GB450287A - Improvements in and relating to photo-electric relay systems - Google Patents

Abstract

450,287. Controlling apparatus by light. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London. Oct. 17, 1935, No. 28721. Convention date, Oct. 17, 1934. [Class 40 (v)] A relay is operated when a cell is illuminated by the main beam and an auxiliary beam which is controlled by the main beam falling on the cell. Where the relay is to be operated on the illumination of the cell, the main beam falling on the cell 2, Fig. 6, produces corresponding current in the valve 4 which is sufficient to ignite the lamp 5 but insufficient to actuate the relay 7. The auxiliary beam from lamp 5 falls on the cell 2 so that the current through the valve 4 increases to actuate the relay 7 which opens contacts 7<1> de-energizing the lamp 5 and closes contacts 7<11> actuating a counter 8. The cell is thus unilluminated, the main beam having passed off, and the relay is de-energized to prepare the circuit for the next illumination of the cell. Where the relay is to be operated by an occultation of the main beam, the cell 2, Fig. 7, is normally illuminated by both the main beam and the auxiliary beam from lamp 5 and the relay is actuated to open contacts 7<1>, 7<11>. When an occultation of the main beam occurs, the current through the valve 4 is insufficient to maintain the ignition of the lamp 5 and the actuation of the relav 7. The auxiliary beam disappears and the main beam when it re-appears is insufficient to maintain the relay 7 actuated, so that the relay is deenergized to close contacts 7<1> and re-ignite the lamp 5 and close contacts 7<11> to actuate the recorder. The relay cannot be energized over contact 7<1> because of the rectifier 14. The cell is now illuminated by both the main and auxiliary beams so that relay 7 is actuated and the circuit prepared for the next interruption of the main beam. The circuits are stated to be operable by extremely short illuminations or occultations of the cell. Where it is desired to record only illuminations or interruptions longer than a predetermined minimum, the lamps 5 are replaced by filament lamps whose light will only appear or disappear after a predetermined duration or interruption of current.