| 摘要 |
PURPOSE:To apply a DC feedback type lighting device to a wide range of input voltages by employing a high speed switching circuit for a chopper circuit. CONSTITUTION:A tube current flowing through a discharge tube 3 is detected by a tube current detection part 4, and it is fed back to a feedback control part 5. The feedback control part 5 amplifies an error from a reference value by a comparison control part 6, and outputs a pulse voltage Vp in accordance with error quantity by a pulsation part 7. A chopper circuit 1 changes an input voltage Vin in to an input voltage Vcont to a DC/AC converting part 2 by a switching element 8 in accordance with the pulse Vp. In this constitution, a prestage of the switching element 8 of the chopper circuit 1 is composed by push and pull, a switching speed of the switching element 8 can be increased, and a value in accordance with computation instruction quantity can be applied to the DC/AC converting part 2. A device can thus be actuated stably in spite of disturbance such as input voltage fluctuation. |
