| 摘要 |
PURPOSE:To shorten the starting time of a high pressure electric-discharge lamp by preheating a preheating electrode during a half cycle of an alternating power source, and applying voltage across the main electrodes during the other half cycle. CONSTITUTION:When a diode 10 becomes conductive by the application of an alternating power source 8, electric discharge develops across a discharge gap 11. A discharge current flows through a ballast 7 into a resistance 9, a diode 10, a discharge gap 11 and a preheating electrode 3, in that order, and preheats the electrode 3. When the polarity of the alternating power source 8 is reversed, electric discharge doesn't develop across the discharge gap 11 since the diode 10 is cut out, and preheating of the electrode 3 is not carried out. In this condition, the output voltage of the ballast 7 is applied across main electrodes 2a and 2b of an emission tube 4. Consequently, the starting time of a high pressure electric- discharge lamp can be shortened by producing main electric-discharge across the main electrodes 2a and 2b immediately after the electrode 3 is sufficiently heated. |
