Patent GB-405683-A (GB)
Title: Method of and means for operating incandescent electric lamps or like electric apparatus containing incandescent bodies
IPC: H01K1/50
Filed: 1932-08-10
Abstract: 405,683. Electric incandescent lamps ; discharge tubes ; furnaces &c. SKAUPY, F., 27, Paulinenstrasse, Lichterfelde, Berlin. Aug. 10, 1932, No. 22388. Convention date, Aug. 15, 1931. [Classes 39 (ii) and 39 (iii).] An electric incandescent lamp or like apparatus containing a body such as a filament, refractory tube, or the like, which is rendered incandescent by the passage of electric current, comprises a vessel in communication with the atmosphere and containing mercury, with current leads extending into the vessel to the body to be rendered incandescent, the vessel being adapted to be heated to vaporise the mercury to replace the air so that the incandescent body glows in an atmosphere of mercury vapour, thereby enabling heavy currents to be used and preventing oxidation &c. Rectifiers and amplifying and transmitting valves with three or more electrodes may comprise an incandescent cathode operated in mercury vapour which is open to the atmosphere. Fig. 1 shows an electric incandescent lamp wherein a glass bulb a which is open to the atmosphere is provided with a filament e detachably supported by two rods d passing through an insulating plug c, a quantity of mercury b being provided as a source of mercury vapour which is generated by the application of external heat, for example by a gas flame, before the electric current is switched on. The current may be switched on automatically by a thermostat mounted within the bulb and arranged to become operative when a definite amount of mercury vapour has been evolved. A tubular heating element of carbon, tungsten, or tantalum carbide connected across the lower ends of the leading-in conductors may be rendered incandescent by the passage of the current, so that a crucible, boat, or other receptacle inserted within the tubular element is subjected to a high temperature in the mercury vapour atmosphere. Fig. 4 shows a high candle power electric incandescent lamp wherein a thick filament c is supported on metal rods b within a quartz bulb a which is shaped at its bottom portion to receive a quantity of mercury and a heating-element n submerged therein, separate leads o<1>, 02 being connected to the latter from the supply terminals. The bulb a is secured to an upper chamber g by a screwed coupling i which presses a flange w at the top of the bulb on to an insulating body d in the chamber g. Mounted just above the filament is an insulating body e which occupies the entire cross section of the tube with the exception of two longitudinal slots, and carries a bimetallic strip p and contact therefor. The lamp bulb communicates with the atmosphere through a tube passing through the insulating body d to a series of absorption vessels m<1>-m<3>, respectively containing a medium for absorbing mercury vapours tending to pass out of the vessel, a drying medium, and a medium for absorbing oxygen from the air entering the vessel. The bimetallic strip controls a solenoid circuit which operates an armature to make or break the filament circuit. The filament c, Fig. 5, may be made of thick molybdenum wire and secured within holes in the current-conducting rods b by metal wedges v<3>. A central supporting wire v<2> is carried by an insulating member f bridging the rods b.