Method and apparatus for networked illumination devices

• US 20080180040A1
• Filed: 06/07/2007
• Published: 07/31/2008
• Est. Priority Date: 01/30/2007
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Kropf, Benjamin T., Prendergast, Patrick N.
• Granted Patent: US 8,044,612 B2
• Time in Patent Office: Days
• US Class Current: 315/297
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 47/18 via data-bus transmission
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

An intelligent light source converts color and luminous flux data to luminous flux levels of individual color sources and automatically compensates for variations in operating conditions.

Claims

1. A method, comprising:

receiving data encoded with a color point; and

converting the data to a plurality of control signals, wherein each of the plurality of control signals controls a luminous flux of one of a plurality of light sources relative to other ones of the plurality of light sources, wherein a combined output of the plurality of light sources generates the color point.

2. The method of claim 1, wherein the data is further encoded with a total luminous flux value, the method further comprising:

converting the data to modify the plurality of control signals, wherein each of the plurality of control signals controls an absolute luminous flux of one of the plurality of light sources, wherein the combined output of the plurality of light sources generates the total luminous flux value.

3. The method of claim 2, wherein each of the plurality of control signals comprises:

a first stochastic signal of non-uniform frequency to control an average luminous flux of a corresponding one of the plurality of light sources; and

a second stochastic signal of non-uniform frequency to control a peak luminous flux of the corresponding one of the plurality of light sources.

4. The method of claim 2, further comprising:

sensing an operating condition in each of the plurality of light sources; and

modifying the plurality of control signals to compensate for changes in the operating condition, wherein one or more of the color point and the total luminous flux value generated by the plurality of light sources are maintained.

5. The method of claim 4, wherein the operating condition comprises a junction temperature of one or more of the plurality of light sources

6. The method of claim 2, further comprising:

sensing an operating parameter in each of the plurality of light sources; and

modifying the plurality of control signals to compensate for changes in the operating parameter, wherein one or more of the color point and the total luminous flux value generated by the plurality of light sources are maintained.

7. The method of claim 6, wherein the operating parameter comprises one or more of a dominant wavelength and an luminous flux of one or more of the plurality of light sources.

8. The method of claim 2, wherein converting the data to a plurality of control signals comprises:

decoding the data into data representative of the color point and data representative of the total luminous flux value; and

separating the data representative of the color point into a first coordinate and a second coordinate, wherein the first coordinate and the second coordinate correspond to the color point on a standard color chart.

9. The method of claim 8, wherein the first coordinate and the second coordinate comprise entry points to a lookup table, wherein an output of the lookup table comprises a ratio of intensities of the plurality of light sources corresponding to the color point.

10. The method of claim 9, wherein the total luminous flux value determines an average luminous flux of each of the plurality of light sources.

11. The method of claim 2, further comprising:

programming a peak luminous flux value for each of the plurality of light sources; and

programming a pseudorandom sequence for each of the first stochastic signal and the second stochastic signal for each of the plurality of light sources.

12. An apparatus comprising:

a receiving and processing device configured to receive data encoded with a color point and a total luminous flux value of the color point and to convert the data to a plurality of stochastic control signals to control intensities of a plurality of light sources to generate the color point at the total luminous flux value.

13. The apparatus of claim 12, further comprising the plurality of light sources coupled with the receiving and processing device, wherein each of the plurality of control signals comprises:

a first stochastic signal of non-uniform frequency to control an average luminous flux of a corresponding one of the plurality of light sources; and

a second stochastic signal of non-uniform frequency to control a peak luminous flux of the corresponding one of the plurality of light sources.

14. The apparatus of claim 13, wherein the receiving and processing device comprises a plurality of control modules, corresponding to the plurality of light sources, to generate the first and second stochastic signals.

15. The apparatus of claim 14,

wherein each of the plurality of light sources is configured to sense a parameter indicative of a change in an operating condition in the light source and to generate a feedback signal indicative of the operating condition;

and

wherein each of the corresponding control modules is configured to adjust a density of the second stochastic signal to compensate for the change in the operating condition.

16. The apparatus of claim 15, wherein the operating condition is a junction temperature of an LED light source.

17. The apparatus of claim 14,

wherein each of the plurality of light sources is configured to sense a change in an operating parameter of the light source and to generate a feedback signal indicative of the operating parameter;

and

wherein each of the corresponding control modules is configured to adjust a density of the second stochastic signal to compensate for the change in the operating parameter.

18. The apparatus of claim 17, wherein the operating parameter is one of a dominant wavelength of the light source and a luminous flux of the light source.

19. The apparatus of claim 12, wherein to convert the data to the plurality of stochastic control signals, the receiving and processing device is configured to:

decode the data into data representative of the color point and data representative of the total luminous flux value; and

separate the data representative of the color point into a first coordinate and a second coordinate, wherein the first coordinate and the second coordinate correspond to the color point on a standard color chart.

20. The apparatus of claim 19, wherein the receiving and processing device further comprises a lookup table, wherein the first coordinate and the second coordinate comprise entry points to the lookup table, and wherein an output of the lookup table comprises signals indicative of an average luminous flux of each of the plurality of light sources and signals indicative of a relative luminous flux of each of the plurality of light sources.

21. The apparatus of claim 20, wherein the signals indicative of the average luminous fluxes of each of the plurality of light sources are modified by the data representative of the total luminous flux value to determine a total luminous flux of the plurality of light sources.

22. The apparatus of claim 20, wherein the signals indicative of the relative luminous flux of each of the plurality of light sources are modified by the data representative of the color point to generate the color point.

23. The apparatus of claim 20, wherein each of the plurality of control modules is configured to receive a dimming signal corresponding to the average luminous flux and the relative luminous flux of a corresponding light source.

24. The apparatus of claim 14, wherein each of the plurality of control modules comprises:

a stochastic signal density modulation (SSDM) controller to generate the first stochastic signal of non-uniform frequency;

a pseudo-random sequence (PRS) controller to generate the second stochastic signal of non-uniform frequency; and

means for combining the first and second stochastic signals in a control signal to control the corresponding one of the plurality of light sources.

25. The apparatus of claim 24, wherein the SSDM controller and the PRS controller comprise:

a stochastic counter to generate a pseudorandom sequence;

a signal density register to hold a signal density value; and

a comparator coupled with the stochastic counter and the signal density register to compare a value of the pseudorandom sequence with the signal density value and to generate one of an SSDM waveform and a PRS waveform.

26. The apparatus of claim 13, wherein each of the plurality of light sources includes a lowpass filter to separate the first stochastic signal from the second stochastic signal.

27. A system, comprising:

a network controller configured to generate control data encoded with a color point and a total luminous flux value; and

a light source coupled to the network controller, the light source comprising a plurality of differently colored lighting modules, the light source configured to receive and decode the control data and to convert the control data into a plurality of stochastic control signals to control luminous flux of the plurality of differently colored light modules, wherein the light source generates the color point at the total luminous flux value.

28. The system of claim 27, wherein the light source is coupled to the network controller via one of a wired connection and a wireless connection.

29. An apparatus, comprising:

means for converting chrominance and luminance data to peak and average control currents of individual light sources to generate a light of specified color and luminous flux; and

means for maintaining the specified color and luminous flux under varying environmental and operating conditions.

30. The apparatus of claim 29, further comprising means for generating stochastic control signals of non-uniform frequency to control the peak and average currents of the individual light sources.