REAR END WARNING SYSTEM FOR AUTOMOBILES

• US 3,697,985 A
• Filed: 09/23/1970
• Issued: 10/10/1972
• Est. Priority Date: 09/23/1970
• Status: Expired due to Term

• Current Assignee: William P. Harokopus, William R. Faris
• Original Assignee: William P. Harokopus, William R. Faris
• Inventors: Faris, William R., Harokopus, William P.
• Primary Examiner(s): Borchelt, Benjamin A.
• Assistant Examiner(s): Moskowitz, N.
• Application Number:
  US05/074,755
• Time in Patent Office: 748 Days
• Field of Search: 343/5PD,7ED,9,12A 180/82,82.1,98 340/32-34
• US Class Current: 342/72
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/9315 Monitoring blind spots
• CPC Class Codes: G01S 2013/9317 Driving backwards
• CPC Class Codes: G01S 2013/93274 on the side of the vehicles

Abstract

The invention is directed to a system which provides an audible or visual indication to a motor vehicle operator when another vehicle approaches the rear end of his vehicle in an adjacent lane or when a potentially interferring object is located behind the vehicle when backing up. The system covers the blind spots which are present on the right and left sides of the vehicle because of the inherent inadequacies of rearview mirrors and also the invisible area at the rear of the vehicle. A range measuring doppler radar system has its antenna positioned to cover the area which lies on the two sides and behind a vehicle and which normally is within the well known blind spot. The radar system is squarewave modulated to sequentially produce two frequencies F1 and F2. Reflected signals from a moving target produce two doppler signals fd1 and fd2. The comparison of the relevant phases of the two doppler frequencies gives range information. The leading and lagging relationship of the doppler signals is indicative of whether the target is closing or opening with respect to the radar carrying base vehicle. The system is, therefore, readily made responsive to closing targets or slowly opening targets falling within a dangerously close range as the vehicle proceeds along a roadway. Fixed objects such as poles and signs along the road are also prevented from giving a warning signal by the phase information. When the vehicle is backing up, objects or persons present behind the vehicle are detected and a warning given.

Claims

1. A doppler radar system for detecting the presence of targets within a selected range and angular field of view behind a moving base vehicle comprising:

an antenna system physically located on said base vehicle and arranged to transmit energy rearwardly of said base vehicle and receive reflected energy from targets present within said selected angular field of view;

a doppler radar system for energizing said antenna and receiving energy reflected from said targets;

modulation means for modulating said radar system so that said transmitted energy contains two discrete frequencies which sequentially compose said transmitted signal;

mixing means for mixing the reflected energy with said transmitted energy to form a composite signal, said composite signal having a first envelope defining a first doppler frequency, and a second envelope defining a second doppler frequency, the phase relationship of said first and second envelopes representing the range of said targets and the leading-lagging relationship of said envelopes being indicative of the closing and opening relationship of said base vehicle and said targets;

a warning device; and

means for yielding a warning signal representative of said phase relationship to said warning device, said means for yielding being polarity and amplitude responsive so that warning signals representing closing and slowly opening targets within said angular field of view actuate said warning device.

2. The system of claim 1 wherein said base vehicle includes a rearview mirror system and said angular field of view is selected to cover the blind spot of said mirror system.

3. The system of claim 1 wherein said antenna system includes two antennas having similar characteristics respectively located on opposite sides of said base vehicle.

4. The system of claim 1 wherein said means for yielding includes a phase comparator for comparing the phase relationship of said doppler signals, the polarity of the output of said phase comparator being positive when one of said doppler frequencies is leading and negative when the other of said doppler frequencies is leading.

5. The system of claim 4 wherein said means for yielding including a warning actuator receiving the output of said phase comparator, said warning actuator responding only to signals representing closing targets located within said selected range of said base vehicle.

6. The system of claim 5 wherein said antenna system includes two antennas having similar characteristics respectively arranged on the sides of said base vehicle.

7. The system of claim 6 wherein said antennas are designed and arranged so that said selected field of view is covered by said antennas, and said field of view is similar to the blind spot area of a mirror system provided for said base vehicle.

8. A doppler radar system for detecting objects behind a rearwardly moving vehicle comprising:

an antenna system having a field of view coincident with the area behind said vehicle which is normally invisible to the operator of said vehicle;

a radar system for transmitting energy and receiving said reflected energy from objects behind said vehicles;

warning signal means for giving a warning indication when an object is within said field of view; and

threshold means for rendering said system insensitive to targets beyond a preselected range.

9. The system of claim 8 including tuning means for establishing a maximum sensitivity for said system.

10. The system of claim 8 wherein said radar system includes a Gunn diode;

said Gunn diode generating said transmitted energy and mixing said transmitted eneRgy with said reflected energy to produce a doppler signal.