LOW-PRESSURE MERCURY VAPOUR DISCHARGE LAMP

摘要

Low-pressure mercury vapour discharge lamps provided with a luminescent layer, the power consumed being relatively high. Lamps are provided being loaded by at least 500 W per m2 surface area of the luminescent layer. Furthermore lamps are provided having a nominal length of from 60 to 150 cm, an inside diameter of from 20 to 28 mm, which lamp is intended to consume during operation a nominal power of 0.25-0.50 W per cm. length of the discharge tube, the discharge tube being provided with means for maintaining a column discharge and comprises a quantity of mercury, a quantity of rare gas and a luminescent layer containing at least one luminescent material of the group consisting of luminescent aluminates having a hexagonal crystal structure related to the structure of hexagonal ferrites and red-luminescing trivalent europium activated rare earth metal oxides having a composition defined by the formula Ln2O3; pEu, wherein Ln represents at least one of the metals Y, Gd and Lu and wherein 0.01?p?0.20.