×

Capacitive obstacle detector for vehicles in reverse gear

  • US 4,887,066 A
  • Filed: 06/11/1987
  • Issued: 12/12/1989
  • Est. Priority Date: 06/11/1986
  • Status: Expired due to Fees
First Claim
Patent Images

1. A capacitive proximity sensor assembly for motor vehicles comprising:

  • at least one capacitor plate which is fixed to a motor vehicle;

    means for measuring the capacitance existing between said at least one capacitor plate and the environment, the capacitance changing when the capacitor plate on the vehicle comes close to an object;

    said measuring means comprising a measuring device for measuring the capacitance of said capacitor plate against the environment;

    a differential amplifier;

    said measuring device having an input coupled to said at least one capacitor plate and an output coupled to one input of said differential amplifier;

    said differential amplifier having a degenerative feedback control loop comprising a storage device and a switch all coupled in series with an output of said differential amplifier and another input of said differential amplifier, such storage device being provided for storing an instantaneous degenerative feedback signal so that when said switch is opened, the difference between said feedback signal and the capacitance being sensed generates an output signal;

    a comparator;

    said output of said differential amplifier being coupled to one input of said comparator;

    an indicator for indicating that the capacitor plate is close to an object;

    an output of said comparator being coupled to said indicator;

    another input of said comparator being coupled to a reference signal; and

    control means for controlling opening and closing of said switch.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×