Image Quality Enhancement in AMOLED Microdisplay for Mobile Projectors

Abstract

Data driving techniques and circuits to enhance the image quality of the 0.4-inch diagonal VGA AMOLED on silicon substrate have been proposed. The uniformity of a displayed image can be severely degraded by the random offset voltages of the data drivers. The color shift due to the differential OLED material aging is another well-known concern. To alleviate these image quality issues, data driving techniques such as direct driving by the DAC and dynamic compensation of OLED aging by updating the gamma correction curves are presented. Even with these additional features, the circuit area was drastically reduced compared with the authors' previous work by circuit design methods including peak current dispersion. Additionally, the LVDS serial interface, the buck and buck-boost DC-DC converters for the integrated drivers and pixel circuits are also integrated for slim form factor of the microdisplay. The proposed techniques and circuits were validated by both the simulation and fabrication in 0.35 mu m CMOS process.