Color tunable light source

• US 20080278927A1
• Filed: 05/07/2007
• Published: 11/13/2008
• Est. Priority Date: 05/07/2007
• Status: Active Grant

• Current Assignee: Intematix Corporation
• Original Assignee: Intematix Corporation
• Inventors: Dong, Yi, Li, Yi-Qun, Xu, Xiaofeng, Collier, Ian
• Granted Patent: US 7,703,943 B2
• Time in Patent Office: Days
• US Class Current: 362/84
• 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: H05B 45/20 Controlling the colour of the light

Abstract

A color tunable light source comprises: a first light emitting diode (LED) arrangement operable to emit light of a first color and a second LED arrangement operable to emit light of a second color, the combined light output comprising the output of the source. One or both LED arrangements comprises a phosphor provided remote to an associated LED operable to generate excitation energy of a selected wavelength range and to irradiate the phosphor such that it emits light of a different color wherein light emitted by the LED arrangement comprises the combined light from the LED and phosphor and control means operable to control the color by controlling the relative light outputs of the two LED arrangements. The color can be controlled by controlling the relative magnitude of the drive currents of the LEDs or by controlling a duty cycle of PWM drive current.

Claims

1. A color tunable light source comprising:

a first light emitting diode LED arrangement operable to emit light of a first color and a second light emitting diode LED arrangement operable to emit light of a second color, the light emitting diode arrangements being configured such that their combined light output comprises the output of the source;

characterized in that the first LED arrangement comprises a phosphor provided remote to an associated first LED operable to generate excitation energy of a selected wavelength range and to irradiate the phosphor such that it emits light of a different color wherein light emitted by the first LED arrangement comprises the combined light from the first LED and the light emitted from the phosphor and control means operable to control the color by controlling the relative light outputs of the two light emitting diode arrangements.

2. The source of claim 1, wherein the second light emitting diode arrangement comprises a respective phosphor provided remote to an associated second LED operable to generate excitation energy of a selected wavelength range and to irradiate the phosphor such that it emits light of a different color, wherein the light emitted by the second LED arrangement comprises the combined light from the second LED and the light emitted from the phosphor and wherein the control means is operable to control the color by controlling the relative irradiation of the phosphors.

3. The light source of claim 1 or claim 2, wherein the control means is operable to select the color by controlling the relative magnitude of the drive currents of the respective light emitting diodes.

4. The light source of claim 1 or claim 2, wherein the control means is operable to dynamically switch the drive currents of the respective light emitting diodes and wherein the color is tunable by controlling a duty cycle of the drive current.

5. The light source of claim 4, wherein the control means comprises a pulse width modulated power supply operable to generate a pulse width modulated drive current.

6. The light source of claim 1, wherein the second LED arrangement comprises a respective phosphor provided remote to the first LED and wherein the first LED is operable to generate excitation energy for the two phosphors and further comprising a respective light controller associated with each phosphor and wherein the control means is operable to select the color by controlling the light controller to control the relative irradiation of the phosphors.

7. The light source of claim 6, wherein the light controller comprises a liquid crystal shutter.

8. The light source of claim 6, wherein the control means is operable to select the color temperature by controlling the relative drive voltages of the respective light controllers.

9. The light source of claim 6, wherein the control means is operable to dynamically switch the drive voltage of the light controllers and wherein the color temperature is tunable by controlling a duty cycle of the voltage.

10. The light source of claim 9, wherein the control means comprises a pulse width modulated power supply operable to generate a pulse width modulated drive voltage.

11. The light source of any preceding, and comprising a plurality of first and second LED arrangements.

12. A method of generating light with a selected color comprising:

providing a first light emitting diode arrangement and operating it to emit light of a first color and providing a second light emitting diode arrangement and operating it to emit light of a second color;

characterized by the first LED arrangement comprising a phosphor provided remote to an associated first LED operable to generate excitation energy of a selected wavelength range and to irradiate the phosphor such that it emits light of a different color wherein light emitted by the first LED arrangement comprises the combined light from the first LED and the light emitted from the phosphor and controlling color of generated light by controlling the relative light outputs of the two LED arrangements.

13. The method of claim 12, wherein the second LED arrangement comprises a respective phosphor provided remote to an associated second LED operable to generate excitation energy of a selected wavelength range and to irradiate the phosphor such that each emits light of a color, wherein the light emitted by the second LED arrangement comprises the combined light from the second LED and the light emitted from the phosphor and comprising selecting a color by controlling relative irradiation of the phosphors.

14. The method of claim 12 or claim 13, and comprising selecting the color by controlling the relative magnitudes of the drive currents of the respective LEDs.

15. The method of claim 12 or claim 13, and comprising dynamically switching the drive currents of the respective light emitting diodes and selecting the color by controlling a duty cycle of the drive current.

16. The method of claim 15, and comprising generating a pulse width modulated drive current and operating the respective LEDs on opposite phases of the drive current.

17. The method of claim 12, wherein the second LED arrangement comprises a respective phosphor provided remote to the first LED and wherein the first LED is operable to generate excitation energy for the two phosphors and further comprising providing a respective light controller associated with each phosphor and controlling the color by controlling the light controllers to control the relative irradiation of the phosphors.

18. The method of claim 17, wherein the light controller comprises a liquid crystal shutter.

19. The method of claim 17, and comprising controlling the color by controlling the relative drive voltages of the respective light controllers.

20. The method of claim 17, and comprising dynamically switching the drive voltage of the light controllers and controlling the color by controlling a duty cycle of the voltage.

21. The method of claim 20, and comprising generating a pulse width modulated drive voltage and operating the respective light controllers on opposite phases of the drive voltage.

22. A color tunable light source comprising:

a first light emitting diode LED arrangement operable to emit light of a first color and a second light emitting diode LED arrangement operable to emit light of a second color, the light emitting diode arrangements being configured such that their combined light output comprises the output of the source;

characterized in that the first LED arrangement comprises a phosphor provided remote to an associated first blue/UV LED operable to generate excitation energy of a selected wavelength range and to irradiate the phosphor such that it emits light of a different color wherein light emitted by the first LED arrangement comprises the combined light from the first LED and the light emitted from the phosphor and wherein the second light emitting diode arrangement comprises a respective phosphor provided remote to an associated second blue/UV LED operable to generate excitation energy of a selected wavelength range and to irradiate the phosphor such that it emits light of a different color, wherein the light emitted by the second LED arrangement comprises the combined light from the second LED and the light emitted from the phosphor and wherein the control means is operable to control the color by controlling the relative irradiation of the phosphors.

23. The light source of claim 22, wherein the control means is operable to select the color by controlling the relative magnitude of the drive currents of the first and second light emitting diodes.

24. The light source of claim 22, wherein the control means is operable to dynamically switch the drive currents of the first and second light emitting diodes and wherein the color is tunable by controlling a duty cycle of the drive current.

25. The light source of claim 24, wherein the control means comprises a pulse width modulated power supply operable to generate a pulse width modulated drive current.