Hybrid driving method for outdoor public information displays

Abstract

This paper proposes a pixel structure and a hybrid driving method for improving the transmittance of the liquid crystal display (LCD) for the outdoor public information display (PID) while maintaining the image quality. The proposed driving method uses the pixel consisting of subpixels using red (R), green (G), and blue (B) color filters and white (W) subpixels, and performs in either of two operation modes selected according to the amount of sunlight and the temperature. Mode 1 is a hybrid field sequential mode in which W subpixels are operated to increase the transmittance without the simultaneous contrast problem under the very bright condition. Mode 2 is a low-temperature mode in which only red–green–blue (RGB) subpixels are operated to prevent image distortion under a low-temperature condition. The measurement results from the fabricated LCD were 14.5% transmittance, an over 4000 contrast ratio, and 82.5% color gamut. In addition, the ratio of RGB luminance to the W image is similar to that of the conventional LCD. Therefore, the proposed pixel structure and driving method are appropriate for outdoor PIDs.