| 摘要 |
PURPOSE:To enhance the safety of a metal vapor electric-discharge lamp by making the distance between a lead wire, which connects a lighting tube and a current-limiting resistance, and another conductive member having an electric potential corresponding to that of the lead wire smaller than the distance between the lead wire and any other conductive member installed within the outer tube. 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 polar electric potential. In addition, the lead wire 17b is coated with a matter 21 easily discharging electrons. Owing to the above constitution, the outer tube electric discharge is immediately stoped after its development, since the outer tube electric discharge always develops from the lead wire 17b working as a luminous point and the discharge current always flows through the current- limiting resistance 18. Consequently, the fusing of the conductive members and the breakdown of the outer tube 1 can be prevented. |
