| 摘要 |
PURPOSE:To suppress surge current and reduce noise by sensing a lighting changeover signal to a switching element in the period from the inverter circuit output voltage nullifying to immediately before the current flowing in an EL lamp nullifying. CONSTITUTION:Changeover signals Sa, Sb... produced by a changeover circuit 4 are sent to gate G of triode AC switches 3a, 3b... at the timing in which changeover of EL lamps 2a, 2b... is synchronized with their power supply phase. The signal transmitting timing of the signals Sa, Sb... to the triode AC switches 3a, 3b... is set to either of the periods P1, P2 from the times b1, b2 at which the output voltage V of the inverter circuit 1 nullifies to immediately before the zero cross points a2, a1 at which the current flowing in the EL lamps 2a, 2b... nullifies. Even in case the EL lamps 2a, 2b... are changed over at a high speed, the potential difference between the EL lamps 2a, 2b... and the inverter output can be reduced to no larger than + or -Vmax. Thereby surge current is reduced, and noise not easily generated. |
