LCD backlighting inverter circuit and LCD

Abstract

An improved electronic LCD backlighting inverter circuit for high frequency operation under low frequency pulse width modulation (PWM) for dimming control. The improved electronic LCD backlighting inverter is based on a voltage-fed push-pull LLC resonant inverter circuit configuration including a resonant inductor (L), magnetizing inductance of an output transformer (L), and resonant capacitor (C). For large values of magnetizing inductance the LLC circuit effectively becomes an LC resonant circuit. By synchronizing the high frequency switching signal and the low frequency modulation frequency using logic control circuitry, a wide dimming range and higher efficiency are achieved under PWM control.

Description

technical field [0001] In general, the present invention relates to a liquid crystal display backlight inverter circuit suitable for liquid crystal display backlight or similar applications, and more particularly to a high efficiency, small size, and wide dimming range liquid crystal display backlight inverter circuit. Background technique [0002] Liquid crystal display backlight applications require efficient, small-sized backlights for information display. Narrow diameter cold cathode fluorescent lamps (CCFLs), such as the T1 type, are widely used in such industrial applications. To drive these CCFLs, an electronic LCD backlight inverter circuit with high efficiency, small size, and wide dimming range is required. Currently, half-bridge resonant converter circuits using voltage feeding, such as figure 1 , and a current-fed push-pull resonant converter circuit such as figure 2 Shown, to drive CCFL and other fluorescent lamps. Although widely used, these circuits have ...

AI Technical Summary

Problems solved by technology

However, the usually high inductance of L1 limits the current start-up characteristics and limits the dimming range

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