Ryuji Nishikawa

Full-color AMOLED with RGBW pixel pattern

Abstract— A full-color AMOLED display with an RGBW color filter pattern has been fabricated. Displays with this format require about one-half the power of analogous RGB displays. RGBW and RGB 2.16-in.-diagonal displays with average power consumptions of 180 and 340 mW, respectively, were characterized for a set of standard digital still camera images at a luminance of 100 cd/m2. In both cases, a white-emitting AMOLED was used as the light source, and standard LCD filters were used to provide the R, G, and B emission. The color gamuts of these displays were identical and the higher overall efficiency of the RGBW format results from two factors. First, a large fraction of a typical image is near neutral in color and can be reproduced using the white sub-pixel. Second, the white sub-pixel in an RGBW AMOLED display is highly efficient because of the absence of any color filter. The efficiency of these displays can be further enhanced by choosing a white emitter optimized to the target display white point (in this case D65). A two-emission layer configuration based upon separate yellow and blue-emitting regions is shown to be well suited for both the RGBW and RGB formats.

Developments in OLEDs with a co-dopant system for improved efficiency and stability

Development of RGB material has already reached the level of commercial products for full color displays devices such as digital cameras. However, the key challenges that still remain are improving luminance efficiency for lower power consumption and better stability. Applying a co-dopant into the EML is an effective way to adjust device performance. A large proportion of power is consumed in red sub-pixels in full-color displays with RGB sub-pixels. Previously we found that rubrene doping of red emitting layer improved the luminance efficiency and operational stability by enhancing the energy transfer from host material to emitting dopant. To increase the efficiency, a phosphorescent material as a red emitter was studied. We review the requirements for and characteristics of RGB OLEDs and the impact of co-doping systems on the performance of full-color displays.

31.5L: Late-News Paper: Development of a Combined Liquid Crystal and Fine Pitch Light Source Display (LFD)

We propose a novel display system that we call an LFD (combined liquid crystal and fine pitch light source display). In an LFD, an auxiliary light source patterned with a fine pitch is attached to a reflective liquid crystal display (LCD), and a light shield is formed on the observers side of the light source. A vertical alignment LCD (VA-LCD) is attached as the reflective LCD, and an organic light-emitting diode (OLED) is attached as the fine pitch light source. An LFD can produce bright, high-contrast images under any ambient light. We built a test sample and confirmed its display characteristics.