GB433371A - Improvements in photo-electric control apparatus for escalators - Google Patents

Abstract

433,371. Escalators. BRITISH THOMSON - HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Allgemeine Elektricitõts-Ges.; 2, Friedrich Karl- Ufer, Berlin) Feb. 2, 1934, Nos. 3503, 3504, and 3505. Convention dates, Feb. 2, 1933, Feb. 3, 1933, and Feb. 4, 1933. [Class 78 (i)] [See also Group XXXVII] In order that an escalator may run only when required by a passenger, control mechanism is provided which is actuated by the interruption of a beam of light directed upon a photoelectric cell by an approaching passenger. Light from a source 11 is directed on to a photo-electric cell 10, the output from which is amplified by means 13, such as a thermionic amplifier. The output circuit of the amplifier contains a coil 9 which is energized to close momentarily the contacts 1, 2 when current flow through the cell 10 is interrupted. When contacts 1 close, relay 7 is energized momentarily, and the closure of its contacts effects the energization of the operating coil 17 of the circuit-breaker 14, thereby causing the starting of the motor 15. Relay 7 is kept closed by current through the resistance 6. When contacts 2 close, relay 5 is energized momentarily and its contacts opened. After the passenger has passed through the light beam, the relay 9 is de-energized and the contacts 1, 2 opened, thereby causing the closing of the contacts of relay 5 and the energization of the time relay 8. The contacts 3 of the relay 8 close after a period of time designed to allow the passenger to be conveyed to the end of the escalator, and relay 4 becomes energized, thereby breaking the control circuit which includes the contact 1. The coil 17 is thus de-energized, and the motor stopped with the circuits in condition for a further cycle of operations. In order to reduce the number of actuations of the relay 8 when passengers are numerous, the energizing circuit of the relay 9 is interrupted for a predetermined period after its energization by a further time relay 19, the coil of which is energized simultaneously with the winding of relay 8. The normally closed contacts of the relay 19 are in series with the coil of a relay 18, the contacts of which are in the output circuit of the amplifier. Reference has been directed by the Comptroller to French Specification 721,369.