KR20130065480A - Display device - Google Patents

Abstract

PURPOSE: A display device is provided to eliminate a light guiding panel by sending light to the upper area of an optical sheet through making change in the light reflecting angle of a light source following the angle change pattern of a reflecting sheet. CONSTITUTION: A reflecting sheet (300) directly opposes optical sheets(500). Light Emitting Diodes(LEDs)(400) is positioned between the optical sheet and the reflecting sheet. The reflecting sheet changes the reflecting angle of 'an incident light which gets in the reflecting sheet' and includes 'an angle change pattern(310) with slope'. The angle of the slope is 15-60 degree.

Description

Display device {DISPLAY DEVICE}

The embodiment relates to a display device.

Light emitting diodes (LEDs) are semiconductor devices that convert electricity into ultraviolet rays, visible rays, and infrared rays by using the characteristics of compound semiconductors. They are mainly used in home appliances, remote controllers, and large electric sign boards.

The high-intensity LED light source is used as an illumination light. It has high energy efficiency, long life and low replacement cost. It is resistant to vibration and shock, and it does not require the use of toxic substances such as mercury. It is replacing incandescent lamps and fluorescent lamps.

Also, the LED is very advantageous as a light source such as a medium and large-sized LCD TV and a monitor. Compared to CCFL (Cold Cathode Fluorescent Lamp), which is mainly used in LCD (Liquid Crystal Display), it has excellent color purity, low power consumption, and easy miniaturization, Is in progress.

In the conventional display device, light incident from the light emitting diodes is emitted upward through total reflection, refraction, and scattering using a light guide plate. That is, it consists of a light source, a wavelength conversion member, and a light guide plate, a light source is incident on the light guide plate, and the light source is emitted upward through total reflection, refraction, and scattering.

However, in the conventional display device, the weight can be increased by such a light guide plate, and a bonding process with the wavelength conversion member is required. In addition, there is a problem in that the brightness can be reduced by the light loss of the light guide plate.

Accordingly, there is a need for a display device capable of omitting the light guide plate.

Embodiments provide a display device having improved color reproducibility and which can be easily manufactured.

In one embodiment, a display device includes an optical sheet; A reflective sheet that directly faces the optical sheet; And a light source positioned between the optical sheet and the reflective sheet, wherein the reflective sheet changes an angle of reflection of incident light incident on the reflective sheet, and includes an angle change pattern having an inclined surface, wherein the angle of the inclined surface is 15 ° to 60 °.

The display device according to the embodiment includes an angle change pattern in the reflective sheet. The angle changing pattern is emitted upward of the optical sheet by changing the angle of reflection angle of light incident by the light source.

As a result, the light guide plate used in the related art can be omitted, thereby making it possible to reduce the weight and thickness of the display device, and to omit the bonding process between the light guide plate and the wavelength conversion member.

In addition, since all light sources incident from the wavelength conversion member are incident on light guide plates, light efficiency may be improved.

1 is an exploded perspective view illustrating a liquid crystal display according to an embodiment.
2 is a cross-sectional view illustrating a light emitting diode, a reflective member, and an optical sheet.
3 to 6 are views showing the shape of the angle change pattern.
7 illustrates an optical path of incident light according to an angle change pattern.

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 cross-sectional view showing a light emitting diode, an optical sheet, and a reflective layer. 3 to 6 are views showing the shape of the angle change pattern. 7 illustrates an optical path of incident light according to an angle change pattern.

1 to 3, the liquid crystal display according to the 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 irradiate uniform light onto the bottom surface of the liquid crystal panel 20 using a surface light source.

The backlight unit 10 is disposed under the liquid crystal panel 20. The backlight unit 10 may include a bottom cover 100, a reflective sheet 300, a light source, for example, a plurality of light emitting diodes 400, a printed circuit board 401, a plurality of optical sheets 500, and And a wavelength converting member.

All of these configurations are not essential, and some configurations may be omitted in some embodiments.

The bottom cover 100 has a shape in which an upper portion thereof is opened. The bottom cover 100 accommodates the light emitting diodes 400, the printed circuit board 401, the reflective sheet 300, and the optical sheets 500.

The light emitting diodes 400 are light sources for generating light. The light emitting diodes 400 generate light to pass through the wavelength conversion member 600 and then directly through the side surface of the reflective sheet 300 or directly through the side surface of the reflective sheet 300. It enters into (300).

The light emitting diodes 400 may be blue light emitting diodes generating blue light or UV light emitting diodes generating 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 rays 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 reflective sheet 300. The optical sheets 500 improve the characteristics of light passing through them.

Alternatively, the optical sheets 500 may include a light conversion diffusion sheet 501, a first prism sheet 502, and a second prism sheet 503.

The light conversion diffusion sheet 501 may be disposed on the reflective sheet 300. In more detail, the light conversion diffusion sheet 501 may be interposed between the reflective sheet 300 and the first prism sheet 502. The light conversion diffusion sheet 501 may be emitted upward by improving the uniformity of incident light.

The light conversion diffusion sheet 501 includes a plurality of wavelength conversion particles and a host layer. The wavelength conversion particles may be uniformly dispersed in the host layer.

For example, when the light emitting diodes 400 are blue light emitting diodes, the light conversion diffusion sheet 501 may convert blue light emitted upward from the reflective sheet 300 into green light and red light. That is, the light conversion diffusion sheet 501 converts a part of the blue light into green light having a wavelength band between about 520 nm and about 560 nm, and converts another part of the blue light into red light having a wavelength band between about 630 nm and 680 nm. Can be.

In addition, when the light emitting diodes 400 are UV light emitting diodes, the light conversion diffusion sheet 501 may convert ultraviolet light emitted from an upper side of the reflective sheet 300 into blue light, green light, and red light. That is, the light conversion diffusion sheet 501 converts a part of the ultraviolet light into blue light having a wavelength band between about 430 nm and about 470 nm, and converts another part of the ultraviolet light into green light having a wavelength band between about 520 nm and 560 nm. The second portion of the ultraviolet light may be converted into red light having a wavelength band between about 630 nm and about 680 nm.

Accordingly, the light passing through the light conversion diffusion sheet 501 without conversion and the light converted by the light conversion diffusion sheet 501 may form white light. That is, blue light, green light, and red light may be combined to allow white light to enter the liquid crystal panel 20.

The reflective sheet 300 is disposed in the bottom cover 100. The reflective sheet 300 emits light incident from the light emitting diodes 400 upward through total reflection, refraction, and scattering. That is, the light incident from the light emitting diodes 400 is emitted upward through refraction and scattering by the angle change pattern formed on the reflective sheet 300.

In addition, the reflective sheet 300 may face the optical sheet 500. Preferably, the reflective sheet 300 may directly face the optical sheet 500. In addition, when the optical sheet 500 includes the light conversion diffusion sheet 501, the reflective sheet 300 may directly face the light conversion diffusion sheet 501.

That is, an empty space may be formed between the optical sheet 500 that directly faces the reflective sheet 300. Alternatively, an empty space may be formed between the light conversion diffusion sheet 501 directly facing the reflective sheet 300.

In addition, the reflective sheet 300 may include an angle change pattern 310. The angle change pattern 310 may change a reflection angle of incident light emitted from the light emitting diode 400 and incident on the reflective sheet 300. That is, the angle change pattern 310 may change the angle of reflection of the incident light. The angle change pattern will be described below.

Material of the reflective sheet 300 may include TAC, PET or PC. In addition, the angle change pattern 310 may be formed by a nano-imprint method using aluminum (Al) and metal nanowires.

The wavelength conversion member 600 may be interposed on side surfaces of the light emitting diodes 400. However, when the optical sheet 500 includes the light conversion member 501 directly facing the reflective sheet 300, the wavelength conversion member 600 is not included.

The wavelength conversion member 600 may have a shape extending in one direction. In more detail, the wavelength conversion member 600 may have a shape extending in the direction in which the reflective sheet 300 extends.

The wavelength conversion member 600 includes a plurality of wavelength conversion particles and a host layer. The wavelength conversion particles may be uniformly dispersed in the host layer.

The wavelength conversion member 600 receives light emitted from the light emitting diodes 400 and converts the wavelength. For example, the wavelength conversion member 600 may convert blue light emitted from the light emitting diodes 400 into green light and red light. That is, the wavelength conversion member 600 converts a part of the blue light into green light having a wavelength band of about 520 nm to about 560 nm, and another part of the blue light having a wavelength band of about 630 nm to about 660 nm. Can be converted to red light.

In addition, the wavelength conversion member 600 may convert ultraviolet light emitted from the light emitting diodes 400 into blue light, green light, and red light. That is, the wavelength conversion member 600 converts a part of the ultraviolet light into blue light having a wavelength band between about 430 nm and about 470 nm, and another part of the ultraviolet light has a wavelength band between about 520 nm and about 560 nm. Green light, and another portion of the ultraviolet light to red light having a wavelength band between about 630 nm and about 660 nm.

That is, when the light emitting diodes 400 are blue light emitting diodes for generating blue light, wavelength converting particles for converting blue light into green light and red light may be used. Alternatively, when the light emitting diodes 400 are UV light emitting diodes that generate ultraviolet light, wavelength converting particles 531 which convert ultraviolet light into blue light, green light, and red light may be used.

The wavelength conversion particles 531 may be a plurality of quantum dots (QDs). The quantum dot may include a core nanocrystal and a shell nanocrystal surrounding the core nanocrystal. 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 host layer surrounds the wavelength converting particles. That is, the host layer uniformly disperses the wavelength conversion particles therein. The host layer may be composed of a polymer. The host layer is transparent. That is, the host layer may be formed of a transparent polymer.

Accordingly, the light passing through the wavelength conversion member 600 and the light converted by the wavelength conversion member 600 may form white light. That is, blue light, green light, and red light may be combined to allow white light to enter the reflective sheet 300.

Hereinafter, the angle change pattern 310 will be described in detail with reference to FIGS. 4 to 7.

The angle change pattern 310 may have various shapes. That is, as illustrated in FIGS. 4 to 7, the pattern having the inclined surface may include various shapes.

The pitch and depth of the angle change pattern 310 may be 1 μm to 10 μm. When the pitch and depth of the angle change pattern 310 are less than 1 μm or more than 10 μm, the angle of the reflection angle of the incident light does not change and may be reflected again without being emitted upward of the optical sheet 500. That is, the reflection angle of the reflected light should be reflected in the direction perpendicular to the axis of the light source. When the pitch and depth are less than 1 μm or more than 10 μm, the angle of the incident light and the angle of the reflected light become equal reflections. The light source may not be emitted above the optical sheet 500.

The angle of the inclined surface may be 15 ° to 60 °. When the angle is less than 15 ° or more than 60 °, the light may not be uniformly emitted above the optical sheet 500, and thus luminance may be uneven.

In addition, the distance between the angle change pattern 310 may be wider as it moves away from the light source. That is, the angle change pattern 310 may be densely arranged in the reflection sheet 300 at a close distance from the light source, and may be arranged at regular intervals in the reflection sheet 300 at a distance from the light source. .

Accordingly, the incident light emitted by the light source can be uniformly reflected and refracted to make the luminance uniform.

In addition, the angle change pattern 310 may include a plane disposed between the angle change pattern and facing the optical sheet. As illustrated in FIG. 6, a plane that may reflect incident light incident from a light source may be included between the angle change patterns 310. That is, the reflective sheet 300 may include a plane for specularly reflecting the angle change pattern 310 for changing the angle of reflection of the incident light and the incident light at the same angle as the angle of the incident light and the angle of the reflected light.

The angle of the plane may be tilted from 0 ° to 3 ° with respect to the optical sheet.

When the angle of the plane is inclined by more than 3 °, the angle of the reflection angle may also be changed in the plane, such that light may not be uniformly emitted above the optical sheet 500, and thus luminance may be uneven.

Preferably the planes can be opposed to and parallel to the optical sheet. In addition, the width of the plane may be 1㎛ to 10㎛. When the width of the plane is less than 1 μm or more than 10 μm, the angle of the reflection angle may also be changed in the plane, such that light may not be uniformly emitted above the optical sheet 500, and thus luminance may be uneven. .

Accordingly, the reflective sheet 300 includes a plane disposed between the angle change pattern 310 and the angle change pattern 310 and facing the optical sheet to reflect and incident incident light incident on the reflective sheet. By refracting, the luminance can be made uniform.

The angle change pattern 310 may include an inclined surface. That is, the shape of the angle change pattern 310 may include an inclined surface. For example, as illustrated in FIGS. 3 to 5, the angle change pattern 310 may include triangular, rectangular, and elliptical shapes. The shape of the angle change pattern 310 is not limited thereto, and may include any shape including an inclined surface and an angled shape, and a pattern capable of changing an angle of reflection of incident light.

8 shows an optical path of incident light according to the angle change pattern.

Referring to FIG. 8, incident light incident on the light emitting diode 400 is incident on the reflective sheet 300. The reflective sheet 300 includes an angle change pattern 310 having a predetermined inclination angle, shape, height, and pitch, and a plane formed between the angle change pattern 310.

The incident light may be incident on the reflective sheet and incident on the plane. Incident light incident on the plane may reflect the light source upward without refraction. Thereafter, when the light source is incident on the angle change pattern 310, the reflection angle of the light source may be changed. In detail, it may be reflected at a reflection angle different from the incident angle. In more detail, the reflection angle may be reflected larger than the angle of the incident angle and reflected on the upper surface of the optical sheet.

The display device according to the exemplary embodiment emits light incident from the light emitting diodes 400 upward through total reflection, refraction, and scattering by the reflective sheet. Accordingly, the light guide plate conventionally used is not required.

Conventionally, light incident from the light emitting diodes 400 by the light guide plate is emitted upward through total reflection, refraction, and scattering. However, in the display device according to the embodiment, since the light guide plate can be omitted, weight reduction and thickness can be reduced, and light loss to the light guide plate can be reduced, thereby improving luminance. Moreover, the bonding process of a wavelength conversion member and a light guide plate can be skipped, and a manufacturing process can be shortened.

Features, structures, effects, and the like 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, the features, structures, effects, and the like illustrated in each embodiment may be combined or modified with respect to other embodiments by those 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 (10)

Optical sheets;
A reflective sheet that directly faces the optical sheet; And
A light source positioned between the optical sheet and the reflective sheet,
The reflective sheet changes an angle of reflection of incident light incident on the reflective sheet, and includes an angle changing pattern having an inclined surface.
The angle of the inclination angle is 15 ° to 60 ° display device. The method of claim 1,
And a wavelength conversion member for changing a wavelength of light emitted from the light source. The method of claim 2,
The wavelength conversion member is disposed between the optical sheet and the reflective sheet. The method of claim 1,
The diffusion sheet includes a light conversion diffusion sheet,
And the light conversion diffusion sheet directly faces the reflective sheet. The method of claim 1,
A pitch of the angle change pattern is 1 μm to 10 μm. The method of claim 1,
And the angle change pattern includes a plane disposed between the angle change patterns and facing the optical sheet. 6. The method of claim 5,
And the plane is inclined from 0 ° to 3 ° with respect to the optical sheet. 8. The method of claim 7,
The display device has a width of 1 μm to 10 μm. The method of claim 1,
The display device of claim 2, wherein the distance between the angle change patterns increases as the distance from the light source increases. The method of claim 1,
The height of the angle change pattern is 1㎛ 10㎛ display device.

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