Image persistence
3183055
220526488
2008-06-20T08:21:38Z
Hankwang
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Replace google cache links by proper inline references
[[Image:iiyama-e430s-image-persistence.jpg|thumb|right|270px|TFT display showing persistence artifacts]]
'''Image Persistence''' is the term used for the [[LCD]] and [[plasma display]] equivalent of [[Phosphor burn-in|screen burn]]. Unlike screen burn, however, the effects are most often only temporary. It should be noted however, that plasma displays can also suffer from burn-in (see the [[plasma display]] article for more information).
==Cause==
[[Liquid crystal]]s have a natural relaxed state. When a [[voltage]] is applied they rearrange themselves to block certain [[light wave]]s. If left with the same voltage for an extended period of time (e.g. displaying a [[mouse cursor]] or the [[Microsoft Windows]] [[Taskbar]] in one place), the liquid crystals can develop a tendency to stay in one position. This ever so slight tendency to stay arranged in one position can throw the requested [[color]] off by a slight degree, which causes the image to look like the traditional [[Phosphor burn-in|"burn-in" on phosphor based display]]s.
The actual cause for this tendency is unclear. It might be due to accumulation of ionic impurities inside the LCD <ref>[http://www.plasma-usa.com/screen%20burn/White_Paper_onscreenburn_NEC.pdf Recommendations for reducing image persistence on large-screen LCDs]. NEC Whitepaper, 2005.</ref>, electric charge building up near the electrodes <ref>[http://www.mitsubishi-presentations.com/pdf/MIT_MDTLCD_IMAGE_PERSISTENCE.pdf Image persistence: LCD monitors]. Mitsubishi Electric, January 2006 (?)</ref>, parasitic capacitance <ref>[http://www.elotouch.com/Support/TechnicalSupport/pixels_image.asp Pixels and Image Sticking]. Tyco Electronics technical support (pre-2008)</ref>, or "a [[Direct current|DC]] voltage component that occurs unavoidably in some display pixels owing to anisotropy in the dielectric constant of the liquid crystal".<ref>K. Kusafuka, H. Shimizu and S. Kimura, [http://www.research.ibm.com/journal/rd/423/kusafuka.html Driving method for gate-delay compensation of TFT/LCD].
IBM Journal of Research and Development, Volume 42, Numbers 3/4, 1998</ref>.
==Prevention/Treatment==
This is easily preventable and can be reversed by allowing the liquid crystals to return to their relaxed state. In other words, turning off an LCD display for as little as 15 minutes a day will relax the crystals and help prevent image retention. For PC monitors, it is also ideal to rotate [[Desktop environment|desktops]], and hide away elements on the screen which normally would be displayed perpetually (like the [[taskbar]] in [[Microsoft Windows]] or the Dock in [[Mac OS X]]). The usage of a [[screensaver]] that has a constantly changing image can help as well.
The fastest remedy for image persistence is to leave the display off for an extended period of time. This time can range anywhere from hours to days. Another useful approach to removing LCD image persistence is to first create a solid white image and display the image as a screensaver covering the entire display area for an extended period of time.[http://docs.info.apple.com/article.html?artnum=88343]
==References==
<references/>
==External links==
*[http://compreviews.about.com/od/monitors/a/LCDBurnIn.htm Article on LCD Image Persistence]
[[Category:Display technology]]