Gasgefüllte elektrische Glühlampe

357,252. Electric incandescent lamps. LEDERER, A., Hermesville, Vienna. June 21, 1930, No. 18993. Convention date, June 25, 1929. [Class 39 (ii).] An electric lamp comprises a glass envelope with a filling of a rare gas at a pressure of 0À5- 50À0 mm. of mercury, at least one filament adapted to be heated electrically to incandescence, and at least one electrode which emits electrons when heated to a temperature lower than that of the filament, the nature and mutual distance of the electrodes, and the gaseous conditions being such that, illumination is provided simultaneously by the incandescent filament and luminous discharge from the electrode. In one form adapted for direct current working, the incandescent filament b, Fig. 1, provided with a leading-in wire a, is connected to a supporting-wire c which is connected to the other leading-in wire d, and a small tube e of nickel or the like provided with a thermionically active layer surrounds the lower end of the filament, the tube being electrically connected to the leading-in wire a. Passage of current produces a luminous discharge between the electrodes e, c. Alternatively the tube e may be omitted, and a part of the filament, preferably the part adjacent to the leading-in wire, coated with materials such as alkaline-earth oxides for the production of the luminous discharge, this portion of the wire being formed of a larger cross section to avoid over-heating. In a modification for alternating current work, two incandescent filaments f, g, Fig. 2, are carried by leading-in wires h, i and a common support k, the lower ends of the filaments being surrounded by, and connected to, short tubes l, m coated with a thermionically active layer. Preferably the electrodes l, m are provided with projecting portions of wire or strip metal which extend towards one another and protect the electrodes by taking up the electron current. Discharge within a glass tube may be effected by arranging a filament in each of two bulbs connected by a transverse tube, or a filament extending the whole length of a tube may have its ends offset at right-angles and surrounded by oxide-coated metal tubes.