Apparatus and method for controlling colour and colour temperature of light generated by a digitally controlled luminaire

• US 20060109219A1
• Filed: 11/23/2005
• Published: 05/25/2006
• Est. Priority Date: 11/23/2004
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: TIR Systems Limited (Koninklijke Philips N.V.)
• Inventors: Robinson, Shane, Jungwirth, Paul
• Granted Patent: US 7,423,387 B2
• Time in Patent Office: Days
• US Class Current: 345/83
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/14 Semiconductor devices, e.g. diodes
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices

Abstract

The present invention provides a method and apparatus for controlling the correlated colour temperature (CCT) or colour of light produced by an array of light-emitting elements by providing multiple selectable paths for the flow of drive current. The apparatus includes a primary path comprising primary light-emitting elements, and one or more secondary paths comprising secondary light-emitting elements that are used for compensation or correction of the colour of light emitted by the primary light-emitting elements. A plurality of control means, for example switches are used to direct current through particular paths. During operation, the drive current primarily flows through the primary light-emitting elements and is redirected, periodically for example, to a secondary path comprising light-emitting elements of a particular colour that is desired in addition to the colour produced by the primary light-emitting elements.

Claims

1. An apparatus for controlling colour temperature or colour of light emitted from an array of light-emitting elements, said apparatus comprising:

a) a power source operatively coupled to primary light-emitting elements and one or more secondary light-emitting elements, the power source for providing current thereto, said primary light-emitting elements emitting light of a particular colour when activated and each of the one or more secondary light-emitting elements emitting light of another colour when activated;

b) a primary path for the current to selectively flow, said primary path including the primary light-emitting elements;

c) one or more secondary paths for the current to selectively flow, each of said one or more secondary paths including one or more secondary light-emitting elements; and

d) a plurality of control means, wherein one or more control means is operatively positioned between the power source and each of the primary path and the one or more secondary paths, the control means for directing the current through one or more of the primary path and the one or more secondary paths;

wherein emitted light is mixed to generate a desired colour temperature or colour of light.

2. The apparatus according to claim 1, wherein the power source is configured to supply current to only one of the primary path and one or more secondary paths at a given time.

3. The apparatus according to claim 1, wherein the power source is configured to supply current to two or more paths simultaneously, the paths including the primary path and one or more secondary paths.

4. The apparatus according to claim 1, wherein the primary path and the one or more secondary paths are in a parallel configuration.

5. The apparatus according to claim 1, wherein the primary path and the one or more secondary paths are configured in a series/parallel configuration.

6. The apparatus according to claim 1, wherein the primary path comprises a plurality of white light producing light-emitting elements.

7. The apparatus according to claim 1, wherein the primary path comprises one or more red light-emitting elements, one or more green light-emitting elements and one or more blue light-emitting elements.

8. The apparatus according to claim 1 wherein there are three or more secondary paths, wherein a first one secondary path comprises one or more red light-emitting elements, a second secondary path comprises one or more green light-emitting elements and a third secondary path comprises one or more blue light-emitting elements.

9. The apparatus according to claim 8, further comprising a fourth secondary path comprising one or more amber light-emitting elements.

10. The apparatus according to claim 1, further comprising a smoothing means operatively coupled to the primary path and one or more secondary paths, said smoothing means for smoothing one or more switching transients.

11. The apparatus according to claim 10, wherein the smoothing means is an inductor.

12. The apparatus according to claim 11, wherein the smoothing means further comprises a resistor.

13. The apparatus according to claim 12, wherein the smoothing means further comprises a free-wheeling diode configured as a return path between a low-side and a high-side of the primary and secondary light-emitting elements.

14. The apparatus according to claim 1, wherein voltage drop across each of the primary path and the one or more secondary paths is about equal.

15. The apparatus according to claim 1, wherein the control means are digitally controlled using one or more switching waveforms, each switching waveform having a phase.

16. The apparatus according to claim 15, wherein the phase of each of the one or more switching waveforms is dynamically adjusted to balance current consumption over a switching period.

17. A method for controlling the colour temperature or colour of light emitted from an array of light-emitting elements, said method comprising the steps of:

a) generating a current for activation of one or more of primary light-emitting elements and one or more secondary light-emitting elements, the primary light-emitting elements emitting light of a particular colour when activated and each of the one or more secondary light-emitting elements emitting light of another particular colour when activated;

b) selectively directing the current through a primary path or one or more secondary paths using a plurality of control means thereby selectively activating one or more primary light-emitting elements and/or secondary light-emitting elements, said primary path including primary light-emitting elements, and each of the one or more secondary paths including one or more secondary light-emitting elements; and

c) mixing the light to generate a desired colour temperature or colour of light.

18. The method according to claim 17, wherein the step of directing the current is performed to direct current to only one of the primary path and one or more secondary paths at a given time.

19. The method according to claim 17, wherein the step of directing the current is performed to direct current to two or more paths simultaneously, the paths including the primary path and one or more secondary paths simultaneously.