| 摘要 |
PURPOSE:To prevent an insulation tube from being broken and current-supply conductors from being fused due to discharge in an outer tube, by covering the current-supply conductors, which are positioned between the pressed sealing parts of the outer tube and a luminous tube, with the insulation tube. CONSTITUTION:A luminous tube 13, which is formed by putting mercury and inert gas into a transmitting container having electrodes 14a and 14b, is housed into an outer tube 17, which has the pressed sealing parts 18a and 18b on both its ends and the inside vacuumized, to compose a double base-type metallic vapor discharge lamp such as a metal halide lamp. Then, one of the current- supply conductors 20a and 20b, which are positioned between the pressed sealing parts 18a and 18b and the luminous tube 13, is covered with an insulation tube 23. Besides, the terminal part 23a of the insulation tube 23 is unified by the pressed sealing part 13a into the outer tube 17. Therefore, the insulation tube 23 can be prevented from being broken due to oscillation or the like, with occurrence of discharge in the outer tube being suppressed, preventing the current supply conductors 20 from being fused and the outer tube 17 from being broken.
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