GB431451A - Improvements in electric discharge tubes - Google Patents

Abstract

431,451. Discharge apparatus. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN, Emmasingel, Eindhoven, Holland. Feb. 27, 1935, No. 6232. Convention date, Feb. 16. [Class 39 (i)] A tube comprises solid, incandescent, preferably dischargeheated electrodes, a mercury and gas filling and has an internal diameter less than 7 mms., and the consumption of energy lies between 15 and 135 watts per cm. length of the tube, the dissipation of heat and the shape of the tube being so adapted to one another that the mercury vapour pressure is higher than 10 atmospheres during operation. The internal diameter may be less than 4 mms. If the tube is operated in a vertical position the distance between the upper electrode and the upper end of the tube should be greater than the distance between the lower electrode and the lower end of the tube. The lead-in wires may be sealed into a quartz tube by means of an intermediate glass, as described in Specifications 431,450 and 431,923. In one arrangement, Fig. 8, a quartz lamp 1 has electrodes 2 consisting of tungsten hooks wrapped with fine tungsten wire and then coated with alkaline earth oxide. The leads 4 are surrounded by magnesium oxide tubes 5 and are connected to metal caps 6 sliding in sleeves 7, 8. A spring 9 facilitates removal of the tube. The sleeves 7, 8 are connected to contacts 13 on a porcelain cap 12 which carries a copper ring 15 supporting a thick hard glass cylinder 14 which may have. apertures at the top and bottom. In a modification, the lamp may be permanently connected by its leads to a cap which carries an apertured reflector and an apertured globe. In another modification, the leads of the lamp are sealed in the pinch of an outer globe which may be apertured or filled with nitrogen. The lamp may be U-shaped. The filling may consist of argon at 10 mms. and mercury vapour at a pressure of 30, 75, 80 or 85 atmospheres. The lamp may be surrounded by a netting or coil of nickel-chromium which may be connected to an electrode to assist ignition. Platinum reflecting layers may be secured to the ends of the lamp and their size may be adjusted to give the desired pressure for a desired voltage.