| 摘要 |
PURPOSE:To prevent the fusing of the conductive members and the breakdown of the outer tube by constituting a metal vapor electric-discharge lamp so that the current of discharge in which a lead wire works as a luminous point always flows through a current-limiting resistance. CONSTITUTION:The distance between a lead wire 17b, which connects a lighting tube 15 and a current-limiting resistance 18, and another conductive member having an electric potential corresponding to that of the lead wire 17b is maintained to be smaller than the distance between the lead wire 17b and any other conductive member, which is installed within an outer tube 1 and has a different electric potential. The lead wire 17b becomes a luminous point all the time when pulse voltage develops outer tube electric discharge without causing any lighting of an emission tube 2. Since the current of the electric discharge, in which the lead wire 17b works as a luminous point, always flows through the current-limiting resistance 18, this electric discharge is stopped immediately after its development. |
