| 摘要 |
PROBLEM TO BE SOLVED: To prevent electromagnetic wave noise, generated when a discharge lamp is lighted, from affecting a sub-circuit.SOLUTION: A main circuit 6 includes a signal switching section 10 and a sub-circuit power supply 12, in addition to an arithmetic control section 8. The signal switching section 10 is interposed electrically between a sub-circuit 4 and the arithmetic control section 8, and switches interruption and connection of the signal path. The sub-circuit power supply 12 performs on/off switching of power supply for operating the sub-circuit 4. Before the discharge lamp of a lamp lighting section 2 is lighted, a lighting start signal of the discharge lamp is transmitted to the signal switching section 10 and the sub-circuit power supply 12 from the arithmetic control section 8, and the power supply of the sub-circuit 4 is turned off by the sub-circuit power supply 12, or the signal path between the sub-circuit 4 and the arithmetic control section 8 is interrupted by the signal switching section 10. |
