Solid state lighting devices including light mixtures

• US 7,821,194 B2
• Filed: 09/10/2009
• Issued: 10/26/2010
• Est. Priority Date: 04/18/2006
• Status: Active Grant

• Current Assignee: IDEAL Industries Lighting, LLC (Ideal Industries Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: van de Ven, Antony P., Negley, Gerald H.
• Primary Examiner(s): Ton; Toan
• Assistant Examiner(s): Hanley; Britt D
• Application Number:
  US12/557,036
• Publication Number:
  US 20100002440A1
• Time in Patent Office: 411 Days
• Field of Search: 313/498, 313501-503, 362230-231, 362/249.02
• US Class Current: 313/498
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• 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

Abstract

A solid state lighting apparatus includes a plurality of light emitting diodes (LEDs). Each of the LEDs includes an LED device configured to emit light having about a first dominant wavelength and a phosphor configured to receive at least some of the light emitted by the LED device and responsively emit light having about a second dominant wavelength. A combined light emitted by the LED device and the phosphor of a first one of the plurality of LEDs has a first color point and a combined light emitted by the LED device and the phosphor of a second one of the plurality of LEDs has a second color point that falls outside a seven step Macadam ellipse around the first color point.

Claims

1. A solid state lighting apparatus comprising:

a plurality of light emitting diodes (LEDs), each of the LEDs comprising an LED device configured to emit light having about a first dominant wavelength and a phosphor configured to receive at least some of the light emitted by the LED device and responsively emit light having a second dominant wavelength wherein each of the plurality of LED devices emits substantially the same color of light and each of the plurality of LEDs comprises the same phosphor;

wherein a combined light emitted by the LED device and the phosphor of a first one of the plurality of LEDs has a first color point and a combined light emitted by the LED device and the phosphor of a second one of the plurality of LEDs has a second color point that falls outside a seven step Macadam ellipse around the first color point.

2. The solid state lighting apparatus of claim 1, wherein the first color point and the second color point each fall within a defined area on a 1931 CIE Chromaticity Diagram enclosed by first, second, third, fourth and fifth line segments, said first line segment connecting a first point to a second point, said second line segment connecting said second point to a third point, said third line segment connecting said third point to a fourth point, said fourth line segment connecting said fourth point to a fifth point, and said fifth line segment connecting said fifth point to said first point, said first point having x, y coordinates of 0.32, 0.40, said second point having x, y coordinates of 0.36, 0.48, said third point having x, y coordinates of 0.43, 0.45, said fourth point having x, y coordinates of 0.42, 0.42, and said fifth point having x, y coordinates of 0.36, 0.38.

3. The solid state lighting apparatus of claim 2, wherein a chromaticity of combined light emitted by the plurality of LEDs has a color point that falls within the defined area on a 1931 CIE Chromaticity Diagram.

4. The solid state lighting apparatus of claim 2, wherein a chromaticity of combined light emitted by the plurality of LEDs has a color point that falls outside a ten-step Macadam ellipse around any point on the planckian locus between 2000 Kelvin and 8000 Kelvin.

5. The solid state lighting apparatus of claim 2, wherein the defined area on a 1931 CIE Chromaticity Diagram comprises a plurality of bins, each of the plurality of bins having approximately a size of a seven step Macadam ellipse, wherein the first color point falls in a first one of the plurality of bins and the second color point falls within a second one of the plurality of bins.

6. The solid state lighting apparatus of claim 1, further comprising:

a constant current source, wherein the plurality of LEDs is coupled to the constant current source and receives a constant current supplied by the constant current source.

7. The solid state lighting apparatus of claim 1, wherein the first dominant wavelength is from about 430 nm to about 480 nm.

8. The solid state lighting apparatus of claim 7, wherein the second dominant wavelength is from 600 nm to 630 nm.

9. The solid state lighting apparatus of claim 7, wherein the second dominant wavelength is from 550 nm to 580 nm.

10. The solid state lighting apparatus of claim 1, wherein the first dominant wavelength is from about 500 nm to about 530 nm.

11. The solid state lighting apparatus of claim 10, wherein the second dominant wavelength is from 600 nm to 630 nm.

12. The solid state lighting apparatus of claim 10, wherein the second dominant wavelength is from 550 nm to 580 nm.

13. The solid state lighting apparatus of claim 1, wherein the plurality of LEDs comprises a first plurality of LEDs, the apparatus further comprising a second plurality of LEDs, each of the second LEDs comprising an LED device configured to emit light having a third dominant wavelength and a phosphor configured to receive at least some of the light emitted by the LED device and responsively emit light having a fourth dominant wavelength, wherein the fourth dominant wavelength is at least 25 nm higher than the second dominant wavelength;

wherein a combined light emitted by the LED device and the phosphor of a first one of the second plurality of LEDs has a third color point and a combined light emitted by the LED device and the phosphor of a second one of the second plurality of LEDs has a fourth color point that falls outside a seven step Macadam ellipse of the third color point.

14. The solid state lighting apparatus of claim 13, wherein the first dominant wavelength is from about 430 nm to about 480 nm, the second dominant wavelength is from 550 nm to 580 nm, the third dominant wavelength is from about 430 nm to about 480 nm, and the fourth dominant wavelength is from 600 nm to 630 nm.

15. The solid state lighting apparatus of claim 13, wherein the first dominant wavelength is from about 430 nm to about 480 nm, the second dominant wavelength is from 550 nm to 580 nm, the third dominant wavelength is from about 500 nm to about 530 nm, and the fourth dominant wavelength is from 600 nm to 630 nm.

16. The solid state lighting apparatus of claim 13, further comprising:

a first constant current source, wherein the first plurality of LEDs is coupled to the first constant current source and receives a constant current supplied by the first constant current source; and

a second constant current source, wherein the second plurality of LEDs is coupled to the second constant current source and receives a constant current supplied by the second constant current source.

17. The solid state lighting apparatus of claim 13, wherein a line segment on a 1931 CIE Chromaticity diagram between a color point of combined light emitted by the first plurality of LEDs and the color point of light emitted by the second plurality of LEDs crosses the planckian locus between about 2500 Kelvin and 4500 Kelvin.

18. The solid state lighting apparatus of claim 1, wherein the plurality of LEDs comprises a first plurality of LEDs, the apparatus further comprising a second plurality of LEDs connected in series, each of the second LEDs comprising an LED device configured to emit light having a third dominant wavelength that is from about 600 nm to about 630 nm.

19. The solid state lighting apparatus of claim 18, wherein a line segment on a 1931 CIE Chromaticity diagram between a color point of combined light emitted by the first plurality of LEDs and the color point of light emitted by the second plurality of LEDs crosses the planckian locus between about 2500 Kelvin and 4500 Kelvin.

20. A solid state lighting apparatus comprising:

a current source; and

a string of light emitting diodes (LEDs) connected to the current source and configured to emit light in response to a drive current supplied by the current source, each of the LEDs in the string comprising an LED device configured to emit light having a first dominant wavelength and a phosphor configured to receive at least some of the light emitted by the LED device and responsively emit light having a dominant wavelength that is different from the first dominant wavelength wherein each of the plurality of LED devices in the string emits substantially the same color of light and each of the plurality of LEDs in the string comprises the same phosphor;

wherein a combined light emitted by the LED device and the phosphor of a first one of the plurality of LEDs has a first color point and a combined light emitted by the LED device and the phosphor of a second one of the plurality of LEDs has a second color point that falls outside a seven step Macadam ellipse around the first color point.