Method and device for communicating data using a light source

• US 8,331,796 B2
• Filed: 09/22/2008
• Issued: 12/11/2012
• Est. Priority Date: 09/26/2007
• Status: Expired due to Fees

• Current Assignee: Philips Lighting BV (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Wernars, Johannes Petrus, Mayr, Victor
• Primary Examiner(s): Bello, Agustin
• Application Number:
  US12/679,320
• Publication Number:
  US 20100196018A1
• Time in Patent Office: 1,541 Days
• Field of Search: 398/118, 398/127, 398/189, 398/191
• US Class Current: 398/172
• CPC Class Codes: H05B 47/19 via wireless transmission
• CPC Class Codes: H05B 47/22 with communication between the lamps and a central unit

Abstract

A method is described for driving a light source, particularly a HID lamp (2), the method comprising the steps of: providing a commutating DC current for supplying the lamp; and varying a commutation period (T) in order to transmit data. In an embodiment, the duration of each commutation period (T) is set to be equal to one of two possible values (T1, T2) such as to encode a digital bit.

Claims

1. Method for transmitting data from a light source comprising a HID lamp by modulating the light generated thereby, the method comprising the steps of:

providing a commutating DC current for supplying the lamp; and

varying a commutation period (T) in order to transmit data.

2. Method according to claim 1, wherein the duration of each commutation period (T) is set to be equal to one of two possible values (T1, T2) to encode a digital bit.

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

receiving a bit of data;

determining whether the data bit has a first value (“

0”

) or a second value (“

1”

);

depending on the outcome of said determination, setting the duration of a commutation period (T) to be equal to either a first one (T1) of said two possible values (T1, T2) or a second one (T2) of said two possible values (T1, T2).

4. Method according to claim 1, wherein the duration of each commutation period (T) is set to be equal to one of N possible values, N being a positive integer.

5. Method according to claim 4, wherein N=2^m, m being a positive integer, to encode for m bits per commutation period.

6. Method according to claim 5, further comprising the steps of:

receiving m bits of data;

determining the value of these m bits in the range from 0 to 2^m−

1;

depending on the outcome of said determination, setting the duration of a commutation period (T) to be equal to one of said N possible values.

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

determining a plurality of M consecutive commutation periods, M being a positive integer;

setting the duration of each commutation period in said plurality of M consecutive commutation periods to be equal to one of N possible values, N being a positive integer;

such that said plurality of M consecutive commutation periods encode for m bits of data, wherein m=²log(N).

8. Method according to claim 1, wherein each commutation period has a duration in the range of 1-25 ms.

9. Electronic driver for a light source comprising a HID lamp, the driver comprising:

current generating means for generating a DC current;

a commutator section for receiving the DC current and providing a commutating lamp current;

a controller controlling the timing of the commutation moments (t1, t2);

wherein the controller is configured for varying a commutation period (T) in order to transmit data via the light emitted by the lamp.