Richard M. Webber

10.4: Image Stability in Active-Matrix Microencapsulated Electrophoretic Displays

Image stability, that is the unpowered maintenance of any desired lightness state over time, is essential to the development of ultra-low power information appliance displays. In this paper, we quantify the image stability of displays made with microencapsulated electrophoretic materials. We describe a metric for image stability and show that the image stability for the saturated black and white states of current electrophoretic materials used in active-matrix displays is at least of order 106 s. Image stability is also demonstrated for grayscales, i.e., lightnesses intermediate to those of the saturated states, and we show that it is maintained when subjected to temperature variations over a typical operating range of 0 to 50 °C.