GB227149A - Improvements relating to flash illumination - Google Patents

Abstract

227,149. Kapitza, P., and Heath, Sir H. F. Sept. 5, 1923. Arc lamps; low-pressure metallic-vapour apparatus.-An arc lamp or mercury-vapour lamp is operated by a storage battery of the kind described in Specification 226,857, [Class 53, Galvanic batteries], capable of giving a current of several thousand amperes for a fraction of a second, so as to produce momentary flashes of high candle-power. In the system shown the battery 5 is connected through a rheostat 3 and ammeter 4 to the terminals 1, 2 of a supply system. One electrode 6 of the arc lamp is connected to one pole of the battery and the other electrode 7 is connected to the other pole through a switch 8. The electrode 7 is also connected to the terminal 1 through a resistance 9. While the switch 8 is open, the battery is being charged and a weak arc is maintained. When the switch is closed the battery is discharged through the arc, producing a flash. The switch preferably comprises a laminar pole formed of a number of yoke-shaped copper strips secured together side by side. The electrodes are of carbon and are preferably electroplated. The leads thereto may be ¢ to 1 sq. cm. in crosssection. Where a mercury vapour lamp is used the container should be a thick quartz tube. The battery circuit is preferably broken before complete discharge to prevent sulphating. To effect this the main switch, which falls under the action of a strong spring to close the circuit, mechanically operates during its fall a trigger releasing a strong spring which effects the opening of the second switch. The interval between closure and opening of the circuit may be controlled by regulation of the link mechanism connecting the first switch with the trigger. The second switch may be coupled with a fuse wire which performs the actual break.