The driving circuit of the plasma discharge type flat backlight

摘要

PURPOSE: A circuit for driving a plasma discharge flat back light is provided which senses a variation in the quantity of current according to a change in a back light luminance value and regenerates a PWM signal for luminance control to adjust the width of a power transistor driving pulse, to allow the input current of a power transformer to be automatically controlled in connection with a variation in the back light. CONSTITUTION: A circuit for driving a plasma discharge flat back light includes a main controller(50) for receiving a voltage value corresponding to a variation in the input current of an inverter circuit and comparing the voltage value with a reference voltage value to generate a luminance control pulse, and a sub-controller(60) for receiving the luminance control pulse from the main controller to generate a driving pulse whose duty and timing are controlled and generating the first and second pulse outputs for switching a power transistor using the driving pulse. The circuit further has a step-up inverter(20) driven by the first and second pulse outputs to generate a control signal for switching the input current of a power transformer, an output unit(30) for outputting a high voltage with a high frequency for driving the back light according to the switching power output of the step-up inverter, and a feedback unit(40) for converting a variation in the input current, detected by a sensing resistor of the step-up inverter into a voltage component to provide the voltage component to the main controller.