CAMERA WITH AUTOMATIC FLUORESCENT LIGHTING MODE

• US 20080239095A1
• Filed: 04/02/2007
• Published: 10/02/2008
• 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, Nagy, Tom, Vanden Heuvel, David Noel
• Granted Patent: US 7,936,379 B2
• Time in Patent Office: Days
• 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;

correlating said time zone with a corresponding frequency of said fluorescent light; and

signaling said photosensor array to operate in accordance with a mode optimized to reduce flicker based on the selected time zone.

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 correlating said time zone with a corresponding frequency of said periodic intensity comprises looking up a table in a memory of said portable electronic device containing a list of time zones and corresponding frequencies.

5. 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.

6. 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.

7. 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.

8. 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.

16. A computer readable medium for storing a set of programming instructions according to the methods of claims 1-8.

9. 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; and

a processor interconnecting said user input device, said chip, said display, and said persistent storage device, and configured to correlate said time zone with a corresponding frequency of said fluorescent light and signal said chip to operate in accordance with a mode optimized to reduce flicker based on the selected time zone.

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

11. The device of claim 9 wherein said processor correlates said time zone with a corresponding frequency of said periodic intensity by looking up a table in said persistent storage device containing a list of time zones and corresponding frequencies.

12. The device of claim 9 wherein said plurality of modes include a 50 Hz fluorescent operating mode and a 60 Hz fluorescent operating mode.

13. The device of claim 9 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.

14. The device of claim 9 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.

15. The device of claim 9 wherein said chip sets an integration time for each pixel of the photosensor array to an integral multiple of said corresponding frequency.