| 摘要 |
PURPOSE:To prevent the occurrence of noise for sure, by absorbing the high frequency pulse generated by switching operation with a choke coil and a capacitor of small capacity connected thereto. CONSTITUTION:A lighting device of an electric discharge lamp 20 is composed of an inverter A where a choke coil 12, the primary winding 13P of an oscillatory transformer 13, switching transistors (hereinafter referred to as Tr's) 14-15 are connected to a DC power source 11. The electric discharge lamp 20 is connected to the secondary winding 13S1 of the oscillatory transformer 13 through a choke coil 19. The switching operation of Tr's 14-15 is alternately performed, so that the electric discharge lamp 20 is turned ON from a parallel resonance circuit by a resonant capacitor 18 through the secondary winding 13S1. In this connection, a capacitor 21 is provided as well as the choke coil 12, with the filter action of which the high-tension pulse caused by turning ON (OFF) the Tr's 14-15 is absorbed. Thus, there comes up with no possibility that this pulse will appear as noise and the occurrence of noise is thereby be prevented. |
