APPARATUS FOR DETECTING TRAFFIC INFORMATION

• US 3,639,894 A
• Filed: 02/11/1970
• Issued: 02/01/1972
• Est. Priority Date: 02/19/1969
• Status: Expired due to Term

• Current Assignee: Ryohei Tanaka
• Original Assignee: Ryohei Tanaka
• Inventors: Tanaka, Ryohei
• Primary Examiner(s): Cooper, William C.
• Application Number:
  US05/010,404
• Time in Patent Office: 720 Days
• Field of Search: 340/31R,38R,38L
• US Class Current: 340/938
• CPC Class Codes: G08G 1/042 using inductive or magnetic detectors

Abstract

An apparatus for detecting traffic information on a street, which includes a vehicle detector provided with a plurality of vehicle-detecting elements having their respective predetermined detection areas on the street. One of the detecting elements is always operatively connected to the detector to provide for the detector a detection area extending a minimum distance or length along the street in the direction in which vehicles run, for measurement of traffic information under the normal traffic condition; while the other detecting elements are selectively and additionally connected to the detector to increase the distance of the detection area of the detector for measurement under stagnated traffic conditions.

Claims

1. An apparatus for detecting traffic information on a street, comprising:

a vehicle detector having a detection area on said street and being operable in response to a vehicle in said detection area to produce a detection signal;

means for substantially changing the length of said detection area in the direction in which vehicles run on said street in accordance with the traffic condition on said street; and

means for providing an output signal proportional to traffic information in response to said detection signal.

2. The apparatus of claim 1, wherein said vehicle detector is provided with a plurality of detecting elements, each of said detecting elements having a respective detection area and said changing means changes the number of said detecting elements that are to be operatively connected to said detector.

3. The apparatus of claim 1, wherein said changing means is manually operable.

4. The apparatus of claim 1, wherein said changing means is automatically operable in response to the magnitude of said output signal.

5. The apparatus of claim 1, wherein said traffic condition is the degree of stagnation on said street.

6. The apparatus of claim 1, wherein said vehicle detector has a plurality of detecting elements each of said detecting elements having a respective detection area, one on which is always operatively connected to said detector while the others thereof are selectively connectable to said detector, and said detection area length changing means comprises switching means interposed between said detector and said other detecting elements to selectively connect the latter to said detector in addition to said one detecting element, thereby varying the number of detecting elements operatively connected to said detector and consequently said detection area length.

7. The apparatus of claim 6, wherein said traffic condition is the degree of traffic stagnation on said street, and further including means for producing an operating signal whenever said stagnation has reached a predetermined degree, said operating signal being applied to said switching means to operate the same.

8. The apparatus of claim 1, wherein said traffic information providing means is means for measuring the time occupancy of said detection area on said street.

9. The apparatus of claim 6, wherein said respective detection area are of substantially the same length in the direction in which vehicles run along said street and are arranged side by side in said direction on said street.

10. The apparatus of claim 6, wherein said respective detection areas are different in length in the direction in which vehicles run on said street and are arranged so that each said detection area encloses therein the next smaller one of said detection areas.

11. The apparatus of claim 1, whereIn said vehicle detector is provided with a plurality of detecting elements having detection areas on said street each different from the others in length in the direction in which vehicles run on said street, and said detection area-length-changing means comprises means for selectively connecting one of said elements to said detector.

12. The apparatus of claim 1, further including means for compensating the output signal from said traffic information providing means for changes in said detection area when said detection area length has been changed.