GB697087A - Fluorescent discharge lamp - Google Patents

Abstract

697,087. Discharge lamps. GRABER, H. Dec. 28, 1949 [Dec. 28, 1948], No. 33160/49. Class 39(i) A discharge lamp (Fig. 1) comprises coaxial inner and outer cylindrical vessels 2, 1 with a single and continuous insulating ribbon 9 arranged spirally and edgewise in tight contact with the vessels to form a helical discharge path at the ends of which are the electrodes 10, 11, fluorescent material covering at least a part of the inner wall of the outer tube, a filling of at least one rare gas and a metal vapour at low pressure in the space between the vessels, and an incandescent filament in the inner cylinder. The two vessels may be interconnected or the inner one filled with a gas e.g. nitrogen or argon at the usual incandescent lamp pressure. The discharge filling may be argon or krypton and mercury. The incandescent filament 12 serves as a ballast resistance in the electrode circuit of the lamp, and is connected to the middle contact 13 of the socket 8 and the electrode 11 respectively. In larger lamps the inner vessel 2 may be bottle-shaped with a restricted neck and a broad flange which is afterward sealed to the outer vessel. In a modification, Fig. 2 (not shown), the supply lead to the incandescent filament passes through a long glass tube in the inner vessel 1. The fluorescent material has a predominantly green emission to compensate for the red emission of the filament. When the two vessels are interconnected, the filament may require special screening to prevent arcing.