| 摘要 |
PURPOSE:To promote a prolongation of life of the electric discharge tube, by deciding a thickness of the quartz bulb at an electrode portion and luminous portion to within an optimum range of dimension. CONSTITUTION:A thickness of the electrode portion including a diameter shrinked part (a') and an electrode sealed part (a) is chosen to a dimension from 0.5- 1.8mm. A thickness of the main luminous portion is taken to within a range from 0.3-1.0mm. A thickness of the luminous portion (b), if taken to a dimension less than 0.3mm, causes a strength to be short decreasing an effect of the life improvement. While a thickness of the electrode portion including the diameter shrinked part (a') and the sealed part (a), being mainly applied a mechanical stress, is made to a dimension above 0.5mm, however, the thickness exceeding a dimension of 1.8mm causes a temperature difference between inner and outer sides of a quartz bulb to increase, rendering more susceptible of caracking the tube due to the strain. |
