| 摘要 |
PURPOSE:To increase the heat retaining efficiency in the entire area within the emission tube so as to improve the luminous efficiency of a metal halide lamp by providing a reflection film for inwardly heating the emission tube on the emission tube or on a part of the outer tube. CONSTITUTION:On the base-5-side area of the outer tube 4' of a reflex-type metal halide lamp, a reflection film 6 is formed by vapordepositioning chromium, having excellent heat resistance and reflecting property, before silicon dioxide coating is performed so as to heat an emission tube 1 by downwardly reflecting arc light discharged from the emission tube 1 by the reflection film 6, thereby equalizing the temperature distribution in the emission tube 1. In an usual metal halide lamp, a reflection film 7 is formed near the electrode 2 of an emission tube 1' and the film 7 is coated with a heat insulating coat 8, thereby equalizing the temperature distribution. As a result, the dissociation of a luminous substance can be accelerated by improving the heat insulation of the emission tube 1, thereby enabling the luminous efficiency of the lamp to be increased. |
