Paper-like electronic media: The case for R2R-processed full-color reflective displays

Hewlett-Packard (HP) is approaching the challenge of generating bright high-quality reflective color images from the perspective of printing by layering subtractive colorants (CYM or CMYK) at every addressable pixel location. Layered colorants in electronic media can be enabled by stacking electro-optic layers that are modulated between colored and transparent optical states. Unlike emissive or transmissive displays, the reflective display does not generate any photons, but merely reflects ambient light as efficiently as possible through optical architectures and electrical designs in order to produce colorful images. The choice of electro-optic switching technology determines attributes such as tonal resolution, spatial resolution, viewing angle, and switching-speed performance. HP has also developed a set of roll-to-roll (R2R) processing capabilities for making fine-scale circuitry and physical features on plastic substrates that are compatible with the needs of reflective displays. A major opportunity for cost savings in R2R manufacturing is minimization or elimination of clean rooms.