Deterministically calculating dimming values for four or more light sources

• US 8,177,389 B1
• Filed: 03/28/2008
• Issued: 05/15/2012
• Est. Priority Date: 09/13/2007
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Kropf, Benjamin T.
• Primary Examiner(s): Truong, Bao Q
• Application Number:
  US12/079,646
• Publication Number:
  US 20120126707A1
• Time in Patent Office: 1,509 Days
• Field of Search: 362/227, 362/230, 362/231, 362/240, 362/236, 362/800, 315/307, 315/308, 315/312, 315/318, 315/360, 315/362, 315/294, 315/297, 315/224, 315/149, 315/158, 345/44, 345/46, 345/82, 345/83, 345/690, 345/691, 345/589, 345/600, 345/601
• US Class Current: 362/231
• CPC Class Codes: G01J 1/32 adapted for automatic variation of the measured or reference value regulation of light intensity G05D25/00
• CPC Class Codes: G01J 3/50 using electric radiation detectors
• CPC Class Codes: G01J 3/505 measuring the colour produced by lighting fixtures other than screens, monitors, displays or CRTs

Abstract

An intelligent light source deterministically calculates luminous flux levels of individual color sources of four or more light sources without a look-up table to determine the luminous flux levels.

Claims

1. A method, comprising:

receiving data encoded with a color point;

deterministically calculating dimming values for each of four or more light sources without using a look-up table of the dimming values to generate a color point, wherein the combined output of the four or more light sources generates the color point;

solving for a plurality of dimming values for each of a plurality of three-color combinations of the four or more light sources using the received data; and

summing the plurality of dimming values for each of the plurality of three-color combinations using superposition, wherein the combined output of the four or more light sources generates the color point.

2. The method of claim 1, further comprising converting the data to a plurality of control signals that correspond to the plurality of dimming values for each of the four or more light sources, wherein each of the plurality of controls signals controls a luminous flux of one of four or more light sources, and wherein said converting comprises:

determining a dimming value for each light source of a first three-color combination of the four or more light sources;

determining a dimming value for each light source of a second three-color combination of the four or more light sources, wherein the first and second three-color combinations do not include the same three light sources; and

summing the dimming values determined for each light source of the first and second three-color combinations, wherein the plurality of control signals correspond to the summed dimming values.

3. The method of claim 1, wherein said determining the dimming value for each light source of the first and second three-color combination comprises:

solving for three dimming values for the first three-color combination using linear algebra; and

solving for three dimming values for the second three-color combination using linear algebra, and wherein said summing comprises adding the three dimming values for the first three-color combination to the three dimming values for the second three-color combination using superposition to determine the dimming value for each of the four or more light sources.

4. The method of claim 1, wherein said determining the dimming value for each light source of the first and second three-color combination comprises:

solving for three dimming values for the first three-color combination using a three-color mixing equation; and

solving for three dimming values for the second three-color combination using the three-color mixing equation, and wherein said summing comprises adding the three dimming values for the first three-color combination to the three dimming values for the second three-color combination using superposition to determine the dimming value for each of the four or more light sources.

5. The method of claim 1, further comprising scaling the dimming values determined for each light source of the first and second three-color combinations.

6. The method of claim 1, wherein the plurality of control signals are stochastic signal density modulation (SSDM) dimming signals.

7. The method of claim 2, further comprising:

sensing an operating condition in each of the four or more light sources; and

modifying the plurality of control signals to compensate for changes in the operating condition, wherein the color point generated by the four or more light sources is maintained.

8. The method of claim 7, wherein the operating condition comprises one or more of a junction temperature, a dominant wavelength, and a luminous flux of one or more of the four or more light sources.

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

decoding the data into data representative of the color point and data representative of a 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.

10. A method, comprising:

receiving data encoded with a color point;

deterministically calculating dimming values for each of four or more light sources without using a look-up table of the dimming values to generate a color point, wherein the combined output of the four or more light sources generates the color point;

solving for a plurality of dimming values for a subset of the total number of three-color combinations of the four or more light sources using the received data; and

summing the plurality of solved dimming values using superposition, wherein the combined output of the four or more light sources generates the color point.

11. An apparatus, comprising:

a processing device configured to receive data encoded with a color point and to deterministically calculate dimming values from the received data for four or more light sources associated with four or more colors by using superposition of a plurality of dimming values of a plurality of different three-color combinations of the four or more light sources determined using a three-color mixing equation, wherein the received data includes a total luminous flux value of the color point in addition to the color point, and wherein the processing device is configured to convert the data to a plurality of control signals to control intensities of the four or more light sources to generate the color point at the total luminous flux value, wherein each of the plurality of control signals corresponds to the dimming value for each of the four or more light sources.

12. The apparatus of claim 11, further comprising the four or more light sources coupled to the processing device, and wherein the processing device comprises four or more control modules, corresponding to the four or more light sources, to each receive a dimming signal to control the luminous flux of a corresponding light source.

13. The apparatus of claim 12, further comprising a sensor for each of the four or more light sources to sense a parameter indicative of a change in an operating condition in the respective light source, wherein the sensor generates a feedback signal indicative of the operating condition, and wherein each of the control modules is configured to adjust the corresponding control signal to compensate for the change in operating condition.

14. The apparatus of claim 11, wherein the plurality of control signals are stochastic signal density modulation (SSDM) dimming signals.

15. The apparatus of claim 11, wherein the plurality of control signals are pulse width modulation (PWM) dimming signals.

16. An apparatus, comprising:

means for receiving data encoded with a color point;

means for deterministically calculating dimming values for each of four or more light sources associated with four or more colors without using a look-up table of the dimming values, wherein a combined output of the four or more light sources generate the color point according to the dimming values;

means for solving for a plurality of dimming values for each of a plurality of three-color combinations of the four or more light sources using the received data; and

means for summing the plurality of dimming values for each of the plurality of three-color combinations using superposition, wherein the combined output of the four or more light sources generates the color point.

17. The apparatus of claim 16, wherein the means for deterministically calculating increases the color rendering index (CRI) of the color point.

18. The apparatus of claim 16, wherein the means for deterministically calculating increases a color gamut of the apparatus.