Method and apparatus for illumination and communication

• US 20060239689A1
• Filed: 01/25/2006
• Published: 10/26/2006
• Est. Priority Date: 01/25/2005
• Status: Active Grant

• Current Assignee: Philips Lighting BV (Koninklijke Philips N.V.)
• Original Assignee: TIR Systems Limited (Koninklijke Philips N.V.)
• Inventors: Ashdown, Ian
• Granted Patent: US 7,689,130 B2
• Time in Patent Office: Days
• US Class Current: 398/130
• CPC Class Codes: H04B 10/1141 One-way transmission
• CPC Class Codes: H04B 10/116 Visible light communication
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/325 Pulse-width modulation [PWM]
• CPC Class Codes: H05B 45/335 Pulse-frequency modulation [PFM]
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

The present invention provides a method and apparatus of using light-emitting elements for illumination as well as communication of data, wherein potential flicker due to sub-fusion frequency data correlations can be reduced compared to prior art techniques, while reducing redundancy in the data transmission. The intensity of the illumination from the light-emitting elements is controlled by a dimming signal such as a pulse width modulation (PWM) signal or a pulse code modulation (PCM) signal, for example. An amplitude-modulated data signal is then superimposed on the dimming signal for communication of data. The dimming signal thus acts as a carrier signal for the data signal. A sensing means is then used to receive the data signal by detecting all or part of the illumination from the light-emitting elements. The data signal can subsequently be extracted from the detected illumination.

Claims

1. An apparatus for illumination and communication of data, the apparatus comprising:

a) one or more light-emitting elements;

b) a control means for generating a carrier signal for controlling desired light output of the one or more light-emitting elements;

c) a modulation means for generating a data signal for superposition on the carrier signal thereby forming a control signal for controlling light emission of the one or more light emitting elements;

d) a sensing means for detecting at least a portion of the light emission; and

e) means for extracting the data signal from the detected light emission.

2. The apparatus according to claim 1 wherein the carrier signal is a pulse width modulated or a pulse code modulated signal.

3. The apparatus according to claim 1, wherein the data signal is an amplitude modulated signal.

4. The apparatus according to claim 2, wherein the carrier signal is a continuous carrier signal.

5. The apparatus according to claim 4 wherein the continuous carrier signal is amplitude modulated by the data signal.

6. The apparatus according to claim 3 wherein the control signal is encoded.

7. The apparatus according to claim 1 wherein the sensing means further comprises a filter.

8. A method for illumination and communication of data, the method comprising the steps of:

a) generating a carrier signal for controlling desired light output of one or more light-emitting elements;

b) generating a data signal;

c) combining the carrier signal and the data signal thereby forming a control signal, the control signal for controlling the light emission of the one or more light-emitting elements;

d) sensing at least a portion of the light emission; and

e) extracting the data signal.

9. The method according to claim 9 wherein the carrier signal is a pulse width modulated or a pulse code modulated signal.

10. The method according to claim 9, wherein the data signal is an amplitude modulated signal.

11. The method according to claim 10 wherein the carrier signal is a continuous carrier signal.

13. The method according to claim 11 wherein the control signal is encoded.

14. The method according to claim 9 further including the step of filtering at least a portion of the light emission, prior to the step of sensing at least a portion of the light emission.

12. The method according to claim 12 wherein the continuous carrier signal is amplitude modulated by the data signal.