×

Proximity detectors with dual-speed tracking circuitry

  • US 4,973,837 A
  • Filed: 02/09/1989
  • Issued: 11/27/1990
  • Est. Priority Date: 08/13/1986
  • Status: Expired due to Fees
First Claim
Patent Images

1. A proximity detector comprising a sensor unit arranged to sense reflected energy received from a predetermined volume or zone and to generate a signal representative of the received energy and circuit means for processing said received signals to control operation of apparatus such a automatic doors, said circuit means including means for generating a signal representative of the signal received by said sensor unit, means sensing when the received signal changes, and means for controlling operation of the apparatus in response to a sensed change, characterised in that the sensing means includes a comparator for comparing the representative signal with a voltage signal, said comparator being arranged to assume a given state when the representative signal varies from said voltage signal, and circuit means associated with said comparator for causing said voltage signal to follow or track changes in said representative signal in a predefined way, and the arrangement being such that when the representative signal changes in a first direction the voltage signal is arranged to follow the change relatively slowly and when the representative signal changes in the opposite direction the voltage signal is arranged to follow the change relatively rapidly.

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