Method and system for modifying a beacon light source for use in a light based positioning system

Patent metadata

Field	Value
Publication number	US-2016192452-A1
Application number	US-201615063763-A
Country	US
Kind code	A1
Filing date	Mar 8, 2016
Priority date	Jul 26, 2011
Publication date	Jun 30, 2016
Grant date	—

Abstract

In one aspect, the present disclosure related to a method for modifying a beacon light source for use in a light-based positioning system. In some embodiments, the method includes selecting a modulation scheme for the light source, determining a duty cycle for the light source based on the modulation scheme, the duty cycle having a proportion of time the light source is in an on state and a corresponding proportion of time the light source is in an off state, the proportion of time the light source is in an off state resulting in reduced luminosity of the light source, and supplying additional power to the light source to compensate for the reduced luminosity of the light source by the duty cycle.

First claim

We claim:

1 . A method, comprising:
periodically modulating an output of a light source from a peak output level to a bottom output level, wherein a period of the modulating is set based on an image sampling time of a rolling shutter camera of a device intended to receive modulated light output by the light source; and applying a DC bias to the light source during modulation that increases the peak output level of an unmodulated output of the light source beyond an un-modulated output of the light source corresponding to a given brightness level and to achieve an average output of the light source equal to the un-modulation output of the light source corresponding to the given brightness level.

2 . The method of claim 1 , further comprising:
setting a duty cycle of the periodic modulating of the light source output based on the image sampling time of the rolling shutter camera, wherein:
the duty cycle has light source ON period and a light source non-zero period in which the output level of the light source modulates between the peak output level and the bottom output level increased by the applied DC bias, wherein electrical power applied to the light source during the ON period is greater than electrical power applied to the light source during the non-zero period.

3 . The method of claim 2 , wherein the light source non-zero period is less than half of the image sampling time of the rolling shutter camera of the intended receiving device.

4 . The method of claim 2 , wherein the light source ON period is less than half of the image sampling time of the rolling shutter camera of the intended receiving device.

5 . The method of claim 1 , wherein the modulating period is set based on a plurality of rolling shutter camera image sampling times.

6 . The method of claim 1 , wherein the peak output level and the bottom output level comprise electrical current levels.

7 . The method of claim 1 , wherein the peak output level and the bottom output level comprise voltage levels.

8 . The method of claim 1 , wherein the light source comprises a light-emitting diode (LED).

9 . A lighting device for use in a light based positioning system, the lighting device comprising:
a controllable light source that emits light; a modulator comprising a data signal input and a dimming device interface; and a driver coupled to the modulator and the light source, wherein the driver outputs driver signals in response to a data signal causing the light source to output light in accordance with the driver signals, wherein the modulator is configured to:
receive a data signal via the data signal input;
select a modulation scheme for the light source based on the received data signal, wherein the modulation scheme periodically varies based on a selected frequency an output of the light source from a peak output level to a bottom output level;
add a DC bias to the modulation scheme;
receive via the dimming device interface a dimming signal; and
set a duty cycle for the pulse width modulation signal based on the received dimming signal, wherein the duty cycle is set based on an image sampling time of a rolling shutter camera intended to receive the light output by the light source, and
output to the driver signals based on the selected modulation scheme having the selected frequency, added DC bias and the set duty cycle to cause the light source to output modulated light.

10 . The lighting device of claim 9 , wherein the set duty cycle has a light source ON period and a light source non-zero period in which the light output by the light source modulates between the peak output level and the bottom output level, wherein the bottom output level is:
increased based on the applied DC bias, and corresponds to the non-zero period.

11 . The lighting device of claim 10 , wherein the peak output level and the bottom output level comprise electrical current levels.

12 . The lighting device of claim 10 , wherein the peak output level and the bottom output level comprise voltage levels.

13 . The lighting device of claim 9 , wherein the duty cycle is set based on a plurality of rolling shutter camera image sampling times.

14 . The lighting device of claim 9 , wherein the light source comprises a light-emitting diode (LED).

15 . A modulated light source for use in a light based positioning system, the light source comprising:
an emitter with a luminosity broadcasting a modulated signal; and a modulator for receiving a modulation scheme and driving the luminosity of the emitter by applying the modulation scheme with a DC bias to the emitter, the modulator configured to:
apply a DC bias to the light source during modulation that increases the peak output level of an unmodulated output of the light source beyond an un-modulated output of the light source corresponding to a given brightness level and to achieve an average output of the light source equal to the un-modulation output of the light source corresponding to the given brightness level,
wherein a period of the modulation scheme is set based on an image sampling time of a rolling shutter camera of a device intended to receive modulated visible light output by the emitter.

16 . The modulated light source of claim 15 , wherein the modulator is further configured to:
prior to applying the modulating scheme, determine a duty cycle of the periodic modulating of the emitter based on the image sampling time of the rolling shutter camera , wherein: the duty cycle has an emitter ON period and an emitter non-zero period in which the output level of the light source modulates between the peak output level and the bottom output level increased by the applied DC bias.

17 . The modulated light source of claim 16 , wherein the emitter non-zero period is less than half of the image sampling time of the rolling shutter camera of the intended receiving device.

18 . The modulated light source of claim 16 , wherein the emitter ON period is less than half of the image sampling time of the rolling shutter camera of the intended receiving device.

19 . The modulated light source of claim 15 , wherein the peak output level and the bottom output level comprise electrical current levels.

20 . The modulated light source of claim 15 , wherein the peak output level and the bottom output level comprise voltage levels.

21 . The modulated light source of claim 15 , wherein the modulating period is set based on a plurality of rolling shutter camera image sampling times.

22 . The modulated light source of claim 15 , wherein the emitter comprises a light-emitting diode (LED).

Assignees

• Abl Ip Holding Llc

Inventors

• Ganick Aaron
• Ryan Daniel

Classifications

• G06F2218/14

  by matching peak patterns · CPC title

• G06F2218/02

  Preprocessing · CPC title

• H05B45/10 Primary

  Controlling the intensity of the light · CPC title

• G06T2207/20056

  Discrete and fast Fourier transform, [DFT, FFT] · CPC title

• H05B47/16

  by timing means · CPC title