Reflectivity Improvement by Particle Neutralization in a Charged Particle-Type Electronic Display

Abstract

Eight sample panels using an indium tin oxide(ITO)-coated glass substrate were fabricated, with barrier ribs formed of 55 <TEX>${\mu}m$</TEX> height and 10 <TEX>${\mu}m$</TEX> width. The upper and lower substrates were designed with the same panel condition, so a cell gap of 110 <TEX>${\mu}m$</TEX> was obtained. The charged particles in a cell consisted of <TEX>$TiO_2$</TEX> (for white color) or carbon black (black color), negative or positive charge control agents, and a polymer. The average diameter of the two types of particles was commonly 10 <TEX>${\mu}m$</TEX>, and their q/m value was -4.5 <TEX>${\mu}C/g$</TEX> and +4.5 <TEX>${\mu}C/g$</TEX>, respectively. The electrically opposite particles mixed by an agitator were loaded into their cells by a simple particle-loading method. The discharging process proceeded at a humidity of 80% and a temperature of <TEX>$30^{\circ}C$</TEX>. Reflectivity was measured depending on discharging time, and a hysteresis curve by bias voltage obtained for comparison between the neutralized and non-neutralized panel, in which the superior optical property of the neutralized panel was ascertained.