| 摘要 |
PURPOSE:To prevent the fusion of a thermally operating switching element by sealing a neon-nitrogen gasious mixture containing neon of a specific amount or less in an external tube of a metal vapor discharge lamp provided with a thermally operating switching element as well as a luminous tube. CONSTITUTION:A thermally operating switching element comprising a fixed contact 14 connected to an auxiliary electrode 10 and a movable contact 15 provided on a bimetal 6 and a luminous tube 2 are provided in an external tube 1 of a lamp such as metal halide lamp, while a neon-nitrogen gasious mixture containing neon of 35% or less is sealed in it. A surge voltage is generated by the opening action between contacts 14, 15 through an auxiliary discharge of the luminous tube 2 when the lamp is to be started, and thus main discharge is started. Accordingly, by assigning the content of neon to 35% or less, the discharge between contacts 14, 15 are depressed to reduce the frequency of fusion, the operational number of times of bimetal for start is reduced and the long life of the discharge lamp can be attained. |
