| 摘要 |
PURPOSE: To prevent the lighting failure of a discharge lamp by the temporary reduction of battery voltage without inviting a reduction in power efficiency of a circuit, a temperature rise and a decrease in reliability. CONSTITUTION: This device has a constant voltage power source circuit 20 for supplying another powers source from the connecting point between the primary winding 8a of a transformer 8 and a MOSFET transistor 10 to a control circuit 16. The constant voltage power source circuit 20 regulates the voltage Va in the connecting point to a prescribed voltage value (e.g. 10V) smaller than the general voltage value (e.g. 12-16V) of a battery 1 and larger than the voltage value at temporary voltage reduction (e.g. 5V of the battery 1, and when the voltage value of the battery 1 is less than the prescribed voltage value, a NPN transistor 26 is ON to supply a constant voltage to the control circuit 16. |
