Stencil-LPD色序法應用於無彩色濾光片之高畫質120Hz顯示器

Abstract

色序型液晶顯示器由於不需彩色濾光片，因此有潛力成為次世代節能型綠色顯示器。傳統色序型液晶顯示器以180Hz的場率，時序性地顯示紅色、綠色以及藍色色場的畫面，利用人眼在視網膜上的積分而形成一全彩的影像。而考慮到現行主要液晶模態的反應時間，雙色場色序法(120Hz)較能提供足夠的反應時間。因此，雙色場色序法已成為現今發展的主流。 然而，只有兩個場卻要顯示由三原色所組成之全彩影像，缺少了一個自由度，導致畫面嚴重失真。為此，先前的演算法為加上特殊彩色濾光片形成雙色場雙彩色濾光片，如此一來可得到完全不失真的影像，但是卻因加上彩色濾光片而降低了光的穿透率，且多了特殊彩色濾光片的成本。另一種演算法則是將人眼最不敏感的藍色資訊分成兩部份分別與紅色及綠色資訊做結合，這種演算法的優點為不需彩色濾光片，但卻犧牲了影像的藍色資訊。 故此研究提出一新型的雙色場色序法，Stencil-LPD，可根據影像內容選取出最適合的背光訊號，如此一來便可降低因自由度不足而造成的影像失真。此演算法與先前two-color-field方法相較之下，有效將影像失真度降低至原先之53%。另外，由於此演算法提供一較低但卻足夠飽和的顏色做為背光訊號，以降低在色帶拖出時兩個色場的差異，其相對色分離也由原先的89%改善至64%。

Since a field-sequential-color LCD (FSC-LCD) does not require color filters, it has potential to be the next-generation eco-display. The conventional FSC-LCD sequentially flashes red, green, and blue field images at 180Hz field rate to form a full color image by the integration on the retina. Considering the currently used LC modes, a two-field method driving at a field rate of 120Hz has been the mainstream to develop. However, only two fields to display full color images formed by the three primaries, it is lack of a degree of freedom resulting image distortion. Thus, in the previous solutions, a specific color filter was applied, known as the 2F2CF method proposed by Phillips. By doing so, it can reproduce exactly the same image with the original one but still needs color filters. The other method, two-color-field proposed by NCTU, is to divide the blue information, which is the least sensitive color to human eyes, into two parts and to combine them with red and green information individually. This method does not require color filters but cause color distortion. In this thesis, a novel two-field display method, Stencil-LPD, was proposed without color filters. The Stencil-LPD method can provide proper backlight colors according to the image content that can decrease the color difference caused by the lack of degree of freedom. Compared to the two-color-field method, the proposed method reduced the color distortion by 53%. Besides, Stencil-LPD method provided less but sufficient saturation colors as backlight signals, the chrominance difference was lowered that diminishes the relative CBU value to 64% while it is 89% in the two-color-field method.