Surveillance camera with flicker immunity

• US 7,084,901 B2
• Filed: 06/28/2002
• Issued: 08/01/2006
• Est. Priority Date: 08/01/2001
• Status: Expired due to Fees

• Current Assignee: Tek84 Engineering Group, LLC (Leidos Holdings, Inc.)
• Original Assignee: Tek84 Engineering Group, LLC (Leidos Holdings, Inc.)
• Inventors: Smith, Steven Winn
• Primary Examiner(s): An, Shawn S.
• Application Number:
  US10/183,620
• Publication Number:
  US 20030025790A1
• Time in Patent Office: 1,495 Days
• Field of Search: 348/143, 348/134, 348/145, 348/207, 348/370, 348/208, 348/23, 358/505
• US Class Current: 348/143
• 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 7/188 Capturing isolated or intermittent images triggered by the occurrence of a predetermined event, e.g. an object reaching a predetermined position signal generation from motion picture films H04N5/253

Abstract

A video surveillance camera capable of operating with flickering illumination is formed from a time-delay-integration linescan camera in conjunction with a mechanical scanner. The line rate of the camera is adjusted to provide an integration time substantially equal to an integer number of periods of the lighting flicker.

Claims

1. Video surveillance apparatus for monitoring a region illuminated by gas discharge lighting, comprising:

a linescan camera, said linescan camera viewing a vertical line in the monitored region, said linescan camera operating in a time-delay-integration mode with a multitude of light sensitive columns, said linescan camera operating with a line rate; and

a scanner, said scanner sweeping the viewed vertical line horizontally across said monitored region in synchronization with said time-delay-integration mode of said linescan camera;

wherein said line rate is substantially equal to twice the number of said light sensitive columns multiplied by the frequency of the power source driving said gas discharge lighting divided by an integer greater than zero.

2. The video surveillance apparatus as claimed in claim 1 wherein said scanner comprises a mirror mounted on a rotational servo.

3. The video surveillance apparatus as claimed in claim 1 wherein said frequency is from the group consisting of 50 cycles per second and 60 cycles per second.

4. The video surveillance apparatus as claimed in claim 2 wherein said frequency is from the group consisting of 50 cycles per second and 60 cycles per second.

5. The video surveillance apparatus as claimed in claim 1 wherein said number of said light sensitive columns is greater than 8.

6. The video surveillance apparatus as claimed in claim 1 wherein said frequency is 60 cycles per second, said number of said light sensitive columns is 96, said integer is one, and said line rate is substantially 2 times 60 cycles per second times 96 columns divided by 1 equaling 11,520 lines per second.

7. The video surveillance apparatus as claimed in claim 6 wherein said line rate is between 9,216 lines per second and 13,824 lines per second.

8. A method of acquiring a video image of a monitored region illuminated by flickering lighting, comprising:

viewing a vertical line in said monitored region with a TDI linescan camera;

scanning said vertical line horizontally across said monitored region; and

acquiring a sequence of vertical profiles from said TDI linescan camera at a repetition rate, said repetition rate being substantially equal to the number of integrating columns in said TDI camera multiplied by the frequency of said flickering lighting divided by a positive integer.

9. A method of acquiring a video image claimed in claim 8, wherein said scanning consists of rotating a mirror.

10. A method of acquiring a video image claimed in claim 9, wherein said frequency of said flickering lighting is from the group 100 cycles per second and 120 cycles per second.

11. A method of acquiring a video image claimed in claim 8, wherein said number of integrating columns is 96, said frequency of said flickering lighting is 120 cycles per second, said positive integer is 1, and said repetition rate is substantially 96 columns times 60 cycles per second divided by 1 equaling 11,520 lines per second.

12. A method of acquiring a video image claimed in claim 11, wherein said repetition rate is between 9,216 lines per second and 13,824 lines per second.

13. A method of acquiring a video image claimed in claim 8, wherein said frequency of said flickering lighting is from the group 100 cycles per second and 120 cycles per second.