| 摘要 |
PURPOSE:To prevent current flow through the lighting circuit of a discharge lamp when no load is applied by forming a circuit for temporally varying the capacity of a condensor in the lighting circuit of the discharge lamp having filaments at both ends. CONSTITUTION:A discharge lamp 2 having filaments 3, 4 at both ends is driven by a transmission circuit 1, and a lighting circuit which is formed by a coil L1, condensor C10, C11 and the like. The condensers C10, C11 are connected together in series and are connected in parallel with the discharge lamp 2 and a timer circuit 11 is provided between a switch 10 connected in parallel with the condensor C10 and the transmission circuit 1. After a predetermined period of time is elapsed from the beginning of oscillation, the timer circuit 11 closes the switch 10 and lighting is maintained with a voltage lower than the voltage applied at the beginning of oscillation. when the discharge lamp 2 is removed connection between the condensers C10 and C11 is canceled and there is no current flow through the lighting circuit and hence no generation of thermal damages that may be caused by currents. |
