KR20130047985A

KR20130047985A - Light emitting apparatus

Info

Publication number: KR20130047985A
Application number: KR1020110112849A
Authority: KR
Inventors: 이규태
Original assignee: 엘지이노텍 주식회사
Priority date: 2011-11-01
Filing date: 2011-11-01
Publication date: 2013-05-09

Abstract

PURPOSE: A light-emitting device is provided to effectively convert light by using light conversion particles. CONSTITUTION: An inside of a transparent pipe(100) is sealed. A light conversion layer(300) is arranged in an inner surface of the transparent pipe. A light-emitting molecule(200) is arranged inside of the light conversion layer. An electrode(400) is arranged in the outside of the transparent pipe. The light conversion layer includes a host layer(310) and a plurality of light conversion particles(320).

Description

[0001] LIGHT EMITTING APPARATUS [0002]

Embodiments relate to a light emitting device.

LCD devices, which are being spotlighted in flat panel display devices, include non-light emitting devices that do not emit light by themselves, and include a backlight device that provides a separate light source.

Typical requirements for these backlights include high brightness, high efficiency, uniformity of brightness, long life, thinness, low weight and low cost. In the case of notebook PCs, high efficiency long life lamps are required to reduce power consumption, and backlights for monitors and TVs require high brightness.

As a backlight, a cold cathode fluorescent lamp (CCFL) is disposed and a phosphor has been used in the past. CCFLs are classified into an edge type method using a light guide plate and a direct type method arranged in a plane according to the arrangement of the light source with respect to the display surface.

CCFL operates at high brightness of about 30,000 cd / m2, but the lamp life is a problem. In particular, the edge type CCFL itself emits high luminance, but the panel brightness is low, which is not suitable for large screen panels. In addition, in the direct type, CCFLs cannot be connected in parallel to be driven by a single inverter, and the number of CCFLs arranged in a plane is limited for proper brightness of the panel. Since the distance between the diffusion plate and the lamp is increased to obtain the brightness, there is a problem that the thickness of the panel is increased.

Therefore, an external electrode fluorescent lamp (EEFL) has been proposed, which is required to develop a backlight which can guarantee high brightness and high efficiency of a liquid crystal display of large size, and at the same time, can have a long life and light weight.

Embodiments provide a light emitting device having improved optical characteristics.

The light emitting device according to the embodiment includes a transparent tube extending in one direction and sealed inside; A light conversion layer disposed on an inner surface of the transparent tube; Light emitting molecules disposed in the light conversion layer; And an electrode disposed outside the transparent tube, wherein the light conversion layer comprises: a host layer disposed on an inner surface of the transparent tube; And a plurality of light conversion particles disposed in the host layer.

The light emitting device according to the embodiment may effectively convert light generated from the light emitting molecules by using the light conversion particles. In particular, a quantum dot or the like may be used as the light conversion particles.

Accordingly, the light emitting device according to the embodiment may generate light having improved color reproducibility by using the light conversion particles.

In addition, the host layer may perform a scattering prevention function. The transparent tube may be formed of glass, and the host layer may be formed of a polymer. Accordingly, when the transparent tube is broken, scattering of fragments of the transparent tube may be prevented by the host layer.

Thus, the light emitting device according to the embodiment may have improved stability.

1 is a view illustrating an external electrode fluorescent lamp according to an embodiment.
2 is a cross-sectional view showing a cross section of the external electrode fluorescent lamp according to the embodiment in a longitudinal direction.
3 is a cross-sectional view showing a cross section of the external electrode fluorescent lamp according to the embodiment in a radial direction.

In the description of the embodiments, in the case where each tube, electrode, layer or pattern is described as being formed "on" or "under" of each tube, electrode, layer or pattern, "On" and "under" include both being formed "directly" or "indirectly" through other components. 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 to 3, the external electrode fluorescent lamp according to the embodiment includes a transparent tube 100, a light emitting molecule 200, a light conversion layer 300, and an external electrode 400.

The transparent tube 100 has a shape extending in one direction. The transparent tube 100 has a pipe shape. In more detail, the transparent tube 100 may have a circular pipe shape. The inside of the transparent tube 100 may be sealed. In particular, the inside of the transparent tube 100 may have a very low pressure. The inside of the transparent tube 100 may be almost vacuum.

The transparent tube 100 is transparent. Glass or the like may be used as the transparent tube 100. Both ends of the transparent tube 100 may be sealed.

The light emitting molecules 200 are disposed in the transparent tube 100. The light emitting molecules 200 are disposed in the light conversion layer 300. The light emitting molecule 200 generates light by electrons guided by the external electrode 400. The light emitting molecule 200 generates ultraviolet or blue light.

The light emitting molecule 200 may include argon, neon, and xenon. In addition, the light emitting molecule 200 may further include mercury.

In more detail, the light emitting molecules 200 may be formed of argon, neon, and xenon. At this time, the electrons by the external electrode 400 is excited in the order of argon, neon, and xenon, and when returning to the ground state, ultraviolet rays may be generated.

In more detail, the light emitting molecules 200 may be formed of neon and argon. At this time, the electrons generated by the external electrode 400 are excited in the order of neon and argon, and when returning to the ground state, blue light may be generated.

The light conversion layer 300 is disposed in the transparent tube 100. In more detail, the light conversion layer 300 is disposed on the inner surface of the transparent tube 100. In more detail, the light conversion layer 300 may be entirely coated on the inner surface of the transparent tube 100.

The light conversion layer 300 receives incident light emitted from the light emitting molecules 200 and converts the wavelength. For example, the light conversion layer 300 may convert blue light emitted from the light emitting molecules 200 into green light and red light. That is, the light conversion layer 300 converts a part of the blue light into green light having a wavelength band of about 500 nm to about 599 nm, and another part of the blue light having a wavelength band of about 600 nm to about 700 nm. Can be converted to red light.

In addition, the light conversion layer 300 may convert ultraviolet light emitted from the light emitting molecules 200 into blue light, green light, and red light. That is, the light conversion layer 300 converts a part of the ultraviolet light into blue light having a wavelength band of about 400 nm to about 499 nm, and another part of the ultraviolet light having a wavelength band of about 500 nm to about 599 nm. Green light, and another portion of the ultraviolet light to red light having a wavelength band between about 600 nm and about 700 nm.

Accordingly, the light passing through the light conversion layer 300 and the light converted by the light conversion layer 300 may form white light. That is, blue light, green light, and red light may be combined to emit white light to the outside.

The light conversion layer 300 may have a thickness of about 5 μm to about 500 μm. Since the light conversion layer 300 is formed entirely on the inner surface of the transparent tube 100, an empty space 330 may be formed in the light conversion layer 300. The light emitting molecules 200 are located in the empty space 330 in the light conversion layer 300.

The light conversion layer 300 includes a host layer 310 and a plurality of light conversion particles 320.

The host layer 310 is disposed in the transparent tube 100. The host layer 310 is disposed on an inner circumferential surface of the transparent tube 100. The host layer 310 is in close contact with the inner surface of the transparent tube 100. The host layer 310 is uniformly coated on the inner surface of the transparent tube 100. In more detail, the host layer 310 may be uniformly coated on the inner circumferential surface of the transparent tube 100.

The host layer 310 surrounds the light conversion particles 320. That is, the host layer 310 uniformly disperses the light conversion particles 320 therein. The host layer 310 may be made of a polymer. The host layer 310 is transparent. That is, the host layer 310 may be formed of a transparent polymer.

The host layer 310 may include a transparent thermoplastic resin. Examples of the material used as the host layer 310, polycarbonate (PC), polystyrene (PS), polyacrylonitrile (PAN), polyvinyliden chloride (PVDC), ethylene vinyl Alcohol (ehthylene vinylalcohol; EVOH), polymethylmethacrylate (PMMA), etc. are mentioned.

In addition, the host layer 310 may include a thermosetting resin or a photocurable resin.

A transparent polymer may be used as the host layer 310. In more detail, the host layer 310 may include a silicone resin or an epoxy resin.

The light conversion particles 320 are disposed in the host layer 310. In more detail, the light conversion particles 320 may be uniformly dispersed in the host layer 310.

The light conversion particles 320 convert the wavelength of the light emitted from the light emitting molecules 200. The light conversion particles 320 receive light emitted from the light emitting molecules 200 to convert wavelengths.

For example, the light conversion particles 320 may convert blue light emitted from the light emitting molecules 200 into green light and red light. That is, the light emitting molecule 200 is made of neon and argon, and may generate blue light. At this time, some of the light conversion particles 320 converts the blue light into green light having a wavelength band of about 500 nm to about 599 nm, and another part of the light conversion particles 320 converts the blue light to about 600 degrees. It can be converted into red light having a wavelength band between nm and about 700 nm.

Alternatively, the light conversion particles 320 may convert ultraviolet light emitted from the light emitting molecules 200 into blue light, green light, and red light. That is, the light emitting molecule 200 is made of argon, neon and xenon, and may generate ultraviolet rays. At this time, some of the light conversion particles 320 converts the ultraviolet light into blue light having a wavelength band between about 400 nm and about 499 nm, and another part of the light conversion particles 320 converts the ultraviolet light to about 500 degrees. It can be converted into green light having a wavelength band between nm and about 599 nm. In addition, another portion of the light conversion particles 320 may convert the ultraviolet light into red light having a wavelength band between about 600 nm and about 700 nm.

The light conversion particles 320 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 external electrode 400 is disposed at both ends of the transparent tube 100. The external electrode 400 is disposed on the outer surface of the transparent tube 100. Silver, copper, aluminum, or an alloy thereof may be used as the external electrode 400.

The plasma is induced inside the transparent tube 100 by the external electrode 400. That is, the light emitting molecules 200 may be excited in a plasma state and return to the ground state to generate light.

An inverter 500 may be connected to the external electrode 400. The inverter 500 may apply a stable driving voltage to the external electrode 400. At this time, space charges are generated in the transparent tube 100 due to the discharge by the driving voltage applied to the external electrode 400. Since the space charges are accumulated in the transparent tube 100, and the transparent tube 100 itself acts as a dielectric, an inner surface of the transparent tube 100, in particular, the external electrode 400 is disposed. On the inner surface of the transparent tube 100, wall charges are generated. By such wall charges, a voltage gain can be generated. As such, the external electrode fluorescent lamp according to the embodiment can be operated more effectively.

As described above, the light emitting device according to the embodiment may effectively convert the light generated from the light emitting molecules 200 by using the light conversion particles 320. In particular, a quantum dot or the like may be used as the light conversion particles 320.

Accordingly, the light emitting device according to the embodiment may generate light having improved color reproducibility by using the light conversion particles 320.

In addition, the host layer 310 may perform a scattering prevention function. The transparent tube 100 may be formed of glass, and the host layer 310 may be formed of a polymer. Accordingly, when the transparent tube 100 is broken, scattering of debris of the transparent tube 100 may be prevented by the host layer 310.

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 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

A transparent tube extending in one direction and sealed inside;
A light conversion layer disposed on an inner surface of the transparent tube;
Light emitting molecules disposed in the light conversion layer; And
An electrode disposed outside the transparent tube,
The light conversion layer is
A host layer disposed on an inner surface of the transparent tube; And
A light emitting device comprising a plurality of light conversion particles disposed in the host layer.

The light emitting device of claim 1, wherein the light conversion particles comprise a compound semiconductor.

The light emitting device of claim 2, wherein the light conversion particles are quantum dots.

The light emitting device of claim 3, wherein the host layer comprises a silicone resin or an epoxy resin.

The light emitting device of claim 1, wherein the light conversion layer has a thickness of about 5 μm to about 500 μm.

The method of claim 1, wherein the light emitting molecule comprises argon, neon and xenon,
The light conversion particles
First light conversion particles for converting light from the light emitting molecules into light having a wavelength of 400 nm to 499 nm;
Second light conversion particles for converting light from the light emitting molecules into light having a wavelength of 500 nm to 599 nm; And
And third light conversion particles for converting light from the light emitting molecules into light having a wavelength of 600 nm to 700 nm.

The method of claim 1, wherein the light emitting molecule comprises argon and neon,
The light conversion particles
Second light conversion particles for converting light from the light emitting molecules into light having a wavelength of 500 nm to 599 nm; And
And third light conversion particles for converting light from the light emitting molecules into light having a wavelength of 600 nm to 700 nm.