Wenderoth, Lind & Ponack
Metal vapor discharge lamp
 A metal vapor discharge lamp having an outer tube having an inert gas filling the inner space and an arc tube disposed in the interior of this outer tube and having in a discharge space in the interior a pair of electrodes. The discharge space is filled with at least a rare gas and mercury. A lower light transmissive covering member covering at least the lower end part of the arc tube is positioned in the vicinity of the end part of the light emitting tube which is the lower end during lighting. This reduces the temperature reduction of the lower part of the arc tube due to convection of the gas within the outer tube, increasing the temperature of the coldest part of the arc tube, whereby the vapor pressure in the interior of the arc tube is raised to improve luminous efficiency. 
Mitsubishi Denki Kabushiki Kaisha
H
H01J
inventional
Keiji Masato Michihiro Ryo
Watanabe Saito Tsuchihashi Suzuki