LED back-light driving system for LCD panels

In this paper, a light emitting diode (LED) back-light driving system for liquid crystal display (LCD) panels is proposed. Due to improvement in luminous efficiency, long life and wide color gamut, LED has gradually substituted for cold cathode fluorescent lamp (CCFL) as back light. In order to compete with other display devices and receive wide acceptance in the commercial arena, back-light driving efficiency, luminous efficiency and LED arrangement need to further improve. In this paper, an LED bypass circuit is proposed to prevent LED arrays from open-circuit, improving back-light reliability and availability significantly. In addition, bi-directional buck+boost converters are adopted to speed up state transition when using a current-type burst-mode dimming control for LED back-light drivers. Moreover, an effective driving circuit for achieving RGB light scan is introduced. Simulated and measured results are presented to verify the feasibility of the proposed driving system.