Abstract: A method and apparatus for automatically controlling the movement of a door over a floor from an open position to a closed position with respect to a door frame, by mounting ultrasonic transmitters at one side of the door frame and oriented to transmit ultrasonic energy downwardly towards the floor and to reflect the energy from the floor upwardly upwardly at the other side of the door frame; mounting ultrasonic receivers over the door frame at the opposite side and oriented to receive the energy from the ultrasonic transmitter reflected by the floor; and processing the reflected energy received by the ultrasonic receiver to detect the presence of an object in the path of the door, when moving toward its closed position, and to automatically interrupt the closing of the door.

Abstract: Method and apparatus for automatically controlling the opening and closing of a door by: (a) ultrasonically monitoring a predetermined approach area located in front of the door for the entry of an object into the approach area and the movement of the object towards the closed door; (b) ultrasonically monitoring a predetermined opening-door protect area laterally outwardly of the outer end of the closed door, and a predetermined closing-door protect area inwardly of the inner end of the door for the presence of an object in the opening-door and closing-door protect areas; and (c) controlling a drive in response to the above monitoring operations.