Door control system providing automatic delayed door reversal

Claim 1

An automatic door control system for controlling a door, said door being located in a doorway having first and second sides, one side being an entrance side, the other side being an exit side, and having a travel lane passing through the doorway, said door being driven by an instantaneously electrically reversible motor, said door control system comprising: a treadle switch which is operated by a bell hose in response to a vehicle driving over the hose in the travel lane; treadle relay means having an actuation circuit which is completed by operation of the treadle switch; door open motor energizing relay means having a relay operated switch which completes an energization circuit for energizing the motor to open the door; reopen delay relay means having an actuation circuit which is completed by operation of the treadle relay except when the door is fully opened; a delay switch connected to the reopen delay relay to be energized by the operation of the reopen delay relay, said delay switch completing an actuation circuit for the open motor relay upon expiration of its delay period; a relay by-pass switch connected to the treadle relay and the open motor relay for immediately completing an energization circuit for the open motor relay when the delay by-pass switch is closed and the treadle relay operates, said delay by-pass switch being operated by a delay selection relay, said switch being closed when the door is fully closed and open at all other times; a light source means located on the first side of the doorway, said liGht source producing a beam of light extending across the travel lane to be interrupted by an object passing through the doorway; a photocell on the first side of the doorway and across the travel lane from the light source and positioned to receive the light beam; a photorelay control circuit for controlling a photorelay in response to the presence or absence of the light beam at the photocell, said photorelay control circuit being in a rest condition and the photorelay is actuated and the light beam is present at the photocell, said photorelay being de-actuated upon interruption of the light beam, said photorelay control circuit containing a timing device which prevents the photorelay from re-actuating in response to re-establishment of the light beam until after the expiration of a delay period, said timing device being reset to its rest condition by the operation of the treadle relay during the delay period; a close preset relay having an actuation circuit which is completed by de-actuation of the photorelay, and having a holding circuit which is broken by operation of the treadle relay; door close motor energizing relay means having an actuation circuit which is completed by re-action of the photorelay while the close preset relay is actuated, said actuation circuit being interrupted by de-actuation of the close preset relay and by de-actuation of the photorelay; a safety edge on the leading edge of the door for sensing the presence of an obstruction in the path of the closing door, said safety edge operating an emergency reverse switch upon striking an object; emergency reverse relay means having an actuating circuit which is completed by operation of the emergency reverse switch, said emergency reverse relay actuating the treadle relay to break the holding circuits of the close preset relay and the close motor relay to de-energize the motor from its door close condition, said emergency reverse relay also completing an actuation circuit for the open motor relay to instantaneously reverse the motor and reopen the door; an interlock relay having an actuation circuit which is completed by de-actuation of the photo-relay, except when the door is completely closed, said interlock relay operating an interlock switch which when closed completes an actuation circuit for the reopen delay relay, except when the door is fully open, whereby interruption of the light beam while the door is closing breaks the operating circuit for the close motor relay and operates the reopen delay relay to energize the delay switch to energize the open motor relay after a predetermined delay time whereby the closing door is stopped for a moment and then reopened.