Apparatus and method for controlling colour and colour temperature of light generated by a digitally controlled luminaire
View Patent ↗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.
1. An apparatus for correcting colour of light emitted from light-emitting elements, comprising:
a) a power source operatively coupled to a plurality of primary light-emitting elements and to at least one secondary light-emitting element, the power source being configured to provide current to the primary light-emitting elements and to the at least one secondary light-emitting element, each of the primary light-emitting elements being configured to emit light of a particular colour when activated, each of the at least one secondary light-emitting element being configured to emit light of another colour when activated;
b) a primary current path comprising a path through the primary light-emitting elements;
c) at least one secondary current path, each secondary current path comprising a path through at least one of the at least one secondary light-emitting element; and
d) a plurality of control means, each of the control means being operatively positioned between the power source and at least one of the primary current path and the at least one secondary current path, the plurality of control means being configured to direct the current principally through the primary current path and selectively through the at least one secondary path, to thereby correct the colour of the light emitted by the primary light-emitting elements,
wherein emitted light from the primary light-emitting elements and the at least one secondary light-emitting element is mixed to generate light having a corrected colour corresponding to at least one of a desired colour temperature and a desired 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 current path and the at least one secondary current path at a given time.
3. The apparatus according to claim 1 , wherein the power source is configured to supply current to two or more current paths simultaneously, the two or more current paths comprising the primary current path and the at least one secondary current path.
4. The apparatus according to claim 1 , wherein the primary current path and the at least one secondary current path are in a parallel configuration.
5. The apparatus according to claim 1 , wherein to primary current path and the at least one secondary current path paths are configured in a series/parallel configuration.
6. The apparatus according to claim 1 , wherein the primary light-emitting elements comprise a plurality of white light producing light-emitting elements.
7. The apparatus according to claim 1 , wherein the primary light-emitting elements comprise at least one red light-emitting element, at least one green light-emitting element and at least one blue light-emitting element.
8. The apparatus according to claim 1 , wherein the apparatus comprises at least three secondary light-emitting elements, the at least three secondary light-emitting elements comprising at least one red light-emitting element, at least one green light-emitting element, and at least one blue light-emitting element, and
wherein the apparatus comprises at least three secondary current paths, a first of the secondary current paths comprising a path through the at least one red light-emitting element, a second of the secondary current paths comprising a path through the at least one green light-emitting element, and a third of the secondary current paths comprising a path through the at least one blue light-emitting element.
9. The apparatus according to claim 1 , wherein the apparatus comprises at least four secondary light-emitting elements, the four secondary light-emitting elements comprising at least one red light-emitting element at least one green light-emitting element, and at least one blue light-emitting element, and at least one amber light-emitting element, and
wherein the apparatus comprises at least four secondary current pats, a first of the secondary current paths comprising a path through the at least one red light-emitting element, a second of the secondary current paths comprising a path through the at least one green light-emitting element, a third of the secondary current paths comprising a path through the at least one blue light-emitting element, and a fourth of the secondary current paths comprising a path through the at least one amber light-emitting element.
10. The apparatus according to claim 1 , further comprising a smoothing means operatively coupled to the primary current path and at least one of the at least one secondary path, said smoothing means being configured to smooth one or more switching transients.
11. The apparatus according to claim 10 , wherein the smoothing means comprises 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 current path and the at least one secondary path is about equal.
15. The apparatus according to claim 1 , wherein the control means are digitally controlled using at least one switching waveform, each switching waveform having a phase.
16. The apparatus according to claim 15 , wherein the phase of each of the at least one switching waveform is dynamically adjusted to balance current consumption over a switching period.
17. A method for correcting colour of light emitted from light-emitting elements, comprising the steps of:
a) generating a current to activate at least one primary light-emitting element and at least one secondary light-emitting element, each primary light-emitting element being configured to emit light of a particular colour when activated, each secondary light-emitting element being configured to emit light of another particular colour when activated;
b) correcting colour of light emitted by the primary light-emitting elements by using a plurality of control means to direct the current principally through a primary path and selectively through at least one secondary path, thereby principally activating at least one primary light-emitting element selectively activating the at least one secondary light-emitting element, the primary path comprising a path through the at least one primary light-emitting element, the secondary path comprising a path through the at least one secondary light-emitting element; and
c) mixing the light emitted by the at least one primary light-emitting element with the light emitted by the at least one secondary light-emitting element to generate light having a corrected colour corresponding to at least one of a desired colour temperature and a desired colour of light.
18. The method according to claim 17 , wherein the step of providing colour correction comprises the step of directing current to only one of the primary path and the at least one secondary path at a given time.
19. The method according to claim 17 , wherein the step of providing colour correction comprises the step of directing current to two or more paths simultaneously, the paths comprising the primary path and the at least one secondary paths.