| 摘要 |
PURPOSE:To make it possible to narrow the variable frequency width and to reduce the switching loss of switching elements by converting the duty cycle of the driving frequency, as well as converting the driving frequencies of the switching elements. CONSTITUTION:A control circuit 13 to convert the period of the positive electrode property of the output signal wave-form of a variable frequency linking to the frequency is composed of an unstable multivibrator and the like. The dimming device is composed of an oscillator 14 to set the output frequency of an inverter, a capacitor 15, duplex variable resistors 16 and 17, a single multivibrator 18 to form the pause period, a capacitor 19, and AND circuits 20 and 21. And by converting the opening and the closing operations of the switching elements 3 and 4 of inverters 1-10 linking to the driving frequency making the pause period inconstant, the duty cycle is converted largely, making the duty cycle smaller as the frequency is made larger. Consequently, the width of the variable frequency can be decreased, and the switching loss of the switching elements can be also decreased. |
