| 摘要 |
PURPOSE:To increase lamp voltage while raising the temperature at the coldest point of the lamp and also raise lamp efficiency by providing a metal reflecting surface on the internal end part of a luminescent lamp. CONSTITUTION:Thermal reflecting surfaces 8, 8a where metal has been vacuum evaporated are provided on the internal end part of a luminescent lamp 1, i.e., for example on the internal end surface of a cap 2. Hereby, it is possible to make lamp voltage larger than that of a conventional luminescent lamp even if the cross sectional area Sa of a metal part in the area S of the internal end surface of the luminescent lamp is relatively small. The reason is that the reflecting surface 8 (or 8a) acts as a heat shielding surface. Moreover, this is particularly effective when Sa/S is small, and said effect in case of Sa/S>0.20 is almost the same as that in case of no metal part. This is because the rate of metal part is large enough in the region of Sa/S>0.20, causing a thermal shielding effect of disappear. |
