GB427462A - Improvements in electric discharge lamps - Google Patents

Abstract

427,462. Discharge lamps. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London.-(Assignees of Patent-Treuhand- Ges. fur Elektrische Gl³hlampen; 11, Ehrenbergstrasse, Berlin) Jan. 2, 1935, No. 167. Convention date, Jan. 4, 1934. [Class 39 (i)] In a lamp containing a substance emitting ultra - violet radiation such as mercury, magnesium or cadmium vapour and a rare gas such as neon, argon or helium, a luminescent screen either in or on or outside the valve envelope being caused to fluoresce by the radiation, the vapour pressure of the substance is arranged so low that the negative glow due to the rare gas takes effective part in forming the colour of the light and this glow will have an edging of light due to the discharge through substance, i.e. mercury &c. The required low pressure can be obtained by limiting the operating current or by admitting only a small quantity of mercury &c. to the envelope. The substance to be introduced may be contained in a side tube sealed to the envelope and heated, the vapour diffusing while a discharge takes place. With a luminescent layer of zinc silicate and a mercury and neon filling, the blue edging round the red neon glow will with the green fluorescence give a colour varying between white and yellow depending on the intensity of the blue edging. If calcium tungstate is used instead for the layer, a pinky, violet colour results. Two or more fluorescent materials may be used side by side or mixed together. The luminescent material may be contained in the glass forming the envelope.