![Screen burn screen off](https://upload.wikimedia.org/wikipedia/commons/4/45/Screen_burn_screen_off.png)
Screen burn-in, image burn-in, or ghost image, is a permanent discoloration of areas on an electronic display such as a
cathode ray tube (CRT) in an old
computer monitor or
television set
A television set or television receiver, more commonly called the television, TV, TV set, telly, tele, or tube, is a device that combines a tuner, display, and loudspeakers, for the purpose of viewing and hearing television broadcasts, or using ...
. It is caused by cumulative non-uniform use of the screen.
Newer
liquid-crystal displays (LCDs) may suffer from a phenomenon called
image persistence
Image persistence, or image retention, is the LCD and plasma display equivalent of screen burn-in. Unlike screen burn, the effects are usually temporary and often not visible without close inspection. Plasma displays experiencing severe image p ...
instead, which is not permanent.
One way to combat screen burn-in was the use of
screensaver
A 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. The original purpose of screensavers was to prevent phosphor ...
s, which would move an image around to ensure that no one area of the screen remained illuminated for too long.
Causes
With phosphor-based electronic displays (for example CRT-type computer monitors, oscilloscope screens or
plasma display
A plasma display panel (PDP) is a type of flat panel display that uses small cells containing plasma: ionized gas that responds to electric fields. Plasma televisions were the first large (over 32 inches diagonal) flat panel displays to be releas ...
s), non-uniform use of specific areas, such as prolonged display of non-moving images (text or graphics), repetitive contents in gaming graphics, or certain broadcasts with tickers and flags, can create a permanent ghost-like image of these objects or otherwise degrade image quality. This is because the phosphor compounds which emit light to produce images lose their
luminance with use. This wear results in uneven light output over time, and in severe cases can create a ghost image of previous content. Even if ghost images are not recognizable, the effects of screen burn are an immediate and continual degradation of image quality.
The length of time required for noticeable screen burn to develop varies due to many factors, ranging from the quality of the phosphors employed, to the degree of non-uniformity of sub-pixel use. It can take as little as a few weeks for noticeable ghosting to set in, especially if the screen displays a certain image (example: a menu bar at the top or bottom of the screen) constantly and displays it continually over time. In the rare case when horizontal or vertical deflection circuits fail, all output energy is concentrated to a vertical or horizontal line on the display which causes almost instant screen burn.
CRT
![ScreenBurn amber](https://upload.wikimedia.org/wikipedia/commons/2/21/ScreenBurn_amber.JPG)
Phosphor burn-in is particularly prevalent with monochromatic CRT screens, such as the amber or green
monochrome monitor
A monochrome monitor is a type of computer monitor in which computer text and images are displayed in varying tones of only one color, as opposed to a color monitor that can display text and images in multiple colors. They were very common in t ...
s common on older computer systems and
dumb terminal
A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. The teletype was an example of an early-day hard-copy terminal a ...
stations. This is partly because those screens displayed mostly non-moving images, and at one intensity: fully on. Yellow screens are more susceptible than either green or white screens because the yellow phosphor is less efficient and thus requires a higher beam current. Color screens, by contrast, use three separate phosphors (red, green, and blue), mixed in varying intensities to achieve specific colors, and in typical usage patterns such as "traditional" TV viewing (non-gaming, non-converged TV usage, non-Internet browsing, broadcasts without tickers or flags, no prolonged or permanent
letterboxing) are used for operations where colors and on-screen object placement approach uniformity.
Modern CRT displays are less susceptible than older CRTs prior to the 1960s because they have a layer of aluminum behind the phosphor which offers some protection. The aluminum layer was provided to reflect more light from the phosphor towards the viewer. As a bonus, the aluminum layer also prevented ion burn of the phosphor and the
ion trap
An ion trap is a combination of electric and/or magnetic fields used to capture charged particles — known as ions — often in a system isolated from an external environment. Atomic and molecular ion traps have a number of applications in phy ...
, common to older monochrome televisions, was no longer required.
Plasma, LCD, and OLED displays
Plasma displays produced until around 2007 were highly susceptible to burn-in, while
LCD-type displays are rarely affected. The wide variation in luminance degradation with RGB-based OLED will cause noticeable color drift over time (where one of the red-green-blue colors becomes more prominent). OLEDs do not need a backlight to light up; each pixel is a self-illuminating LED. The pixels on OLEDs inevitably lose their brightness over time. The longer an OLED pixel is used (illuminated), the dimmer it will appear next to a lesser used pixel.
In the case of LCDs, the physics of burn-in are different than plasma and OLED, which develop burn-in from luminance degradation of the light-emitting pixels. For LCDs, burn-in develops in some cases because pixels permanently lose their ability to return to their relaxed state after a continued static use profile. In most typical usage profiles, this
image persistence
Image persistence, or image retention, is the LCD and plasma display equivalent of screen burn-in. Unlike screen burn, the effects are usually temporary and often not visible without close inspection. Plasma displays experiencing severe image p ...
in LCD is only transient.
Both plasma-type and LCD-type displays exhibit a similar phenomenon called transient image persistence, which is similar to screen burn but is not permanent. In the case of plasma-type displays, transient image persistence is caused by charge build-up in the pixel cells (not cumulative luminance degradation as with burn-in), which can be seen sometimes when a bright image that was set against a dark background is replaced by a dark background only; this image retention is usually released once a typical-brightness image is displayed and does not inhibit the display's typical viewing image quality.
Mitigation
Screensaver
A 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. The original purpose of screensavers was to prevent phosphor ...
s derive their name from their original purpose, which was an active method of attempting to stave off screen burn. By ensuring that no pixel or group of pixels was left displaying a static image for extended periods of time, phosphor luminosity was preserved. Modern screensavers can turn off the screen when not in use.
In many cases, the use of a screensaver is impractical. Most plasma-type display manufacturers include methods for reducing the rate of burn-in by moving the image slightly, which does not eliminate screen burn but can soften the edges of any ghost image that does develop. Similar techniques exist for modern OLED displays. For example, manufacturers of
Android Wear
Wear OS (also known simply as Wear and formerly Android Wear) is a version of Google's Android operating system designed for smartwatches and other wearables. By pairing with mobile phones running Android version 6.0 "Marshmallow" or newer, or ...
watches with OLED displays can request that Android Wear enable "burn protection techniques" that
periodically shift the contents of the screen by a few pixels.
Other examples: Apple's
iPhone X
The iPhone X (Roman numeral "X" pronounced "ten", also known as iPhone 10) is a smartphone designed, developed and marketed by Apple Inc. It is part of the 11th generation of the iPhone. Available for pre-order from October 27, 2017, it was re ...
and Samsung's
Galaxy series both mitigate or delay the onset of burn-in by shifting the pixels every minute or so for the battery, Wi-Fi, location, and service bars. Also,
parallax scrolling
Parallax scrolling is a technique in computer graphics where background images move past the camera more slowly than foreground images, creating an illusion of depth in a 2D scene of distance. The technique grew out of the multiplane camera tec ...
may be enabled for the home screen to give icons a 3D-like effect, a setting Apple refers to as "perspective zoom".
AG Neovo patented Anti-burn-in technology is also using
pixel shifting to activate the pixels to move by the designed time interval to prevent burn in effect on LCD monitors.
Google requests that when these techniques are enabled, watch face developers do not use large blocks of pixels so that different pixels are burned in with each shift, reducing the overall wear of the pixels.
Some screensavers move around, such as those on DVD players or those on some
television set
A television set or television receiver, more commonly called the television, TV, TV set, telly, tele, or tube, is a device that combines a tuner, display, and loudspeakers, for the purpose of viewing and hearing television broadcasts, or using ...
s that move around paused video after a long period of inactivity.
Depending on the type of screen, it is sometimes possible to remedy screen burn-in through the use of remedial software and remedial devices. In the case of OLED screens on
Android phones, burn-in reduction apps can display an inverted image of the navigation and status bars (which are constantly displayed and therefore the most likely elements to be burned in) to burn in opposite pattern, resulting in a screen whose sub-pixels have more even luminosity and therefore less visible burn-in artifacts.
Historical notes
The most prevalent burn-in image on early televisions was said to be that of the RCA
Indian-head test pattern
The Indian-head test pattern is a test card created by RCA of Harrison, New Jersey, which became the standard image of the RCA TK-1 monoscope. It features a drawing of a Native American wearing a headdress and numerous graphic elements designe ...
, which would often follow the formal television station
sign-off. This was due to the viewer leaving the television set on at the end of the day, which was not recommended by the television manufacturers.
References
{{reflist
Display technology
Visual artifacts