METHOD AND APPARATUS FOR ELECTRONICALLY MONITORING A FIELD OF VIEW

• US 3,743,768 A
• Filed: 04/02/1971
• Issued: 07/03/1973
• Est. Priority Date: 04/02/1971
• Status: Expired due to Term

• Current Assignee: George V. Copland
• Original Assignee: George V. Copland
• Inventors: Copland, George V.
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US05/130,643
• Time in Patent Office: 823 Days
• Field of Search: 178/DIG.33,DIG.38,6.8,DIG.37 250/219DF 340/146.3Y,146.3ED,146.3SY
• US Class Current: 348/154
• 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 13/19641 Multiple cameras having overlapping views on a single scene

Abstract

A method and apparatus for electronically monitoring a field of view and manifesting significant optical changes occurring therein to detect unauthorized intrusion into an area defined by the field of view. The number of times that the amplitude of successive electronic signatures of the field of view exceeds a predetermined threshold is counted for two different electronic signatures. The two numbers counted are compared and if the numerical difference therebetween exceeds a selected number, an alarm indication is provided.

Claims

1. A method for monitoring a predetermined field of view comprising the steps of:

a. generating successive electronic signatures of the field of view;

b. counting the number of times that the amplitude of each of the electronic signatures exceeds a predetermined threshold; and

, c. comparing the number counted in one of said electronic signatures with the number counted in another of said electronic signatures.

2. The method of claim 1 including the step of indicating an alarm condition responsively to said comparison.

3. The method of claim 1 wherein the step of counting includes:

generating a pulse each time the amplitude of said electronic signatures exceeds said threshold;

counting the number of pulses generated for each oF said electronic signatures; and

, storing the number counted for one of said electronic signatures.

4. The method of claim 3 wherein the step of comparing comprises determining the difference between said stored number and the number counted in another of said electronic signatures.

5. The method of claim 4 including the step of indicating an alarm condition when said difference exceeds a predetermined number.

6. A method for monitoring a field of view comprising the steps of:

electronically scanning an entire optical image of a selected field of view at predetermined time intervals to generate analog video signals each related in amplitude to the light reflected from at least a portion of each entire optical image;

generating a pulse each time the amplitude of a video signal related to one entire optical image exceeds a predetermined threshold;

counting the number of pulses generated for said one entire optical image;

storing the number of pulses counted;

generating a pulse each time the amplitude of a video signal related to another entire optical image exceeds said threshold;

counting the number of pulses generated for said other entire optical image; and

, comparing said stored number with said last counted number.

7. The method of claim 6 including the step of indicating an alarm condition responsively to said comparison.

8. Apparatus for monitoring a predetermined field of view comprising:

means for generating successive electronic signatures of said field of view;

means for counting the number of times that the amplitude of each of said electronic signatures exceeds a predetermined threshold; and

, means for comparing the number counted in one of said electronic signatures with the number counted in another of said electronic signatures.

9. The apparatus of claim 8 including means for indicating an alarm condition in response to an inequality between said compared numbers.

10. The apparatus of claim 8 wherein said electronic signatures each comprise a composite video signal having an amplitude related to the light reflected from an optical image within said field of view and having scan synchronization signals superimposed thereon, and wherein said counting means comprises:

means for isolating at least a portion of said scan synchronization signals from said composite video signal;

means for generating a pulse each time the amplitude of said video signals exceeds a predetermined threshold;

means for counting the number of said generated pulses for said video signals; and

, means responsive to said counting means and said isolating means for storing said counted number for one of said video signals.

11. The apparatus of claim 10 wherein said comparing means comprises:

means for generating a digital signal representative of the numerical difference between said stored number and the number of pulses counted for another of said electronic signals; and

, means for generating an alarm signal when said digital signal exceeds a predetermined number.

12. The apparatus of claim 8 wherein said generating means comprises a television camera tube.

13. The apparatus of claim 12 wherein said counting means comprises:

means for generating a pulse each time the amplitude of said electronic signatures exceeds said threshold;

means for counting the number of pulses generated for each of said electronic signatures; and

, means for storing the number of pulses counted for one of said electronic signatures.

14. The apparatus of claim 13 wherein said comparing means comprises means responsive to said counting means and said storing means for determining the difference between said stored number and the number of pulses counted for another of said electronic signatures.

15. The apparatus of claim 14 including means for generating an alarm signal when said difference exceeds a predetermined number.

16. In a surveillance system for monitoring unaUthorized intrusion into a predetermined area, said system comprising television camera means for generating successive electronic signatures of a field of view which includes said area, means for supplying said successive electronic signatures to a remote security station, visual monitor means at said security station for providing a visual reproduction of said area responsively to said successive electronic signatures and automatic monitor means at said security station for automatically detecting unauthorized intrusion into said area, the improvement wherein said automatic monitor means comprises:

means responsive to each of said successive electronic signatures for generating an electrical pulse each time that the amplitude of said electronic signatures exceeds a predetermined threshold;

means for counting the number of generated electricl pulses;

means for storing the number of pulses counted in a first one of said successive electronic signatures;

means for comparing the stored number in said first one of said successive electronic signatures with the number of pulses subsequently counted in a second one of said electronic signatures;

means responsive to said comparing means for generating an alarm signal when a selected numerical difference between the numbers compared is exceeded.