New Discharge Bulb Lamps

Abstract

THE new discharge bulb lamps are already in use on the Continent, and fudging from the fact that they were shown at a meeting of the Illuminating Engineering Society on October 13, they will probably be soon on sale in Great Britain. In appearance, they are like the ordinary ‘pearl’ lamp but they have no filament. They contain a small quartz mercury vapour discharge lamp “about the size of half a cigarette” and they are corrected for colour. Internally the bulb is coated with a fluorescent powder, in the same way as the lower area of the inside of the cathode ray tube, where the picture is shown in television reception. According to the Electrical Contractor of November, the lamps are available in two sizes, 80 watts and 125 watts. The light output of these lamps is about 40 lumens per watt. This compares with the 12 lumens per watt of the ordinary coiled-coil incandescent lamp. The life is stated to be about 1,500 hours. The ‘colour correction’ of these lamps is effected by the fluorescent powder used. The human complexion when illuminated by the lamps shown at the meeting was very little altered, the change being scarcely noticeable. Owing to the fact that the internal film transforms the invisible ultra-violet light emitted by the mercury vapour lamp into light of visible wave-length, the loss of light by the absorption of the bulb is compensated for by this fluorescence. No details are yet available as to the price of the lamp, but we seem to be on the eve of a new development in house lighting.