SED is short for Surface-Conduction Electron-Emitter Display.
Like regular cathode ray tubes, SEDs consists of conductive electron emitters that are based on palladium oxide. However, the difference to cathode ray tubes using one single electron emitter is that, with SED, each sub pixel is dedicated its own electron emitter.
Developed by Toshiba and Canon, SEDs are expected to find their way into TV sets in the near future. They particularly stand out in terms of their enormous contrast ratio, which can be as high as up to 100000:1.