GB353776A - Improvements in or relating to the control of doors - Google Patents

Abstract

353,776. Operating doors electrically. LYONS & CO., Ltd., J., Cadby Hall, DOUG. LASS, P. G., 12, Auriol Man. sions, both in Kensington, and PASSMORE, C. R., Ardneil, Oakleigh Park, Whetstone, both in London. Sept. 30, 1930, No. 29249. [Class 65 (i).] An electrically operated door is opened in response to the interruption of a beam of light falling on a light-sensitive cell, caused by a person approaching the door. The door remains open for a predetermined interval after the interruption of the light or after any subsequent interrup. tion during this interval. When light from a lamp 2 is momentarily cut off from the light-sensitive cell 3, the variation in the current in the cell, amplified by the thermionic valve 23, energizes a pilot relay 4 to close a contact 4b for a moment. The closing of this contact completes a circuit from mains L to a coil 5a, which closes a contact 5b. This contact completes the circuit for a relay 15, and through the contact of a relay 6 to a time relay 19. Relay 15 energizes a solenoid 1, which opens the door against the action of a spring. After a predetermined interval, the contact of relay 19 closes and energizes a coil 5d, which attracts the armature 5c and opens contact 5b, thus de-energizing relay 15 ; the solenoid 1 is therefore de-energized, and the door closes ; relay 19 is also de-energized, and returns immediately to its initial position. The closing of contact 4b will also momentarily energize the relay 6, and the contact of this relay will open for a moment; this has no effect on the operation described, but if the beam of light is interrupted a second time during the operation, the relay 6 will again be energized momentarily and will break the circuit of the time relay 19 ; the relay 19 will therefore drop, and will not close its contact until the correct time has elapsed after the second interruption of the light. The door will therefore remain open for a number of persons following one another. The coil 5a is made stronger than 5d, so that in case of simultaneous energization of these two coils the armature 5c will remain against contact 5b.