| 摘要 |
PROBLEM TO BE SOLVED: To provide a high voltage discharge lamp lighting device capable of reducing malfunction by surely detecting a half-wave discharge state. SOLUTION: In step S1 for reading an output value of a chopper voltage detection circuit 18 as VL<SB>n</SB>at timing synchronized with reversal of polarity, and step S2 for comparing the read voltage value VL<SB>n</SB>with a read value VL<SB>n-1</SB>read at a half cycle before it, when the value of (VL<SB>n</SB>-VL<SB>n-1</SB>) is not greater than -5 V, this high voltage discharge lamp lighting device moves to step S3 for comparing the value VL<SB>n-1</SB>read at a half cycle before the value is read this time with a value VLn-2 at a half cycle before it. In step S3, when a value (VL<SB>n-1</SB>-VL<SB>n-2</SB>) is exceeds +5 V, the lighting device moves to step S4 for increasing the value of a counter C by one, and, when the value (VL<SB>n-1</SB>-VL<SB>n-2</SB>) is not greater than +5 V, the lighting device moves to step S5 for resetting the value of a counter C. When the value of the counter C exceeds 10 in step S6, the lighting device moves to step S7 for stopping a lighting circuit by identifying this state as half-wave discharge. COPYRIGHT: (C)2007,JPO&INPIT |
