AUTOMATIC DOOR CONTROL UNIT

摘要

An automatic door control unit for connection to an operating mat and a safety mat to actuate the unit. The unit includes an amplifier connected to the operating mat to provide a signal actuating a door operating relay, and the amplifier includes an input impedance forming a network decreasing sensitivity to operating mat degradation of resistance. A transistor circuit is connected across the amplifier unit and controlled by the safety mat to prevent operation of the amplifier. The safety mat actuates the transistor circuit when the door is closed and there is traffic on the safety mat. The transistor circuit includes an impedance forming a network decreasing sensitivity to safety mat degradation of resistance and further includes a Zener diode at the input thereof to provide a barrier to voltage resulting from open circuit safety mat resistance degradation. There is a separate time delay associated with the operating mat and with the safety mat.