180Hz Stencil-FSC及RGBW四合一LED用於無彩色濾光片之液晶顯示器

Abstract

近年來，溫室效應所帶來的氣候變遷，已嚴重影響地球生態。因此，如何「減緩地球毀壞的速度」成為各領域科學家努力的議題。在顯示器方面，不需要彩色濾光片的場色序法顯示技術能夠提升光使用效率，並且有高影像解析度，高色彩飽和度，以及低成本的優點。然而此技術有一先天上的問題，色分離現象，此現象會降低影像品質，甚至讓觀賞者感到不適。雖然目前已提出許多解法，然而這些方法仍然面臨許多問題，如液晶反應速度不足使影像失真……等等。 對於抑制色分離，我們提出了240Hz, 180Hz Stencil-FSC法及Two-Color-Field法有效抑制色分離現象。但其中180Hz Stencil-FSC法演算法中有漏光問題。 為了解決此漏光問題，本篇論文提出「適應性基底之180Hz Stencil-FSC法」，根據輸入影像選取第一色場適合之主色能有效降低漏光以維持影像正確性；其平均影像失真(ΔE00)小於一，色分離只有傳統場色序法的59%。此法也用 46吋的MVA-LCD實際驗證，其色分離幾乎看不見。 另一方面，本篇論文也提出RGBW 四合一 LED背光系統進一步降低場色序型顯示器的耗能；影像中的白色部分由高效率的白光LED呈現取代低效率的紅、綠、藍LED混色，剩下的色彩部份才由原色LED呈現，如此一來顯示器的耗能可以再進一步降低。而我們提出的解法也應用於RGBW 四合一 LED背光系統上。然而Two-Color-Field法在一個場裡只有兩種原色色彩，不能用RGBW LED 降低耗能，因此此篇論文也修改其演算法，提出120Hz Stencil-FSC法。在耗能評估上，三種Stencil-FSC法應用於RGBW LED的背光耗能能夠分別降至傳統場色序法顯示器的62%，52%及24%。因此Stencil-FSC法加上RGBW四合一LED背光系統能夠在低耗能下提供高影像品質。

The Global warming issue has become more seriously in recent years. Therefore, how to reduce the speed of earth damage becomes a hot issue in many research areas. In the display area, field-sequential-color (FSC) technology not requiring color filter was proposed to enhance light transmittance of LCDs. It has some advantages like high image resolution, high color gamut, and low material cost. However, FSC technology has a fatal drawback, color breakup (CBU) phenomenon. CBU phenomenon seriously decreases image quality. Therefore, there are some CBU suppression method were proposed. However, those methods also have some issues like low LC response time. Therefore, our group proposed 240Hz, 180Hz Stencil-FSC methods and Two-color-field method to suppress CBU, however, the 180Hz Stencil-FSC method has a minor issue, color distortion. In this thesis, the “adaptive base 180Hz Stencil-FSC method” was proposed to reduce color distortion of 180Hz Stencil-FSC method. By determining the dominant color of first field, the color distortion was much reduced to average ΔE00<1. The relative CBU was reduced to 59% of conventional RGB-FSC method. Furthermore, the adaptive base 180Hz Stencil-FSC method was verified in a 46” 120Hz MVA-LCD and made CBU almost imperceptible. On the other hand, this thesis also proposed RGBW 4-in-1 LEDs backlight system to further reduce the power consumption of FSC-LCDs. The gray/white part of image was generated using high efficiency white-light LED instead of low efficiency RGB LED. The remaining color part was generated using RGB LED. By this way, the power consumption of FSC-LCDs was further reduced. However, the two-color-field method could not reduce power with RGBW 4-in-1 LEDs because there were only two primary colors in each field. Therefore, this thesis modified the algorithm to be 120Hz Stencil-FSC method by making first field become a multi-color single field. Then 240Hz, adaptive base 180Hz, and 120Hz Stencil-FSC methods were applied on RGBW 4-in-1 LEDs backlight system and reduced optical power to 62%, 52%, and 24% of conventional RGB-FSC method respectively. Therefore, the Stencil-FSC method with RGBW 4-in-1 LEDs backlight system provide high image quality with low power consumption.