Legability Investigations of the BiNem Display for e-Reader Applications

Abstract: The electronic reader (e-reader) application is a new device that recently has entered the commercial market. The device is thin, light weighted and portable with a display that is developed for longtime reading books. Since the display technology used in e-readers differs from conventional displays used in e.g. computer monitors and TV-screens, it is not fully known how the optical properties of this new display technology are translated into legibility and reading comfort. The BiNem® display is a bistable reflective liquid crystal display. The purpose of this thesis is to investigate and optimize the legibility of the BiNem display for e-reader applications. BiNem displays with various optical properties have been investigated and also benchmarked against an E-Ink Vizplex display present in the Amazon Kindle 2 e-reader device. Real users have performed various tasks such as visual letter recognition, preference ranking, and long time reading along with subjective measures to evaluate the legibility and reading experience of the different displays. The results show no statistic difference between the BiNem and E-Ink Vizplex display in terms of legibility. Further, higher contrast displays were preferred over higher brightness and sharp and well-defined letters were requested. We have found that the BiNem e-reader display is competitive to the E-Ink Vizplex display present in Amazon Kindle 2 device in terms of legibility. An optimized optical stack for the BiNem display for e-reader applications is presented.