초 고해상도 LCD용 Pixel 고 충방전율 구동 방식

Abstract

최근에 선명하고 큰 디스플레이에 대한 수요가 증가함에 따라 디스플레이의 크기가 커지고 해상도 또한 높아지고 있다. 이러한 소비자들의 요구를 만족 시키기 위해 display는 크기와 해상도 면에서 많은 발전을 이루어 왔다. 2000년 대 FHD TV (해상도: 1920X1080)의 등장에 이어 2010년 이후 UHD TV (해상도: 3840X2160)의 시장 점유율이 점점 더 커져가고 있다. 그리고 2020년 시험 방송 예정인 QUHD 제품 (해상도: 7680X4320)도 여러 display 업체에서 연구 개발 및 제품 개발 중에 있다. 디스플레이의 크기 또한 최대 크기인 110인치부터 55인치에 이르기 까지 다양한 제품들이 출시되고 있다. 이렇게 디스플레이의 해상도와 크기가 커짐에 따라 액정 디스플레이의 데이터 라인 load는 증가하게 되고 이는 panel의 pixel에 데이터를 충전하고 방전하는 것을 어렵게 한다. 본 논문에서는, 액정 디스플레이의 증가한 데이터 라인 load를 극복하고 보다 원활하게 pixel의 충전과 방전을 하기 위해 두 가지 구동 방식을 제안하였다. 이 구동 방식은 데이터 전압의 변화 량에 따라 과 충전을 이용한 방식과 디스플레이의 위치에 따라 수평 라인 충전 시간을 조절하는 방식으로 그로 인해 충방전율이 상당히 개선된다. 제안한 방식을 평가하기 위해 UHD 60 Hz triple rate driving 모델과 QUHD 120 Hz single rate driving 모델을 사용하였다. 효과를 평가하기 위해서 0 계조와 255 계조가 반복되는 단색 pattern의 휘도를 측정하여 평가하였다. 과 충전 방식을 통해서 단색 기준으로 최대 24%의 충방전율이 개선되었고 수평 라인 충전 시간 조절을 통해서 단색 중간 계조 pattern에서 23.5%의 충방전율 개선을 확인 하였다. 그러므로, 제안한 구동 방식은 초고해상도 대형 디스플레이를 구현하기에 적합하다.|In recent years, as interest in vivid and large-sized displays has continued to increase, high-resolution displays are increasingly demanded. Full high definition (FHD) TVs with a resolution of 1920X1080 have started to appear in the market in 2000’s, and the market share of ultra-high definition (UHD) TVs with a resolution of 3840X2160 have been growing since 2010. Quad ultra-high definition (QUHD) TVs with a resolution of 7680X4320 have been actively researched and developed by several global display makers and expected to begin experimental broadcasting in 2020. Currently, various products with large display sizes from 55-inch to 110-inch have been introduced. As the resolution and size of the display increase, the data line load of the liquid crystal display increase, thereby having difficulty in charging and discharging the data voltage of the pixels in the panel. In this thesis, two driving methods are proposed to prevent the increase in the data line load and to charge the pixels smoother. The proposed driving methods include the over driving method and the charging time control method, of which the first one changes the target voltage according to variation of the pixel data, whereas the second one controls the horizontal line time according to the panel position. Both methods are very effective to improve the charging and dis-charging ratio of the pixel. To evaluate the proposed methods, UHD 60 Hz triple rate driving and QUHD 120 Hz single rate driving liquid crystal display modules (LCMs) are used. The luminance of single color pattern is measured to evaluate the effectiveness of the proposed methods. The over driving method and charging time control methods improves the charging and discharging ratio up to 24% in single color pattern and 23.5% in single color pattern of middle gray, respectively. Therefore, the proposed methods are suitable for large-sized ultra-high resolution displays.; In recent years, as interest in vivid and large-sized displays has continued to increase, high-resolution displays are increasingly demanded. Full high definition (FHD) TVs with a resolution of 1920X1080 have started to appear in the market in 2000’s, and the market share of ultra-high definition (UHD) TVs with a resolution of 3840X2160 have been growing since 2010. Quad ultra-high definition (QUHD) TVs with a resolution of 7680X4320 have been actively researched and developed by several global display makers and expected to begin experimental broadcasting in 2020. Currently, various products with large display sizes from 55-inch to 110-inch have been introduced. As the resolution and size of the display increase, the data line load of the liquid crystal display increase, thereby having difficulty in charging and discharging the data voltage of the pixels in the panel. In this thesis, two driving methods are proposed to prevent the increase in the data line load and to charge the pixels smoother. The proposed driving methods include the over driving method and the charging time control method, of which the first one changes the target voltage according to variation of the pixel data, whereas the second one controls the horizontal line time according to the panel position. Both methods are very effective to improve the charging and dis-charging ratio of the pixel. To evaluate the proposed methods, UHD 60 Hz triple rate driving and QUHD 120 Hz single rate driving liquid crystal display modules (LCMs) are used. The luminance of single color pattern is measured to evaluate the effectiveness of the proposed methods. The over driving method and charging time control methods improves the charging and discharging ratio up to 24% in single color pattern and 23.5% in single color pattern of middle gray, respectively. Therefore, the proposed methods are suitable for large-sized ultra-high resolution displays.