| 摘要 |
PROBLEM TO BE SOLVED: To provide a unit with high efficiency and high safety by installing an intermediate terminal in a primary coil and switching an input terminal of the primary coil in response to the variation of output following to the variation of load impedance. SOLUTION: When voltage is not outputted to a secondary coil N2 of a transformer 2, intermediate terminals 4, 5 of a primary coil are connected to transistors 9, 10 through a switching circuit 12, and terminals 6, 7 are opened. In this state, high voltage required to start the discharge of a discharge tube 13 is induced. The discharge tube 13 is discharged, tube current flows, impedance is lowered, voltage applied to the discharge tube 13 becomes discharge maintaining voltage of low voltage. The discharge maintaining voltage is inputted to a control circuit 16 through a voltage feedback circuit 14, and tube current is also inputted to the control circuit 16 through a current feedback circuit 15, the switching circuit 12 is operated by the output signal of the control circuit 16, the terminals 6, 7 and transistors 9, 10 are connected, and the intermediate terminals 4, 5 are opened. In this state, the winding number ratio of the primary coil and the secondary coil is made small, and the magnetic bonding between the primary coil and the secondary coil is made dense. |
