TELEVISION SURVEILLANCE SYSTEM

• US 3,781,468 A
• Filed: 06/21/1972
• Issued: 12/25/1973
• Est. Priority Date: 06/21/1972
• Status: Expired due to Term

• Current Assignee: Donald E. Ellison, Marc Chomet
• Original Assignee: Donald E. Ellison, Marc Chomet
• Inventors: Chomet, Marc, Ellison, Donald E.
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): Orsino, Jr., Joseph A.
• Application Number:
  US05/265,105
• Time in Patent Office: 552 Days
• Field of Search: 178/DIG.33,DIG.37,DIG.38,6.8 340/258B,258R
• US Class Current: 348/155
• CPC Class Codes: G08B 13/19602 Image analysis to detect motion of the intruder, e.g. by frame subtraction
• CPC Class Codes: G08B 13/19634 Electrical details of the system, e.g. component blocks for carrying out specific functions
• CPC Class Codes: G08B 13/19676 Temporary storage, e.g. cyclic memory, buffer storage on pre-alarm

Abstract

A surveillance system is described in which a television camera views the general scene under surveillance and in which the magnitude of the video signal pertaining to a preselected portion thereof and occurring during one or more fields is stored and compared with a reference signal or with the magnitude of the video signal pertaining to the same preselected portion and occurring during one or more subsequent fields, whereby, in either case, a difference in magnitude in excess of a predetermined threshold is indicative of the motion of an object in such portion.

Claims

1. A surveillance system including a closed circuit television arrangement having a camera viewing a scene which includes the area to be protected and having a monitor for displaying an image of the scene viewed by said camera, said system including means for separating the horizontal and vertical synchronizing signals from the video signals generated by said camera, first means responsive to said synchronizing signals for generating a window signal indicative of that portion of the time during each field that a preselected rectangular fraction thereof is being scanned, and second means responsive to said synchronizing signals for generating timing waveforms, characterized in that said second means comprises a binary counter operated by said vertical synchronizing signals for generating repeatedly a series of successive binary number signals from zero to its capacity and also comprises a decoder operated by said binary number signals for generating a plurality of repetitivE series of voltage pulses on a like plurality of output conductors, each of said series having a duration approximately equal to the duration of an integral multiple of fields, and in that said system includes a peak detector for detecting and storing the peak magnitude of a video signal applied thereto, means controlled by said timing waveforms and said window signal for applying that portion of the video signal occurring during the time defined by said window signal and one of said series of pulses to said peak detector, means for generating a reference signal, means enabled by one of said waveforms for comparing the magnitudes of the signal stored by said peak detector and said reference signal, and means responsive to a difference in said magnitudes in excess of a predetermined threshold for generating a warning signal.

2. A surveillance system in accordance with claim 1 in which said means for generating a reference signal comprises a second peak detector for detecting and storing the peak magnitude of a video signal applied thereto and also comprises second means controlled by said timing waveforms and said window signal for applying that portion of the video signal occurring during the time defined by said window signal and another one of said series of pulses to said second peak detector.

3. A surveillance system in accordance with claim 1 which includes means for adjusting the size and location of said preselected rectangular fraction.

4. A surveillance system in accordance with claim 1 which includes means responsive to said warning signal for varying the magnitude of that portion of said video signal which occurs during said preselected rectangular fraction of each field.

5. A surveillance system in accordance with claim 1 in which said means for generating a reference signal comprises a circuit for furnishing a constant voltage signal.

6. A surveillance system in accordance with claim 5 which includes a threshold circuit for limiting the video signal passed to said peak detector to those portions which exceed a predetermined magnitude.

7. A surveillance system in accordance with claim 6 which includes an adjusting circuit responsive to slow changes in the level of the output of said peak detector for adjusting the predetermined magnitude of the signals passed by said threshold circuit.