LED LAMP COLOR CONTROL SYSTEM AND METHOD

• US 20100264834A1
• Filed: 12/02/2008
• Published: 10/21/2010
• Est. Priority Date: 12/07/2007
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Van Erp, Josephus A. M., Gaines, James, Clauberg, Bernd
• Granted Patent: US 8,368,315 B2
• Time in Patent Office: Days
• US Class Current: 315/152
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

An LED lamp color control system and method including an LED lamp having an LED controller 58; and a plurality of LED channels 60 operably connected to the LED controller 58, each of the plurality of LED channels 60 having a channel switch 62 in series with at least one shunted LED circuit 83, the shunted LED circuit 83 having a shunt switch 68 in parallel with an LED source 80. The LED controller 58 determines whether the LED source 80 is in a feedback controllable range, stores measured optical flux for the LED source 80 when the LED source 80 is in the feedback controllable range, and bypasses storing the measured optical flux when the LED source 80 is not in the feedback controllable range.

Claims

1. An LED lamp comprising:

an LED controller 58; and

a plurality of LED channels 60 operably connected to the LED controller 58, each of the plurality of LED channels 60 having a channel switch 62 in series with at least one shunted LED circuit 83, the shunted LED circuit 83 having a shunt switch 68 in parallel with an LED source 80;

wherein the LED controller 58 determines whether the LED source 80 is in a feedback controllable range, stores measured optical flux for the LED source 80 when the LED source 80 is in the feedback controllable range, and bypasses storing the measured optical flux when the LED source 80 is not in the feedback controllable range.

2. The LED lamp of claim 1 wherein the LED controller 58 determines whether the LED source 80 is in the feedback controllable range by determining whether pulse width for the LED source 80 is greater than a pulse width limit, the LED source 80 being in the feedback controllable range when the pulse width for the LED source 80 is greater than the pulse width limit and the LED source 80 not being in the feedback controllable range when the pulse width for the LED source 80 is not greater than the pulse width limit.

3. The LED lamp of claim 1 wherein the LED controller 58 bypasses storing the measured optical flux when pulse width for the LED source is not greater than a pulse width limit and LED current for the LED source 80 is less than a minimum LED current.

4. The LED lamp of claim 1 wherein the LED controller 58 decreases LED current for the LED source 80 and increases pulse width for the LED source 80 when the pulse width for the LED source 80 is not greater than a pulse width limit and LED current for the LED source 80 is not less than a minimum LED current.

5. The LED lamp of claim 4 further comprising an optical sensor 56 operably connected to measure optical flux for the LED source 80, wherein the LED controller 58 increases gain of the optical sensor 56 when the LED controller 58 decreases the LED current for the LED source 80.

6. The LED lamp of claim 1 wherein the LED controller 58 determines whether the LED source 80 is in the feedback controllable range by determining whether intensity for the measured optical flux for the LED source 80 is greater than an intensity limit, the LED source 80 being in the feedback controllable range when the intensity for the measured optical flux for the LED source 80 is greater than the intensity limit and the LED source 80 not being in the feedback controllable range when the intensity for the measured optical flux for the LED source 80 is not greater than the intensity limit.

7. The LED lamp of claim 1 wherein the LED controller 58 determines whether the LED source 80 is in the feedback controllable range by determining whether signal-to-noise ratio for the measured optical flux for the LED source 80 is greater than a signal-to-noise ratio limit, the LED source 80 being in the feedback controllable range when the signal-to-noise ratio for the measured optical flux for the LED source 80 is greater than the signal-to-noise ratio limit and the LED source 80 not being in the feedback controllable range when the signal-to-noise ratio for the measured optical flux for the LED source 80 is not greater than the signal-to-noise ratio limit.

8. The LED lamp of claim 7 wherein the signal-to-noise ratio is a standard deviation of a predetermined number of optical flux measurements.

9. The LED lamp of claim 1 wherein each of the LED sources 80 in the plurality of LED channels 60 generates light of a different color.

10. The LED lamp of claim 1 wherein the LED controller 58 determines whether the LED source 80 is in the feedback controllable range for each of the LED sources 80 in the plurality of LED channels 60.

11. A method of LED lamp color control comprising:

providing an LED lamp having a plurality of LED channels, each of the plurality of LED channels having a channel switch in series with at least one shunted LED circuit, the shunted LED circuit having a shunt switch in parallel with an LED source;

initializing LED lamp settings for the LED lamp 202;

determining whether the LED source is in a feedback controllable range 220;

storing measured optical flux for the LED source when the LED source is in the feedback controllable range 214; and

bypassing storage of the measured optical flux when the LED source is not in the feedback controllable range.

12. The method of claim 11 wherein the determining 220 comprises determining whether pulse width for the LED source is greater than a pulse width limit 206, the LED source being in the feedback controllable range when the pulse width for the LED source is greater than the pulse width limit and the LED source not being in the feedback controllable range when the pulse width for the LED source is not greater than the pulse width limit.

13. The method of claim 11 further comprising:

determining whether pulse width for the LED source is greater than a pulse width limit 206;

determining whether LED current for the LED source is less than a minimum LED current 232; and

bypassing storage of the measured optical flux when the pulse width for the LED source is not greater than the pulse width limit and the LED current for the LED source is less than the minimum LED current.

14. The method of claim 11 further comprising:

determining whether pulse width for the LED source is greater than a pulse width limit 206;

determining whether LED current for the LED source is less than a minimum LED current 232; and

decreasing the LED current for the LED source and increasing the pulse width for the LED source 234 when the pulse width for the LED source is not greater than the pulse width limit and the LED current for the LED source is not less than the minimum LED current.

15. The method of claim 14 wherein the LED Lamp has an optical sensor operably connected to measure optical flux for the LED source, further comprising increasing gain of the optical sensor in response to the decreasing LED current for the LED source.

16. The method of claim 11 wherein the determining 220 comprises determining whether intensity for the measured optical flux for the LED source is greater than an intensity limit 210, the LED source being in the feedback controllable range when the intensity for the measured optical flux for the LED source is greater than the intensity limit and the LED source not being in the feedback controllable range when the intensity for the measured optical flux for the LED source is not greater than the intensity limit.

17. The method of claim 11 wherein the determining 220 comprises determining whether signal-to-noise ratio for the measured optical flux for the LED source is greater than a signal-to-noise ratio limit 212, the LED source being in the feedback controllable range when the signal-to-noise ratio for the measured optical flux for the LED source is greater than the signal-to-noise ratio limit and the LED source not being in the feedback controllable range when the signal-to-noise ratio for the measured optical flux for the LED source is not greater than the signal-to-noise ratio limit.

18. The method of claim 17 wherein the signal-to-noise ratio is a standard deviation of a predetermined number of optical flux measurements.

19. The method of claim 11 further comprising determining whether the LED source is in the feedback controllable range for each of the LED sources in the plurality of LED channels.

20. A system of LED lamp color control comprising:

an LED lamp having a plurality of LED channels, each of the plurality of LED channels having a channel switch in series with at least one shunted LED circuit, the shunted LED circuit having a shunt switch in parallel with an LED source;

means for initializing LED lamp settings for the LED lamp;

means for determining whether the LED source is in a feedback controllable range;

means for storing measured optical flux for the LED source when the LED source is in the feedback controllable range; and

means for bypassing storage of the measured optical flux when the LED source is not in the feedback controllable range.