I just got a Cybook Opus. While playing with it, I noticed an option in the menu to disable the all-black reflashing that happens every time a more-than-minimal change occurs on the screen. Disabling it, I finally figured out why it happens - without a full blank refresh, there's noticeable ghosting from what was on the display previously.
But this got me wondering. E-ink displays eat power only when they change their content, with each changed pixel contributing to the power draw. During a full blank the entire display gets energized so all pixels draw power, but during a non-full-blank page change, only the pixels making up the current text and those making up that of the next page need energy to switch state. Since their number is relatively small compared to that of the entire screen, disabling full-blanking should return quite a dramatical increase in battery life.
Is this theory wrong? I don't particularly mind the ghosting, so if I can significantly increase battery life I'll keep full blanking off.
Thanks
