LED driver and method of operating a camera

Patent metadata

Field	Value
Publication number	US-11388347-B2
Application number	US-201917059840-A
Country	US
Kind code	B2
Filing date	Jun 3, 2019
Priority date	Jun 1, 2018
Publication date	Jul 12, 2022
Grant date	Jul 12, 2022

Abstract

Disclosed is a method of capturing an image of a scene using a user device having a rolling shutter camera. The scene is subjected to an illumination by an LED light source. The method includes providing, by the user device, a notification signal to the LED light source, the notification signal being indicative of a capturing or imminent capturing of an image; adjusting, by the LED light source, an operating characteristic of the LED light source, based on the notification signal; and capturing, by the rolling shutter camera, the image of the scene, while the LED light source is operating at the adjusted operating characteristic.

First claim

The invention claimed is:

1. A method of capturing an image of a scene using a user device having a rolling shutter camera, the scene being subjected to an illumination by an LED light source, the method comprising:
receiving, by the user device, an illumination signal of the LED light source;
establishing, by the user device, that the LED light source is operating in a visible light communication (VLC) mode;
providing, by the user device, a notification signal to the LED light source, the notification signal being indicative of a capturing or imminent capturing of an image;
adjusting, by the LED light source, an operating characteristic of the LED light source, based on the notification signal; and
capturing, by the rolling shutter camera, the image of the scene, while the LED light source is operating at the adjusted operating characteristic.

2. The method according to claim 1 , wherein adjusting an operating characteristic comprises an operating in an adjusted VLC mode or a constant current mode.

3. The method according to claim 2 , wherein operating in the adjusted VLC mode comprises reducing a modulation depth of the VLC mode.

4. The method according to claim 1 , wherein the step of capturing the image further comprises:
providing, by the user device, a further notification signal to the LED light source, the further notification signal being configured to instruct the LED light source to resume operating with a previous operating characteristic.

5. The method according to claim 1 , wherein the operating characteristic comprises a modulation depth of the VLC mode.

6. The method according to claim 1 , wherein the notification signal comprises a light flash, generated by a light source of the user device.

7. The method according to claim 6 , wherein the light flash comprises encoded data representing the notification signal and wherein the step of adjusting the operating characteristic is preceded by a step of decoding the light flash.

8. The method according to claim 1 , wherein the notification signal comprises a Bluetooth signal or Wi-Fi signal generated by the user device.

9. The method according to claim 1 , wherein the notification signal comprises rolling shutter operational data and wherein the LED light source is configured to control the operating characteristic based on the rolling shutter operational data.

10. The method according to claim 9 , wherein the rolling shutter operational data comprises a capturing rate and/or capturing duration of the rolling shutter camera.

11. A method of capturing an image of a scene using a user device, the scene being subjected to an illumination by an LED light source, the method comprising:
receiving, by the user device, an illumination signal of the LED light source;
establishing, by the user device, that the LED light source is operating in a visible light communication (VLC) mode;
providing, by the user device, a notification signal to the LED light source, the notification signal being indicative of a capturing or imminent capturing of an image;
adjusting, by the LED light source, an operating characteristic of the LED light source, based on the notification signal; and
capturing the image of the scene by the user device while the LED light source is operating at the adjusted operating characteristic.

12. The method according to claim 11 , wherein the step of capturing the image comprises:
applying, by the user device, a first light flash;
setting an operating parameter of the user device; and
applying, by the user device, a second light flash during the capturing of the image.

13. An LED driver for powering an LED based light source, the LED driver comprising:
a power converter configured to convert a supply power to an output power for the LED based light source;
a control unit configured to: receive an input signal representing a desired illumination;
control the output power so as to generate the desired illumination, and to operate the LED based light source in a visible light communication (VLC) mode; and
receive a notification signal from a user device, the notification signal indicative of a capturing or imminent capturing of an image;
wherein the control unit is further configured to, upon receipt of the notification signal, adjust an operating characteristic of the power converter, at least during the capturing of the image, thereby operating the LED based light source at an adjusted illumination.

14. The LED driver according to claim 13 , wherein the control unit is further configured to operate the power converter to generate a VLC mode output power and wherein the operating characteristic comprises a modulation depth of a VLC signal generated by the VLC mode output power.

15. The LED driver according to claim 14 , the control unit is configured to reduce the modulation depth of the VLC signal, at least during the capturing of the image.

16. The LED driver according to claim 13 , wherein the control unit is configured to adjust the operating characteristic of the power converter by operating the power converter in a continuous current mode, at least during the capturing of the image.

17. The LED driver according to claim 13 , wherein an intensity and color of the adjusted illumination, as perceived by a human observer, substantially correspond to the intensity and color of the desired illumination.

18. The LED driver according to claim 13 , wherein the control unit is further configured to operate the power converter such that an intensity and color of the adjusted illumination, as perceived by a human observer, substantially correspond to the intensity and color of the desired illumination.

19. The LED driver according to claim 13 , wherein the user device comprises a rolling shutter camera.

20. The LED driver according to claim 19 , wherein the notification signal comprises a capturing rate or capturing period of the rolling shutter camera and wherein the control unit is configured to adjust the operating characteristic of the power converter based on the capturing rate or capturing period.

21. The LED driver according to claim 13 , wherein the control unit is configured to adjust the operating characteristic of the power converter during a predetermined period of time.

22. The LED driver according to claim 13 , wherein the control unit is configured to adjust the operating characteristic of the power converter until a further notification signal is received.

23. The LED driver according to claim 13 , further comprising a sensor configured to receive the notification signal.

24. The LED driver according to claim 23 , wherein the sensor comprises a photosensor.

Assignees

• Eldolab Holding Bv

Inventors

• Otten Andy Johanna Elisabeth

Classifications

• H04N23/74 Primary

  by influencing the scene brightness using illuminating means · CPC title

• H04N25/531

  by controlling rolling shutters in CMOS SSIS · CPC title

• H04N23/667

  Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes · CPC title

• H04N23/56

  provided with illuminating means · CPC title

• H04N23/71

  Circuitry for evaluating the brightness variation · CPC title