Automatic door control unit

Claim 2

An automatic door control unit for controlling the opening and closing of a power operated door in accordance with the state of a traffic responsive operating mat and a traffic responsive safety mat positioned one on each side of the door, each mat having a closed state where the resistance under ideal conditions is substantially zero and an open state where the resistance under ideal conditions is substantially infinite, the mats being subject to degradation of resistance values with use, said unit comprising amplifier means having an input and an output, a door operating relay connected to said output and being responsive to a signal at said output to change from a door closed to a door opened state, a first impedance connected to said input and including means for connection to said operating mat to form a network decreasing the operating mat resistance degradation sensitivity of the unit, a transistor circuit connected across said input and having a non-conducting and a conducting state, said transistor circuit in its conducting state preventing operation of said amplifier means to actuate said relay to said door opened state, a second impedance connected to said transistor circuit and including means for connection to said safety mat to form a network decreasing safety mat resistance degradation sensitivity, a Zener diode and a diode series connected in back to back relationship between said second impedance and said transistor circuit to provide a barrier to voltage resulting from open state safety mat resistance degradation to a predetermined value.

Claim 3

An automatic door control unit as defined in claim 1 in which said first and second impedances are resistances and in which the value of the resistance is between the lowest permissible degraded open state resistance and the highest permissible degraded closed state resistance presented at the respective means for connection to said operating mat and to said safety mat.

Claim 4

An automatic door control unit for controlling the opening and closing of a power operated door in accordance with the state of a traffic responsive operating mat and a traffic responsive safety mat positioned one on each side of a door where the traffic flow is over the operating mat, through the door; and over the safety mat, amplifier means having an input and an output, a door operating relay connected to said output and being responsive to a signal at said output to change from a door closed to a door opened state, an operating mat connection means connected to said input of said amplifier means and being responsive to a resistance change from a first value to a second value to provide said signal at said output, a first delay network connected to said input of said amplifier means for continuing said signal at said output for a predetermined time after a reversal of said resistance change from said second value to said first value, a transistor circuit connected across said input of said amplifier means and having a non-conducting and a conducting state, said transistor circuit in its conducting state preventing operation of said amplifier means to actuate said relay to said door opened state, a safety mat connection means connected to said transistor circuit switching said transistor circuit to said conducting state, in response to a resistance change from a first value to a second value, and a second delay network connected to said transistor circuit for retaining said transistor circuit in its conducting state for a predetermined time after a reversal of said resistance change from said second value to said first value.

Claim 5

An automatic door control unit for controlling the opening and closing of a power operated door in accordance with the state of a traffic responsive operating mat and a traffic responsive safety mat positioned one on each side of a door where the traffic flow is over the operating mat, through the door; and over the safety mat, amplifier means having an input and an output, a door operating relay connected to said output and being responsive to a signal at said output to change from a door closed to a door opened state, an operating mat connection means connected to said input of said amplifier means and being responsive to a resistance change from a first value to a second value to provide said signal at said output, a first delay network connected to said input of said amplifier means for continuing said signal at said output for a predetermined time after a reversal of said resistance change from said second value to said first value, a transistor circuit connected across said input of said amplifier means and having a non-conducting and a conducting state, said transistor circuit in its conducting state preventing operation of said amplifier means to actuate said relay to said door opened state, a safety mat connection means connected to said transistor circuit switching said transistor circuit to said conducting state, in response to a resistance change from a first value to a second value, and a second delay network connected to said transistor circuit for retaining said transistor circuit in its conducting state for a predetermined time after a reversal of said resistance change from said second value to said first value.