SED is probably the closest concept to the Cathode Ray Tube (CRT) that is predominant today. However, it also provides the flat-panel benefits we gain from Liquid Crystal Display (LCD) and Plasma Display Panel (PDP) technology as well. Consider SED to be the best of both worlds: bright, high-quality images with less bulk. Let's see how it works to better understand this.
Similar to a CRT, the display is created with electrons that collide with a phosphor-coated screen. CRTs use a single electron gun to emit the particles that create the display. The one electron gun essentially draws the screen by passing all of the electrons to the screen. Since the electron gun has to cover the entire screen, the set tends to be deep, although some slimmer sets are coming to market. Additionally, since the electron gun is constantly sending particles to the entire screen, it tends to be a heavy consumer of power.
SED technology applies the electron-phosphorus concept, but radically changes one key element: the electron mechanism. Instead of a single electron gun, SED sets have one electron emitter for each pixel. This brings two key CRT advantages to the flat panel world. Less power is needed because the electrons don't need to travel as far. Since the electrons are close to the display surface, the set is much slimmer than a CRT set, as well. If that doesn't get you as excited as a charged electron, then just wait, there's more!
Here's the key reason that SEDs are likely to gain a stranglehold over other flat-panel technologies in the long run: brightness and contrast. Currently, there isn't a flat-panel or microdisplay technology that can compete with CRTs for either brightness or contrast. The real beauty of SED technology is that it has the same brightness and contrast qualities of a CRT because the same electron-phosphor display approach is used; it simply does so more efficiently and in less space!
There are plenty of additional technical details on SED technology, but at least this provides the basics. The real question is: now that you know what SED is, how likely are you to consider an SED purchase in your not-so-distant future?