METHODS AND APPARATUS FOR ENCODING INFORMATION ON AN A.C. LINE VOLTAGE

• US 20110043124A1
• Filed: 04/21/2009
• Published: 02/24/2011
• Est. Priority Date: 04/30/2008
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Johnston, Scott D., Blackwell, Michael Keenan
• Granted Patent: US 8,957,595 B2
• Time in Patent Office: Days
• US Class Current: 315/250
• CPC Class Codes: H05B 47/185 via power line carrier transmission

Abstract

An AC line voltage may be encoded with control information, such as dimming information derived from an output signal of a conventional dimmer, so as to provide an encoded AC power signal. One or more lighting units, including LED-based lighting units, may be both provided with operating power and controlled (e.g., dimmed) based on the encoded power signal. In one implementation, information may be encoded on the AC line voltage by inverting some half cycles of the AC line voltage to generate an encoded AC power signal, with the ratio of positive half-cycles to negative half-cycles representing the encoded information. In other aspects, the encoded information may relate to one or more parameters of the light generated by the LED-based lighting unit(s) (e.g., intensity, color, color temperature, etc.).

Claims

1. A method, comprising:

A) deriving dimming information from an output signal of a dimmer;

B) encoding an AC line voltage with the dimming information so as to generate an encoded AC power signal having a substantially similar RMS value as the AC line voltage; and

C) controlling and providing operating power to at least one LED-based lighting unit based at least in part on the encoded AC power signal.

2. The method of claim 1, wherein C) comprises changing at least one of an intensity, color, and/or color temperature of light generated by the at least one LED-based lighting unit.

3. The method of claim 1, wherein B) comprises electrically isolating the AC line voltage from the encoded AC power signal.

4. The method of claim 1, wherein A) comprises digitally sampling the output signal to obtain the dimming information.

5. The method of claim 4, wherein A) comprises calculating a time-average voltage potential of the output signal of the dimmer.

6. The method of claim 4, wherein A) comprises sampling the output signal of the dimmer using a resistor divider circuit.

7. The method of claim 1, wherein A) comprises providing a dummy load connected to the output signal to facilitate operation of the dimmer.

8. The method of claim 1, wherein B) comprises periodically frequency modulating the AC line voltage.

9. The method of claim 1, wherein B) comprises encoding the AC line voltage using an X10 protocol.

10. The method of claim 1, wherein B) comprises controlling a plurality of switches connected to the AC line voltage to invert at least some half cycles of the AC line voltage so as to generate the encoded AC power signal, wherein a ratio of positive half-cycles to negative half-cycles of the encoded AC power signal represents the dimming information.

11. The method of claim 1, wherein the output signal of the dimmer is a duty-cycle modulated or an amplitude modulated AC signal.

12. The method of claim 1, wherein the output signal of the dimmer is a 0-10 volt analog DC signal.

13. An apparatus, comprising:

a first input for receiving an AC line voltage;

a second input for receiving an output signal of a dimmer;

an output for generating an encoded AC power signal;

at least one light source controlled based at least in part on the encoded AC power signal; and

a controller, coupled to the first input, the second input, and the output, for deriving dimming information from the output signal of the dimmer and encoding the AC line voltage with the dimming information so as to generate the encoded AC power signal.

14. The apparatus of claim 13, wherein the controller further comprises an isolation circuit for isolating the AC line voltage from the encoded AC power signal.

15. The apparatus of claim 13, wherein the controller further comprises a microprocessor for sampling the output signal of the dimmer to derive the dimming information.

19. A method of encoding information on an AC line voltage, the method comprising:

controlling a plurality of switches connected to the AC line voltage to invert at least some half cycles of the AC line voltage so as to generate an encoded AC power signal,

wherein a ratio of positive half-cycles to negative half-cycles of the encoded AC power signal represents the information.

20. The method of claim 19, wherein controlling the plurality of switches comprises controlling the plurality of switches in pairs.

21. The method of claim 19, wherein the plurality of switches forms an H-bridge circuit.

22. The method of claim 19, wherein the plurality of switches includes at least one bipolar junction transistor and/or at least one MOSFET.

23. The method of claim 19, wherein the information is dimming information provided by a dimmer apparatus.

24. The method of claim 19, further comprising controlling the plurality of switches via a microprocessor coupled to the switches.

25. The method of claim 28, further comprising controlling at least one LED-based lighting unit based at least in part on the encoded AC power signal.

16. The apparatus of claim 18, wherein the controller further comprises a conversion circuit for encoding the AC line voltage with the dimming information.

17. The apparatus of claim 18, further comprising a dummy load to which the output signal of the dimmer is connected to maintain a consistent operation of the dimmer.

18. The apparatus of claim 25, wherein the dummy load is a power resistor.