| 摘要 |
PURPOSE: To make possible securing safety by avoiding the danger of an electric shock due to leakage-induced energy generated by high-voltage pulses, without taking any special measures against insulation, such as doubly insulating a ballast. CONSTITUTION: A leakage current flowing via a ballast case 7 enclosing a ballast 5 which starts a discharge lamp 3 by generating high-voltage pulses is constantly monitored by a leakage current detecting circuit 13. If the leakage current is increased to a great value exceeding an allowable reference value, a switch portion 19 in a power opening circuit 14 opens a power line 18 to the ballast 5 according to the result of comparison by a comparing portion 15. Safety is thus ensured. |
