System for monitoring spaces by electro-optical means

• US 3,972,021 A
• Filed: 05/21/1975
• Issued: 07/27/1976
• Est. Priority Date: 05/27/1974
• Status: Expired due to Term

• Current Assignee: Eckart Schneider, Knut Heitmann, Ludwig Leitz
• Original Assignee: Eckart Schneider, Knut Heitmann, Ludwig Leitz
• Inventors: Schneider, Eckart, Heitmann, Knut, Leitz, Ludwig
• Primary Examiner(s): Habecker, Thomas B.
• Application Number:
  US05/579,568
• Time in Patent Office: 433 Days
• Field of Search: 340/32, 340/38 P, 340/258 B, 250/237 G, 250/221, 250/222
• US Class Current: 340/942
• CPC Class Codes: F16P 3/144 using light grids
• CPC Class Codes: G08G 1/04 using optical or ultrasonic detectors

Abstract

System for monitoring spaces by electro-optical means, using optical imaging means (1) capable of detecting objects present in the monitored spaces and beam splitting means (2) for grating resolution of the object images into geometric, mutually complementary components. The imaging and beam splitting means form a correlation imaging sensor system equipped with photoelectric detectors (4,5) for the purpose of separately converging light fluxes corresponding to the image components into analogue electrical signals, and electrical means for measuring the amplitudes and phases of the signals as well as their variations. The correlation sensor system analyzes these values with respect to presence and/or motion of objects within the monitored spaces.

Claims

1. In a system for monitoring spaces by electro-optical means, the improvement comprising:

optical imaging means (1) for detecting objects present in said spaces to be monitored and beam splitting means (2) for grating-resolution of images of said objects into geometric, mutually complementary components, said imaging and beam splitting means defining an imaging correlation sensor system having photoelectric detectors (4,

     5) for separately converting light fluxes corresponding to components of said images into analogue electrical signals and electrical means for measuring signal phase and amplitude and their variations, and for analyzing said signals with respect to the presence and/or motion of said objects within said spaces.

2. The system of claim 1, wherein said optical imaging means and said photoelectric detectors are adjusted for given distances and given solid angles for the purposes of monitoring.

3. The system of claim 1, wherein said optical imaging means (1) have exit pupils with different pupil parts and said photoelectric detectors (4, 5) are mounted in said exit pupils for sensing said different pupil parts separately.

4. The system of claim 1, having means for periodically moving said beam splitting means in at least one direction and for generating reference signals proportional to said motion.

5. The system of claim 1, having analyzing means determining the distance between said objects and said sensor from the relative phases of the signals appropriate to the various pupil parts and ascertaining the sign and magnitude of a transverse object motion from comparison of the phases and frequencies of said signals and said reference signals.

6. The system of claim 2, having a stop arrangement (19, 20) located in the plane of said beam splitting means (2) for covering given image parts.

7. The system of claim 1, having said optical means (1) with the principal planes intersecting the plane of said beam splitting means (2) and an object plane of interest in a straight line.

8. The system of claim 1, used for traffic monitoring, having at least two of said optical correlation sensor systems each comprising one grating in one image plane and at least one of said photoelectric detectors and generating electrical signals containing directional information, based on the movement of the grating or on the beam splitting of optical elements said correlation sensor systems mounted above a traffic path for sensing the traffic of vehicles and the traffic of pedestrians crossing the road.

9. The system of claim 8, wherein said correlating sensor systems are mounted on the traffic light poles above the traffic lights.

10. The system of claim 8, having a computer receiving all the output signals from said correlation sensor systems and controlling traffic at a given number of neighboring traffic junctions.

11. The system of claim 8, wherein said correlation sensor systems have gratings which are subdivided into segments with associated photoelectric detectors for separately monitoring different street segments being detected by said imaging means.

12. The system of claim 8, having said correlation sensor systems monitoring the traffic path along several segments for incoming flow and having optical spectral filtering and electronic frequency sifting for sensing a moving blue flashing light vehicle and actuating switching means providing said vehicle with priority by means of computer controlled traffic lights.

13. The system of claim 1, for monitoring the safety of people and objects, having said optical means (1) and said photoelectric detectors (4, 5) which are adjustable to three-dimensional spaces inside or before said objects and which upon the entry of objects into said spaces activate electrical means following said photoelectric detectors for activating surveillance systems.

14. The system of claim 11, used for monitoring spaces before elevator enclosures, said electrical means activating doors of said elevator enclosures.

15. The system of claim 14, for controlling said elevator doors, said correlation sensor system controlling door closing divided into two measurement sectors, one for signalling the presence of persons in the segment near the door and the other one for recording persons moving towards the elevator in a segment farther away by means of a corresponding orientation of the spatial frequency filter grating and for transmitting the information of said movement to a logic circuit for controlling said door closing.

16. The system of claim 1, used for safety measures in machines and facilities safeguarding a 3-D potentially dangerous space by signalling penetration(s) into same and by actuating protective systems.