Design of a Local Dimming Scan Matrix for a Direct Type LED Backlight Module

[[abstract]]直下式LED背光搭配Local Dimming技術是下一波在液晶電視（LCD TV）上主力發展的背光源。其好處是可大幅降低耗電量、提高顯示畫面對比值、灰階數、及減少殘影等，為其它背光源難以取代之處。現行高效率LED背光模組設計，是採用發光效率較佳的白光LED（白光LED發光效率一般為80 lm/W，然R、G、B發光效率不一，分別為40、80、10 lm/W）。Local Dimming，為LCD顯示器背光源可作到不同區域、不同程度輝度明暗變化的技術，故又稱為區域控制技術。而能將Local Dimming技術發揮到最佳的效果則屬2D Dimming。目前LCD陣營降低耗電量作法大致分以下方式，高效率LED背光模組開發、提高LCD面板開口率、新式光學模開發及減少電路使用數。本文將探討高效率LED背光模組，開發於直下式LED背光搭配2D Local Dimming技術，使用掃描式和脈衝寬度調變（Pulse Width Modulation）下的電路架構，模擬CRT脈衝方式，提升對比度、降低功率消耗和動態影像殘影等問題。[[abstract]]The direct type of LED backlight, with Local Dimming Technology, is destined to be the next generation of LCD TV design, with its main developmental focus on the source of the backlight. The advantages of this innovative light source are varied, such as significantly lower power consumption, increased display contrast ratio, higher gray scale numbers, and reduced blur, among others means this type of light source will be difficult to replace. The existing high-efficiency LED backlight module design uses the white light-emitting efficiency of LED, which typically has an 80 lm/W, Red, Green, and Blue luminous efficiency level, however, there are different levels, namely, 40, 80, 10 lm/W.Local Dimming of the LCD backlight can be achieved in different regions, with different levels of technology changes in both light and dark luminance, known as Regional Control. Local Dimming technology displays its best effects through 2D Dimming. The reduction of power consumption in an LCD lamp follows the current practice of broadly dividing the high level of efficiency LED available in the backlight module, improving the aperture ratio of the LCD panels, applying new optical module developments, and reducing the number of circuits.This paper discusses a highly efficient LED backlight module, which is developed in a direct type LED backlight using an innovative 2D Local Dimming Technology. It is based on a scanning and pulse width modulation circuit structure, which runs under a simulated CRT pulse mode in order to enhance contrast, reduce power consumption, and improve dynamic image blur