Purpose

Before LCD screens appeared, the main technology of computer screen production was based on cathode ray tubes (CRTs). The disadvantage of  CRT screens  is appearance of a dark shadow which happens due to the changes of phosphor coating after the same image is displayed for a long time. In fact, the devices with CRTs  have a problem with phosphor burn-in as well as plasma displays.

In order to eliminate this effect screen-saver programs were invented. They  change the images on the screen automatically when the user is inactive.

For  public CRTs devices such as ATMs  it is especially important because the stand-by displays appears here every time the device is not in use and the risk of burn-in increases. Furthermore, the older devices are more susceptible to this problem than modern ones. In modern CRTs phosphor coatings are much more improved and the contrast of images is lower in comparison with the text and graphics of older devices. In  up-to-date LCD monitors the problem  of burn-in is no more the issue of the day as the technology of producing images is different. That’s why the function of screensavers today is decoration and entertainment .  

Screensavers can be applied in different ways. One of them is background task activation, for example, a virus scan. This feature is available in Avast. There is a blue window displaying the progress. It turns red when a virus is found.

Considerations

Energy consumption of monitors which are running screensavers does not increases and varies from a few watts to several hundred depending on the kind of a display. Most modern computers have the function of switching the monitor into a low power mode. Such mode is included in power management options of any operation system but the computer hardware and monitor must support it, too.

Additionally, if you use screensavers on flat panels or LCD screens instead of switching the screen off, the lifetime of displays can be reduced because fluorescent backlight is lit and it leads to faster ageing. It should be mentioned that fluorescent tubes are difficult and expensive to replace as the whole assembly  must be replaced. During the product lifetime of  any LCD screen the loss of brightness  reaches 50%.

That is why the term ‘screensaver’ turns out to be incorrect. In order to save the screen and electricity it’s better to is to turn off the monitor.

It should be taken into consideration that screensavers  utilize a great amount of CPU time which leads to  increasing of  power consumption.

Entertainment

The first screensaver for Macintosh   and then to PC/Windows was After Dark. Flying toasters were one of its fantastic designs. They started a tendency  of creating such screen savers as animals, fish, fractals which enliven an idle monitor. By the way, the screensaver’s ability to entertain is  often used to promote different kinds of products( for example, feature films).Creating  screen savers computer programmers give an outlet for their  imagination.