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

• US 8,704,456 B2
• Filed: 01/15/2013
• Issued: 04/22/2014
• 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:
  US13/741,896
• Publication Number:
  US 20130140989A1
• Time in Patent Office: 462 Days
• Field of Search: 315/247, 315/246, 315/224, 315/225, 315/291, 315307-326, 315/185.S
• US Class Current: 315/291
• 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 solid state lighting system, comprising:

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

a driver circuit coupled to the first 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 the driver circuit, wherein the controller is configured to retrieve the parameter from the memory and to convert the parameter into a corresponding control signal to the driver circuit to provide a combined first electrical biasing and second electrical biasing to the first 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.

2. The system of claim 1, wherein the predetermined variance is substantially zero or is a selected tolerance level.

3. The system of claim 1, wherein the second emitted spectrum is an overall color generated within the predetermined variance, or 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.

4. The system of claim 1, 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.

5. The system of claim 1, 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.

6. The system of claim 1, wherein the controller is further configured to synchronize the control signal with a switching cycle of the driver circuit.

7. The system of claim 1, further comprising:

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

wherein the controller is coupled to each driver circuit, and wherein the controller is configured to generate a separate, corresponding control signal to the corresponding driver circuit to provide a corresponding combined first electrical biasing and second electrical biasing to the corresponding array from the plurality of arrays of light emitting diodes to generate a corresponding second emitted spectrum within the predetermined variance of the corresponding first emitted spectrum.

8. The system of claim 1, further comprising:

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

a plurality of controllers, wherein each controller from the plurality of controllers is coupled to a corresponding driver circuit, and wherein each controller is configured to generate a separate, corresponding control signal to the corresponding driver circuit to provide a corresponding combined first electrical biasing and second electrical biasing to the corresponding array from the plurality of arrays of light emitting diodes to generate a corresponding second emitted spectrum within the predetermined variance of the corresponding first emitted spectrum.

9. The system of claim 1, wherein each combined first electrical biasing and second electrical biasing corresponds to a type of light emitting diode comprising the corresponding array from the plurality of arrays of light emitting diodes.

10. The system of claim 1, wherein the plurality of arrays of light emitting diodes comprises an array of red light emitting diodes, an array of green light emitting diodes, and an array of blue light emitting diodes.

11. The system of claim 1, further comprising:

a cooling element coupled to an array from the plurality of arrays of light emitting diodes,

wherein the controller is configured to generate a second control signal to the cooling element to lower a temperature of the array to maintain the overall second emitted spectrum within the predetermined variance of the first emitted spectrum.

12. The system of claim 1, wherein the plurality of parameters further corresponds to a plurality of temperatures.

13. The system of claim 12, further comprising:

a temperature sensor coupled to an array from the plurality of arrays,

wherein the controller is configured to retrieve the parameter and to convert the parameter into a corresponding control signal in response to a sensed or determined temperature of the array from the plurality of arrays of light emitting diodes.

14. The system of claim 13, wherein the controller is further configured to generate a second control signal to modify a temperature of a selected array from the plurality of arrays of light emitting diodes to maintain the overall second emitted spectrum within the predetermined variance of the first emitted spectrum.

15. The system of claim 12, further comprising:

a temperature sensor coupled to an array from the plurality of arrays,

wherein the controller is further configured to select corresponding parameters and to provide the corresponding control signal in response to a temperature signal from the temperature sensor.

16. The system of claim 1, wherein the controller comprises:

a dimming frame register;

an intensity register;

a programmable look-up table memory;

a programmable frame counter and cycle counter;

a block of operational signal registers;

an analog multiplexer; and

a digital-to-analog converter.

17. The system of claim 16, wherein the controller is configured to program the operational signal registers with at least two peak current amplitude values, at least two current amplitude modulation values, and two current duty cycle values to provide the corresponding control signal to the driver circuit to provide the combination of the first electrical biasing and the second electrical biasing for the selected intensity level and emission wavelength control specified by the interface.

18. The system of claim 17, wherein the controller is further configured to vary the intensity of the light emitting diodes without substantial optical output flickering by alternatively multiplexing the corresponding control signal to the driver circuit from a first set of operational signal registers synchronously to an end of a current dimming frame counter while programming asynchronously a second set of operational signal registers with a second corresponding control signal.

19. The system of claim 18, wherein the controller is further configured to queue the second corresponding control signal to a current status at the end of the current dimming frame counter.