Method and device for driving a lamp

• US 9,025,966 B2
• Filed: 01/07/2010
• Issued: 05/05/2015
• Est. Priority Date: 06/30/2009
• Status: Expired due to Fees

• Current Assignee: Philips Lighting BV (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Schenk, Tim C. W., Wernars, Johannes P., Linnartz, Johan P. M. G., Feri, Lorenzo, Colak, Sel B., Damink, Paulus H. A., Penning de Vries, Hendricus T. G. M.
• Primary Examiner(s): Bello, Agustin
• Application Number:
  US13/381,382
• Publication Number:
  US 20120105266A1
• Time in Patent Office: 1,944 Days
• Field of Search: 398/172
• US Class Current: 398/172
• CPC Class Codes: H05B 41/2887 characterised by a controllable bridge in the final stage
• CPC Class Codes: H05B 47/19 via wireless transmission
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A method for driving a lamp (2) comprises the steps of: generating a lamp current (I_CONST) having a constant magnitude; defining a commutation period having a duration T_COMM; defining a time base of original commutation moments, having fixed mutual intervals of 0.5*T_COMM; receiving data to be embedded in the light output; commutating the lamp current at commutation moments; wherein individual commutations are time-modulated in order to encode said received data. Preferably, a commutation moment is: either equal to an original commutation moment if there are no data to embed; or advanced over a modulation distance (Δ) with respect to the corresponding original commutation moment in order to encode data having a first value (“0”); or delayed over said modulation distance (Δ) with respect to the corresponding original commutation moment in order to encode data having a second value (“1”).

Claims

1. Method for driving a lamp, the method comprising the steps of:

generating a lamp current having a constant magnitude;

defining a commutation period having a duration T_COMM;

receiving data to be embedded in the light output of the lamp;

commutating the lamp current at commutation moments;

defining a time base of original commutation moments, having fixed mutual intervals of 0.5*T_COMM; and

time-modulating individual commutations relative to the original commutation moments in order to encode said received data in the light at a constant data rate.

2. Method according to claim 1, comprising the steps of:

calculating commutation moments on the basis of said time base of original commutation moments and on the basis of the received data, wherein the calculated commutation moment is;

either equal to an original commutation moment if there are no data to embed;

or advanced over a modulation distance with respect to the corresponding original commutation moment in order to encode data having a first value;

or delayed over said modulation distance with respect to the corresponding original commutation moment in order to encode data having a second value.

3. Method according to claim 2, wherein the modulation distance has one fixed value in order to be able to encode one bit per commutation moment.

4. Method according to claim 2, further comprising the step of selecting the value of the modulation distance from a predetermined range of possible values in order to be able to encode multiple bits per commutation moment.

5. Method according to claim 1, wherein every second commutation moment always coincides with the time base while only the commutation moments in between said second commutation moments are time-modulated.

6. Method according to claim 1, wherein all commutation moments are time-modulated independently from each other.

7. Method according to claim 1, wherein a series of one or more received data bits are translated to a packet containing an even number of outgoing transmission bits, wherein in each packet the number of transmission bits with a first value is equal to the number of transmission bits with a second value, and wherein modulation of the commutation moments is always performed on the basis of the transmission bits.

8. Method according to claim 1, further comprising the step of regularly embedding a predetermined data sequence leading to a predetermined pattern of commutation moments for facilitating synchronisation in a receiver.

9. Method according to claim 1, wherein said data to be embedded includes an identification code of the lamp concerned.

10. Driver for driving a light source, comprising a current source for producing a constant current and a commutator for commutating this current, the driver being designed for executing the method of claim 1.