| 摘要 |
PROBLEM TO BE SOLVED: To provide an inverter for liquid crystal back light with small size and high efficiency by forming a current wave form supplying to a discharge lamp in a rectangular wave, and arranging separators of secondary winding of an output transformer five or more, then winding. SOLUTION: A chopping transistor 2 performs on/off operation with the output of a voltage comparator 19. The chopping transistor 2 is turned on in the period of time when the output voltage of the voltage comparator 19 is low. The output voltage is smoothed with a choke coil 6 and a smoothing capacitor 7 in an output circuit, d.c. current corresponding to on-duty of the chopping transistor 2 is inputted to a transistor 8. Switching transistors 9, 10 repeat on/off operation with the output signal of a control signal generator 13. Voltage about twice the input voltage of a transformer is generated in a collector of the transistor 9. In order to decrease the floating capacity of secondary winding of the transformer, reduce rush current, and reduce switching loss, separators of winding are increased to five or more. |
