Methods and Devices for Transmitting /Obtaining Information by Visible Light Signals

• US 20140321859A1
• Filed: 12/27/2013
• Published: 10/30/2014
• Est. Priority Date: 04/25/2013
• Status: Active Grant

• Current Assignee: StepTech Global Sagl
• Original Assignee: Beijing Guo Cheng Wan Tong Information Technology Co Ltd.
• Inventors: GUO, Cheng, HU, Hong
• Granted Patent: US 9,407,367 B2
• Time in Patent Office: Days
• US Class Current: 398/118
• CPC Class Codes: H04B 10/116 Visible light communication

Abstract

The present invention discloses methods and devices for transmitting/obtaining information by visible light signals. The method for transmitting information by visible light signals of two or more wavelengths from light sources comprises: modulating, on the basis of the information to be transmitted, two or more driving signals of the light sources to obtain two or more modulated driving signals for driving the light sources to emit the visible light signals of two or more wavelengths having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes; and emitting the visible light signals of two or more wavelengths having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes on the basis of the two or more modulated driving signals, so as to transmit information corresponding to a pattern of color stripes shown in an image obtained from the visible light signals.

Claims

1. A method for transmitting information by visible light signals of two or more wavelengths from light sources, the method comprising:

modulating, on the basis of the information to be transmitted, two or more driving signals of the light sources to obtain two or more modulated driving signals for driving the light sources to emit the visible light signals of two or more wavelengths having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes; and

emitting the visible light signals of two or more wavelengths having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes on the basis of the two or more modulated driving signals, so as to transmit information corresponding to a pattern of color stripes shown in an image obtained from the visible light signals.

2. The method according to claim 1, wherein modulating on the basis of the information to be transmitted two or more driving signals of the light sources to obtain two or more modulated driving signals comprises:

modulating, on the basis of the information to be transmitted, two or more driving voltages or two or more driving currents of the light sources to obtain a first set of modulated driving voltages or a first set of modulated driving currents.

3. The method according to claim 2, wherein the first set of modulated driving currents are respectively greater than un-modulated driving currents, so that luminous flux of the light sources driven by the first set of modulated driving currents is equal to luminous flux of light sources driven by the un-modulated driving currents.

4. The method according to claim 2, further comprising:

emitting the visible light signals on the basis of a second set of modulated driving currents which are greater than un-modulated driving currents together with a high frequency carrier wave signal, so that luminous flux of the light sources driven by the second set of modulated driving currents is constant among periods comprising peak levels and bottom levels.

5. The method according to claim 1, wherein the information corresponding to the pattern of color stripes comprises data bits, which comprise data corresponding to the number, color, brightness, or arranging order of the color stripes.

6. The method according to claim 5, wherein the information corresponding to the pattern of color stripes further comprises one or more start bits and/or one or more error correction bits, the start bits being used to identify a start position of a set of data bits, and the error correction bits being used to check error in the data bits.

7. The method according to claim 1, wherein modulating on the basis of the information to be transmitted two or more driving signals of the light sources to obtain two or more modulated driving signals comprises:

modulating the frequencies and/or phases and/or amplitudes of the two or more driving signals to obtain two or more modulated driving signals.

8. The method according to claim 1, wherein the color stripes in the image are derived from combination of the visible light signals having two or more wavelengths, and the information corresponding to the pattern of the color stripes comprises data bits, the number of the data bits transmitted at a time point being equal to or greater than the number of wavelengths of the visible light signals.

9. A method for obtaining information from visible light signals of two or more wavelengths from light sources, the method comprising:

obtaining an image from the visible light signals of two or more wavelengths having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes emitted by the light sources;

measuring a pattern of color stripes in the image obtained from the visible light signals; and

obtaining information corresponding to the pattern of the color stripes.

10. The method according to claim 9, wherein obtaining an image comprises obtaining the image by an image capturing device comprising an image sensor whose exposure mode is rolling shutter mode, and a sampling rate of the rolling shutter is higher than a frame rate of the image sensor.

11. The method according to claim 9, wherein obtaining an image comprises capturing, on an image sensor with a rolling shutter, the image in which different portions of the image sensor are exposed at different time points.

12. The method according to claim 9, wherein the visible light signals are emitted by the light sources on the basis of the modulated driving signals, which drive the light sources to emit the visible light signals having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes.

13. The method according to claim 9, wherein the light sources are one or more sets of light sources,

obtaining an image from the visible light signals having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes emitted by the light sources comprises:

obtaining the image from the visible light signals having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes emitted by the one or more sets of light sources, wherein one or more exposed regions in the image correspond to the one or more sets of light sources,

measuring a pattern of the color stripes in the image obtained from the visible light signals comprises;

measuring patterns of the color stripes of the one or more exposed regions in the image, and

obtaining information corresponding to the pattern of the color stripes comprises;

obtaining the information corresponding to the patterns of the color stripes of the one or more exposed regions in the image.

14. The method according to claim 9, wherein the color stripes in the image are derived from a combination of the visible light signals having two or more wavelengths, and the information corresponding to the pattern of the color stripes comprises data bits, the number of the data bits transmitted at a time point being equal to or greater than the number of wavelengths of the visible light signals.

15. A light source for transmitting information by visible light signals of two or more wavelengths, comprising:

a modulator configured to modulate, on the basis of the information to be transmitted, two or more driving signals of the light source to obtain two or more modulated driving signals for driving the light source to emit the visible light signals of two or more wavelengths having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes; and

an emitter configured to emit the visible light signals of two or more wavelengths having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes on the basis of the two or more modulated driving signals, so as to transmit information corresponding to a pattern of color stripes shown in an image obtained from the visible light signals.

16. The light source according to claim 15, wherein the modulator is configured to modulate, on the basis of the information to be transmitted, two or more driving voltages or two or more driving currents of the light source to obtain a first set of modulated driving voltages or a first set of modulated driving currents.

17. The light source according to claim 16, wherein the first set of modulated driving currents are respectively greater than un-modulated driving currents, so that luminous flux of the light source driven by the first set of modulated driving currents is equal to luminous flux of light source driven by the un-modulated driving currents.

18. The light source according to claim 16, wherein the emitter is configured to emit the visible light signals on the basis of a second set of modulated driving currents which are greater than un-modulated driving currents together with a high frequency carrier wave signal, so that luminous flux of the light sources driven by the second set of modulated driving currents is constant among periods comprising peak levels and bottom levels.

19. The light source according to claim 15, wherein the information corresponding to the pattern of color stripes comprises data bits, which comprise data corresponding to the number, color, brightness, or arranging order of the color stripes.

20. The light source according to claim 19, wherein the information corresponding to the pattern of color stripes further comprises one or more start bits and/or one or more error correction bits, the start bits being used to identify a start position of a set of data bits, and the error correction bits being used to check error in the data bits.

21. The light source according to claim 15, wherein the modulator is configured to modulate the frequencies and/or phases and/or amplitudes of the two or more driving signals to obtain two or more modulated driving signals.

22. The light source according to claim 15, wherein the color stripes in the image are derived from combination of the visible light signals having two or more wavelengths, and the information corresponding to the pattern of the color stripes comprises data bits, the number of the data bits transmitted at a time point being equal to or greater than the number of wavelengths of the visible light signals.

23. A device for obtaining information from visible light signals of two or more wavelengths from light sources, the device comprising:

an image sensor configured to obtain an image from the visible light signals of two or more wavelengths having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes emitted by the light sources;

a memory configured to store the image obtained by the image sensor; and

a processor configured to measure a pattern of color stripes in the image stored in the memory and obtain information corresponding to the pattern of the color stripes.

24. The device according to claim 23, wherein an exposure mode of the image sensor is rolling shutter mode, and a sampling rate of the rolling shutter is higher than a frame rate of the image sensor.

25. The device according to claim 23, wherein the image sensor is an image sensor with a rolling shutter and is configured to obtain the image from the visible light signals in which different portions of the image sensor are exposed at different time points.

26. The device according to claim 23, wherein the visible light signals are emitted by the light sources on the basis of the modulated driving signals, which drive the light sources to emit the visible light signals having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes.

27. The device according to claim 23, wherein the light sources are one or more sets of light sources,

the image sensor is configured to obtain the image from the visible light signals having their levels changed between peak levels and bottom levels with different frequencies and/or different phases and/or different amplitudes emitted by the one or more sets of light sources, wherein one or more exposed regions in the image correspond to the one or more sets of light sources,

the memory is configured to store the image obtained by the image sensor, and

the processor is configured to measure patterns of the color stripes of the one or more exposed regions in the image, and obtain information corresponding to the patterns of the color stripes of the one or more exposed regions in the image.

28. The device according to claim 23, wherein the color stripes in the image are derived from a combination of the visible light signals having two or more wavelengths, and the information corresponding to the pattern of the color stripes comprises data bits, the number of the data bits transmitted at a time point being equal to or greater than the number of wavelengths of the visible light signals.