| 摘要 |
PURPOSE:To eliminate a circuit element deteriorated by a high voltage pulse applied to a high luminance discharge lamp, and improve durability in a long period. CONSTITUTION:A high voltage pulse is superposed on an AC, raised, and applied to a high luminance discharge lamp 28 connected to the output terminal of a chalk coil 24. The high voltage pulse to be applied to the high luminance discharge lamp 28 at start is generated through a pulse generating circuit 26 or the basis of the voltage divided by series resistors R12, R13 and capacitor C9 for dividing the input side voltage of the chalk coil 24. After a determined time after the high luminance discharge lamp 28 is started, the operation of the pulse generating circuit 26 is stopped by the operation of a timer circuit 22. The operation of the pulse generating circuit 26 is stopped through the operation of a pulse generation operating circuit 29 on the basis of the high voltage pulse generated at the start of the high luminance discharge lamp 28. |
