Efficient lighting system with wide color range

Patent metadata

Field	Value
Publication number	US-9559272-B2
Application number	US-201314422778-A
Country	US
Kind code	B2
Filing date	May 2, 2013
Priority date	Sep 13, 2012
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

Broadband solid state light sources include remote phosphor LED(s), short-wavelength direct emitting LED(s), and long-wavelength direct emitting LED(s). A diffuse or clear cover member covers these LEDs. Each remote phosphor LED includes an LED, a phosphor layer, and a dichroic reflector. The light sources can provide a broadband output light over a wide color range, and can do so efficiently while energizing a high percentage or proportion of the total number of LEDs in the system. The broadband output may for example exhibit a color difference of at least 0.2 in CIE chromaticity units, and/or a correlated color temperature difference of at least 4000 or 5000 Kelvin, while energizing more than half, or at least 60%, or at least 70%, of the total number of LEDs. Numbers of LEDs can be replaced with effective numbers of LEDs if LEDs of substantially different sizes are included in the light source.

First claim

The invention claimed is:

1. A lighting system for emitting broad band light, comprising:
a total number N of LEDs; and
a light-transmissive cover member that covers the N LEDs and transmits the broad band light;
wherein the N LEDs include:
a number N1 of pump LEDs, each pump LED configured as a remote phosphor LED, wherein the pump LED is combined with a dichroic reflector and a phosphor layer such that at least some light from the pump LED is reflected by the dichroic reflector onto the phosphor layer to cause the phosphor layer to emit phosphor light, the dichroic reflector also configured to substantially transmit the phosphor light;
a number N2 of direct emitting short-wavelength LEDs having peak output wavelengths in a range from 400 to 500 nm, each short-wavelength LED disposed to emit at least some light that propagates from the short wavelength LED to the cover member without being substantially reflected by any dichroic reflector; and
a number N3 of direct emitting long-wavelength LEDs having peak output wavelengths in a range from 600 to 700 nm, each long-wavelength LED disposed to emit at least some light that propagates from the long wavelength LED to the cover member without being substantially reflected by any dichroic reflector;

wherein the pump LEDs, the direct emitting short wavelength LEDs, and the direct emitting long wavelength LEDs are respectively wired for independent electrical control;
wherein the broad band light transmitted by the cover member has a color that is a function of which ones of the N LEDs are energized;
wherein the N LEDs are configured such that the broad band transmitted light can have a first color associated with a first group of the N LEDs being energized, and a second color associated with a second group of the N LEDs being energized; and
wherein the first and second colors have a color difference of at least 0.2 in CIE chromaticity units, and wherein the first and second groups of the N LEDs each involve energizing more than half of the N LEDs.

2. The system of claim 1 , wherein the first and second groups of the N LEDs each involve energizing at least 60% of the N LEDs.

3. The system of claim 1 , wherein the first and second groups of the N LEDs each involve energizing all of the N1 pump LEDs.

4. The system of claim 1 , wherein the first and second colors are sufficiently close to the Planckian locus such that they have respective first and second correlated color temperatures.

5. The system of claim 4 , such that the first and second correlated color temperatures differ by at least 4000 Kelvin.

6. The system of claim 1 , wherein N1 is at least 2, and wherein there are a plurality of remote phosphor LEDs.

7. The system of claim 6 , wherein the plurality of remote phosphor LEDs utilize phosphor layers having a same phosphor composition.

8. The system of claim 6 , wherein the plurality of remote phosphor LEDs utilize phosphor layers having different phosphor compositions.

9. The system of claim 1 , wherein N1 >N2 +N3.

10. The system of claim 1 , wherein for at least one of the remote phosphor LED(s), the pump LED, the phosphor layer, and the dichroic reflector are arranged such that at least some excitation light propagates from the pump LED to the dichroic reflector without passing through the phosphor layer.

11. The system of claim 1 , wherein at least some of the pump LED(s) have a peak wavelength of less than 420 nm.

12. The system of claim 1 , wherein at least some of the direct emitting short-wavelength LED(s) have a peak output wavelength in a range from 420 to 480 nm.

13. The system of claim 1 , further comprising:
a control system configured to drive the N1 pump LEDs, the N2 direct emitting short-wavelength LEDs, and the N3 direct emitting long-wavelength LEDs independently.

14. The system of claim 13 , wherein the control system is configured to provide first and second control outputs, the first control output being effective to energize the first group of the N LEDs to provide the first color for the transmitted broad band light, and the second control output being effective to energize the second group of the N LEDs to provide the second color for the transmitted broad band light.

15. The system of claim 1 , wherein the light-transmissive cover member is light-diffusing.

16. A lighting system for emitting broad band light, comprising:
a total effective number NE of LEDs; and
a light-transmissive cover member that covers the NE LEDs and transmits the broad band light;
wherein the NE LEDs include:
an effective number NE1 of pump LEDs, each pump LED configured as a remote phosphor LED, wherein the pump LED is combined with a dichroic reflector and a phosphor layer such that at least some light from the pump LED is reflected by the dichroic reflector onto the phosphor layer to cause the phosphor layer to emit phosphor light, the dichroic reflector also configured to substantially transmit the phosphor light;
an effective number NE2 of direct emitting short-wavelength LEDs having peak output wavelengths in a range from 400 to 500 nm, each short-wavelength LED disposed to emit at least some light that propagates from the short wavelength LED to the cover member without being substantially reflected by any dichroic reflector; and
an effective number NE3 of direct emitting long-wavelength LEDs having peak output wavelengths in a range from 600 to 700 nm, each long-wavelength LED disposed to emit at least some light that propagates from the long wavelength LED to the cover member without being substantially reflected by any dichroic reflector;

wherein the pump LEDs, the direct emitting short wavelength LEDs, and the direct emitting long wavelength LEDs are respectively wired for independent electrical control;
wherein the broad band light transmitted by the cover member has a color that is a function of which ones of the NE LEDs are energized;
wherein the NE LEDs are configured such that the broad band transmitted light can have a first color associated with a first group of the NE LEDs being energized, and a second color associated with a second group of the NE LEDs being energized; and
wherein the first and second colors have a color difference of at least 0.2 in CIE chromaticity units, and wherein the first and second groups of the NE LEDs each involve energizing more than half of the NE LEDs.

17. The system of claim 16 , wherein the first and second groups of the NE LEDs each involve energizing at least 60% of the NE LEDs.

18. The system of claim 16 , wherein the first and second groups of the NE LEDs each involve energizing all of the NE1 pump LEDs.

19. The system of claim 16 , wherein NE1 is at least 2.

20. The system of claim 16 , wherein NE1 >NE2 +NE3.

Assignees

• 3M Innovative Properties Co

Inventors

• Ouderkirk Andrew J

Classifications

• F21V13/14

  the elements being filters or photoluminescent elements, reflectors and refractors · CPC title

• H10W90/00 Primary

  Package configurations · CPC title

• F21Y2115/10

  Light-emitting diodes [LED] · CPC title

• H05B45/20

  Controlling the colour of the light · CPC title

• F21V3/02

  characterised by the shape · CPC title