Development of Bistable Electronic Inks for Reflective Color Media

Electronic inks have been developed for each primary color to serve as the imaging fluids for novel electro-kinetic display (EKD) technology, which uses in-plane optical effects and out of plane switching fields to switch between color and clear states, allowing a stacked color layer approach. The need for compaction into small volumes to achieve a clear state and repeated cycles of spreading and compaction creates challenges for the stabilization and charging of colorant particles. Surfactants play a critical role in determining system behaviors. This paper reports on the latest findings of surfactant influence on optical switching and bistability characteristics of display performance for some proprietary surfactant formulations. HP's combination of novel device architecture, proprietary inks, and R2R manufacturing platform enables the required attributes for electronic media such as flexibility, robustness, low power, transparency, print-quality color, and scalability at low cost. The innovations described in this paper are applicable to either segmented or pixilated electronic media, and are currently being developed for both digital signage and electronic paper markets.