U.S. patent application number 13/446735 was filed with the patent office on 2012-08-02 for wavelength conversion plate and light emitting device using the same.
This patent application is currently assigned to Samsung LED Co., Ltd.. Invention is credited to Dong Hyun Cho, Bae Kyun Kim, Jae Il KIM, In Hyung Lee, Kyoung Soon Park.
Application Number | 20120193604 13/446735 |
Document ID | / |
Family ID | 41725191 |
Filed Date | 2012-08-02 |
United States Patent
Application |
20120193604 |
Kind Code |
A1 |
KIM; Jae Il ; et
al. |
August 2, 2012 |
WAVELENGTH CONVERSION PLATE AND LIGHT EMITTING DEVICE USING THE
SAME
Abstract
Provided is a wavelength conversion plate having excellent
luminous efficiency of a wavelength-converted light. The wavelength
conversion plate includes a dielectric layer with nano pattern, a
metal layer formed inside the nano pattern, and a wavelength
conversion layer formed on the metal layer and having quantum dot
or phosphor which wavelength-converts an excitation light to
generate a wavelength-converted light.
Inventors: |
KIM; Jae Il; (Seoul, KR)
; Kim; Bae Kyun; (Seongnam, KR) ; Cho; Dong
Hyun; (Gimhae, KR) ; Park; Kyoung Soon;
(Suwon, KR) ; Lee; In Hyung; (Seoul, KR) |
Assignee: |
Samsung LED Co., Ltd.
Gyunggi-do
KR
|
Family ID: |
41725191 |
Appl. No.: |
13/446735 |
Filed: |
April 13, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12397115 |
Mar 3, 2009 |
|
|
|
13446735 |
|
|
|
|
Current U.S.
Class: |
257/9 ;
257/E33.005; 438/46; 977/773 |
Current CPC
Class: |
H01L 2924/181 20130101;
H01L 2924/181 20130101; H01L 33/507 20130101; H01L 33/501 20130101;
H01L 2224/48091 20130101; H01L 2924/00012 20130101; H01L 2224/48091
20130101; H01L 2924/00014 20130101 |
Class at
Publication: |
257/9 ; 438/46;
257/E33.005; 977/773 |
International
Class: |
H01L 33/04 20100101
H01L033/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 3, 2008 |
KR |
10-2008-0086983 |
Claims
1-15. (canceled)
16. A wavelength conversion plate comprising: a dielectric layer
having a planar upper surface and a nano pattern formed in a
cylindrical shape with a curved bottom, wherein the nano pattern
comprises a plurality of nano scale grooves; a metal layer formed
on an inside wall of the nano scale grooves of the nano pattern;
and a wavelength conversion layer formed on the metal layer and
comprising quantum dots or phosphors which wave length-convert
excited light to generate wavelength-converted light.
17. The wavelength conversion plate of claim 16, wherein the
dielectric layer comprises a polymer resin or a metal oxide.
18. The wavelength conversion plate of claim 17, wherein the
polymer resin comprises poly methyl methacrylate (PMMA), poly
lauryl methacrylate (PLMA), or polystyrene.
19. The wavelength conversion plate of claim 17, wherein the metal
oxide comprises SiO.sub.2 or TiO.sub.2.
20. The wavelength conversion plate of claim 16, wherein the metal
layer comprises any one of Au, Ag, Al, Cu, Pt, Pd, and alloys
thereof.
21. The wavelength conversion plate of claim 16, wherein the
quantum dot comprises any one of an Si nanocrystal, a group II-VI
compound semiconductor nanocrystal, a group III-V compound
semiconductor nanocrystal, a group IV-VI compound semiconductor
nanocrystal, and compounds thereof.
22. The wavelength conversion plate of claim 21, wherein the group
II-VI compound semiconductor nanocrystal comprises any one material
selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe,
ZnTe, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe,
HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe,
HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS,
CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe.
23. The wavelength conversion plate of claim 21, wherein the group
III-V compound semiconductor nanocrystal comprises any one material
selected from the group consisting of GaN, GaP, GaAs, AlN, AlP,
AlAs, InN, InP, InAs, GaNP, GaNAa, GaPAs, AlNP, AlNAs, AlPAs, InNP,
InNAs, InPAs, GaAlP, GaAlNAs, GaAIPAs, GaInNP, GaInAs, GaInPAs,
InAlNP, InAlNAs, and InAlPAs.
24. The wavelength conversion plate of claim 21, wherein the group
IV-VI compound semiconductor nanocrystal comprises SbTe.
25. The wavelength conversion plate of claim 16, wherein the
dielectric layer is formed by using an Anodic Aluminum Oxide
template.
26. A method of manufacturing a wavelength conversion plate
comprising: forming a nano pattern in a dielectric layer, wherein
the nano pattern comprises a plurality of nano scale grooves and is
formed in a cylindrical shape with a curved bottom; forming a metal
layer on an inside wall of the nano scale grooves of the nano
pattern; and forming a wavelength conversion layer comprising
quantum dots or phosphors which wave length-convert excited to
generate wave length-converted light, on the metal layer.
27. The method of claim 26, wherein the dielectric layer comprises
a polymer resin or a metal oxide.
28. The method of claim 27, wherein the polymer resin comprises
poly methyl methacrylate (PMMA), poly lauryl methacrylate (PLMA),
or polystyrene.
29. The method of claim 27, wherein the metal oxide comprises
SiO.sub.2 or TiO.sub.2.
30. The method of claim 26, wherein the metal layer comprises any
one of Au, Ag, Al, Cu, Pt, Pd, and alloys thereof.
31. The method of claim 26, wherein the quantum dot comprises any
one of an Si nanocrystal, a group II-VI compound semiconductor
nanocrystal, a group III-V compound semiconductor nanocrystal, a
group IV-VI compound semiconductor nanocrystal, and compounds
thereof.
32. The method of claim 31, wherein the group II-VI compound
semiconductor nanocrystal comprises any one material selected from
the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS,
HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS,
HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS,
HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe,
CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe.
33. The method of claim 31, wherein the group III-V compound
semiconductor nanocrystal comprises any one material selected from
the group consisting of GaN, GaP, GaAs, AlN, AlP, AlAs, InN, InP,
InAs, GaNP, GaNAa, GaPAs, AlNP, AlNAs, AlPAs, InNP, InNAs, InPAs,
GaAlP, GaAlNAs, GaAIPAs, GaInNP, GaInAs, GaInPAs, InAlNP, InAlNAs,
and InAlPAs.
34. The method of claim 31, wherein the group IV-VI compound
semiconductor nanocrystal comprises SbTe.
35. The method of claim 26, wherein the dielectric layer is formed
by using an Anodic Aluminum Oxide template.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the priority of Korean Patent
Application No. 2008-0086983 filed on Sep. 3, 2008, in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a light emitting device and
a method for manufacturing the same, and more particularly, to a
wavelength conversion plate having excellent luminous efficiency of
a wavelength-converted light, and a light emitting device using the
same.
[0004] 2. Description of the Related Art
[0005] Light emitting diode (LED) is characterized in that it emits
light substantially identical to monochromatic light, while light
from other light emitting devices such as an incandescent lamp has
a wide light emission spectrum. Since LEDs have different energies
according to their electron-hole recombination, they emit a red
light, a green light, a blue light, a reddish yellow light, or a
yellow light according to their characteristics.
[0006] Recently, there have been developed LEDs which can emit a
white light or reproduce a plurality of colors. A white LED is
manufactured by combination of several color LED chips, or
combination of LED chips emitting specific color light and
phosphors emitting specific color fluorescence. The currently
commercialized white LED generally employs the latter method.
[0007] For example, a white LED package can be obtained by
encapsulating a blue LED chip with a molding resin where a yellow
phosphor is dispersed. If light having a wavelength of 460 nm is
generated from the blue LED chip, the yellow phosphor absorbs the
light and generates light having a wavelength of 545 nm. The two
lights having the different wavelengths are mixed to output a white
light. Therefore, a desired color light can be obtained by
combining different kinds of phosphors.
[0008] Although the desired color can be obtained using the
phosphors, the increase of the luminous efficiency is still
required in view of the emission of the LED.
SUMMARY OF THE INVENTION
[0009] An aspect of the present invention provides a wavelength
conversion plate having excellent luminous efficiency of a
wavelength-converted light, and a light emitting device using the
same.
[0010] According to an aspect of the present invention, there is
provided a wavelength conversion plate including: a dielectric
layer with nano pattern; a metal layer formed inside the nano
pattern; and a wavelength conversion layer formed on the metal
layer and comprising quantum dot or phosphor which
wavelength-converts an excitation light to generate a
wavelength-converted light.
[0011] The dielectric layer may include polymer resin or metal
oxide. The polymer resin may include poly methyl methacrylate
(PMMA), poly lauryl methacrylate (PLMA), or polystyrene. The metal
oxide may include SiO.sub.2 or TiO.sub.2. The metal layer may
include any one of Au, Ag, Al, Cu, Pt, Pd, and alloy thereof.
[0012] The quantum dot may include any one of Si nanocrystal, group
II-VI compound semiconductor nanocrystal, group III-V compound
semiconductor nanocrystal, group IV-VI compound semiconductor
nanocrystal, and compounds thereof. The group II-VI compound
semiconductor nanocrystal may include any one material selected
from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS,
HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS,
HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS,
HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe,
CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe. The group III-V compound
semiconductor nanocrystal may include any one material selected
from the group consisting of GaN, GaP, GaAs, AlN, AlP, AlAs, InN,
InP, InAs, GaNP, GaNAa, GaPAs, AlNP, AlNAs, AlPAs, InNP, InNAs,
InPAs, GaAlP, GaAlNAs, GaAlPAs, GaInNP, GaInAs, GaInPAs, InAlNP,
InAlNAs, and InAlPAs. The group IV-VI compound semiconductor
nanocrystal may include SbTe.
[0013] According to another aspect of the present invention, there
is provided a light emitting device including: a light emitting
element; a groove part having a bottom surface where the light
emitting element is mounted, and aside surface where a reflection
part is formed; a support part supporting the groove part and
having an electrode part electrically connected to the light
emitting element; and a wavelength conversion plate disposed in at
least one of the bottom surface and the side surface of the groove
part, wherein the wavelength conversion plate includes: a
dielectric layer with nano pattern; a metal layer formed inside the
nano pattern; and a wavelength conversion layer formed on the metal
layer and comprising quantum dot or phosphor which
wavelength-converts an excitation light to generate a
wavelength-converted light.
[0014] The light emitting device may further include a wavelength
conversion unit disposed on the light emitting element and having
quantum dot or phosphor which wavelength-converts light from the
light emitting element. The wavelength conversion unit may be
implemented with a plurality of layers. In this case, the
wavelength conversion unit may be formed inside the groove part
where the light emitting element is mounted.
[0015] When the wavelength conversion unit is implemented with a
plurality of layers, at least two wavelength conversion units among
the plurality of wavelength conversion units may include quantum
dots or phosphors which convert the light emitted from the light
emitting element into light having different wavelengths.
Therefore, the light emitting element may emit an infrared light;
the wavelength conversion plate may emit a blue light; a first
wavelength conversion unit among the plurality of wavelength
conversion units may emit a red light; and a second wavelength
conversion unit different from the first wavelength conversion unit
among the plurality of wavelength conversion units may emit a green
light. In this way, the light emitting device can emit a white
light.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The above and other aspects, features and other advantages
of the present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0017] FIG. 1 illustrates a wavelength conversion plate according
to an embodiment of the present invention;
[0018] FIG. 2 illustrates a light emitting device including the
wavelength conversion plate according to an embodiment of the
present invention;
[0019] FIG. 3 illustrates a light emitting device including the
wavelength conversion plate on the bottom surface of a groove part
according to another embodiment of the present invention;
[0020] FIG. 4 illustrates a light emitting device further including
a wavelength conversion unit according to another embodiment of the
present invention; and
[0021] FIG. 5 illustrates a light emitting device further including
a plurality of wavelength conversion units according to another
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0022] Exemplary embodiments of the present invention will now be
described in detail with reference to the accompanying drawings.
The invention may, however, be embodied in many different forms and
should not be construed as being limited to the embodiments set
forth herein; rather, these embodiments are provided so that this
disclosure will be thorough and complete and will fully convey the
concept of the invention to those skilled in the art. In the
drawings, the thicknesses of layers and regions are exaggerated for
clarity.
[0023] FIG. 1 illustrates a wavelength conversion plate according
to an embodiment of the present invention. The wavelength
conversion plate 10 according to the embodiment of the present
invention includes a dielectric layer 11 with nano pattern 12, a
metal layer 13 formed inside the nano pattern 12, and a wavelength
conversion layer 14 formed on the metal layer 13 and having quantum
dot or phosphor wavelength-converting an excitation light to
generate a wavelength-converted light.
[0024] Since the wavelength conversion plate 10 according to the
embodiment of the present invention includes the dielectric layer
11 with the nano pattern 12 and the film-type metal layer 13 inside
the nano pattern 12, that is, the patterned metal layer 13,
incident light is amplified by surface plasmon phenomenon generated
at an interface of the dielectric layer 11 and the metal layer
13.
[0025] The surface plasmon phenomenon is a collective charge
density oscillation generated at the surface of the metal film, and
a surface plasmon wave generated by the collective charge density
oscillation is a surface electromagnetic wave which propagates
along the interface of the metal and the dielectric. Such a
phenomenon is generated in metals, such as gold (Au), silver (Ag),
copper (Cu) or aluminum (Al), which are easily subject to emission
of electrons by external stimulation and have a negative dielectric
constant. Among those metals, silver (Ag) exhibiting the sharpest
surface plasmon resonance (SPR) peak and gold (Au) exhibiting
excellent surface stability are usually used.
[0026] The excitation of the surface Plasmon refers to the
phenomenon that, when an electric field is applied from the outside
to the interface of two media (i.e., metal and dielectric) having a
different dielectric constant, surface charges are induced because
of the discontinuity of vertical components of the electric field
at the interface of the two media, and oscillation of those surface
charges is exhibited as the surface plasmon wave.
[0027] Recently, the emission increase phenomenon derived from the
surface plasmon phenomenon has been reported (Nano Letters, Vol. 5,
No. 8, 1557-1561, 2005). According to this document, after
patterning a polymer resin with constant sizes and intervals, an Ag
layer was formed and a visible ray was irradiated thereon. In this
case, the luminous efficiency was rapidly increased more than 10
times.
[0028] In the wavelength conversion plate 10 according to the
embodiment of the present invention, if the quantum dot or phosphor
included in the wavelength conversion layer 14 wavelength-converts
the excitation light, the surface plasmon phenomenon is generated
in the metal layer 13 and thus the wavelength-converted light is
amplified.
[0029] The dielectric layer 11 may include a material having a
different dielectric function from the metal layer 13 in order to
generate the surface plasmon phenomenon in the metal layer 13. For
example, the dielectric layer 11 may include polymer resin or metal
oxide. The polymer resin used herein may be, but is not limited to,
poly methyl methacrylate (PMMA), poly lauryl methacrylate (PLMA),
or polystyrene. Also, the metal oxide used herein may be, but is
not limited to, SiO.sub.2 or TiO.sub.2.
[0030] The nano pattern 12 is formed in the dielectric layer 11.
Referring to FIG. 1, the nano pattern 12 may be formed in a
cylindrical shape with a curved bottom. However, there is no
special limitation in the shape of the nano pattern 12 only if the
pattern itself is nano-sized.
[0031] As a method of forming the nano pattern 12 in the dielectric
layer 11, an Anodic Aluminum Oxide template (AAO template) formed
by oxidizing aluminum may be used. In the method using the AAO
template, aluminum is used because of its unique characteristic in
that aluminum forms a pore arrangement in itself in an oxidation
process for forming aluminum oxide. In this case, the pore is
several ten to several hundred nanometers in diameter and is
several micrometers in length according to voltage and
concentration of an acid solution in the aluminum oxidation
process.
[0032] Therefore, if the dielectric layer is formed and its upper
surface is etched using the AAO template, the nano pattern 12 is
formed in the same shape as the pore formed in the AAO
template.
[0033] The metal layer 13 patterned along the pattern inside the
nano pattern 12 is formed on the dielectric layer 11. As described
above, the metal layer 13 may be formed using a metal where the
surface Plasmon phenomenon is easily generated, that is, a metal
which is easily subject to emission of electrons by external
stimulation and has a negative dielectric constant. The metal may
include, but is not limited to, Au, Ag, Al, Cu, Pt, or Pd. There
are many methods of forming the metal layer 13. As one method, the
metal layer 13 may be formed by sputtering a metal onto the
dielectric layer 11 where the nano pattern 12 is formed.
[0034] The wavelength conversion layer 14 is formed on the metal
layer 13. The wavelength conversion layer 14 includes quantum dot
or phosphor which wavelength-converts the excitation light to
generate the wavelength-converted light. The wavelength conversion
layer 14 is formed while filling the inside of the pattern of the
metal layer 13.
[0035] The quantum dot is a nano-sized light emitting body which
has a diameter of 10 nm or less and exhibits a quantum confinement
effect. The quantum dot generates stronger light than a typical
phosphor in a narrow wavelength. The emission of the quantum dot is
generated when excited electrons move from a conduction band to a
valence band. Even the same material exhibits different wavelengths
according to the particle size. As the size of the quantum dot is
smaller, light having a shorter wavelength is emitted. Thus, light
having a desired wavelength range can be obtained by adjusting the
size of the quantum dot.
[0036] The quantum dot emits light even at an arbitrary excitation
wavelength. Thus, when several kinds of quantum dots exist, several
color light can be observed at a time even though the quantum dot
is excited at a single wavelength. Furthermore, since the quantum
dot moves from the ground oscillation state of the conduction band
to the ground oscillation state of the valence band, it is
advantageous that the emission wavelength is almost the
monochromatic light.
[0037] The quantum dot may be a semiconductor nanocrystal. Examples
of the quantum dot may include Si nanocrystal, group II-VI compound
semiconductor nanocrystal, group III-V compound semiconductor
nanocrystal, or group IV-VI compound semiconductor nanocrystal. In
the current embodiment, the quantum dots may be used solely or in
mixture thereof.
[0038] The group II-VI compound semiconductor nanocrystal may
include, but is not limited to, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe,
HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS,
HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS,
HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe,
CdHgSTe, HgZnSeS, HgZnSeTe, or HgZnSTe.
[0039] Furthermore, the group III-V compound semiconductor
nanocrystal may include, but is not limited to, GaN, GaP, GaAs,
AlN, AlP, AlAs, InN, InP, InAs, GaNP, GaNAa, GaPAs, AlNP, AlNAs,
AlPAs, InNP, InNAs, InPAs, GaAlP, GaAlNAs, GaAlPAs, GaInNP, GaInAs,
GaInPAs, InAlNP, InAlNAs, or InAlPAs.
[0040] Moreover, the group IV-VI compound semiconductor nanocrystal
may include, but is not limited to, SbTe.
[0041] As a method of synthesizing the nanocrystal as the quantum
dot, the quantum dot is formed by a vapor deposition method, such
as a metal organic chemical vapor deposition (MOCVD) or a molecular
beam epitaxy (MBE), or a chemical wet method of growing a crystal
by putting a precursor material into an organic solvent.
[0042] The phosphor may be selected from an oxide phosphor, a
sulfide phosphor, and a nitride phosphor according to the
conversion wavelength. For example, the phosphor may include a
yellow emission phosphor based on .beta.-SiAlON:Eu,Re, a
silicate-based green emission phosphor such as
(Ba,Sr,Ca,Mg).sub.2SiO.sub.4:Eu,Re, or a sulfide-based green
emission phosphor such as (Ba,Sr,Ca,Mg)
(Ga,Al,In).sub.2(S,Se,Te).sub.4:Eu,Re, a nitride-based red emission
phosphor such as (Sr,Ca,Ba,Mg)AlSiN.sub.x:Eu,Re
(1.ltoreq.x.ltoreq.5), or a sulfide-based red emission phosphor
such as (Sr,Ca,Ba,Mg) (S,Se,Te):Eu,Re. Herein, Re may be any one of
Nd, Pm, Sm, Tb, Dy, Ho, Er, Tm, Yb, F, Cl, Br, and I.
[0043] The wavelength conversion layer 14 may be used by dispersing
the quantum dot in a dispersive medium. The dispersive medium may
be a resin such as epoxy resin or silicon. The wavelength
conversion layer 14 may be formed by dispersing the quantum dot or
phosphor in the dispersive medium and coating the dispersive medium
on the metal layer 13. The wavelength conversion performance of the
wavelength conversion layer 14 may be selected by adjusting the
concentration of the quantum dot or phosphor dispersed in the
dispersive medium.
[0044] In the wavelength conversion plate 10, the quantum dot or
phosphor included in the wavelength conversion layer 14 absorbs the
incident light and emits the wavelength-converted light. Thus, in
addition to the wavelength conversion function, the wavelength
conversion plate 10 can amplify the emission of the
wavelength-converted light due to the surface plasmon phenomenon
generated in the metal layer 13 formed inside the nano pattern
12.
[0045] Therefore, the wavelength conversion plate 10 can be
variously used when it is necessary to receive an excitation light
from a light source, wavelength-convert the received excitation
light and then amplify the wavelength-converted light. For example,
the wavelength conversion plate 10 may be used as a reflection
plate of a light guide panel in an LED package or backlight unit,
but it is not limited thereto. Hereinafter, a light emitting device
using the wavelength conversion plate 10 will be described in
detail with reference to FIGS. 2 to 5.
[0046] FIG. 2 illustrates a light emitting device including a
wavelength conversion plate according to an embodiment of the
present invention. Herein, duplicate description about the
dielectric layer, the nano pattern, the metal layer, and the
wavelength conversion layer in the light emitting device 100 of
FIG. 2 will be omitted, except when necessary.
[0047] The light emitting device 100 according to the embodiment of
the present invention includes a light emitting element 140, a
groove part, a support part 110, and a wavelength conversion plate
160. The groove part has a bottom surface where the light emitting
element 140 is mounted, and a side surface where a reflection part
120 is formed. The support part 110 supports the groove part and
includes an electrode part 130 electrically connected to the light
emitting element 140. The wavelength conversion plate 160 is
disposed in at least one of the bottom surface and the side surface
of the groove part. The wavelength conversion plate 160 includes a
dielectric layer with nano pattern, a metal layer formed inside the
nano pattern, and a wavelength conversion layer formed on the metal
layer and including quantum dot or phosphor which
wavelength-converts an excitation light to generate a
wavelength-converted light. The electrode part 130 is formed with
two sections which are electrically separated.
[0048] The light emitting element 140 may be one of a light
emitting diode and a laser diode. A blue LED may be used as the
light emitting element 140. The blue LED may be a GaN-based LED
emitting a blue light of 420-480 nm. The electrode part 130 is
formed on the support part 110 and is electrically connected to the
light emitting element 140 through a wire.
[0049] An encapsulation part 150 is formed of an encapsulation
material on the light emitting element 140 in order to encapsulate
the light emitting element 140. The encapsulation part 150 is
formed by filling the groove part with an encapsulation material,
such as epoxy, silicon, acryl-based polymer, glass, carbonate-based
polymer, or a mixture thereof.
[0050] The reflection part 120 formed in the side surface of the
groove part reflects light generated from the light emitting
element 140 toward the outside of the groove part. In FIG. 2, the
wavelength conversion plate 160 is formed in the reflection part
120.
[0051] The wavelength conversion plate 160 includes the dielectric
layer with the nano pattern, the metal layer formed on the
dielectric layer, and the wavelength conversion layer formed on the
metal layer and including the quantum dot or phosphor which
wavelength-converts the light generated from the light emitting
element 140 to generate the wavelength-converted light. As
described above with reference to FIG. 1, the wavelength conversion
layer may be used by dispersing the quantum dot or phosphor in the
dispersive medium. Since the dispersive medium may be a resin such
as epoxy resin or silicon, it may be an identical or similar
material to the encapsulation material.
[0052] Since the wavelength conversion plate 160
wavelength-converts and amplifies the light from the light emitting
element 140, the quantum dot or phosphor inside the wavelength
conversion plate 160 may be selected considering color and
intensity of light desired to be obtained from the light emitting
device 100. For example, when the light emitting element 140 emits
a blue light, the light emitting device 100 can emit a white color
by selecting the quantum dot or phosphor inside the wavelength
conversion plate 160 such that it emits a yellow color.
[0053] Although the wavelength conversion plate 160 shown in FIG. 2
is disposed at the reflection part 120 located on the side surface
of the groove part, it can also be disposed on the bottom surface
of the groove part. FIG. 3 illustrates a light emitting device
according to another embodiment of the present invention, in which
a wavelength conversion plate is disposed on a bottom surface of a
groove part. Regarding a dielectric layer, a nano pattern, a metal
layer, and a wavelength conversion layer in the light emitting
device 200 of FIG. 3, the description of the same parts as
described with reference to FIGS. 1 and 2 will be omitted, except
when necessary. Also, regarding a support part 210, a reflection
part 220, an electrode part 230, a light emitting element 240, an
encapsulation part 250, and a wavelength conversion plate 260, the
description of the same parts as described with reference to FIG. 2
will be omitted.
[0054] Unlike in FIG. 2, the wavelength conversion plate 260 is
disposed on the bottom surface of the groove part where the light
emitting element 240 is mounted. The wavelength conversion plate
260 is formed in a region other than the region where the light
emitting element 240 is formed. The case where the wavelength
conversion plate 260 is formed on the bottom surface of the groove
part is related to the shape of the light emitting device 200. In
order for the wavelength conversion plate 260 to effectively
wavelength-convert and amplify the light from the light emitting
element 240, the quantity of light reaching the wavelength
conversion plate 260 should be large. However, if the width of the
light emitting device 200 is wide, the case where the excitation
light reaches the bottom surface may be much more than the case
where the excitation light reaches the reflection part 220.
Therefore, in such a case, the wavelength conversion plate 260 is
formed on the bottom surface of the groove part.
[0055] According to another embodiment of the present invention, in
addition to the wavelength conversion plate formed in at least one
of the side surface and the bottom surface of the groove part, a
light emitting device further includes a wavelength conversion unit
which wavelength-converts light from the light emitting element.
FIG. 4 illustrates the light emitting device which further includes
the wave conversion unit according to the embodiment of the present
invention. Regarding a dielectric layer, a nano pattern, a metal
layer, and a wavelength conversion layer in the light emitting
device 300 of FIG. 4, the description of the same parts as
described with reference to FIGS. 1 to 3 will be omitted, except
when necessary. Also, regarding a support part 310, a reflection
part 320, an electrode part 330, a light emitting element 340, an
encapsulation part 350, and a wavelength conversion plate 360, the
description of the same parts as described with reference to FIGS.
2 and 3 will be omitted.
[0056] In the current embodiment, the wavelength conversion unit
370 further included in the light emitting device 300 includes a
wavelength conversion body 371 and a dispersive medium 372. The
wavelength conversion body 371 may be a typical quantum dot or
phosphor. The dispersive medium 372 may be a medium which properly
disperses polymer resin and the wavelength conversion body 371. The
dispersive medium 372 may be an identical or similar material to an
encapsulation material of the encapsulation part 350.
[0057] After mounting the light emitting element 340, the
wavelength conversion unit 370 may be formed on the light emitting
element 340 before the groove part is filled with the encapsulation
material 350. The wavelength conversion unit 370 can include an
appropriate quantum dot or phosphor according to the wavelength of
light desired to be obtained from the light emitting device 300,
the color of the light emitted from the light emitting device 300
can be controlled together with the quantum dot or phosphor
included in the wavelength conversion plate 360. Although the
wavelength conversion unit 370 shown in FIG. 4 is formed in a layer
type, it can also be formed to cover the surface of the light
emitting device 340. Also, the wavelength conversion unit 370 may
be disposed in any shape only if the light incident from the light
emitting element 340 can be wavelength-converted at the wavelength
conversion unit 370.
[0058] At this point, the light emitting device 300 can emit a
white light, when the light emitting element 340 emits a blue
light, the quantum dot or phosphor of the wavelength conversion
unit 370 emits a red light, and the quantum dot or phosphor of the
wavelength conversion plate 360 emits a green light. Furthermore,
the light emitting element 340 can be made to emit a blue light,
and the quantum dot or phosphor of the wavelength conversion unit
370 can be made to emit a yellow light. In this case, the quantum
dot of the wavelength conversion plate 360 can be selected to emit
a blue light or a yellow light. The color rendering of the light
emitted from the light emitting device 300 can be controlled by
making the quantum dot of the wavelength conversion plate 360 emit
the light having the lower intensity of the blue light and the
yellow light.
[0059] According to another embodiment of the present invention, a
light emitting device may further include a plurality of wavelength
conversion units. FIG. 5 illustrates the light emitting device
which further includes the plurality of wave conversion units
according to the embodiment of the present invention. Regarding a
dielectric layer, a nano pattern, a metal layer, and a wavelength
conversion layer in the light emitting device 400 of FIG. 5, the
description of the same parts as described with reference to FIGS.
1 to 4 will be omitted, except when necessary. Also, regarding a
support part 410, a reflection part 420, an electrode part 430, a
light emitting element 440, an encapsulation part 450, and a
wavelength conversion plate 460, the description of the same parts
as described with reference to FIGS. 2 and 4 will be omitted.
[0060] In the current embodiment, the wavelength conversion units
further included in the light emitting device 400 include a first
wavelength conversion unit 470 and a second wavelength conversion
unit 480. In FIG. 5, a wavelength conversion unit nearer to the
light emitting element 440 is referred to as the first wavelength
conversion unit 470, and another is referred to as the second
wavelength conversion unit 480. The first wavelength conversion
unit 470 includes a first wavelength conversion body 471 and a
first dispersive medium 472, and the second wavelength conversion
unit 480 includes a second wavelength conversion body 481 and a
second dispersive medium 482. The first and second wavelength
conversion bodies 471 and 481 may be typical quantum dots or
phosphors. The first and second dispersive media 472 and 482 may be
media which properly disperse polymer resin and the first and
second wavelength conversion bodies 471 and 481. The first and
second dispersive media 472 and 482 may be an identical or similar
material to an encapsulation material of the encapsulation part
450.
[0061] When the wavelength conversion unit is implemented with a
plurality of layers, at least two wavelength conversion units may
include quantum dots or phosphors which can convert the light
emitted from the light emitting element into light having different
wavelengths. Therefore, the light emitting element 440 emits a blue
light, any one of the wavelength conversion units emits a red
light, and the second wavelength conversion unit 480 different from
the first wavelength conversion unit emits a green light. In this
way, the light emitting device can emit a white light. Furthermore,
the wavelength conversion plate 460 can select quantum dots to emit
light by appropriately selecting the wavelength of the light
required to be amplified among the blue light, the red light, and
the green light.
[0062] Alternatively, the light emitting device can emit a white
light, when the light emitting element 440 emits an infrared ray,
and the wavelength conversion plate 460, the first wavelength
conversion unit 470 and the second wavelength conversion unit 480
emit a blue light, a green light and a red light, respectively.
[0063] The light emitting devices are shown in a package type in
FIGS. 2 to 5, but they are not limited thereto. For example, the
light emitting devices may be lamp-type light emitting devices.
[0064] The wavelength conversion plates according to the
embodiments of the present invention can use the surface plasmon
phenomenon by forming the metal layer on the dielectric layer with
the nano pattern. Therefore, the wavelength-converted light
generated by the wavelength conversion of the excitation light at
the quantum dot, or the light emitted from the light emitting
source can be amplified by the surface plasmon phenomenon.
[0065] Furthermore, if the wavelength conversion plate capable of
amplifying the light by using the surface plasmon phenomenon is
used on the side surface of the light emitting package, the
luminous efficiency of the light emitting package can be increased.
In addition, if the wavelength conversion plate is used as the
reflection plate or wavelength conversion plate of the light
emitting source, the light of the light emitting source can be
amplified. Thus, the light emitting device having excellent
efficiency can be manufactured.
[0066] While the present invention has been shown and described in
connection with the exemplary embodiments, it will be apparent to
those skilled in the art that modifications and variations can be
made without departing from the spirit and scope of the invention
as defined by the appended claims.
* * * * *