液晶顯示器於老化實驗後之光源損失避免策略及其可行性分析

Abstract

液晶顯示器由1976年發展至今，手持式智慧平板已成為各大廠商積極投入開發與搶攻的標地，研發端如何改善既有產品設計，將光能發揮極致，並達到節能要求乃是重要任務之一。

本研究的目的是探討平板顯示器老化後光源效率衰弱的因子，藉由發掘出此關鍵因子，在設計階段將這些因子納入設計規範內，可在老化程序後，免除非必要性的光源損失，達到優化產品性能的目標。

本研究使用8吋背光模組，量測原始亮度進行紀錄，並將確認後的材料投入老化機台進行加速跨越生命週期的動作，把老化後的模組取出確認老化對於亮度變異。拆解分析找出光源增加或減損的原因，並利用模擬軟體SPEOS建立相同背光模組架構，藉由軟體確認所推論的理論正確性，並進行背光模組的修正，以達到優化背光模組的可能。

研究結果顯示，陣列光源與導光板受結構限制時，導光板會因老化產生膨脹，當膨脹量增加，其位移量也相對增大。老化結束後，導光板回復常溫亦因結構限制，導光板與陣列光源將產生間距，其間距則是導致光源損失因子。本研究的實驗與模擬證實原始背光模組因既有設計易導致材料間互相干涉，當陣列光源固定於背板的模組，老化後最終會導致出光損失。將內部堆疊架構進行修改後，使陣列光源跟隨導光板脹縮量同步移動，可有效減少老化後零件配合度不佳的風險。經實驗與模擬軟體確認，當導光板與陣列光源間距由0 mm增加至0.01 mm時，其背光光源5點平均亮度將下降1%，若改善並減少導光板與陣列光源間距，可有效增加光源利用率。

關鍵字：液晶顯示器、老化測試、光源損失避免分析

Abstract Liquid crystal display was developed from 2000 till now; each panel makers aggressively put much resource to develop the portable tablet in order to share this market. Therefore, one of the most important matters is how to improve the current product’s designs to ensure best light efficiency and save power consumption.

The purpose of this research is to find out the factors which affect the light efficiency of tablet display after aging procedure. By finding out these factors, designers could set up these factors as the check-list of design criteria to avoid the unnecessary reduction of light efficiency after aging process.

This research uses the 8” backlight as the research target. Make several experiments with the different design parameters to compare the brightness difference before and after aging process, and then analyze the root causes that increase or reduce the light efficiency. Also use the simulation tool “SPEOS” to confirm the accuracy of the experiment’s results and further modify the backlight structure to optimize the designs.

Base on the results of this research, the dimension of LGP (Light Guide Plate) expands and has the displacement during the aging process. After the aging process, LGP has to contract to the original dimension in normal room temperature. But due to the restrictions from the backlight’s structure, the LGP cannot freely recover to the original position and cause the space between LGP and LED light bar. And this space is the main reason that makes the reduction of light efficiency.

The results of this experiments and simulation prove that the original design of this backlight, LED light bar was fixed on the back plate, easily cause the interference to reduce light efficiency after aging process. Modify the designs of backlight’s structure to let LED light bar shift along with the expansion of LGP could effectively reduce the interference after aging process. Base on the experiments’ and simulation’s results, the 5-points brightness uniformity of the backlight will reduce 1% when the space between LGP and LED light bar increases from 0 mm to 0.01 mm. Well control and reduce the space between LGP and LED light bar could effectively increase the light efficiency.

Key word: TFT-LCD, Aging, Light Leakage avoid