Apparatus and method for adjusting the color temperature of white semiconduct or light emitters

• US 6,636,003 B2
• Filed: 09/06/2001
• Issued: 10/21/2003
• Est. Priority Date: 09/06/2000
• Status: Expired due to Term

• Current Assignee: Signify North America Corporation (Signify N.V.)
• Original Assignee: Spectrum Kinetics Co.
• Inventors: Rahm, Peter R., McGrath, William R.
• Primary Examiner(s): Philogene, Haissa
• Application Number:
  US09/948,209
• Publication Number:
  US 20020048177A1
• Time in Patent Office: 775 Days
• Field of Search: 315/178, 315/179, 315/291, 315/307, 315/312, 315/360, 315/362, 362/208, 362/800, 362/285
• US Class Current: 315/179
• CPC Class Codes: F21Y 2105/10 comprising a two-dimensional array of point-like light-generating elements
• CPC Class Codes: F21Y 2105/12 characterised by the geometrical disposition of the light-generating elements, e.g. arranging light-generating elements in differing patterns or densities
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• 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 25/13 the devices being of a type provided for in group H01L33/00
• 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: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/28 using temperature feedback
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

An LED arrangement which produces a color temperature adjustable white light. The LED arrangement includes one or more white LEDs and a first drive circuit operable to supply a first drive current to the one or more white LEDs such that a white light is output at a desired intensity. The LED arrangement further includes one or more colored LEDs arranged such that a light output from the one or more colored LEDs combines with the white light to produce a resultant light having a desired color temperature. The colored LEDs are driven by a second drive circuit which supplies a second drive current to the one or more colored LEDs such that a colored light is output at a desired intensity, the intensity of the colored light output from the one or more colored LEDs being adjustable so as to adjust the color temperature of the resultant light.

Claims

1. A temperature adjustable LED arrangement comprising:

at least one white LED;

a first drive circuit operable to supply a first drive current to the at least one white LED such that a white light is output at a first intensity;

at least one colored LED arranged such that a colored light is output from the at least one colored LED and combines with the white light to produce a resultant light having a color temperature; and

a second drive circuit operable to supply a second drive current to the at least one colored LED such that the colored light is output at a second intensity, the second drive circuit being adjustable so as to adjust a level of the second drive current supplied so as to vary the color temperature of the resultant light;

wherein the color temperature of the resultant light is adjustable between about 2500 to about 5000 degrees Kelvin.

2. The LED arrangement according to claim 1, wherein the first drive circuit is adjustable so as to adjust a level of the first drive current supplied to the at least one white LED so as to vary the brightness of the white light.

3. The LED arrangement according to claim 1, wherein the at least one colored LED is an amber LED.

4. The LED arrangement according to claim 1, wherein the at least one colored LED is a combination of red and yellow LEDs.

5. The LED arrangement according to claim 1, wherein the first drive circuit is a pulse width modulated drive circuit with active current limiting.

6. The LED arrangement according to claim 5, wherein the second drive circuit is a pulse width modulated drive circuit with active current limiting.

7. The LED arrangement according to claim 1, wherein the second drive circuit is a pulse width modulated drive circuit with active current limiting.

8. The LED arrangement according to claim 1, wherein the first drive circuit is a pulse width modulated drive circuit with passive current limiting.

9. The LED arrangement according to claim 5, wherein the second drive circuit is a pulse width modulated drive circuit with passive current limiting.

10. The LED arrangement according to claim 1, wherein the second drive circuit is a pulse width modulated drive circuit with passive current limiting.

11. The LED arrangement according to claim 1, wherein the at least one white LED is a discrete LED.

12. The LED arrangement according to claim 11, wherein the at least one white LED is mounted on a printed circuit board.

13. The LED arrangement according to claim 1, wherein the at least one white LED is a chip-on-board LED.

14. The LED arrangement according to claim 1, wherein the at least one white LED comprises at least two white LEDs arranged in series.

15. The LED arrangement according to claim 1, wherein the at least one colored LED is a discrete LED.

16. The LED arrangement according to claim 15, wherein the at least one colored LED is mounted on a printed circuit board.

17. The LED arrangement according to claim 1, wherein the at least one colored LED is a chip-on-board LED.

18. The LED arrangement according to claim 1, wherein the at least one colored LED comprises at least two colored LEDs arranged in series.

19. The LED arrangement according to claim 1, wherein the color temperature of the resultant light is adjustable to about 3600 degrees Kelvin.

20. A method of adjusting the color temperature of light output from an LED arrangement, the method comprising:

supplying a first drive current to at least one white LED such that a white light is output at a first intensity;

supplying a second drive current to at least one colored LED such that a colored light is output at a second intensity;

combining the white light with the colored light to produce a resultant light having a desired color temperature; and

adjusting the color temperature of the resultant light by adjusting the second intensity of the colored light;

wherein the color temperature of the resultant light is adjusted between about 2500 to about 5000 degrees Kelvin.

21. The method of adjusting the color temperature of light output from an LED arrangement according to claim 20, wherein the color temperature of the resultant light is adjusted to about 3600 degrees Kelvin.

22. A temperature adjustable LED arrangement comprising:

at least one white LED;

a first drive circuit operable to supply a first drive current to the at least one white LED such that a white light is output at a first intensity;

at least one red LED arranged to output a red light that combines with the white light;

a second drive circuit operable to supply a second drive current to the at least one red LED such that the red light is output at a second intensity;

at least one yellow LED arranged to output a yellow light that combines with the white light and the red light to produce a resultant light having a color temperature;

a third drive circuit operable to supply a third drive current to the at least one yellow LED such that the yellow light is output at a third intensity,

the second drive circuit being adjustable so as to adjust a level of the second drive current supplied to the at least one red LED and the third drive circuit being adjustable so as to adjust a level of the third drive current supplied to the at least one yellow LED so as to vary the color temperature of the resultant light;

wherein the color temperature of the resultant light is adjustable between about 2500 to about 5000 degrees Kelvin.

23. The LED arrangement according to claim 22, wherein the at least one white LED is a discrete LED.

24. The LED arrangement according to claim 23, wherein the at least one white LED is mounted on a printed circuit board.

25. The LED arrangement according to claim 22, wherein the at least one white LED is a chip-on-board LED.

26. The LED arrangement according to claim 22, wherein the at least one white LED comprises at least two white LEDs arranged in series.

27. The LED arrangement according to claim 22, wherein the at least one red LED and the at least one yellow LED are discrete LEDs.

28. The LED arrangement according to claim 27, wherein the at least one red LED and the at least one yellow LED are mounted on a printed circuit board.

29. The LED arrangement according to claim 22, wherein the at least one red LED and the at least one yellow LED are chip-on-board LEDs.

30. The LED arrangement according to claim 22, wherein the at least one red LED comprises at least two red LEDs arranged in series.

31. The LED arrangement according to claim 30, wherein the at least one yellow LED comprises at least two yellow LEDs arranged in series.

32. The LED arrangement according to claim 22, wherein the first drive circuit is adjustable so as to adjust a level of the first drive current supplied to the at least one white LED so as to vary the brightness of the white light.

33. The LED arrangement according to claim 22, wherein the color temperature of the resultant light is adjustable to about 3600 degrees Kelvin.

34. A temperature adjustable LED arrangement comprising:

at least one white LED which outputs a white light;

at least one colored LED which outputs a colored light, the at least one colored LED being arranged at a distance from the at least one white LED such that the output colored light combines with the output white light to produce a resultant light having a color temperature;

wherein the color temperature of the resultant light is adjustable between about 2500 to about 5000 degrees Kelvin.

35. The LED arrangement according to claim 34, wherein an intensity of the output colored light is adjustable so as to vary the color temperature of the resultant light.

36. The LED arrangement according to claim 34, wherein the at least one colored LED is a chip-on-board LED.

37. The LED arrangement according to claim 34 wherein the color temperature of the resultant light is adjustable to about 3600 degrees Kelvin.

38. The LED arrangement according to claim 35, wherein an intensity of the output white light is adjustable so as to vary the brightness of the resultant light.

39. The LED arrangement according to claim 34, wherein an intensity of the output white light is adjustable so as to vary the brightness of the output white light.

40. The LED arrangement according to claim 34, wherein the at least one colored LED is an amber LED.

41. The LED arrangement according to claim 34, wherein the at least one colored LED is a combination of red and yellow LEDs.

42. The LED arrangement according to claim 34, wherein the at least one white LED is a discrete LED.

43. The LED arrangement according to claim 42, wherein the at least one white LED is mounted on a printed circuit board.

44. The LED arrangement according to claim 34, wherein the at least one white LED is a chip-on-board LED.

45. The LED arrangement according to claim 34, wherein the at least one colored LED is a discrete LED.

46. The LED arrangement according to claim 45, wherein the at least one colored LED is mounted on a printed circuit board.