Average speed detection with flash illumination

Patent metadata

Field	Value
Publication number	US-9641806-B2
Application number	US-201313796534-A
Country	US
Kind code	B2
Filing date	Mar 12, 2013
Priority date	Mar 12, 2013
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

An average speed detection system includes a first automatic license plate reader (ALPR) camera having an infrared camera for capturing identification information from a vehicle passing an entrance point. A first communication module is coupled to the first ALPR camera for transmitting the identification information and either an entrance timestamp or an exit timestamp for the vehicle. A second ALPR camera includes an infrared camera and an overview camera is coupled to a second communication module. The second communication module receives the vehicle identification information and the reference time stamp from the first communication module. The infrared camera of the second ALPR camera captures identification information from the vehicle as it passes the exit point, and if the time at which the vehicle passes an exit point is prior to an exit timestamp for the vehicle, the overview camera flash illuminates the vehicle and captures an image of the vehicle.

First claim

What is claimed is:

1. An average speed detection camera system comprising:
a first automatic license plate reader (ALPR) camera having an infrared camera for capturing vehicle identification information from a vehicle passing an entrance point;
a first communication module coupled to the first ALPR camera for transmitting the vehicle identification information and either an entrance timestamp or an exit timestamp for the vehicle;
a second ALPR camera including an infrared camera and an overview camera which reside in a single unit, the second ALPR camera coupled to a second communication module, wherein the second communication module receives the vehicle identification information and transmitted time stamp from the first communication module; and
wherein the infrared camera of the second ALPR camera captures identification information from the vehicle as it passes an exit point irrespective of whether the time at which the vehicle passes the exit point is prior to the exit timestamp for the vehicle, and only if the time at which the vehicle passes an exit point is prior to the exit timestamp for the vehicle and the vehicle identification information received at the second communication module matches the identification information captured by the second ALPR camera, the overview camera flash illuminates the vehicle with visible light and the overview camera captures an image of the vehicle.

2. The system of claim 1 , wherein exit timestamp is the entrance timestamp increased by a minimum travel time between the first ALPR camera and the second ALPR camera.

3. The system of claim 2 , wherein the minimum travel time is the minimum time for a legal journey between an entrance and exit pair of cameras.

4. The system of claim 1 , wherein the first ALPR camera calculates the exit timestamp for the vehicle and the first communication module transmits the exit timestamp for the vehicle to the second communication module.

5. The system of claim 1 , wherein the first communication module transmits the entrance timestamp to the second communication module, and wherein the second ALPR camera calculates the exit timestamp for the vehicle.

6. The system of claim 1 , wherein the entrance point is the last point at which the first ALPR camera can capture identification information from the vehicle, and wherein the exit point is the first point at which the second ALPR camera can capture identification information from the vehicle.

7. The system of claim 1 , further comprising a third ALPR camera, wherein the communication module associated with the first ALPR camera further transmits the vehicle identification information and an exit timestamp for the vehicle to the third ALPR camera, and wherein the exit timestamp transmitted to the third ALPR camera is different from the exit timestamp transmitted to the second ALPR camera.

8. The system of claim 1 , wherein the first ALPR camera and second ALPR camera are part of a network of a plurality of ALPR cameras, wherein each ALPR camera in the network may be associated with both an entrance point and an exit point.

9. The system of claim 8 , wherein the network is controlled by a central processor, and wherein the processor is capable of dynamically changing calculations associated with exit timestamps and the network topology between the plurality of ALPR cameras.

10. The system of claim 1 , wherein the overview camera of the second ALPR camera is a color camera.

11. The system of claim 1 , wherein the communication module coupled to the second ALPR camera sends a message to the communication module coupled to the first ALPR camera instructing the first ALPR camera to send evidence of a violation to a central processor.

12. The system of claim 1 , wherein the first ALPR camera further comprises an overview camera.

13. The system of claim 1 , wherein the first communication module is an integrated component of the first ALPR camera.

14. The system of claim 1 , wherein the first communication module communicates with the second communication by means of a TCP/IP network.

15. The system of claim 1 , wherein the vehicle identification information is at least one of a license plate number or a barcode.

16. The system of claim 1 , wherein the flash illumination runs for less than one second.

17. A method of detecting average speed of a vehicle comprising:
capturing identification information for the vehicle with an infrared camera of a first automatic license plate reader (ALPR) camera as the vehicle passes an entrance point;
transmitting the identification information with either an entrance timestamp or an exit timestamp for the vehicle to a second communication module coupled to a second ALPR camera, the second ALPR camera including an infrared camera and an overview camera which reside in a single unit;
capturing the vehicle identification information with the infrared camera of the second ALPR camera as the vehicle passes an exit point irrespective of whether the time at which the vehicle passes the exit point is prior to the exit timestamp for the vehicle;
determining whether the time at which the vehicle passes the exit point is prior to the exit timestamp for the vehicle; and
only if the time at which the vehicle passes the exit point is prior to the exit timestamp for the vehicle and the vehicle identification information received at the second communication module matches the identification information captured by the second ALPR camera, flash illuminating the vehicle with visible light and capturing an image of the vehicle with the overview camera.

18. The method of claim 17 , wherein the exit timestamp is the entrance timestamp increased by a minimum travel time between the first ALPR camera and the second ALPR camera.

19. The method of claim 18 , wherein the minimum travel time is the minimum time for a legal journey between an entrance and exit pair of cameras.

20. The method of claim 17 , wherein the first ALPR camera calculates the exit timestamp for the vehicle and the first communication module transmits the exit timestamp for the vehicle to the second communication module.

21. The method of claim 17 , wherein the first communication module transmits the entrance timestamp to the second communication module, and wherein the second ALPR camera calculates the exit timestamp for the vehicle.

22. The method of claim 17 , wherein the entrance point is the last point at which the first ALPR camera can capture identification information from the vehicle, and wherein the exit point is the first point at which the second ALPR camera can capture identification information from the vehicle.

23. The method of claim 17 , wherein the overview camera of the second ALPR camera is a color camera.

24. The method of claim 17 , further comprising the second communication module transmitting the image of the vehicle captured by the overview camera to a central processor.

25. The method of claim 17 , wherein the first communication module communicates with the second communication by means of a TCP/IP network.

26. The method of claim 17 , wherein the vehicle identification information is at least one of a license plate number or a barcode.

27. The method of claim 17 , wherein the flash illumination runs for less than one second.

28. An average speed detection system comprising:
a first vehicle identification device for capturing identif

Assignees

• 3M Innovative Properties Co

Inventors

• Smith Brian

Classifications

• G08G1/054

  photographing overspeeding vehicles · CPC title

• G08G1/0175 Primary

  by photographing vehicles, e.g. when violating traffic rules · CPC title

• H04N7/18 Primary

  Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast · CPC title