Light emitting device and system providing white light with various color temperatures

• US 8,459,832 B2
• Filed: 07/31/2012
• Issued: 06/11/2013
• Est. Priority Date: 09/10/2008
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Yu-Sik
• Primary Examiner(s): Dzierzynski, Evan
• Assistant Examiner(s): ALLEN, DANIELLE NICOLE
• Application Number:
  US13/562,888
• Publication Number:
  US 20120293093A1
• Time in Patent Office: 315 Days
• Field of Search: 362/800, 362/84, 362/230, 362/231, 362/293, 362/2, 362/510, 362/166, 362/260, 362/310, 362/296.02, 362/254, 362/255, 362/256, 362/311.01, 362/311.02, 362/1, 362/51, 362/165, 257 79-103, 361600-837
• US Class Current: 362/231
• CPC Class Codes: F21V 9/30 Elements containing photoluminescent material distinct from or spaced from the light source shades F21V1/17; globes, bowls or cover glasses F21V3/08, F21V3/12; refractors F21V5/10; reflectors F21V7/26, F21V7/30; elements with provision for controlling the spectral properties or intensity F21V9/40
• CPC Class Codes: F21W 2131/103 of streets or roads
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source
• CPC Class Codes: H05B 45/20 Controlling the colour of the light

Abstract

In a light emitting device and system providing white light with various color temperatures are provided, a light emitting device includes a light emitting element (LED) that is operated by a driving bias and emits first light, and a phosphor layer including a phosphor that partially wavelength-converts first light and emits second light, thereby emitting white light using the first light and the second light, wherein the phosphor has a maximum conversion efficiency at a first level of the driving bias, and the LED has a maximum conversion efficiency at a second level of the driving bias, the first level being different from the first level.

Claims

1. A light emitting device comprising:

a light emitting element which is operated by a forward driving bias to emit first light and includes a first conductive layer of a first conductivity type, a second conductive layer of a second conductivity type, a light emitting layer disposed between the first conductive layer and the second conductive layer, a first electrode connected to the first conductive layer, and a second electrode connected to the second conductive layer, wherein the first conductive layer, the second conductive layer and the light emitting layer are represented by In_xAl_yGa_(1-x-y)N (0≦

x≦

1, 0≦

y≦

1); and

a phosphor layer including a phosphor which partially wavelength-converts the first light to emit second light, wherein the phosphor layer includes only the phosphor or a combination of transparent resin and a phosphor,

wherein the light emitting element emits blue light, the phosphor layer includes a yellow phosphor which partially wavelength-converts the blue light to emit yellow light and a red phosphor which partially wavelength-converts the blue light to emit red light, or a green phosphor which partially wavelength-converts the blue light to emit green light and a red phosphor which partially wavelength-converts the blue light to emit red light, and

wherein the light emitting device emits white light using the first light and the second light such that a color temperature of the white light is varied by adjusting a level of the driving bias.

2. The light emitting device of claim 1, wherein the phosphor is at least one selected from the group consisting of a nitride-/oxynitride-based phosphor, mainly activated by lanthanoids such as Eu and Ce;

an alkaline earth halogen apatite phosphor, mainly activated by lanthanoids such as Eu or by transition metal elements such as Mn;

an alkaline earth metal borate halogen phosphor;

an alkaline earth metal aluminate phosphor;

an alkaline earth sulfide phosphor;

a rare earth aluminate phosphor, mainly activated by lanthanoids such as Ce;

an alkaline earth silicate phosphor;

an alkaline earth thiogallate phosphor;

an alkaline earth silicon nitride phosphor;

a germinate phosphor;

a rare earth silicate phosphor; and

an organic and an organic complexes, mainly activated by lanthanoids such as Eu.

3. The light emitting device of claim 1, wherein the phosphor is at least one selected from the group consisting of M₂Si₅N₈:

Eu, MSi₇N₁₀;

Eu, M_1.8Si₅O_0.2N₈;

Eu, M_0.9Si₇O_0.1N₁₀;

Eu (M represents at least one element selected from among Sr, Ca, Ba, Mg and Zn), MSi₂O₂N₂;

Eu, M₅(PO₄)₃ X;

R(X represents at least one element selected from among F, Cl, Br, and I, and R represents at least one element selected from among Eu and Mn), M₂B₅O₉X;

R, SrAl₂O₄;

R, Sr₄Al₁₄O₂₅;

R, CaAl₂O₄;

R, BaMg₂Al₁₆O₂₇;

R, BaMg₂Al₁₆O₁₂;

R, BaMgAl₁₀O₁₇;

R, La₂O₂S;

Eu, Y₂O₂S;

Eu, Gd₂O₂S;

Eu, YAG-based phosphors represented by Y₃Al₅O₁₂;

Ce, (Y_0.8Gd_0.2)₃Al₅O₁₂;

Ce, Y₃(Al_0.8Ga_0.2)₅ O₁₂;

Ce, and (Y, Gd)₃ (Al, Ga)₅ O₁₂, Tb₃Al₅O₁₂;

Ce, Lu₃Al₅O₁₂;

Ce in which portion or all of Y is substituted with Tb or Lu, alkaline earth silicate phosphor, (SrBa)₂SiO₄;

Eu, ZnS;

Eu, and Zn₂GeO₄;

Mn, MGa₂S₄;

Eu (if necessary, the phosphor can contain at least one element selected from among Tb, Cu, Ag, Au, Cr, Nd, Dy, Co, Ni and Ti, in place of Eu, or in addition to Eu).

4. The light emitting device of claim 1, wherein the light emitting device is a package disposed within a slot of a package body, wherein the slot is larger than the light emitting element, and the light emitting element is placed in the middle of the slot, and

wherein the package body is at least one selected from the group consisting of an organic material having high light transmittance such as silicon resin, epoxy resin, acryl resin, glass resin, fluorine resin and imide resin, an inorganic material such as glass and silica gel, a variety of fillers including aluminum nitride, aluminum oxide, and composite materials thereof, and a metallic or ceramic material.

5. The light emitting device of claim 4, further comprising a transparent resin layer in the slot of the package body, wherein the transparent resin layer fills approximately 90% of the slot.

6. The light emitting device of claim 5, wherein the transparent resin layer is formed of a material, filling the slot of the package body, which is at least one selected from the group consisting of epoxy resin, silicon resin, hardened silicon resin, denatured silicon resin, urethane resin, ocetane resin, acryl resin, polycarbonate resin and polyimide resin.

7. The light emitting device of claim 1, wherein the driving bias is DC power.

8. A light emitting system comprising:

the light emitting device described in claim 1; and

a sensor which senses a user'"'"'s body temperature,

wherein the level of the driving bias is controlled by the sensor.

9. A light emitting system comprising the light emitting device described in claim 1.