Camera with automatic fluorescent lighting mode

• US 7,936,379 B2
• Filed: 04/02/2007
• Issued: 05/03/2011
• Est. Priority Date: 04/02/2007
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Lee, Matthew, Andrade, Russell Raymond, Vanden Heuvel, David Noel, Nagy, Tom
• Primary Examiner(s): Ye; Lin
• Assistant Examiner(s): Hogue; Dennis
• Application Number:
  US11/695,171
• Publication Number:
  US 20080239095A1
• Time in Patent Office: 1,492 Days
• Field of Search: None
• US Class Current: 348/226.1
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene
• CPC Class Codes: H04N 23/745 Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination
• CPC Class Codes: H04N 7/0132 the field or frame frequency of the incoming video signal being multiplied by a positive integer, e.g. for flicker reduction

Abstract

A novel method and apparatus for controlling operation of a photosensor array in a portable electronic device to reduce flicker resulting from fluorescent light having a periodic intensity. The method comprises selecting a time zone in which the device is to be operated, correlating the time zone with a corresponding frequency of the fluorescent light, and signaling the photosensor array to operate in accordance with a mode optimized to reduce flicker based on the selected time zone.

Claims

1. A method for controlling operation of a photosensor array in a portable electronic device to reduce flicker resulting from fluorescent light having a periodic intensity, the method comprising:

selecting a time zone in which said device is to be operated;

determining a corresponding frequency of said fluorescent light from the selected time zone by using a table containing a list of time zones and corresponding frequencies; and

signaling said photosensor array to operate in accordance with a mode arranged to reduce flicker based on said corresponding frequency.

2. The method of claim 1 wherein said corresponding frequency is one of either 50 Hz or 60 Hz.

3. The method of claim 1 wherein selecting the time zone comprises user manipulation of an input device on said portable electronic device.

4. The method of claim 1 wherein said mode is one of either a 50 Hz fluorescent operating mode or a 60 Hz fluorescent operating mode.

5. The method of claim 1 wherein said mode includes filtering out beats associated with a 100 Hz intensity resulting from capturing an image illuminated with 50 Hz fluorescent light at a frame rate of 30 Hz.

6. The method of claim 1 wherein said mode includes synchronizing a frame capture rate of said photosensor array to 100 Hz beats resulting from capturing an image illuminated with 50 Hz fluorescent light.

7. The method of claim 1 wherein said mode includes setting an integration time for each pixel of the photosensor array to an integral multiple of said corresponding frequency.

14. A persistent storage device for storing a set of programming instructions in executable form according to the method of claim 1.

8. A portable electronic device comprising:

at least one user input device for selecting a time zone in which said device is to be operated;

a chip having a photosensor array adapted to operate in one of a plurality of modes for reducing flicker resulting from fluorescent light having a periodic intensity;

a display;

a persistent storage device storing a table containing a list of time zones and corresponding frequencies; and

a processor interconnecting said user input device, said chip, said display, and said persistent storage device that determines a corresponding frequency of said fluorescent light from the selected time zone by using said table and signals said chip to operate in accordance with a mode arranged to reduce flicker based on said corresponding frequency.

9. The device of claim 8, wherein said at least one user input is a trackball.

10. The device of claim 8 wherein said plurality of modes include a 50 Hz fluorescent operating mode and a 60 Hz fluorescent operating mode.

11. The device of claim 8 wherein said chip filters out beats associated with a 100 Hz intensity resulting from capturing an image illuminated with 50 Hz fluorescent light at a photosensor array frame rate of 30 Hz.

12. The device of claim 8 wherein said chip synchronizes a frame capture rate of said photosensor array to 100 Hz beats resulting from capturing an image illuminated with 50 Hz fluorescent light.

13. The device of claim 8 wherein said chip sets an integration time for each pixel of the photosensor array to an integral multiple of said corresponding frequency.

15. A persistent storage device having a computer readable program code adapted to be executed to implement a method for controlling operation of a photosensor array in a portable electronic device to reduce flicker resulting from fluorescent light having a periodic intensity, the method comprising:

selecting a time zone in which said device is to be operated;

determining a corresponding frequency of said fluorescent light from the selected time zone by using a table containing a list of time zones and corresponding frequencies; and

signaling said photosensor array to operate in accordance with a mode arranged to reduce flicker based on said corresponding frequency.

16. The persistent storage device of claim 15, wherein said corresponding frequency is one of either 50 Hz or 60 Hz.

17. The persistent storage device of claim 15, wherein said mode is one of either a 50 Hz fluorescent operating mode or a 60 Hz fluorescent operating mode.

18. The persistent storage device of claim 15, wherein said mode includes filtering out beats associated with a 100 Hz intensity resulting from capturing an image illuminated with 50 Hz fluorescent light at a frame rate of 30 Hz.

19. The persistent storage device of claim 15, wherein said mode includes synchronizing a frame capture rate of said photosensor array to 100 Hz beats resulting from capturing an image illuminated with 50 Hz fluorescent light.

20. The persistent storage device of claim 15, wherein said mode includes setting an integration time for each pixel of the photosensor array to an integral multiple of said corresponding frequency.