Intrusion detection system

• US 20040169131A1
• Filed: 12/31/2003
• Published: 09/02/2004
• Est. Priority Date: 07/06/1999
• Status: Active Grant

• Current Assignee: Larry C. Hardin
• Original Assignee: Larry C. Hardin
• Inventors: Hardin, Larry C., Nash, Lawrence V.
• Granted Patent: US 7,208,720 B2
• Time in Patent Office: Days
• US Class Current: 250/221
• CPC Class Codes: G01P 3/38 using photographic means
• CPC Class Codes: G01P 3/68 using optical means, i.e. using infrared, visible, or ultraviolet light G01P3/80 takes precedence ; by reflection of waves G01S17/58
• CPC Class Codes: G01S 11/12 using electromagnetic waves other than radio waves
• CPC Class Codes: G08B 13/19602 Image analysis to detect motion of the intruder, e.g. by frame subtraction
• CPC Class Codes: G08B 13/19608 Tracking movement of a target, e.g. by detecting an object predefined as a target, using target direction and or velocity to predict its new position
• CPC Class Codes: G08B 13/1961 Movement detection not involving frame subtraction, e.g. motion detection on the basis of luminance changes in the image
• CPC Class Codes: G08B 13/19641 Multiple cameras having overlapping views on a single scene
• CPC Class Codes: H04N 13/239 using two 2D image sensors having a relative position equal to or related to the interocular distance H04N13/243 takes precedence

Abstract

An intrusion detection system comprises a pair of optical lenses arranged a predetermined distance apart and having overlapping fields of view within an area to be monitored to form a common field of view; at least one light-sensitive device responsive to light from each of the optical lenses; a range detector responsive to signals from the light-sensitive device and operable to determine a range to an object within the common field of view; and a range discriminator for setting at least one range gate to sense objects within the common field of view at predetermined ranges and for ignoring objects outside of the predetermined ranges.

Claims

1. An intrusion detection system comprising:

(a) a pair of optical lenses arranged a predetermined distance apart and having overlapping fields of view within an area to be monitored to form a common field of view;

(b) at least one light-sensitive device responsive to light from each of the optical lenses;

(c) a range detector responsive to signals from said light-sensitive device operable to determine a range to an object within the common field of view; and

(d) a range discriminator for setting at least one range gate so as to sense objects within said common field of view at predetermined ranges and for ignoring objects that appear outside of said predetermined ranges.

2. The intrusion detection system of claim 1 further including a light-sensitive device for each lens.

3. The intrusion detection system of claim 1 wherein the light-sensitive devices include light-sensitive elements arranged in lines of pixels operably selected by the range discriminator to define the ranges included within the range gate.

4. The intrusion detection system of claim 3 wherein multiple sets of lines of pixels are operably selected by the range discriminator to provide multiple range gates for the selective detection of objects within said common field of view.

5. The intrusion detection system of claim 4 further including a velocity detector responsive to signals from a light-sensitive device and operable to determine velocity of an object sensed by said range detector within the ranges spanned by said range gates.

9. The intrusion detection system of claim 1 wherein the area to be monitored is defined at least in part by a horizontal ground surface and the pair of optical lenses are situated a predetermined distance above the horizontal ground surface and have lines of sight that intersect the horizontal ground surface at predetermined distances from the lenses.

10. The intrusion detection system of claim 9 further including a light-sensitive device for each lens.

11. The intrusion detection system of claim 9 wherein the light-sensitive devices include light-sensitive elements arranged in lines of pixels operably selected by the range discriminator to define the ranges included within the range gate.

12. The intrusion detection system of claim 11 wherein multiple sets of lines of pixels are operably selected by the range discriminator to provide multiple range gates for the selective detection of objects within said common field of view.

13. The intrusion detection system of claim 12 further including a velocity detector responsive to signals from a light-sensitive device and operable to determine velocity of an object sensed by said range detector within the ranges spanned by said range gates.

6. An intrusion detection system for monitoring a secure area comprising:

(a) a pair of electro-optical devices arranged a predetermined distance apart having a common field of view in the secure area to be monitored, each electro-optical device comprising a lens and a light-sensitive element, each light-sensitive element having a pixel array of multiple lines of pixels; and

(b) a data processing device responsive to the light-sensitive element of each electro-optical device, the data processing device having a range detector to detect the presence of objects in the area to be monitored, said data processing device including a range gate selector for discriminating among said objects sensed by the range detector by extracting image data from selected ones of said multiple lines of pixels in each said respective pixel array.

7. The intrusion detection system of claim 6 wherein said range gate selector is operable to create multiple zones of ranges within said secure area to be monitored.

8. The intrusion detection system of claim 6 wherein said data processing device further includes a velocity detector for determining velocity of objects detected by said range detector.

14. An intrusion detection system for monitoring a secured area comprising:

(a) a pair of passive electro-optical sensors, each sensor including a lens and a light-sensitive device having rows of electronically scanned pixel elements, each row of pixel elements being responsive to light from objects appearing within said area at respective ranges, said pair of sensors being mounted a predetermined distance apart and aimed downward into said secured area at an angle obtuse to a horizontal reference line; and

(b) a data processing module coupled to the light-sensitive devices and having a range gate selector for selecting predetermined lines of pixels for processing scanned image data from objects appearing at predetermined ranges.

15. The intrusion detection system of claim 14 wherein said range gate selector is operable to create multiple zones of ranges within said secure area to be monitored.

16. The intrusion detection system of claim 14 wherein said data processing device further includes a velocity detector for determining velocity of objects detected by said range detector.