U.S. patent application number 14/498886 was filed with the patent office on 2015-01-15 for led lighting apparatus and method for fabricating wavelength conversion member for use in the same.
The applicant listed for this patent is Posco LED Company Ltd.. Invention is credited to Jae Young KIM, Jung Hwa KIM, Sun Hwa LEE, Won Kuk SON.
Application Number | 20150014733 14/498886 |
Document ID | / |
Family ID | 49620905 |
Filed Date | 2015-01-15 |
United States Patent
Application |
20150014733 |
Kind Code |
A1 |
KIM; Jung Hwa ; et
al. |
January 15, 2015 |
LED LIGHTING APPARATUS AND METHOD FOR FABRICATING WAVELENGTH
CONVERSION MEMBER FOR USE IN THE SAME
Abstract
A light-emitting diode (LED) lighting apparatus is provided. The
LED lighting apparatus includes at least one LED, and a wavelength
conversion member spaced apart from the LED and configured to
convert a wavelength of light emitted from the LED. The wavelength
conversion member includes a light-transmitting member, and a
transfer molded wavelength conversion layer disposed on at least
one surface of the light-transmitting member. The transfer molded
wavelength conversion layer includes a resin and a phosphor.
Inventors: |
KIM; Jung Hwa; (Seongnam-si,
KR) ; LEE; Sun Hwa; (Seongnam-si, KR) ; KIM;
Jae Young; (Seongnam-si, KR) ; SON; Won Kuk;
(Seongnam-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Posco LED Company Ltd. |
Seongnam-si |
|
KR |
|
|
Family ID: |
49620905 |
Appl. No.: |
14/498886 |
Filed: |
September 26, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13868571 |
Apr 23, 2013 |
8871538 |
|
|
14498886 |
|
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Current U.S.
Class: |
257/98 |
Current CPC
Class: |
H01L 2924/0002 20130101;
H01L 33/507 20130101; H01L 33/54 20130101; H01L 25/0753 20130101;
H01L 33/505 20130101; H01L 33/56 20130101; H01L 33/483 20130101;
H01L 2924/00 20130101; H01L 2924/0002 20130101; H01L 2933/0033
20130101; H01L 33/50 20130101; H01L 2933/0041 20130101; H01L 33/58
20130101; H01L 33/642 20130101; H01L 2933/0075 20130101 |
Class at
Publication: |
257/98 |
International
Class: |
H01L 33/50 20060101
H01L033/50; H01L 33/58 20060101 H01L033/58; H01L 33/54 20060101
H01L033/54 |
Foreign Application Data
Date |
Code |
Application Number |
May 7, 2012 |
KR |
10-2012-0047882 |
Claims
1. A light-emitting diode (LED) lighting apparatus, comprising: at
least one LED; and a wavelength conversion member spaced apart from
the LED and configured to convert a wavelength of light emitted
from the LED, wherein the wavelength conversion member comprises a
light-transmitting member, and a transfer molded wavelength
conversion layer disposed on at least one surface of the
light-transmitting member, and wherein the transfer molded
wavelength conversion layer comprises a resin and a phosphor.
2. The LED lighting apparatus of claim 1, wherein the
light-transmitting member comprises a glass or a plastic
material.
3. The LED lighting apparatus of claim 1, wherein the
light-transmitting member comprises an uneven pattern in a region
which is covered with the transfer molded wavelength conversion
layer.
4. The LED lighting apparatus of claim 1, wherein the
light-transmitting member comprises an uneven pattern in a region
which is not covered with the transfer molded wavelength conversion
layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 13/868,571, filed on Apr. 23, 2013, and claims priority
from and the benefit of Korean Patent Application No.
10-2012-0047882, filed on May 7, 2012, each of which is hereby
incorporated by reference for all purposes as if fully set forth
herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a light-emitting diode
(LED) lighting apparatus and a method for fabricating a wavelength
conversion member which is spaced apart from an LED in the LED
lighting apparatus and converts a wavelength of light emitted from
the LED.
[0004] 2. Description of the Related Art
[0005] As light sources for illumination, fluorescent lamps and
incandescent bulbs have been widely used. Incandescent bulbs have
low efficiency and economic feasibility due to their high power
consumption. For this reason, the demand for incandescent bulbs
tends to significantly decrease. It is expected that such a
decreasing trend will continue in the future. On the contrary,
since fluorescent lamps have about 1/3 of power consumption of
incandescent bulbs, they are high-efficient and cost-efficient.
However, since fluorescent lamps are blackened by application of
high voltage, the lifespan of fluorescent lamps is short. In
addition, fluorescent lamps are environmentally unfriendly because
they use a vacuum glass tube into which mercury being a heavy metal
is injected together with argon gas.
[0006] Recently, the demand for LED lighting apparatuses has been
rapidly increasing. LED lighting apparatuses have a long lifespan
and are driven with low power. In addition, LED lighting
apparatuses are environmentally friendly because they use no
environmentally harmful substances such as mercury. A typical LED
lighting apparatus includes an LED module, and the LED module
includes package-level or chip-level LEDs, and a printed circuit
board (PCB) on which the LEDs are mounted. Each of the LEDs
includes an LED chip configured to emit light in a specific
wavelength range, and a wavelength conversion material (for
example, a phosphor) configured to generate desired color light,
especially white light, by converting a wavelength of light emitted
from the LED chip. Generally, the wavelength conversion material is
included in an encapsulation material covering the LED chip, or is
directly formed on the LED by conformal coating.
[0007] In the LED lighting apparatus, much heat is generated when
the LEDS are supplied with power and operated. This heat has a bad
influence on the wavelength conversion material included in the
encapsulation material covering the LED chip or directly formed on
the LED chip. That is, the encapsulation material including the
wavelength conversion material may be separated from the surface of
the LED chip by heat, and the original characteristic of the
wavelength conversion material may be changed by heat. Therefore,
feature values, such as color coordinates or color temperature of
light generated by the LED lighting apparatus, may deviate from an
originally intended or designed range.
[0008] In this regard, there has been proposed an LED lighting
apparatus configured such that an optical member or an optical
cover spaced apart from LEDs includes phosphors. Since the optical
member is spaced apart from the LEDs, the phosphors included in the
optical member may not be badly affected by heat generated from the
LEDs. As a method of adding the phosphors to the inside of the
optical member, there are a method of molding an optical member
with a resin material mixed with phosphors, and a method of coating
a phosphor on one surface of an optical member in a printing
technique. Since the former method is limited to the molding
technique using the resin material, it is difficult to apply to an
optical member such as a glass. In addition, air bubbles may be
formed within the optical member together with the phosphors.
According to the latter method, the phosphor layer is formed on one
surface of the optical member. The phosphor layer is formed with an
uniform surface in the early stage, but the surface of the phosphor
layer may be rough as times goes by. In worse cases, the phosphor
layer may be separated from the surface of the optical member.
SUMMARY OF THE INVENTION
[0009] An aspect of the present invention is directed to provide a
method for fabricating a wavelength conversion member reliably at
low cost, in which the wavelength conversion member is used for an
LED lighting apparatus and includes a uniform and dense wavelength
conversion layer on at least one surface thereof.
[0010] Another aspect of the present invention is directed to
provide an LED lighting apparatus that can improve reliability by
covering LEDs with a wavelength conversion member including a
uniform and dense wavelength conversion layer on at least one
surface thereof, and can always emit light in an intended color
coordinate or color temperature range, in spite of passage of
time.
[0011] According to an aspect of the present invention, an LED
lighting apparatus includes at least one LED, and a wavelength
conversion member spaced apart from the LED and configured to
convert a wavelength of light emitted from the LED. The wavelength
conversion member includes a light-transmitting member, and a
wavelength conversion layer formed on at least one surface of the
light-transmitting member. The wavelength conversion layer includes
a resin and a phosphor, and is formed by a transfer molding.
[0012] According to one embodiment, the light-transmitting member
may include a glass or a plastic material.
[0013] According to one embodiment, the light-transmitting member
may include an uneven pattern. The uneven pattern may be formed in
a region which is covered with the wavelength conversion layer or a
region which is not covered with the wavelength conversion
layer.
[0014] According to another aspect of the present invention, there
is provided a method for fabricating a wavelength conversion member
to be applied to an LED lighting apparatus. The method for
fabricating the wavelength conversion member includes: preparing a
light-transmitting member; arranging a mold to cover one surface of
the light-transmitting member and; performing a transfer molding
process to soften a solid molding material, including a phosphor
and a resin, by heating and pressurizing the solid molding
material, and fill a gap between the mold and the
light-transmitting member with the softened molding material.
[0015] According to one embodiment, the mold may include a transfer
port, and a runner extending from the transfer port to the gap. The
transfer molding process may include putting the solid molding
material into the transfer port, pressurizing the solid molding
material with a plunger, and injecting the softened molding
material into the gap through the runner.
[0016] According to one embodiment, the transfer port and the
runner may be disposed in a region right above the
light-transmitting member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a cross-sectional view of an LED lighting
apparatus according to an embodiment of the present invention.
[0018] FIG. 2 is a plan view illustrating a state in which a mold
for molding a wavelength conversion layer is disposed to cover one
surface of a light-transmitting member.
[0019] FIG. 3 is a cross-sectional view taken along line I-I of
FIG. 2.
[0020] FIGS. 4 and 5 are diagrams for describing a transfer molding
process of forming the wavelength conversion layer on one surface
of the light-transmitting member by using the mold illustrated in
FIGS. 2 and 3.
[0021] FIG. 6 is a cross-sectional view of a wavelength conversion
member in which the wavelength conversion layer is formed on one
surface of the light-transmitting member in the transfer molding
process illustrated in FIGS. 4 and 5.
[0022] FIGS. 7A to 7D are cross-sectional views illustrating
various modifications of the wavelength conversion member.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0023] Exemplary embodiments of the present invention will be
described below in detail with reference to the accompanying
drawings. These embodiments are provided so that this disclosure
will be thorough and complete, and will fully convey the scope of
the invention to those skilled in the art. The invention may,
however, be embodied in many different forms and should not be
construed as being limited to the embodiments set forth herein. In
the drawings, the widths, lengths and thicknesses of elements may
be exaggerated for clarity. Throughout the drawings and
description, like reference numerals will be used to refer to like
elements.
[0024] FIG. 1 is a cross-sectional view of an LED lighting
apparatus according to an embodiment of the present invention.
[0025] Referring to FIG. 1, the LED lighting apparatus 1 includes a
plurality of LEDs 2, and a wavelength conversion member 10 spaced
apart from the LEDs 2 and covering top sides of the LEDs 2. The
plurality of LEDs 2 are mounted on a printed circuit board (PCB).
In addition, the PCB 3 is attached on a heat sink 5 and
thermoconductively connected to the heat sink 5. The heat sink 5
may include a plurality of heat dissipation fins 51. In addition,
the LED lighting apparatus 1 may include a housing 6 for
accommodating the above-described LEDs 2 inside.
[0026] Although not illustrated, the LED lighting apparatus 1 may
include circuits and parts for driving the LEDs 2. The LED 2 may
include an LED chip and an encapsulation material encapsulating the
LED chip. The LED chip may be directly mounted on the PCB 3, or may
be disposed on the PCB 3 while being embedded in a package with
lead terminals.
[0027] The LEDs 2 may include a GaN-based LED chip configured to
emit blue light, and an LED chip with a wavelength of about 430
.mu.m to 470 .mu.m, which includes an InGaN-based active layer. In
addition, the wavelength conversion member 10 includes a
light-transmitting member 11 configured to transmit light, and a
wavelength conversion layer 12 formed on the surface of the
light-transmitting member 11. The wavelength conversion member 10
includes a phosphor that converts blue light generated by the LED 2
into long-wavelength light, and the phosphor may be a yellow
phosphor or a combination of a green phosphor and a red
phosphor.
[0028] After light passes through the wavelength conversion member
10, the wavelength-converted long-wavelength light and the
non-wavelength-converted blue light may be mixed to generate white
light. Since the phosphor within the wavelength conversion layer 12
provided in the wavelength conversion member 10 is spaced apart
from the LED 2, the characteristic or performance of the wavelength
conversion member 10 is not deteriorated by heat and/or light
generated by the LED 2.
[0029] The light-transmitting member 11 may be made of a plate type
transparent glass or a plastic. However, the light-transmitting
member 11 may be made of light-transmitting materials other than
glass. In addition, the wavelength conversion member 10 illustrated
in FIG. 1 includes the wavelength conversion layer 12 only on the
bottom surface of the light-transmitting member 11, but the
wavelength conversion layer 12 may be formed only on the top
surface of the light-transmitting member 11 or may be formed on
both the top surface and the bottom surface. The wavelength
conversion layer 12 is formed on the surface of the
light-transmitting member 11 to a predetermined thickness by the
transfer molding, and has a uniform phosphor distribution.
[0030] A method for fabricating the wavelength conversion member by
forming the wavelength conversion layer 12 on one surface of the
light-transmitting member 11 by the transfer molding will be
described in more detail.
[0031] FIG. 2 is a plan view illustrating a state in which a mold
80 is disposed to cover one surface of the light-transmitting
member 11 in order for the transfer molding of the wavelength
conversion layer 12 (see FIG. 1). FIG. 3 is a cross-sectional view
taken along line I-I of FIG. 2.
[0032] Referring to FIGS. 2 and 3, the plate type mold 80 is
disposed to cover one surface of the light-transmitting member 11
having an area equal to or smaller than that of the mold 80. In
FIG. 2, the light-transmitting member 11 is covered with the plate
type mold 80 and is indicated by a hidden line. The plate type mold
80 includes one or more resin injection portions 81. The mold 80
having an appropriate number of the resin injection portions 81 may
be selected and used according to the area of one surface of the
light-transmitting member 11 or the area of the wavelength
conversion layer 12 (see FIG. 1) formed on one surface of the
light-transmitting member 11 by the transfer molding. In this case,
a circumference of a gap between the light-transmitting member 11
and the plate type mold 80 is filled.
[0033] The resin injection portion 81 includes a transfer port 812
and a runner 814 having a cross-sectional area smaller than that of
the transfer port 812. The runner 814 extends from the transfer
port 812 to a space covering one surface of the light-transmitting
member 11, and may include a runner of a narrow sense, a gate
and/or a sprue. In this embodiment, both the transfer port 812 and
the runner 814 of the resin injection portion 81 are disposed in a
region right above the light-transmitting member 11.
[0034] In this embodiment, a gap between one surface of the
light-transmitting member 11 and the mold 80 facing each other
becomes a space in which the wavelength conversion layer 12 is to
be formed by the transfer molding. The runner 814 extends from the
transfer port 812 to the space.
[0035] As illustrated in FIGS. 2 and 3, before the mold is
arranged, a solid molding material 70 mixed with a phosphor is
prepared in a tablet form. The solid molding material 70 may be
prepared in a tablet form by pressing a powder in which a phosphor
and a powder-type resin are uniformly mixed. As the resin used
herein as the solid molding material 70, epoxy, especially epoxy
molding compound (EMC) having excellent absorption resistance, may
be advantageously used.
[0036] FIGS. 4 and 5 are diagrams for describing the transfer
molding process of forming the wavelength conversion layer on one
surface of the light-transmitting member by using the
above-described mold.
[0037] Referring to FIGS. 4 and 5, under a high-temperature and
high-pressure condition, the transfer molding process is performed
to inject the phosphor-containing resin into the gap (or space)
between the light-transmitting member 11 and the mold 80 through
the resin injection portion 81. More specifically, the
tablet-shaped solid molding material 70 is put into the transfer
port 812 of the resin injection portion 81. While raising a
temperature, a plunger 60 disposed in the transfer port 812 moves
vertically downward to pressurize the solid molding material 70.
The molding material 70, which is heated at a high temperature and
pressurized at a high pressure, is softened into a gel phase or a
liquid phase. The molding material 70 is densely filled into the
gap between the light-transmitting member 11 and the mold 80
through the runner 814 and is then cured.
[0038] In this manner, the wavelength conversion layer 12 with the
phosphors uniformly distributed is formed on the surface of the
light-transmitting member 11 to a uniform thickness. In a case
where the resin injection portion 81 is provided in plurality (see
FIG. 2), the plungers 60 are provided as many as the number of the
resin injection portions 81, and the plungers 60 are vertically
moved in synchronization. A heating unit such as a heater for
heating the molding material 70 may be installed in the plunger 60
or the mold 80.
[0039] FIG. 6 is a cross-sectional view of the wavelength
conversion member with the wavelength conversion layer formed on
one surface of the light-transmitting member by the transfer
molding step.
[0040] Referring to FIG. 6, the light-transmitting member 11 with
the wavelength conversion layer 12 is separated from the mold 80.
The cured resin r, which exists in the runner 814 (see FIGS. 2 to
5), may remain in the wavelength conversion layer 12. In this case,
this resin r is removed. As a result, it is possible to fabricate
the wavelength conversion member 10 in which the wavelength
conversion layer 12 is uniformly formed on one surface of the
light-transmitting member 11 by the transfer molding.
[0041] The structure or shape of the mold 80 can be variously
modified. For example, the transfer port 812 of the resin injection
portion 81 may be disposed at a position deviating from the
light-transmitting member 11, and the runner 814 may extend to the
lateral space of the light-transmitting member 11 instead of the
upper space of the light-transmitting member 11.
[0042] Various modifications of the wavelength conversion members
10 according to the present invention are provided.
[0043] A wavelength conversion member 10 illustrated in FIG. 7A
includes a pair of wavelength conversion layers 12 formed by a
transfer molding on two opposite surfaces of a light-transmitting
member 11, that is, top and bottom surfaces thereof. The pair of
wavelength conversion layers 12 may include the same phosphor or
may include different phosphors. In a wavelength conversion member
10 illustrated in FIG. 7B, a wavelength conversion layer 12 is
formed on one surface of a light-transmitting member 11, and an
uneven pattern 13 for light diffusion or scattering is formed on an
opposite surface of the light-transmitting member 11. The uneven
pattern 13 diffuses or scatters light so that wavelength-converted
light and non-wavelength-converted light can be mixed more
efficiently. Therefore, more uniform white light can be obtained.
In a wavelength conversion member 10 illustrated in FIG. 7C, an
uneven pattern 13 is formed on one surface of a light-transmitting
member 11, and a wavelength conversion layer 12 is formed by a
transfer molding to cover the uneven pattern 13. A wavelength
conversion member 10 illustrated in FIG. 7D includes a curved
portion, and a wavelength conversion layer 12 is formed on the
surface of the curved portion.
[0044] While the embodiments of the present invention have been
described with reference to the specific embodiments, it will be
apparent to those skilled in the art that various changes and
modifications may be made without departing from the spirit and
scope of the invention as defined in the following claims.
* * * * *