Improvements in or relating to low-pressure mercury vapour positive column electric discharge lamps

摘要

706,004. Discharge lamps; luminescent materials. GENERAL ELECTRIC CO., Ltd., BOWTELL, J. N., JENKINS, H. G., and MILES, E. E. May 16, 1950 [June 8; 1949], No. 15289/49. Class 39(1) [Also in Group XI] Means for illumination comprises at least one low-pressure mercury vapour positive column fluorescent electric discharge lamp wherein the fluorescent material is such that the combined fluorescent and mercury light is a warm white light similar to that of a tungsten filament lamp, and includes a non-luminescent colour filter adapted to absorb light having wave lengths mainly in the region of the blue and violet lines at 4358 and 4047 A, the arrangement being such that the light emitted in normal operation is similar in appearance and colour rendering properties to the light emitted by a tungsten filament operating at a temperature within the range of 2300‹K to 2800‹K. The colour filter may be provided by a sleeve fitted around the envelope of the lamp or by a coating applied either internally or externally to the envelope of the lamp or may be carried as shown at 15 in Fig. 3 by a fitting 13 having an internal reflecting surface 14 and within which the lamp 16 is housed. The colour filter may comprise one or more dyes in a gelatine medium, or one or more acetone soluble dyes in a cellulose acetate medium or may comprise tinted glass such as a pale-yellowish lime-soda glass incorporating cadmium and sulphur or a paler yellow uranium glass. The glass may be powdered and applied as a coating to the envelope of the lamp or the envelope of the lamp may be formed from the tinted glass. The fluorescent material for the lamp may comprise a mixture of cadmium borate activated by manganese and orange-fluorescing calcium fluoro-chloro-phosphate activated by antimony and manganese in approximately equal proportions by weight, with or without a small proportion of zinc silicate activated by manangese. Specifications 463,755, 505,697, 529,576 and 29731/38, (as open to inspection under Sect. 91) are referred to.