Regulation of wavelength shift and perceived color of solid state lighting with intensity variation

• US 8,368,636 B2
• Filed: 10/29/2007
• Issued: 02/05/2013
• Est. Priority Date: 09/21/2007
• Status: Active Grant

• Current Assignee: Chemtron Research LLC (Intellectual Ventures LLC)
• Original Assignee: Point Somee LLC (Intellectual Ventures LLC)
• Inventors: Shteynberg, Anatoly, Rodriguez, Harry, Lehman, Bradley M., Zhou, Dongsheng
• Primary Examiner(s): Vo, Tuyet Thi
• Application Number:
  US11/927,084
• Publication Number:
  US 20090079357A1
• Time in Patent Office: 1,926 Days
• Field of Search: 315/291, 315307-326, 315/247, 315/185.S, 345/102, 345/204, 345/211, 345/212, 345/213, 345/214
• US Class Current: 345/102
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/37 Converter circuits

Abstract

Representative embodiments of the invention provide a system, apparatus, and method of controlling an intensity and spectrum of light emitted from a solid state lighting system. The solid state lighting system has a first emitted spectrum at a full intensity level and at a selected temperature, with a first electrical biasing for the solid state lighting system producing a first wavelength shift, and a second electrical biasing for the solid state lighting system producing a second, opposing wavelength shift. Representative embodiments provide for receiving information designating a selected intensity level or a selected temperature; and providing a combined first electrical biasing and second electrical biasing to the solid state lighting system to generate emitted light having the selected intensity level and having a second emitted spectrum within a predetermined variance of the first emitted spectrum over a predetermined range of temperatures.

Claims

1. A method of controlling an intensity of light emitted from a solid state lighting system, the method comprising:

receiving information designating a selected intensity level lower than a full intensity level, wherein the solid state lighting system is configured to have a first emitted spectrum at the full intensity level, wherein a first electrical biasing for the solid state lighting system produces a first wavelength shift, and wherein a second electrical biasing for the solid state lighting system produces a second, opposing wavelength shift; and

providing a combined first electrical biasing and second electrical biasing to the solid state lighting system to generate emitted light having the selected intensity level and having a second emitted spectrum within a predetermined variance of the first emitted spectrum.

2. The method of claim 1, wherein the combined first electrical biasing and second electrical biasing is a superposition of or an alternation between at least two of the following types of electrical biasing:

pulse width modulation, constant current regulation, pulse frequency modulation, and pulse amplitude modulation.

3. The method of claim 1, wherein the combined first electrical biasing and second electrical biasing is configured to have a first duty cycle ratio of peak electrical biasing, a second duty cycle ratio of no forward biasing, and an average current level, wherein the first duty cycle ratio, the second duty cycle ratio, and the average current level are related to the selected intensity level according to a first relation of

4. The method of claim 1, wherein the combined first electrical biasing and second electrical biasing is a superposition of the first electrical biasing and the second electrical biasing.

5. The method of claim 4, wherein the superposition of the first electrical biasing and the second electrical biasing is a predetermined parameter to produce the second emitted spectrum within the predetermined variance for the selected intensity.

6. The method of claim 4, wherein the combined first electrical biasing and second electrical biasing comprises a superposition of a symmetric or asymmetric AC signal on a DC signal having an average component.

7. The method of claim 4, wherein the combined first electrical biasing and second electrical biasing is configured to have a duty cycle and an average current level, and wherein the duty cycle and the average current level are parameters stored in a memory and correspond to the selected intensity level.

8. An apparatus for adjusting an intensity of light emitted from a solid state lighting system, the apparatus comprising:

an interface configured to receive information designating a selected intensity level lower than a full intensity level, wherein the solid state lighting system is configured to have a first emitted spectrum at the full intensity level, wherein a first electrical biasing for the solid state lighting system produces a first wavelength shift, and wherein a second electrical biasing for the solid state lighting system produces a second, opposing wavelength shift;

a memory configured to store a plurality of parameters corresponding to a plurality of intensity levels, wherein a parameter from the plurality of parameters corresponds to the selected intensity level; and

a controller coupled to the memory, wherein the controller is configured to retrieve the parameter from the memory and to convert the parameter into a corresponding control signal to provide a combined first electrical biasing and second electrical biasing to the solid state lighting system to generate emitted light having the selected intensity level and having a second emitted spectrum within a predetermined variance of the first emitted spectrum.

9. The apparatus of claim 8, wherein the control signal is configured to provide the combined first electrical biasing and second electrical biasing as a superposition of the first electrical biasing and the second electrical biasing.

10. The apparatus of claim 8, wherein the control signal is configured to provide the combined first electrical biasing and second electrical biasing as superposition of a symmetric or asymmetric AC signal on a DC signal having an average component.

11. The apparatus of claim 8, wherein the plurality of parameters comprises a duty cycle parameter and an average current level parameter for the combined first electrical biasing and second electrical biasing.

12. The apparatus of claim 8, wherein the combined first electrical biasing and second electrical biasing is a superposition of or an alternation between at least two of the following types of electrical biasing:

pulse width modulation, constant current regulation, pulse frequency modulation, and pulse amplitude modulation.

13. The apparatus of claim 8, wherein the combined first electrical biasing and second electrical biasing is configured to have a first duty cycle ratio of peak electrical biasing, a second duty cycle ratio of no forward biasing, and an average current level, wherein the first duty cycle ratio, the second duty cycle ratio, and the average current level are related to a selected intensity level according to a first relation of

14. The apparatus of claim 8, wherein the solid state lighting system comprises a plurality of arrays of light emitting diodes, and wherein at least three arrays from the plurality of arrays of light emitting diodes have corresponding emission spectra of different colors.

15. A solid state lighting system, comprising:

a plurality of arrays of light emitting diodes having a first emitted spectrum at a full intensity level, a first electrical biasing for an array from the plurality of arrays producing a first wavelength shift, and a second electrical biasing for the array from the plurality of arrays producing a second, opposing wavelength shift;

a plurality of driver circuits, wherein each driver circuit is coupled to a corresponding array from the plurality of arrays of light emitting diodes;

an interface configured to receive information designating a selected intensity level lower than the full intensity level;

a memory configured to store a plurality of parameters corresponding to a plurality of intensity levels, wherein a parameter from the plurality of parameters corresponds to the selected intensity level; and

a controller coupled to the memory and to a first driver circuit from the plurality of driver circuits, wherein the controller is configured to retrieve the parameter from the memory and to convert the parameter into a corresponding control signal to the first driver circuit to provide a combined first electrical biasing and second electrical biasing to the corresponding array to generate emitted light having the selected intensity level and having a second emitted spectrum within a predetermined variance of the first emitted spectrum.

16. The system of claim 15, wherein the second emitted spectrum is one of an overall color generated within the predetermined variance, a sequence of a single color emitted at a given time, or a dynamic lighting effect as requested by a second signal received by the interface.

17. The system of claim 15, wherein the control signal is configured to provide the combined first electrical biasing and second electrical biasing as a superposition of or an alternation between at least two of the following types of electrical biasing:

pulse width modulation, constant current regulation, pulse frequency modulation, and pulse amplitude modulation.

18. The system of claim 15, wherein the plurality of parameters comprises a duty cycle parameter and an average current level parameter for the combined first electrical biasing and second electrical biasing.

19. The system of claim 15, wherein the controller is configured to synchronize the control signal with a switching cycle of the first driver circuit.

20. A computer-readable storage medium having instructions stored thereon that, in response to execution by a computing device, cause the computing device to:

receive information designating a selected intensity level lower than a full intensity level for a solid state lighting system, wherein the solid state lighting system is configured to have a first emitted spectrum at the full intensity level;

generate a first electrical biasing for the solid state lighting system, wherein the first electrical biasing produces a first wavelength shift;

generate a second electrical biasing for the solid state lighting system, wherein the second electrical biasing produces a second, opposing wavelength shift; and

provide a combined first electrical biasing and second electrical biasing to the solid state lighting system to generate emitted light having the selected intensity level and having a second emitted spectrum within a predetermined variance of the first emitted spectrum.

21. A computer-readable storage medium having instructions stored thereon that, in response to execution by a computing device, cause the computing device to:

receive information designating a selected intensity level lower than a full intensity level for a solid state lighting system, wherein the solid state lighting system is configured to have a first emitted spectrum at the full intensity level;

generate a first electrical biasing for the solid state lighting system, wherein the first electrical biasing produces a first wavelength shift;

generate a second electrical biasing for the solid state lighting system, wherein the second electrical biasing produces a second, opposing wavelength shift;

store a plurality of parameters corresponding to a plurality of intensity levels for the solid state lighting system, wherein a parameter from the plurality of parameters corresponds to the selected intensity level; and

convert the parameter into a corresponding control signal that causes a combined first electrical biasing and second electrical biasing to be provided to the solid state lighting system to generate emitted light having the selected intensity level and having a second emitted spectrum within a predetermined variance of the first emitted spectrum.