| 摘要 |
PURPOSE:To relieve the problem of short lifetime inherent to DC lighting by setting the tube wall temp. of a low pressure mercury vapor discharge lamp to a high level over the drop commencing point, at which the cathode drop voltage of the discharge lamp begins to exhibit the sinking tendency. CONSTITUTION:Mercury and an inert gas are encapsulated in the tube of a low pressure mercury vapor discharge lamp 1. When the tube wall temp. of this, discharge lamp 1 has risen to a certain level, the cathode drop voltage begins to exhibit a sinking tendency. According to this DC lighting system, the tube wall temp. is raised and the cathode drop voltage is sunk to relieve sputtering exhaustion of cathode oxides. That is, the tube wall temp. of the discharge lamp 1 is set to a high level over the drop commencing point, at which the cathode drop voltage of the discharge lamp 1 begins to exhibit the sinking tendency. This enhances the lifetime characteristic of the discharge lamp 1. Also the light decremental phenomenon due to DC lighting can be relieved. |
