Low-pressure mercury vapour discharge lamp and method of manufacturing same

Abstract

A low-pressure mercury vapor discharge lamp with a tubular discharge vessel (1) with an internal diameter D. The discharge vessel (1) encloses a discharge space (3), which comprises mercury and a rare gas, in a gastight manner. Electrodes (5A, 5B) are arranged in end portions (4A, 4B) of this discharge space. The discharge vessel (1) has a luminescent layer (10) which supports a protective layer (11) comprising a metal oxide at an inner surface (9). In the lamp according to the invention, at least 75% by weight of the metal oxide is present in total in the end portions (4A, 4B), said end portions (4A, 4B) each extending up to a distance beyond the electrodes (5A, 5B) which is three times the internal diameter of the discharge vessel (1). The lamp has a comparatively low luminous decrement and can be manufactured comparatively efficiently. The lamp may be manufactured comparatively efficiently in that the suspension is sprayed in the direction of the luminescent layer from a position outside the discharge vessel under construction, opposite each end portion.

Dependencies are inferred from the claim text.