GB1044839A - Improvements in and relating to means for opening and closing garage doors - Google Patents

Abstract

1,044,839. Control of A.C. motors. B. J. LUKES. June 28, 1963 [July 2, 1962], No. 25248/62. Heading H2J. [Also in Divisions E2 and G1] Control means for opening and closing garage doors comprises a door-actuating mechanism driven by a motor in circuit with an operating switch or switches operable by the passage of a vehicle, a switching device being actuated by the doors to condition the motor circuit for door closing or opening when the doors are in their open or closed positions respectively. Rotary motion of the motor shaft 10 of a reversible electric motor M, Fig. 7, is converted, by way of a universal joint and a screw 11, Fig. 4, engaging a nut having a tubular extension 13, to axial displacement of the tubular extension 13 which carries a ball joint 14. The ball joint 14 is connected to a lever 15 which moves two bell cranks 16 about fixed pivots 21 to open or close the garage doors 19 through levers 17. Two photo-transistors OS2 and OS1, Fig. 1, mounted on the garage door and on the rear wall of the garage respectively, are operable by car headlights so that OS2 opens the doors and OS1 closes or opens the doors behind the car in the garage. A manually operable switch OS3 is also provided for this purpose. When any one of these switches is closed, the bias on a transistor TR2 drops to zero, and therefore TR2 is cut off and its collector voltage rises. This causes a negative pulse to be transmitted through a condenser C1 to the base of an amplifying transistor TR1, which then conducts to energize a relay SR which remains energized through contacts SR2 and switches SW2, SW3 and closes the motor circuit at switch SR1. The drive direction of the motor depends upon the position of changeover switch contacts COS1 and COS2, which are actuated by a system of levers and springs, Fig. 2 (not shown) to turn the change-over switch operating spindle according to the position of the doors so that the motor circuit is conditioned as described above. A switch SW1 in the emitter circuit of OS2 can be left open so that the doors cannot be opened from the outside. The motor M is mounted in a U frame 27, Fig. 7, between resilient packing pieces 28 through which the operating spindles of switches SW2, SW3 extend. In the event of an object obstructing movement of the doors, the motor will move on its resilient mounting to open either SW2 or SW3 to break the " holdon " condition of relay SR and thus stop the motor M. A switch SW4 is mounted so that its operating spindle 25 is engaged by the closed door so that tampering of the doors closes SW4 and operates an alarm I through contacts COS3 and SR2.