Primarily these are for decorative/entertainment purposes, or for password protection. While modern screens are not susceptible to the issues discussed above, screensavers are still used.
Gnome-screensaver has an option for password protection LCD computer monitors, including the display panels used in laptop computers, are not susceptible to burn-in because the image is not directly produced by phosphors (although they can suffer from a less extreme and usually non-permanent form of image persistence). Later CRTs were much less susceptible to burn-in than older models due to improvements in phosphor coatings, and because modern computer images are generally lower contrast than the stark green- or white-on-black text and graphics of earlier machines. In these applications, burn-in can be prevented by shifting the position of the display contents every few seconds, or by having a number of different images that are changed regularly. Blanking the screen is out of the question as the machine would appear to be out of service. Older machines designed without burn-in problems taken into consideration often display evidence of screen damage, with images or text such as "Please insert your card" (in the case of ATMs) visible even when the display changes while the machine is in use. Screen-saver programs were designed to help avoid these effects by automatically changing the images on the screen during periods of user inactivity.įor CRTs used in public, such as ATMs and railway ticketing machines, the risk of burn-in is especially high because a stand-by display is shown whenever the machine is not in use. Cathode ray televisions, oscilloscopes and other devices that use CRTs are all susceptible to phosphor burn-in, as are plasma displays to some extent. When the same image is displayed on a CRT screen for long periods, the properties of the exposed areas of the phosphor coating on the inside of the screen gradually and permanently change, eventually leading to a darkened shadow or "ghost" image on the screen, called a screen burn-in. Purpose Screen protection īefore the advent of LCD screens, most computer screens were based on cathode ray tubes (CRTs). Īs well as computers, modern television operating systems, media players, and other digital entertainment systems may include optional screensavers. Some screensaver programs also use otherwise-idle computer resources to do useful work, such as processing for volunteer computing projects. Screensavers are often set up to offer a basic layer of security by requiring a password to re-access the device. Though most modern monitors are not susceptible to this issue (with the notable exception of OLED technology, which has individual pixels vulnerable to burnout), screensaver programs are still used for other purposes. The original purpose of screensavers was to prevent phosphor burn-in on CRT or plasma computer monitors (hence the name). For CAD scripts, see CadSoft EAGLE.Ī screensaver (or screen saver) is a computer program that blanks the display screen or fills it with moving images or patterns when the computer has been idle for a designated time.
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