| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp control circuit with a ground fault protection function capable of detecting a ground fault in a high-safety state while suppressing mercury migration. SOLUTION: To the discharge lamp 1, an electronic neon transformer type discharge lamp control circuit 3 controlling the lighting and extinction of the discharge lamp 1 is connected. In the discharge lamp control circuit 3, a ground fault protection circuit 22 capable of detecting a ground fault on a secondary side by monitoring a voltage (midpoint voltage) at a midpoint 15 of a secondary winding 14 of a transformer 12 is incorporated. When the ground fault protection circuit 22 detects a ground fault, the discharge lamp control circuit 3 stops the operation of an inverter circuit 11 to forcibly terminates the lighting of the discharge lamp 1. An output capacitor 19 for suppressing mercury migration is connected to the midpoint 15 of the secondary winding 14. Thereby, ground fault current sensitivity when the secondary winding 14 causes a left-side ground fault is set substantially identical to that when the secondary winding causes a right-side ground fault. COPYRIGHT: (C)2009,JPO&INPIT |
