Patent ID: 6232728
Filing Date: 2001-05-15
Classification: H05B,Y10S

Abstract:
A discharge lamp apparatus having a d.c. voltage source for supplying a d.c. voltage, comprising:a discharge lamp;a transformer for boosting the voltage of the d.c. voltage source to produce a boosted voltage;an inverter circuit including a plurality of switching devices for converting the boosted voltage into an a.c. voltage to supply electric power to the discharge lamp; anda fail-safe circuit for stopping a supply of electric power by turning off the plurality of switching devices according to a determination, said determination being that a voltage between the transformer and the inverter circuit is less than a predetermined voltage and that a current flowing from the inverter circuit to a negative side of the d.c. voltage source is less than a predetermined current,wherein, subsequent to said stopping, said fail-safe circuit (A) holds a turned-off condition of all among the plurality of switching devices when said determination continues for a predetermined period of time, and (B) restarts the supply of electric power otherwise.