Scrummie

Screensavers were originally developed to avoid “burning” an image into a CRT monitor. CRTs create an image by hitting phospors with electrons; the phosphors emit light. Over time, the phosphors lose their brightness, and if you keep a single image on screen for an extended period, some phosphors will lose more brightness than others, because some will be emitting all the time. As a result, when you display a different image on the screen- or even just a full white screen- you might see  a ”shadow” of the original image. Screensavers were meant to turn off most of the image, but display something that indicates that the computer is still on, usually through some moving element.

CRTs have improved to the point where burn-in is less of a problem, and screensavers have become more a means of entertainment than a solution to a technical problem. In fact, many use largely static images- such as an aquarium tank- in which only a small portion of the image changes.

LCD’s can also be susceptible to image burn-in, though it isn’t as common as with CRTs. If you’re going to use a screensaver, it should have a black background with a small moving image. The best solution, however, is to use energy-saving feature within Windows, telling the monitor to shut off when the system has been idle for a given period. This will not only prevent burn-in but also save energy. Plus, it can extend the life of the display. An LCD uses a backlight that loses brightness over time, so it’s better to turn off the monitor- and thus the backlight- than to leave it on for some entertaining screensaver. An additional benefit for notebooks. Turning off the display when idle can significantly extend battery life.