WO2013058548A1 - Lighting device - Google Patents

Lighting device Download PDF

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Publication number
WO2013058548A1
WO2013058548A1 PCT/KR2012/008489 KR2012008489W WO2013058548A1 WO 2013058548 A1 WO2013058548 A1 WO 2013058548A1 KR 2012008489 W KR2012008489 W KR 2012008489W WO 2013058548 A1 WO2013058548 A1 WO 2013058548A1
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WO
WIPO (PCT)
Prior art keywords
light
light source
emitting device
light emitting
phosphor
Prior art date
Application number
PCT/KR2012/008489
Other languages
French (fr)
Inventor
Jun Hyoung Kim
Hwa Young Kim
Jung Oh Chun
Original Assignee
Lg Innotek Co., Ltd.
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Filing date
Publication date
Application filed by Lg Innotek Co., Ltd. filed Critical Lg Innotek Co., Ltd.
Publication of WO2013058548A1 publication Critical patent/WO2013058548A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L25/00—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
    • H01L25/03—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes
    • H01L25/04—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers
    • H01L25/075—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00
    • H01L25/0753—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00 the devices being arranged next to each other
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/0883—Arsenides; Nitrides; Phosphides
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7715—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing cerium
    • C09K11/7721—Aluminates
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7728—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing europium
    • C09K11/7734—Aluminates
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7728—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing europium
    • C09K11/77347—Silicon Nitrides or Silicon Oxynitrides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
    • F21K9/00—Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
    • F21K9/60—Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction
    • F21K9/64—Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/20—Controlling the colour of the light
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
    • F21K9/00—Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2113/00—Combination of light sources
    • F21Y2113/10—Combination of light sources of different colours
    • F21Y2113/13—Combination of light sources of different colours comprising an assembly of point-like light sources
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00—Light-generating elements of semiconductor light sources
    • F21Y2115/10—Light-emitting diodes [LED]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001—Technical content checked by a classifier
    • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements
    • H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
    • H01L33/502—Wavelength conversion materials
    • H01L33/504—Elements with two or more wavelength conversion materials

Definitions

  • This embodiment relates to a lighting device.
  • a light emitting diode is a semiconductor device converting electric current into light.
  • Variously-shaped light emitting diodes are now being used in a variety of fields with wide-ranged purposes.
  • the light emitting diode excites electrons across a band gap between a conduction band and a valance band of a semiconductor active (light emitting) layer and then generates light. Electronic transitions generate light having a wavelength variable according to the band gap. Accordingly, the color (wavelength) of the light emitted by the light emitting diode is changed according to the semiconductor material of the active layer of the light emitting diode.
  • the objective of the present invention is to provide a lighting device capable of obtaining a high color rendering index.
  • One embodiment is a lighting device including: a first light source including a first light emitting device and a first member which is disposed on the first light emitting device and includes a phosphor; and a second light source including a second light emitting device and emitting red light.
  • the first light emitting device of the first light source emits blue light.
  • the phosphor of the first light source includes a yellow phosphor and a green phosphor.
  • the first light emitting device emits blue light having a peak wavelength of 400 nm to 480 nm.
  • the second light emitting device emits red light having a peak wavelength of 590 nm to 630 nm.
  • a ratio of the yellow phosphor to the green phosphor is from 5:5 to 8:2.
  • a set of color points of light mixed with the light emitted from the first light source and the light emitted from the second light source occupies a portion of a first area of a 1931 CIE chromaticity diagram.
  • the first area is a set of color points of light mixed with the blue light of the first light emitting device, yellow light emitted from the yellow phosphor and green light emitted from the green phosphor.
  • the set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source is changed according to a target color temperature range.
  • the target color temperature is a color temperature on a black body locus.
  • the set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source corresponds to an intersection area between the first area and an area formed by two straight lines which start from the color point of the red light emitted from the second light emitting device and contact with the target color temperature range.
  • the set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source corresponds to an area defined by straight lines connecting coordinates (0.36, 0.50), (0.32, 0.525), (0.28, 0.41) and (0.32, 0.4) in the 1931 CIE chromaticity diagram.
  • the second light source is disposed on the second light emitting device and includes a second member including a red phosphor.
  • the second light emitting device of the second light source emits unsaturated non-white light.
  • the lighting device further includes: a heat sink on which the first light source and the second light source are disposed; a reflector which is coupled to the heat sink and is disposed to surround the first and the second light sources; and a diffusion plate which is disposed on the first and the second light sources and is coupled to the reflector.
  • Another embodiment is a lighting device including: a first light source which includes a yellow phosphor, a green phosphor and a first light emitting device emitting blue light; and a second light source which is apart from the first light source and includes a second light emitting device and emits red light.
  • Light mixed with the light emitted from the first light source and the light emitted from the second light source includes a target color temperature.
  • a set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source corresponds to an intersection area between a first area and an area formed by two straight lines which start from the color point of the red light emitted from the second light emitting device and contact with a range of the target color temperature.
  • the first area is a set of color points of light mixed with the blue light of the first light emitting device, yellow light emitted from the yellow phosphor and the green light emitted from green phosphor.
  • the first light emitting device emits blue light having a peak wavelength of 400 nm to 480 nm.
  • the second light emitting device emits red light having a peak wavelength of 590 nm to 630 nm.
  • a ratio of the yellow phosphor to the green phosphor is from 5:5 to 8:2.
  • the set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source corresponds to an area defined by straight lines connecting coordinates (0.36, 0.50), (0.32, 0.525), (0.28, 0.41) and (0.32, 0.4) in the 1931 CIE chromaticity diagram.
  • the second light source is disposed on the second light emitting device and includes a second member including a red phosphor.
  • the second light emitting device of the second light source emits unsaturated non-white light.
  • the lighting device further includes: a heat sink on which the first light source and the second light source are disposed; a reflector which is coupled to the heat sink and is disposed to surround the first and the second light sources; and a diffusion plate which is disposed on the first and the second light sources and is coupled to the reflector.
  • a lighting device is able to obtain a high color rendering index.
  • Fig. 1 is a 1931 CIE chromaticity diagram
  • Fig. 2 is a view for describing a lighting device according to an embodiment
  • Fig. 3 is a view that mixed light emitted from the lighting device shown in Fig. 2 is represented in the 1931 CIE chromaticity diagram;
  • Fig. 4 is a graph showing intensity (W) according to the wavelength of the mixed light emitted from the lighting device shown in Fig. 2.
  • each layer is magnified, omitted or schematically shown for the purpose of convenience and clearness of description.
  • the size of each component does not necessarily mean its actual size.
  • an element when it is mentioned that an element is formed “on” or “under” another element, it means that the mention includes a case where two elements are formed directly contacting with each other or are formed such that at least one separate element is interposed between the two elements.
  • the “on” and “under” will be described to include the upward and downward directions based on one element.
  • Fig. 1 is a 1931 CIE chromaticity diagram.
  • a black body locus 106 is shown in the diagram of Fig. 1.
  • Fig. 1 includes a temperature list according to the black body locus 106.
  • the temperature list shows the color path of light emitted by the black body locus 106 heated at a corresponding temperature.
  • the black body locus 106 emits red light according to the temperature increase, and then emits yellow light, and then emits white light, and emits finally blue light. Therefore, a luminous body emitting light on or in the vicinity of the black body locus 106 may be represented by a correlated color temperature (CCT).
  • CCT correlated color temperature
  • a chromaticity of a particular light source may be designated as a ‘color point’.
  • a chromaticity of a white light source may be designated as a ‘white color point’ of the light source.
  • the white color point of the white light source may be included in the black body locus 106. Therefore, the white color point can be identified by the correlated color temperature (CCT) of the light source.
  • the white light has generally a correlated color temperature (CCT) of about 2,000 K to 8,000 K.
  • White light having a CCT of 4, 000 K may be shown as yellow.
  • White light having a CCT of 8,000 K may be shown as blue.
  • a color coordinate located on or in the vicinity of the black body locus 106 at a color temperature of about 2,500 K to 6,000 K may emit white light capable of satisfying a human observer.
  • the ‘white’ light includes light which is located in the vicinity of and not directly on the black body locus 106.
  • Macadam ellipse can be used on a 1931 CIE chromaticity diagram in order that the observer identifies color points which are so closely related to each other as to look the same or almost the same as each other.
  • Seven step Macadam ellipse includes color points that a common observer cannot identify in seven standard deviations.
  • Ten step Macadam ellipse includes color points that a common observer cannot identify in ten standard deviations. Therefore, it can be thought that light having the color point within the vicinity of ten step Macadam ellipse has the same color as that of the point on the black body locus 106.
  • Fig. 2 is a view for describing a lighting device according to an embodiment.
  • the lighting device emits light.
  • it may mean that the lighting device, a light source or a light emitting device emit light when predetermined external current is supplied to the lighting device, the light source or the light emitting device.
  • the lighting device may include a heat sink 110, a first light source 130a, a second light source 130b, a reflector 150 and a diffusion plate 170.
  • the heat sink 110 receives heat from the first and the second light sources 130a and 130b and then radiates the heat.
  • the heat sink 110 may have one side on which the first and the second light sources 130a and 130b are disposed.
  • the one side may be flat or may have a predetermined curvature.
  • the one side may also have a predetermined cavity formed therein.
  • the heat sink 110 may include a fin 115.
  • the fin 115 may project or extend outwardly from one side of the heat sink 110.
  • the fin 115 increases the surface area of the heat sink 110. Therefore, the lighting device including the fin 115 may have improved heat radiation efficiency.
  • the heat sink 110 may be formed of a metallic material or a resin material, each of which has excellent heat radiation efficiency.
  • the material of the heat sink 120 may include at least one of Al, Ni, Cu, Ag and Sn.
  • the first and the second light sources 130a and 130b are disposed on the heat sink 110. Specifically, the first and the second light sources 130a and 130b are disposed on one side of the heat sink 110 and emit light upwardly from the one side of the heat sink 110.
  • the first and the second light sources 130a and 130b may be disposed apart from each other at a predetermined interval.
  • the first and the second light sources 130a and 130b will be described in detail.
  • the first light source 130a may include a first substrate 131a, a first light emitting device 133a and a first member 135a.
  • the first substrate 131a may be one of a common PCB, a metal core PCB (MCPCB), a standard FR-4 PCB, a flexible PCB or a ceramic substrate.
  • the first substrate 131a may directly contact with the heat sink 110.
  • the first substrate 131a is disposed on the one side of the heat sink 110.
  • the first light emitting device 133a is disposed on the first substrate 131a.
  • the first substrate 131a may be formed of a material capable of efficiently reflecting light, or the surface of the first substrate 131a may be coated or deposited with a light reflective material.
  • the first substrate 131a may selectively include a thermally conductive adhesive tape or a thermal pad.
  • the thermally conductive adhesive tape or the thermal pad may be disposed on the bottom surface of the first substrate 131a.
  • the first light emitting device 133a is disposed on the first substrate 131a.
  • a plurality of the first light emitting devices 133a may be disposed on the first substrate 131a.
  • the first light emitting device 133a may be a blue light emitting device emitting blue light.
  • the first light emitting device 133a may be a light emitting diode (LED) chip emitting blue light.
  • the LED chip may have a lateral type or vertical type.
  • the LED chip may have a flip type.
  • the first light emitting device 133a emits blue light having a peak wavelength of 400 nm to 480 nm. Most preferably, the first light emitting device 133a may emit blue light having a peak wavelength of 445 nm to 455 nm.
  • the first member 135a is disposed on the first substrate 131a and the first light emitting device 133a.
  • the first member 135a is disposed on the first substrate 131a in such a manner as to cover the first light emitting device 133a.
  • the first member 135a is able to protect the first light emitting device 133a from external impurities and moisture.
  • the first member 135a may be basically formed of synthetic resins like silicon, and a phosphor may be added to the synthetic resins.
  • the first member 135a may include a yellow phosphor and a green phosphor.
  • the yellow phosphor is excited by blue light (430 nm to 480 nm) emitted from the first light emitting device 133a and emits excited light having a peak wavelength of 540 nm to 585 nm.
  • the yellow phosphor may be a silicate phosphor, a garnet (YAG) phosphor and an oxynitride phosphor.
  • the yellow phosphor may be selected from Y 3 Al 5 O 12 :Ce 3+ (Ce:YAG), CaAlSiN 3 :Ce 3+ and Eu 2+ -SiAlON phosphor and/or may be selected from BOSE phosphor.
  • the yellow phosphor may be doped at an arbitrary appropriate level so as to provide light output of a desired wavelength.
  • Ce and/or Eu may be doped in the phosphor at a dopant concentration of about 0.1 % to about 20 %.
  • a phosphor appropriate for this purpose may include products produced by Mitsubishi Chemical Company (Tokyo, Japan), Leuchtstoffwerk Breitungen GmbH (BreitInstitut, Germany) and Intermatix Company (Fremont, California).
  • the green phosphor is excited by blue light (430 nm to 480 nm) emitted from the first light emitting device 133a and emits excited light having a peak wavelength of 510 nm to 535 nm.
  • the green phosphor may be a silicate phosphor, a nitride phosphor and an oxynitride phosphor.
  • a ratio of the yellow phosphor to the green phosphor, both of which are included in the first member 135a, may be from 5:5 to 8:2.
  • the blue light emitted from the first light emitting device 133a may pass through the first member 135a as it is or may excite the yellow or the green phosphors of the first member 135a. Therefore, the first light source 130a emits light formed by a mixture of the blue light of the first light emitting device 133a, yellow light emitted from the yellow phosphor of the first member 135a and green light emitted from the green phosphor of the first member 135a.
  • the mixed light of the first light emitting device 133a is greenish white light.
  • the second light source 130b may include a second substrate 131b, a second light emitting device 133b and a second member 135b.
  • the second substrate 131b may be one of a common PCB, a metal core PCB (MCPCB), a standard FR-4 PCB, a flexible PCB, a ceramic substrate.
  • the second substrate 131b may directly contact with the heat sink 110.
  • the second substrate 131b is disposed on the one side of the heat sink 110.
  • the second light emitting device 133b is disposed on the second substrate 131b.
  • the second substrate 131b may be formed of a material capable of efficiently reflecting light, or the surface of the second substrate 131b may be coated or deposited with a light reflective material.
  • the second substrate 131b may selectively include a thermally conductive adhesive tape or a thermal pad.
  • the thermally conductive adhesive tape or the thermal pad may be disposed on the bottom surface of the second substrate 131b.
  • the second light emitting device 133b is disposed on the second substrate 131b.
  • a plurality of the second light emitting devices 133b may be disposed on the second substrate 131b.
  • the second light emitting device 133b may be a red light emitting device emitting red light.
  • the second light emitting device 133b may be a light emitting diode (LED) chip emitting red light.
  • the LED chip may have a lateral type or vertical type.
  • the LED chip may have a flip type.
  • the second light emitting device 133b emits red light having a peak wavelength of 590 nm to 630 nm. Most preferably, the second light emitting device 133b may emit red light having a peak wavelength of 615 nm to 625 nm.
  • the second member 135b is disposed on the second substrate 131b and the second light emitting device 133b.
  • the second member 135b is disposed on the second substrate 131b in such a manner as to cover the second light emitting device 133b.
  • the second member 135b is able to protect the second light emitting device 133b from external impurities and moisture.
  • the second member 135b may be basically formed of synthetic resins like silicon. Unlike the first member 135a, the second member 135b may not have the phosphor. Therefore, the second member 135b may emit red light.
  • the second light emitting device 133b may be an LED chip emitting non-white light and the second member 135b may include a red phosphor.
  • the red phosphor emits red light having a peak wavelength of from 600 nm to 650 nm in response to the blue light (430 nm to 480 nm).
  • the red phosphor may be a nitride phosphor and a sulfide phosphor.
  • the red phosphor may include CaAlSiN 3 :Eu 2+ and Sr 2 Si 5 N 8 :Eu 2+ . These phosphors are able to cause a quantum efficiency to be maintained greater than 80 % at a temperature higher than 150 °C.
  • Another usable red phosphor may be selected from not only CaSiN 2 :Ce 3+ and CaSiN 2 :Eu 2+ but Eu 2+ -SiAlON phosphor and/or may be selected from (Ca,Si,Ba)SiO 4 :Eu 2+ (BOSE) phosphor.
  • a CaAlSiN:Eu 2+ phosphor of the Mitsubishi Chemical Company may have a dominant wavelength of about 624 nm, a peak wavelength of about 628 nm and FWHM of about 100 nm.
  • the first light emitting device 133a of the first light source 130a together with the second light emitting device 133b of the second light source 130b may be disposed on a single substrate (not shown).
  • the reflector 150 reflects the light emitted from the first and the second light sources 130a and 130b. Specifically, the reflector 150 surrounds the first and the second light sources 130a and 130b and reflects the light emitted from the first and the second light sources 130a and 130b to the diffusion plate 170.
  • the reflector 150 may have a reflective surface reflecting the light emitted from the first and the second light sources 130a and 130b.
  • the reflective surface may be coated or deposited with a material capable of easily reflecting the light.
  • the diffusion plate 170 diffuses the light emitted from the first and the second light sources 130a and 130b and emits the light to the outside. Specifically, the light which passes through the diffusion plate 170 and is emitted outwardly is light mixed with the mixed light from the first light source 130a and the red light from the second light source 130b.
  • the diffusion plate 170 is disposed apart from the first and the second light sources 130a and 130b at a predetermined interval.
  • the diffusion plate 170 may be disposed on the upper portion of the reflector in order to be apart from the first and the second light sources 130a and 130b.
  • the diffusion plate 170, the reflector 150 and the one side of the heat sink 110 form a predetermined space.
  • the predetermined space the light emitted from the first light source 130a is mixed with the light emitted from the second light source 130b.
  • Fig. 3 is a view that mixed light emitted from the lighting device shown in Fig. 2 is represented in the 1931 CIE chromaticity diagram. Particularly, in the chromaticity diagram of Fig. 3, a target color temperature of the mixed light emitted from the lighting device shown in Fig. 2 is set to 3,000 K.
  • ‘P1’ is a color point of the blue light emitted from the first light emitting device 133a of the first light source 130a.
  • ‘P2’ is a color point of yellow light emitted from the yellow phosphor of the first member 135a, which has been excited by the blue light of the first light emitting device133a.
  • ‘P3’ is a color point of green light emitted from the green phosphor of the first member 135a, which has been excited by the blue light of the first light emitting device133a. Therefore, the mixed light emitted from the first light source 130a has any one color point within a first area ‘S1’.
  • the first area ‘S1’ may be formed when a ratio of the yellow phosphor to the green phosphor, both of which are included in the first member 135a, is from 5:5 to 8:2.
  • a second area ‘S2’ is an area of bins corresponding to 3,000 K on the black body locus.
  • the second area ‘S2’ may correspond to the seven step Macadam ellipse or ten step Macadam ellipse.
  • the second area ‘S2’ may be changed according to the target color temperature that a user desires.
  • P4 is a color point of the red light emitted from the second light emitting device 133b of the second light source 130b.
  • a third area ‘S3’ corresponds to a portion of the first area ‘S1’. Specifically, the third area ‘S3’ corresponds to an intersection area between the first area ‘S1’ and an area formed by two straight lines which start from ‘P4’ and contact with ‘S2’.
  • the mixed light emitted from the lighting device according to the embodiment has any one color point within the third area ‘S3’.
  • the third area ‘S3’ may be defined by straight lines connecting coordinates (0.36, 0.50), (0.32, 0.525), (0.28, 0.41) and (0.32, 0.4) in the 1931 CIE chromaticity diagram.
  • a set of the color points of the mixed light emitted from the lighting device according to the embodiment is expected to occupy a predetermined area other than the third area ‘S3’ shown in Fig. 3, for example, a predetermined area within the first area ‘S1’.
  • the set of the color points of the mixed light emitted from the lighting device according to the embodiment corresponds to a portion of the first area ‘S1’.
  • Fig. 4 is a graph showing intensity (W) according to the wavelength of the mixed light emitted from the lighting device shown in Fig. 2. Particularly, in the graph of Fig. 4, the target color temperature of the mixed light emitted from the lighting device shown in Fig. 2 is set to 3,000 K.
  • the mixed light emitted from the lighting device shown in Fig. 2 has intensity greater than 1 mW at a wavelength of 430 nm to 480 nm.
  • a color rendering index is approximately greater than 93.

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Abstract

A lighting device may be provided that includes: a first light source including a first light emitting device and a first member which is disposed on the first light emitting device and includes a phosphor; and a second light source including a second light emitting device and emitting red light, wherein the first light emitting device of the first light source emits blue light, wherein the phosphor of the first light source includes a yellow phosphor and a green phosphor, and wherein a ratio of the yellow phosphor to the green phosphor is from 5:5 to 8:2.

Description

LIGHTING DEVICE
This embodiment relates to a lighting device.
A light emitting diode is a semiconductor device converting electric current into light. Variously-shaped light emitting diodes are now being used in a variety of fields with wide-ranged purposes.
The light emitting diode excites electrons across a band gap between a conduction band and a valance band of a semiconductor active (light emitting) layer and then generates light. Electronic transitions generate light having a wavelength variable according to the band gap. Accordingly, the color (wavelength) of the light emitted by the light emitting diode is changed according to the semiconductor material of the active layer of the light emitting diode.
The objective of the present invention is to provide a lighting device capable of obtaining a high color rendering index.
One embodiment is a lighting device including: a first light source including a first light emitting device and a first member which is disposed on the first light emitting device and includes a phosphor; and a second light source including a second light emitting device and emitting red light. The first light emitting device of the first light source emits blue light. The phosphor of the first light source includes a yellow phosphor and a green phosphor.
The first light emitting device emits blue light having a peak wavelength of 400 nm to 480 nm. The second light emitting device emits red light having a peak wavelength of 590 nm to 630 nm.
A ratio of the yellow phosphor to the green phosphor is from 5:5 to 8:2.
A set of color points of light mixed with the light emitted from the first light source and the light emitted from the second light source occupies a portion of a first area of a 1931 CIE chromaticity diagram. In the 1931 CIE chromaticity diagram, the first area is a set of color points of light mixed with the blue light of the first light emitting device, yellow light emitted from the yellow phosphor and green light emitted from the green phosphor.
The set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source is changed according to a target color temperature range. The target color temperature is a color temperature on a black body locus.
In the 1931 CIE chromaticity diagram, the set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source corresponds to an intersection area between the first area and an area formed by two straight lines which start from the color point of the red light emitted from the second light emitting device and contact with the target color temperature range.
When the target color temperature is 3,000K, the set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source corresponds to an area defined by straight lines connecting coordinates (0.36, 0.50), (0.32, 0.525), (0.28, 0.41) and (0.32, 0.4) in the 1931 CIE chromaticity diagram.
The second light source is disposed on the second light emitting device and includes a second member including a red phosphor. The second light emitting device of the second light source emits unsaturated non-white light.
The lighting device further includes: a heat sink on which the first light source and the second light source are disposed; a reflector which is coupled to the heat sink and is disposed to surround the first and the second light sources; and a diffusion plate which is disposed on the first and the second light sources and is coupled to the reflector.
Another embodiment is a lighting device including: a first light source which includes a yellow phosphor, a green phosphor and a first light emitting device emitting blue light; and a second light source which is apart from the first light source and includes a second light emitting device and emits red light. Light mixed with the light emitted from the first light source and the light emitted from the second light source includes a target color temperature. In a 1931 CIE chromaticity diagram, a set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source corresponds to an intersection area between a first area and an area formed by two straight lines which start from the color point of the red light emitted from the second light emitting device and contact with a range of the target color temperature. In the 1931 CIE chromaticity diagram, the first area is a set of color points of light mixed with the blue light of the first light emitting device, yellow light emitted from the yellow phosphor and the green light emitted from green phosphor.
The first light emitting device emits blue light having a peak wavelength of 400 nm to 480 nm. The second light emitting device emits red light having a peak wavelength of 590 nm to 630 nm.
A ratio of the yellow phosphor to the green phosphor is from 5:5 to 8:2.
When the target color temperature is 3,000K, the set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source corresponds to an area defined by straight lines connecting coordinates (0.36, 0.50), (0.32, 0.525), (0.28, 0.41) and (0.32, 0.4) in the 1931 CIE chromaticity diagram.
The second light source is disposed on the second light emitting device and includes a second member including a red phosphor. The second light emitting device of the second light source emits unsaturated non-white light.
The lighting device further includes: a heat sink on which the first light source and the second light source are disposed; a reflector which is coupled to the heat sink and is disposed to surround the first and the second light sources; and a diffusion plate which is disposed on the first and the second light sources and is coupled to the reflector.
A lighting device according to the embodiment is able to obtain a high color rendering index.
Fig. 1 is a 1931 CIE chromaticity diagram;
Fig. 2 is a view for describing a lighting device according to an embodiment;
Fig. 3 is a view that mixed light emitted from the lighting device shown in Fig. 2 is represented in the 1931 CIE chromaticity diagram; and
Fig. 4 is a graph showing intensity (W) according to the wavelength of the mixed light emitted from the lighting device shown in Fig. 2.
A thickness or size of each layer is magnified, omitted or schematically shown for the purpose of convenience and clearness of description. The size of each component does not necessarily mean its actual size.
In description of embodiments of the present invention, when it is mentioned that an element is formed “on” or “under” another element, it means that the mention includes a case where two elements are formed directly contacting with each other or are formed such that at least one separate element is interposed between the two elements. The “on” and “under” will be described to include the upward and downward directions based on one element.
Hereafter, a lighting device according to an embodiment will be described with reference to the accompanying drawings.
Fig. 1 is a 1931 CIE chromaticity diagram.
A black body locus 106 is shown in the diagram of Fig. 1.
Also, Fig. 1 includes a temperature list according to the black body locus 106. The temperature list shows the color path of light emitted by the black body locus 106 heated at a corresponding temperature. The black body locus 106 emits red light according to the temperature increase, and then emits yellow light, and then emits white light, and emits finally blue light. Therefore, a luminous body emitting light on or in the vicinity of the black body locus 106 may be represented by a correlated color temperature (CCT).
A chromaticity of a particular light source may be designated as a ‘color point’. A chromaticity of a white light source may be designated as a ‘white color point’ of the light source. As described above, the white color point of the white light source may be included in the black body locus 106. Therefore, the white color point can be identified by the correlated color temperature (CCT) of the light source. The white light has generally a correlated color temperature (CCT) of about 2,000 K to 8,000 K. White light having a CCT of 4, 000 K may be shown as yellow. White light having a CCT of 8,000 K may be shown as blue. A color coordinate located on or in the vicinity of the black body locus 106 at a color temperature of about 2,500 K to 6,000 K may emit white light capable of satisfying a human observer.
The ‘white’ light includes light which is located in the vicinity of and not directly on the black body locus 106. Macadam ellipse can be used on a 1931 CIE chromaticity diagram in order that the observer identifies color points which are so closely related to each other as to look the same or almost the same as each other. Seven step Macadam ellipse includes color points that a common observer cannot identify in seven standard deviations. Ten step Macadam ellipse includes color points that a common observer cannot identify in ten standard deviations. Therefore, it can be thought that light having the color point within the vicinity of ten step Macadam ellipse has the same color as that of the point on the black body locus 106.
Fig. 2 is a view for describing a lighting device according to an embodiment.
The lighting device according to the embodiment emits light. In this specification, it may mean that the lighting device, a light source or a light emitting device emit light when predetermined external current is supplied to the lighting device, the light source or the light emitting device.
Referring to Fig. 2, the lighting device according to the embodiment may include a heat sink 110, a first light source 130a, a second light source 130b, a reflector 150 and a diffusion plate 170.
The heat sink 110 receives heat from the first and the second light sources 130a and 130b and then radiates the heat.
The heat sink 110 may have one side on which the first and the second light sources 130a and 130b are disposed. Here, the one side may be flat or may have a predetermined curvature. The one side may also have a predetermined cavity formed therein.
The heat sink 110 may include a fin 115. The fin 115 may project or extend outwardly from one side of the heat sink 110. The fin 115 increases the surface area of the heat sink 110. Therefore, the lighting device including the fin 115 may have improved heat radiation efficiency.
The heat sink 110 may be formed of a metallic material or a resin material, each of which has excellent heat radiation efficiency. However, there is no limit to the material of the heat sink 120. For example, the material of the heat sink 120 may include at least one of Al, Ni, Cu, Ag and Sn.
The first and the second light sources 130a and 130b are disposed on the heat sink 110. Specifically, the first and the second light sources 130a and 130b are disposed on one side of the heat sink 110 and emit light upwardly from the one side of the heat sink 110.
The first and the second light sources 130a and 130b may be disposed apart from each other at a predetermined interval. The first and the second light sources 130a and 130b will be described in detail.
The first light source 130a may include a first substrate 131a, a first light emitting device 133a and a first member 135a.
The first substrate 131a may be one of a common PCB, a metal core PCB (MCPCB), a standard FR-4 PCB, a flexible PCB or a ceramic substrate. The first substrate 131a may directly contact with the heat sink 110.
The first substrate 131a is disposed on the one side of the heat sink 110. The first light emitting device 133a is disposed on the first substrate 131a.
For the purpose of easily reflecting the light from the first light emitting device 133a, the first substrate 131a may be formed of a material capable of efficiently reflecting light, or the surface of the first substrate 131a may be coated or deposited with a light reflective material.
For structural purpose and/or so as to enhance the heat transfer to the heat sink 110, the first substrate 131a may selectively include a thermally conductive adhesive tape or a thermal pad. Here, the thermally conductive adhesive tape or the thermal pad may be disposed on the bottom surface of the first substrate 131a.
The first light emitting device 133a is disposed on the first substrate 131a. Here, a plurality of the first light emitting devices 133a may be disposed on the first substrate 131a.
The first light emitting device 133a may be a blue light emitting device emitting blue light. Specifically, the first light emitting device 133a may be a light emitting diode (LED) chip emitting blue light. The LED chip may have a lateral type or vertical type. The LED chip may have a flip type.
The first light emitting device 133a emits blue light having a peak wavelength of 400 nm to 480 nm. Most preferably, the first light emitting device 133a may emit blue light having a peak wavelength of 445 nm to 455 nm.
The first member 135a is disposed on the first substrate 131a and the first light emitting device 133a. The first member 135a is disposed on the first substrate 131a in such a manner as to cover the first light emitting device 133a. The first member 135a is able to protect the first light emitting device 133a from external impurities and moisture.
The first member 135a may be basically formed of synthetic resins like silicon, and a phosphor may be added to the synthetic resins.
Here, the first member 135a may include a yellow phosphor and a green phosphor.
The yellow phosphor is excited by blue light (430 nm to 480 nm) emitted from the first light emitting device 133a and emits excited light having a peak wavelength of 540 nm to 585 nm. The yellow phosphor may be a silicate phosphor, a garnet (YAG) phosphor and an oxynitride phosphor. The yellow phosphor may be selected from Y3Al5O12:Ce3+(Ce:YAG), CaAlSiN3:Ce3+ and Eu2+-SiAlON phosphor and/or may be selected from BOSE phosphor. The yellow phosphor may be doped at an arbitrary appropriate level so as to provide light output of a desired wavelength. Ce and/or Eu may be doped in the phosphor at a dopant concentration of about 0.1 % to about 20 %. A phosphor appropriate for this purpose may include products produced by Mitsubishi Chemical Company (Tokyo, Japan), Leuchtstoffwerk Breitungen GmbH (Breitungen, Germany) and Intermatix Company (Fremont, California).
The green phosphor is excited by blue light (430 nm to 480 nm) emitted from the first light emitting device 133a and emits excited light having a peak wavelength of 510 nm to 535 nm. The green phosphor may be a silicate phosphor, a nitride phosphor and an oxynitride phosphor.
A ratio of the yellow phosphor to the green phosphor, both of which are included in the first member 135a, may be from 5:5 to 8:2.
The blue light emitted from the first light emitting device 133a may pass through the first member 135a as it is or may excite the yellow or the green phosphors of the first member 135a. Therefore, the first light source 130a emits light formed by a mixture of the blue light of the first light emitting device 133a, yellow light emitted from the yellow phosphor of the first member 135a and green light emitted from the green phosphor of the first member 135a. The mixed light of the first light emitting device 133a is greenish white light.
The second light source 130b may include a second substrate 131b, a second light emitting device 133b and a second member 135b.
The second substrate 131b may be one of a common PCB, a metal core PCB (MCPCB), a standard FR-4 PCB, a flexible PCB, a ceramic substrate. The second substrate 131b may directly contact with the heat sink 110.
The second substrate 131b is disposed on the one side of the heat sink 110. The second light emitting device 133b is disposed on the second substrate 131b.
For the purpose of easily reflecting the light from the second light emitting device 133b, the second substrate 131b may be formed of a material capable of efficiently reflecting light, or the surface of the second substrate 131b may be coated or deposited with a light reflective material.
For structural purpose and/or so as to enhance the heat transfer to the heat sink 110, the second substrate 131b may selectively include a thermally conductive adhesive tape or a thermal pad. Here, the thermally conductive adhesive tape or the thermal pad may be disposed on the bottom surface of the second substrate 131b.
The second light emitting device 133b is disposed on the second substrate 131b. Here, a plurality of the second light emitting devices 133b may be disposed on the second substrate 131b.
Unlike the first light emitting device 133a, the second light emitting device 133b may be a red light emitting device emitting red light. Specifically, the second light emitting device 133b may be a light emitting diode (LED) chip emitting red light. The LED chip may have a lateral type or vertical type. The LED chip may have a flip type.
The second light emitting device 133b emits red light having a peak wavelength of 590 nm to 630 nm. Most preferably, the second light emitting device 133b may emit red light having a peak wavelength of 615 nm to 625 nm.
The second member 135b is disposed on the second substrate 131b and the second light emitting device 133b. The second member 135b is disposed on the second substrate 131b in such a manner as to cover the second light emitting device 133b. The second member 135b is able to protect the second light emitting device 133b from external impurities and moisture.
The second member 135b may be basically formed of synthetic resins like silicon. Unlike the first member 135a, the second member 135b may not have the phosphor. Therefore, the second member 135b may emit red light.
While the second light source 130b emit red light, the second light emitting device 133b may be an LED chip emitting non-white light and the second member 135b may include a red phosphor.
The red phosphor emits red light having a peak wavelength of from 600 nm to 650 nm in response to the blue light (430 nm to 480 nm). The red phosphor may be a nitride phosphor and a sulfide phosphor. The red phosphor may include CaAlSiN3:Eu2+ and Sr2Si5N8:Eu2+. These phosphors are able to cause a quantum efficiency to be maintained greater than 80 % at a temperature higher than 150 ℃. Another usable red phosphor may be selected from not only CaSiN2:Ce3+ and CaSiN2:Eu2+ but Eu2+-SiAlON phosphor and/or may be selected from (Ca,Si,Ba)SiO4:Eu2+(BOSE) phosphor. Particularly, a CaAlSiN:Eu2+ phosphor of the Mitsubishi Chemical Company may have a dominant wavelength of about 624 nm, a peak wavelength of about 628 nm and FWHM of about 100 nm.
Meanwhile, though not shown in the drawing, the first light emitting device 133a of the first light source 130a together with the second light emitting device 133b of the second light source 130b may be disposed on a single substrate (not shown).
The reflector 150 reflects the light emitted from the first and the second light sources 130a and 130b. Specifically, the reflector 150 surrounds the first and the second light sources 130a and 130b and reflects the light emitted from the first and the second light sources 130a and 130b to the diffusion plate 170.
The reflector 150 may have a reflective surface reflecting the light emitted from the first and the second light sources 130a and 130b. The reflective surface may be coated or deposited with a material capable of easily reflecting the light.
The diffusion plate 170 diffuses the light emitted from the first and the second light sources 130a and 130b and emits the light to the outside. Specifically, the light which passes through the diffusion plate 170 and is emitted outwardly is light mixed with the mixed light from the first light source 130a and the red light from the second light source 130b.
The diffusion plate 170 is disposed apart from the first and the second light sources 130a and 130b at a predetermined interval. The diffusion plate 170 may be disposed on the upper portion of the reflector in order to be apart from the first and the second light sources 130a and 130b.
The diffusion plate 170, the reflector 150 and the one side of the heat sink 110 form a predetermined space. In the predetermined space, the light emitted from the first light source 130a is mixed with the light emitted from the second light source 130b.
In the lighting device shown in Fig. 2, when no arbitrary light is added, light formed by a mixture of the mixed light from the first light source 130a and the red light from the second light source 130b may be emitted.
Fig. 3 is a view that mixed light emitted from the lighting device shown in Fig. 2 is represented in the 1931 CIE chromaticity diagram. Particularly, in the chromaticity diagram of Fig. 3, a target color temperature of the mixed light emitted from the lighting device shown in Fig. 2 is set to 3,000 K.
In Fig. 3, ‘P1’ is a color point of the blue light emitted from the first light emitting device 133a of the first light source 130a. ‘P2’ is a color point of yellow light emitted from the yellow phosphor of the first member 135a, which has been excited by the blue light of the first light emitting device133a. ‘P3’ is a color point of green light emitted from the green phosphor of the first member 135a, which has been excited by the blue light of the first light emitting device133a. Therefore, the mixed light emitted from the first light source 130a has any one color point within a first area ‘S1’. Here, the first area ‘S1’ may be formed when a ratio of the yellow phosphor to the green phosphor, both of which are included in the first member 135a, is from 5:5 to 8:2.
A second area ‘S2’ is an area of bins corresponding to 3,000 K on the black body locus. The second area ‘S2’ may correspond to the seven step Macadam ellipse or ten step Macadam ellipse. Here, the second area ‘S2’ may be changed according to the target color temperature that a user desires.
‘P4’ is a color point of the red light emitted from the second light emitting device 133b of the second light source 130b.
A third area ‘S3’ corresponds to a portion of the first area ‘S1’. Specifically, the third area ‘S3’ corresponds to an intersection area between the first area ‘S1’ and an area formed by two straight lines which start from ‘P4’ and contact with ‘S2’.
That is, when a target color temperature of the mixed light emitted from the lighting device according to the embodiment is set to 3,000 K, the mixed light emitted from the lighting device according to the embodiment has any one color point within the third area ‘S3’. Specifically, the third area ‘S3’ may be defined by straight lines connecting coordinates (0.36, 0.50), (0.32, 0.525), (0.28, 0.41) and (0.32, 0.4) in the 1931 CIE chromaticity diagram.
When the target color temperature of the mixed light emitted from the lighting device according to the embodiment is changed into another one, a set of the color points of the mixed light emitted from the lighting device according to the embodiment is expected to occupy a predetermined area other than the third area ‘S3’ shown in Fig. 3, for example, a predetermined area within the first area ‘S1’. Here, even though the target color temperature is changed, the set of the color points of the mixed light emitted from the lighting device according to the embodiment corresponds to a portion of the first area ‘S1’.
Fig. 4 is a graph showing intensity (W) according to the wavelength of the mixed light emitted from the lighting device shown in Fig. 2. Particularly, in the graph of Fig. 4, the target color temperature of the mixed light emitted from the lighting device shown in Fig. 2 is set to 3,000 K.
Referring to Fig. 4, it can be seen that the mixed light emitted from the lighting device shown in Fig. 2 has intensity greater than 1 mW at a wavelength of 430 nm to 480 nm.
Meanwhile, when a device having a peak wavelength around 620 nm is used as the second light emitting device 133b of the second light source 130b of the lighting device shown in Fig. 2, it can be seen that a color rendering index (CRI) is approximately greater than 93.
Although embodiments of the present invention were described above, these are just examples and do not limit the present invention. Further, the present invention may be changed and modified in various ways, without departing from the essential features of the present invention, by those skilled in the art. For example, the components described in detail in the embodiments of the present invention may be modified. Further, differences due to the modification and application should be construed as being included in the scope and spirit of the present invention, which is described in the accompanying claims.

Claims (14)

  1. A lighting device comprising:
    a first light source comprising a first light emitting device and a first member which is disposed on the first light emitting device and comprises a phosphor; and
    a second light source comprising a second light emitting device and emitting red light,
    wherein the first light emitting device of the first light source emits blue light,
    wherein the phosphor of the first light source comprises a yellow phosphor and a green phosphor,
    and wherein a ratio of the yellow phosphor to the green phosphor is from 5:5 to 8:2.
  2. The lighting device of claim 1, wherein the first light emitting device emits blue light having a peak wavelength of 400 nm to 480 nm, and wherein the second light emitting device emits red light having a peak wavelength of 590 nm to 630 nm.
  3. The lighting device of claim 1, wherein a set of color points of light mixed with the light emitted from the first light source and the light emitted from the second light source occupies a portion of a first area of a 1931 CIE chromaticity diagram, and wherein, in the 1931 CIE chromaticity diagram, the first area is a set of color points of light mixed with the blue light of the first light emitting device, yellow light emitted from the yellow phosphor and green light emitted from the green phosphor.
  4. The lighting device of claim 3, wherein the set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source is changed according to a target color temperature range, and wherein the target color temperature is a color temperature on a black body locus.
  5. The lighting device of claim 4, wherein, in the 1931 CIE chromaticity diagram, the set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source corresponds to an intersection area between the first area and an area formed by two straight lines which start from the color point of the red light emitted from the second light emitting device and contact with the target color temperature range.
  6. The lighting device of claim 5, wherein when the target color temperature is 3,000K, the set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source corresponds to an area defined by straight lines connecting coordinates (0.36, 0.50), (0.32, 0.525), (0.28, 0.41) and (0.32, 0.4) in the 1931 CIE chromaticity diagram.
  7. The lighting device of claim 1, wherein the second light source is disposed on the second light emitting device and comprises a second member including a red phosphor, and wherein the second light emitting device of the second light source emits non-white light.
  8. The lighting device of claim 1, further comprising:
    a heat sink on which the first light source and the second light source are disposed;
    a reflector which is coupled to the heat sink and is disposed to surround the first and the second light sources; and
    a diffusion plate which is disposed on the first and the second light sources and is coupled to the reflector.
  9. A lighting device comprising:
    a first light source which comprises a yellow phosphor, a green phosphor and a first light emitting device emitting blue light; and
    a second light source which is apart from the first light source and comprises a second light emitting device and emits red light,
    wherein light mixed with the light emitted from the first light source and the light emitted from the second light source comprises a target color temperature,
    wherein, in a 1931 CIE chromaticity diagram, a set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source corresponds to an intersection area between a first area and an area formed by two straight lines which start from the color point of the red light emitted from the second light emitting device and contact with a range of the target color temperature,
    and wherein, in the 1931 CIE chromaticity diagram, the first area is a set of color points of light mixed with the blue light of the first light emitting device, yellow light emitted from the yellow phosphor and the green light emitted from green phosphor.
  10. The lighting device of claim 9, wherein the first light emitting device emits blue light having a peak wavelength of 400 nm to 480 nm, and wherein the second light emitting device emits red light having a peak wavelength of 590 nm to 630 nm.
  11. The lighting device of claim 9, wherein a ratio of the yellow phosphor to the green phosphor is from 5:5 to 8:2.
  12. The lighting device of claim 9, wherein when the target color temperature is 3,000K, the set of color points of the light mixed with the light emitted from the first light source and the light emitted from the second light source corresponds to an area defined by straight lines connecting coordinates (0.36, 0.50), (0.32, 0.525), (0.28, 0.41) and (0.32, 0.4) in the 1931 CIE chromaticity diagram.
  13. The lighting device of claim 9, wherein the second light source is disposed on the second light emitting device and comprises a second member including a red phosphor, and wherein the second light emitting device of the second light source emits non-white light.
  14. The lighting device of claim 9, further comprising:
    a heat sink on which the first light source and the second light source are disposed;
    a reflector which is coupled to the heat sink and is disposed to surround the first and the second light sources; and
    a diffusion plate which is disposed on the first and the second light sources and is coupled to the reflector.
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JP2019062236A (en) * 2014-10-28 2019-04-18 株式会社東芝 White light source
JP2021122014A (en) * 2014-10-28 2021-08-26 東芝マテリアル株式会社 Method for using white light source and method for using white light source system
JP7285877B2 (en) 2014-10-28 2023-06-02 ソウル セミコンダクター カンパニー リミテッド white light source system

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