高擴散印刷網點對背光模組之效率研究

Abstract

液晶顯示器本身擁有輕、薄與高亮度等多項優點，為了提高顯示器的特性，高輝度、高均勻度，省電及輕薄的背光模組系統是非常重要。在背光模組中，導光板為關鍵零組件。導光板的主要目的是做液晶顯示器的光照度能夠分佈均勻，而導光板設計的優劣與否，對於LCD畫質有很大的影響。而背光模組可因為光源配置方式的不同，可分為直下式背光模組及側光式背光模組。在側入式背光模組中光線入射導光板後容易產生全反射現像，不利光線由導光板正向出射。導光板的背面有網點分佈，當光照射至網點上，網點會破壞全反射現像。導光板以印刷方式塗佈光擴散劑，即是印刷式導光板。適當地控制網點的型狀，分佈與大小可達到均勻發光的目的。 在本論文中將介紹導光板並分析其光擴散劑。本論文主要目的為應用印刷製程技術，在7吋導光板上印刷，並改變其光擴散劑比例，分析其對背光模組輝度光學增益。 與傳統的導光板比較結果，新型光擴散劑使導光板輝度增益約25%，可應用於背光模組或照明系統使用。

Liquid crystal displays (LCDs) have a lot of advantages, such as thin thickness, slight weight and high brightness, etc. In order to improve the characteristic of the display, the technologies for high brightness uniformity, low power consumption and thin backlight module have been developed. In terms of backlight module, the light guide plate is a key-component, which is used to manage the luminance uniformity of a LCD. Thus, the design of a light-guide plate directly impacts the performance of LCD image quality. We can classify the backlight module into two types, the direct-emitting and edge-emitting backlight module according to the location of the light sources. Generally, the light coupled into a LGP from the edge sources is mostly guided inside the LGP by the totally internal reflection (TIR). This condition results in the non-uniform distribution of the output light on the top surface of the LGP. There are scattering dots on the bottom of the LGP to redirect the guided flux to the air. The LGP with the scattering dots coated by the printing method is called printing-type LGP. By controlling the shape, dimension, and distribution of the scattering points, the uniform distribution of the output light on a LGP can be achieved. In this paper we will introduce LGP and analyze the scattering characteristics of the optical diffusive agent. The objective is to apply the printing technology on a 7-inch LGP and analyze the optical properties with varying diffusion agent rate. The brightness enhancement of the backlight module will be discussed. Compare with a conventional LGP, the new optical diffusion agent had 25% enhancement of brightness. The new optical diffusion agent can be applied to the backlight module or lighting system.