one material from 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. In addition, the shell nanocrystals may include CuZnS, CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe or HgS. The diameter of the quantum dot may be 1nm to 10nm.

The wavelength of light emitted from the quantum dots can be adjusted according to the size of the quantum dots. The organic ligand may include pyridine, mercapto alcohol, thiol, phosphine and phosphine oxide. The organic ligand serves to stabilize unstable quantum dots after synthesis. After synthesis, dangling bonds are formed on the outside, and due to the dangling bonds, the quantum dots may become unstable. However, one end of the organic ligand is unbound, and one end of the unbound organic ligand can be combined with a dangling bond to stabilize the quantum dot.

Particularly, when the size of the quantum dot is smaller than the Bohr raidus of the exciton formed by electrons and holes excited by light, electricity, etc., a quantum confinement effect occurs to have a remarkable energy level and an energy gap. The size of the will change. In addition, electric charges are confined within the quantum dots, resulting in high luminous efficiency.

Unlike the general fluorescent dye, the fluorescence wavelength of the quantum dots varies depending on the particle size. That is, as the particle size decreases, light of a short wavelength is emitted, and the size of the particle can be adjusted to fluoresce the visible light region of a desired wavelength. In addition, since the extinction coefficient is 100 to 1000 times larger than that of a general dye and the quantum efficiency is high, very strong fluorescence is generated.

The quantum dots can be synthesized by a chemical wet method. Here, the chemical wet method is a method of growing particles by putting a precursor material in an organic solvent, and the quantum dots may be synthesized by a chemical wet method.

The host layer 506 surrounds the wavelength conversion particles 505. That is, the host layer 506 uniformly disperses the wavelength conversion particles 505 therein. The host layer 506 may be made of polymer. The host layer 506 is transparent. That is, the host layer 506 may be formed of a transparent polymer.

The host layer 506 is disposed between the lower substrate 501 and the upper substrate 502. Preferably, the host layer 506 is disposed on a central region with respect to the lower substrate 501 and the upper substrate 502. In addition, the host layer 506 may be in close contact with the upper surface of the lower substrate 501 and the lower surface of the upper substrate 502.

The reflective layer 504 is positioned on the lower substrate 501. In detail, the reflective layer 504 may be formed on at least one surface of the lower substrate 501. In more detail, the reflective layer 504 may be formed on an outer surface, an inner surface, or the like of the lower substrate 501. However, embodiments are not limited thereto, and the reflective layer 504 may be formed in all regions of the lower substrate 501.

Referring to FIG. 3, the reflective layer 504 may be positioned between the lower substrate 501 and the wavelength conversion layer 503. The reflective layer may reflect light, which does not pass through the upper substrate 502 of the light passing through the wavelength conversion layer 503, but goes back to the lower substrate 501 again in the direction of the upper substrate 502.

That is, the blue light incident by the light emitting diodes 400 passes through the lower substrate 501 and passes through the wavelength conversion particles 505 accommodated in the wavelength change layer 502. The wavelength of the blue light passing through the wavelength conversion particles 505 is converted to green light or red light, and may pass through the upper substrate 501.

However, since light passing through the wavelength conversion layer 503 emits light in all directions rather than moving only in the direction of the upper substrate 502, either green light or red light converted by the wavelength conversion layer 503 Since some parts move in the opposite direction, not the upper substrate 502 direction, that is, in the lower substrate 501 direction, light loss may occur and luminance and efficiency may decrease.

Accordingly, the light conversion member and the display device according to the exemplary embodiment coat the reflective layer 504 on the lower substrate 501 to return green or red light moving in the lower substrate 501 direction to the upper substrate 502 again. ) Direction.

The reflective layer 504 may include metal. Preferably, the reflective layer may include gold (Au), silver (Ag), or aluminum (Al). More preferably, the reflective layer 504 may include gold.

4 is a graph showing reflectance by wavelength for gold, silver, or aluminum.

Referring to FIG. 4, it can be seen that when the reflective layer 504 includes gold, reflectances of green light and red light are high. That is, the reflective layer 504 including gold has a small reflectance of blue light, while the reflectance of green light and red light is excellent, when the green light or red light converted by the wavelength conversion layer moves in the direction of the lower substrate 501. It can be seen that the green light or the red light can be effectively moved to move in the direction of the upper substrate 502.

In addition, the thickness of the reflective layer 504 may be 0.1 nm or more. Preferably, the thickness of the reflective layer 504 may be 0.1 nm to 5 nm.

5 is a graph showing transmittance by wavelength for the thickness of the reflective layer 504.

Referring to FIG. 5, when the reflective layer 504 includes gold and is formed on the lower substrate 501 with a thickness of 5 nm, it can be seen that the light transmittance, that is, the transmittance of blue light is 70% or more. have. On the other hand, when the thickness of the reflective layer 504 is formed to exceed 5 nm, the transmittance of the blue light is very low, thereby reducing efficiency.

Accordingly, the thickness of the reflective layer 504 is formed to be 0.1 nm to 5 nm to simultaneously improve the transmittance of blue light and the reflectance of the converted green light and red light.

Accordingly, in the light conversion member and the display device according to the embodiment, the reflective layer 504 may reduce luminance and light loss improved by.

That is, since the reflection layer 504 reflects the green light or red light, which is converted through the wavelength conversion layer 503, in the direction of the lower substrate 501, is reflected back to the upper substrate 502 by the reflection layer, so that the light Loss can be reduced and luminance can be improved.

Accordingly, the reflective layer prevents light from leaking, and more light is incident on the upper substrate. Therefore, the display device according to the embodiment may have improved luminance.

The diffusion sheet 520 is disposed on the wavelength conversion member 510. The diffusion sheet 520 improves uniformity of light passing therethrough. The diffusion sheet 520 may include a plurality of beads.

The first prism sheet 530 is disposed on the diffusion sheet 520. The second prism sheet 540 is disposed on the first prism sheet 530. The first prism sheet 530 and the second prism sheet 540 increase the straightness of light passing therethrough.

The liquid crystal panel 20 is disposed on the optical sheets 500. In addition, 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 therethrough. That is, the liquid crystal panel 20 is a display panel that displays 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 two substrates. In addition, the liquid crystal panel 20 includes polarization filters.

Although not shown in detail in the drawing, when the TFT substrate 21 and the color filter substrate 22 are described in detail, the TFT substrate 21 defines pixels by crossing a plurality of gate lines and data lines, and each crossing A thin film transistor (TFT) is provided for each region, and is connected in one-to-one correspondence with a pixel electrode mounted on each pixel. The color filter substrate 22 includes R, G, and B color filters corresponding to each pixel, a black matrix that borders each of them, and covers a gate line, a data line, and a thin film transistor, and a common electrode covering all of them. Includes.

A driving PCB 25 for supplying driving signals to the gate line and the data line is provided at the edge of the liquid crystal display panel 210.

The driving 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 tape carrier package (TCP).

As described above, the light conversion member and the display device according to the embodiment include a reflection layer formed on at least one surface of the lower substrate supporting the wavelength conversion layer. Accordingly, light emitted from the light source and converted by the wavelength conversion layer can be effectively incident on the upper substrate.

That is, the reflective layer reflects light passing through the wavelength conversion member and is incident on the upper substrate. In addition, the reflective layer reflects the light converted by the wavelength conversion member, and is incident on the upper substrate.

Accordingly, the reflective layer prevents light from leaking to the lower substrate, and more light is incident on the upper substrate. Therefore, the display device according to the embodiment can reduce leaking light and have improved luminance, thereby improving optical characteristics.

Features, structures, effects, etc. described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, features, structures, effects, and the like exemplified in each embodiment may be combined or modified for other embodiments by a person having ordinary knowledge in the field to which the embodiments belong. Therefore, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

The embodiments have been mainly described above, but this is merely an example and does not limit the present invention, and those of ordinary skill in the art to which the present invention pertains have not been exemplified above in a range that does not depart from the essential characteristics of the present embodiment. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be implemented by modification. And differences related to these modifications and applications should be construed as being included in the scope of the invention defined in the appended claims.

Claims (17)

A lower substrate on which light emitted from the light source is incident;
A wavelength conversion layer located on the lower substrate; And
It includes an upper substrate located on the wavelength conversion layer,
The lower substrate includes a reflective layer formed on at least one surface of the lower substrate,
The reflective layer includes gold (Au),
The thickness of the reflective layer is 0.1 nm to 5 nm,
The wavelength conversion layer includes a plurality of quantum dots and a host layer,
The quantum dots are light conversion members for converting light emitted from the light source into green light and red light or blue light, green light and red light. delete delete delete According to claim 1,
The reflective layer is a light conversion member formed on the outer surface or the inner surface of the lower substrate. According to claim 1,
The lower substrate or the upper substrate includes a polymer,
The polymer is a light conversion member comprising polyethylene terephthalate (PET). delete delete delete delete delete Light source;
A light conversion member that converts a wavelength of light emitted from the light source; And
And a display panel through which light converted by the light conversion member is incident,
The light conversion member,
Lower substrate;
A wavelength conversion layer located on the lower substrate; And
It includes an upper substrate located on the wavelength conversion layer,
The lower substrate includes a reflective layer formed on at least one surface of the lower substrate,
The reflective layer includes gold (Au),
The thickness of the reflective layer is 0.1 nm to 5 nm,
The wavelength conversion layer includes a plurality of quantum dots and a host layer,
The quantum dots display device for converting light emitted from the light source into green light and red light or blue light, green light and red light. delete delete delete The method of claim 12,
The lower substrate or the upper substrate includes a polymer,
The polymer is a display device comprising polyethylene terephthalate. delete

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