Lighting system

• US 6,234,648 B1
• Filed: 09/24/1999
• Issued: 05/22/2001
• Est. Priority Date: 09/28/1998
• Status: Expired due to Term

• Current Assignee: Philips Lighting North America Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Harbers, Gerard, Börner, Herbert F., Nikol, Hans, Busselt, Wolfgang, Ronda, Cornelis R., Jüstel, Thomas
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): Ton, Anabel M
• Application Number:
  US09/406,284
• Time in Patent Office: 606 Days
• Field of Search: 362/227, 362/800, 362/84, 362/293, 362/231, 362/545, 313/499, 313/512, 313/312, 313/313
• US Class Current: 362/235
• CPC Class Codes: C09K 11/584 with zinc or cadmium
• CPC Class Codes: C09K 11/642 with zinc or cadmium
• CPC Class Codes: C09K 11/7718 with alkaline earth metals
• CPC Class Codes: C09K 11/77342 Silicates
• CPC Class Codes: F21K 9/233 specially adapted for generating a spot light distribution, e.g. for substitution of reflector lamps
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21V 13/08 the elements being filters or photoluminescent elements and reflectors
• CPC Class Codes: F21V 7/24 characterised by the material
• 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: F21Y 2107/00 Light sources with three-dimensionally disposed light-generating elements
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/40 Details of LED load circuits
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A lighting system includes at least two light-emitting diodes each emitting, in operation, visible light in a preselected wavelength range. A converter converts part of the visible light emitted by one of the diodes into visible light in a further wavelength range so as to optimize the color rendition of the lighting system. The diodes include a blue light-emitting diode and a red light-emitting diode. Further, the converter includes a luminescent material for converting a portion of the light emitted by the blue light-emitting diode into green light.

Claims

1. A lighting system comprising at least two light-emitting diodes, each of said at least two light-emitting diodes emitting, in operation, visible light in a preselected wavelength range, and

conversion means for converting a part of the visible light emitted by one of the at least two light-emitting diodes into visible light in a further wavelength range so as to optimize the color rendition of the lighting system;

wherein the at least two light-emitting diodes comprise at least a blue light-emitting diode and at least a red light-emitting diode; and

wherein the conversion means include a luminescent material for converting a portion of the light emitted by the blue light-emitting diode into green light.

2. A lighting system as claimed in claim 1, wherein the luminescent material can be excited by light originating from one of a wavelength range from 400 to 500 nm and another wavelength range from 500 to 560 nm.

3. A lighting system as claimed in claim 1, wherein the luminescent material is chosen from one of a group formed by (Sr,Ca)₂SiO₄:

Eu²⁺, Ba₂SiO₄;

Eu²⁺, SrGa₂S₄, ZnS;

Cu⁺, ZnS;

Au⁺, ZnS;

Al³⁺, (Zn,Cd)S;

Ag⁺ and CaS;

Ce³⁺, and another group formed by CaS;

Eu,Mn;

CaS;

Eu;

SrS;

Eu;

(Zn, Cd)S;

Ag;

SrO;

Eu;

Sr₃B₂O₆;

Eu;

Sr₂Mg(BO₃)₂;

CaS;

Eu, Mn;

CaS;

Eu or SrS;

Eu.

5. A lighting system as claimed in claim 1, wherein a color rendering index of the lighting system is at least equal to or greater than 80.

6. A lighting system as claimed in claim 1 wherein, in operation, each of the at least two light-emitting diodes has a luminous flux of at least 5 lm.

4. A lighting system comprising at least two light-emitting diodes, each of said at least two light-emitting diodes emitting, in operation, visible light in a preselected wavelength range, and

conversion means for converting a part of the visible light emitted by one of the at least two light-emitting diodes into visible light in a further wavelength range so as to optimize the color rendition of the lighting system;

wherein the at least two light-emitting diodes at least comprise a blue light-emitting diode and at least a green light-emitting diode, and wherein the conversion means comprise a luminescent material for converting a portion of the light emitted by at least one of the blue and green light-emitting diodes to red light.

7. A lighting system comprising at least two light-emitting diodes, each of said at least two light-emitting diodes emitting, in operation, visible light in a preselected wavelength range;

conversion means for converting a part of the visible light emitted by one of the at least two light-emitting diodes into visible light in a further wavelength range so as to optimize the color rendition of the lighting system; and

reflection means.

8. A lighting system as claimed in claim 7, wherein the reflection means comprise a material chosen from the group formed by BaSO₄, ZnS, ZnO and TiO₂.

9. A lighting system as claimed in claim 7, wherein the conversion means are provided in or on the reflection means.

11. A lighting system as claimed in claim 7, wherein the conversion means comprise a luminescent material.

12. A lighting system as claimed in claim 11, wherein the luminescent material can be excited by light originating from one of a wavelength range from 400 to 500 nm and another wavelength range from 500 to 560 nm.

13. A lighting system as claimed in claim 11, wherein the luminescent material is chosen from one of a group formed by (Sr,Ca)₂SiO₄:

Eu²⁺, Ba₂SiO₄;

Eu²⁺, SrGa₂S₄, ZnS;

Cu⁺, ZnS;

Au⁺, ZnS;

Al³⁺, (Zn,Cd)S;

Ag⁺ and CaS;

Ce³⁺, and another group formed by CaS;

Eu,Mn;

CaS;

Eu;

SrS;

Eu;

(Zn, Cd)S;

Ag;

SrO;

Eu;

Sr₃B₂O₆;

Eu;

Sr₂Mg(BO₃)₂;

CaS;

Eu, Mn;

CaS;

Eu or SrS;

Eu.

14. A lighting system as claimed in claim 7, wherein a color rendering index of the lighting system is at least equal to or greater than 80.

15. A lighting system as claimed in claim 7 wherein, in operation, each of the at least two light-emitting diodes has a luminous flux of at least 5 lm.

10. A lighting system comprising at least two light-emitting diodes, each of said at least two light-emitting diodes emitting, in operation, visible light in a preselected wavelength range;

conversion means for converting a part of the visible light emitted by one of the at least two light-emitting diodes into visible light in a further wavelength range so as to optimize the color rendition of the lighting system; and

means for separately driving the at least two light-emitting diodes.

16. A lighting system as claimed in claim 10, wherein the conversion means comprise a luminescent material.

17. A lighting system as claimed in claim 16, wherein the luminescent material can be excited by light originating from one of a wavelength range from 400 to 500 nm and another wavelength range from 500 to 560 nm.

18. A lighting system as claimed in claim 16, wherein the luminescent material is chosen from one of a group formed by (Sr,Ca)₂SiO₄:

Eu²⁺, Ba₂SiO₄;

Eu²⁺, SrGa₂S₄, ZnS;

Cu⁺, ZnS;

Au⁺, ZnS;

Al³⁺, (Zn,Cd)S;

Ag⁺ and CaS;

Ce³⁺, and another group formed by CaS;

Eu,Mn;

CaS;

Eu;

SrS;

Eu;

(Zn, Cd)S;

Ag;

SrO;

Eu;

Sr₃B₂O₆;

Eu;

Sr₂Mg(BO₃)₂;

CaS;

Eu, Mn;

CaS;

Eu or SrS;

Eu.

19. A lighting system as claimed in claim 10, wherein a color rendering index of the lighting system is at least equal to or greater than 80.

20. A lighting system as claimed in claim 10 wherein, in operation, each of the at least two light-emitting diodes has a luminous flux of at least 5 lm.