OPTICAL DETECTING AND RANGING SYSTEM FOR AUTOMOTIVE VEHICLES

• US 3,604,805 A
• Filed: 07/07/1969
• Issued: 09/14/1971
• Est. Priority Date: 07/07/1969
• Status: Expired due to Term

• Current Assignee: Gerald C. Scott
• Original Assignee: Gerald C. Scott
• Inventors: Scott, Gerald C.
• Primary Examiner(s): Hubler, Malcolm F.
• Application Number:
  US04/839,346
• Time in Patent Office: 799 Days
• Field of Search: 343/8 356/5,28
• US Class Current: 356/28
• CPC Class Codes: G01S 17/931 of land vehicles

Abstract

A mechanical automatic gain control for a high-frequency detecting and ranging system of the short range type in which the axis of the transmitter is displaced relative to the axis of the receiver to linearize the strength of the received signal over the operating ranges of the system. The system may be used as a range or range rate finder in automotive vehicles in order to determine the distance or range and the range rate or relative velocity between a vehicle in which the system is located and the preceding vehicle. The transmitter transmits high-frequency electromagnetic energy, preferably in the infrared region, toward the rear of the preceding vehicle. This electromagnetic energy is reflected by the reflective lens systems found on the rear of conventional vehicles directionally back toward the transmitter. A small portion of this energy finds its way to the receiver which, as stated above, is displaced from the transmitter. It has been found that the strength or amplitude of the received signal does not vary inversely with the fourth power of the range, as is the case in conventional detecting and ranging systems, but may vary from values of 10 to 100.

Claims

1. A high frequency detecting and ranging system for use in an automotive vehicle, comprising a transmitter and a receiver, said transmitter mounted on said automotive vehicle in a position to direct electromagnetic energy having a wave length in the optical region of the electromagnetic spectrum in the direction of forward movement of the vehicle and onto a target comprised of a pair of spaced optical retroreflectors of a preceding vehicle, said receiver being mounted on said automotive vehicle and separated from said transmitter so that the receiver is displaced from the transmitting axis of said transmitter by a predetermined distance whereby said receiver receives electromagnetic energy having a limited ratio in strength as the range between the system and the target changes.

2. The combination of claim 1 in which said predetermined distance is measured in a direction transverse to the longitudinal axis of said automotive vehicle.

3. The combination of claim 2 in which said transmitter and receiver are located in a plane substantially transverse to said longitudinal axis and the direction of movement of said vehicle.

4. In an automotive detecting and ranging system, an automotive vehicle, a transmitting means mounted on said automotive vehicle for directing electromagnetic radiation having a wave length between about 1.6 mm. and 4 X 10 4 mm. in a direction of forward movement of said automotive vehicle, a receiving means mounted on said automotive vehicle in a position displaced from the axis of said transmitting means, a target for receiving and reflecting the electromagnetic energy transmitted by said transmitting means, said target comprising the optical reflectors positioned on the rearwardly facing portion of a preceding automotive vehicle, said optical reflectors including means for directionally reflecting light back to said transmitter in a direction along the transmitting axis thereof whereby said receiving means receives electromagnetic energy having a limited ratio in strength as the range between the system and the target changes.

5. The combination of claim 4 in which the wavelength of the electromagnetic radiation falls in the nonvisible infrared region of the electromagnetic spectrum.

6. The combination of claim 4 in which the displacement of said receiving means from said transmitting means is measured in a direction transverse to the longitudinal axis of the automotive vehicle.

7. The combination of claim 5 in which the limited ratio in strength varies inversely as a function of the displacement of said receiving means from the axis of said transmitting means.

8. The combination of claim 7 in which the wave length of the electromagnetic radiation falls in the nonvisible infrared region of the electromagnetic spectrum.