| 摘要 |
PURPOSE:To effectively utilize the heating effect and heat conductive effect occurring at each bulb and due to heat generated by its respective electrode by properly setting the distance from the electrode center to the inner surface of a luminous bulb. CONSTITUTION:The relation between the whole length l(mm.) from the free end center of an electrode to the inner surface of a luminous bulb, which surface is in the rear with respect to the opposite electrode, and the weight m(g) of the electrode in the luminous bulb, and the lamp current I(A) is set at follows: 0.1<=m/I<=0.16 and I<=l<13. Thus, the coated area of a heat insulation film provided only at a lower end part of the upright luminous bulb is minimized. As the coated area of the heat insulation film can be reduced, luminous efficiency, average colour display estimation value, luminous flux maintenance rate, starting performance etc. can be improved. |
