側發式背光區域調變技術應用於版畫場色序法之節能顯示器

Abstract

近年來地球暖化現象帶給了環境無限的衝擊與變遷，為了保護我們的地球，綠色能源產業因此而興起。在顯示技術上，為了能達到「能源之星計畫」對於大於50吋顯示器所規範的耗能需低於108瓦的限制，使用LED當背光源的免彩色濾光片之場色序法顯示技術已證實能夠有效地降低耗電量；此技術仍有其他優點，如：高影像解析度、高色彩飽和度、較高的出光效率以及較低的材料成本，但是色分離現象卻限制了此技術的發展性。 我們提出了180Hz Stencil-FSC法能夠有效地抑制色分離的現象，然而此方法會發生紅色與藍色漏光的問題，使得綠色飽和度降低，因此，此篇論文提出了”Limited Backlight Signal Ratio”(LBSR)法來決定較正確的背光訊號，使得漏光與影像失真問題獲得改善；同時，輕薄的顯示器是目前市場的主流，為了能夠發展出低耗能的輕薄顯示器，此篇論文也提出了使用側發式LED背光源的光源分布函數(LSF-Light Spreading Function)模型，藉由結合此LSF模型與LBSR法，未來將能夠實現輕薄低耗能的高影像品質節能顯示器。 根據模擬結果，找出了最佳化的LSF硬體參數與其背光分區數為2x16區，以CIEDE2000色差公式來評估影像品質，其影像擬真度色差小於3的百分比為0.89(色差小於3表示人眼不易分辨顏色差異)；色分離改善程度為傳統RGB-driving方法的28.4%；在耗能評估方面，使用IEC 62087所提供的影片來評估耗電量，其平均耗能約只有38瓦。最後由46吋MVA-LCD實驗結果可知，此技術在色分離現象上有明顯的改善且能夠大大提高影像擬真度，因此，藉由此篇論文所提出的側發式背光區域調變技術應用在版畫場色序法顯示技術上，未來將有機會發展出薄型(小於10mm)的高影像品質之節能顯示器。

Recently, global warming phenomenon impacts and changes the environment. In order to protect the earth, the green energy industry therefore springs up. In the display technology area, to achieve the target of “energy star” which limits the power consumption of display larger than 50-inch should be less than 108 watts, the color filter-less field-sequential-color (FSC) technique by using light emitting-diode (LED) as backlight is proven to effectively reduce power consumption. This technique still has the advantages of high image resolution, high color saturation, higher optical throughput, and lower material cost. However, color breakup (CBU) phenomenon constrains the development of this technique. Our group has proposed the 180Hz Stencil-FSC method to effectively suppress the color breakup phenomenon. Nevertheless, this method has the issue of light leakage in red and blue light resulting in the green color be de-saturated. Therefore, in this thesis, we proposed the “Limited Backlight Signal Ratio” (LBSR) method to determine proper backlight signals to improve the issues of light leakage and image distortion. In addition, light and thin display is the trend in the market; in order to develop the power saving and thin display, we proposed the model of side-lit LED light spread function (LSF-Light Spreading Function) in this thesis. By combining the LSF model and LBSR method, we could realize the thin and high image quality eco-display in the future. According to the simulation result, the LSF parameters are optimized and the optimum backlight division is 2x16. By utilizing the color difference formula of CIEDE2000 to evaluate the image fidelity of the proposed method, which the percentage of color difference less than 3 is 0.89 ( color difference less than 3 represents human eye cannot distinguish the color difference). Color breakup of the proposed method can reduce to 28.4% comparing with conventional RGB-driving method. We use the IEC 62087 video to evaluate the power consumption of the proposed method, which the average power consumption is only 38 watts. By verifying the proposed method on the 46-inch MVA-LCD, we can observe that the image fidelity is increased greatly and the color breakup phenomenon is improved apparently. Therefore, by the proposed side-lit eco-LCDs using locally backlight controlled technology in Stencil-FSC method, it is promising to develop the thin (less than 10mm) and high image quality eco-display in the future.