I’ve seen screen burn on the old green-on-black monitors in ATMs, where they’re displaying the same graphics day in and day out, to the extent that the outline is visible as a sort of dull yellowish mark even when the power is off.
And I know it was always the fear with CRT monitors that they’d suffer the same - which is why screensavers were invented.
But today, I saw an example of something a bit like screen burn on a TFT flkat panel monitor - the user was complaining about a sort of smudgy, wispy mark across the upper part of the desktop (which is just a plain solid colour) - at first, I thought maybe someone had put a background image there with the mark on it, but it was still set to ‘none’ and just a solid colour.
On closer examination, the mark appeared to be a bit blocky and there was a series of little dark blobs running quite regularly down from one end - then it dawned on me that these little blobs looked a bit like open envelope icons. I fired up Outlook and sure enough, the marks lined up exactly with the envelope icons in the inbox view.
So somehow, the image of the Outlook window (or at least those features of it that remain fairly constant in position and colour) has become indelibly ingrained into the screen - but how could this happen? It’s an LCD screen…
I had the same thing happen to my monitor at work. I switched from a CRT to a flat panel and wasn’t aware that flat panels could have burn in issues. After a while, I had an image of outlook burned into the screen. I set up a screen saver, and after a while (not sure how long) the “burn in” went away.
Yep. It’s an LCD screen. And it happens, I’m sorry to tell you. I have a Dell 2005FPW and there is some burn where my bowser’s title bar is and where some of my more permanent icons (trash bin, for example) are.
That’s the bad news. The good news is that it isn’t permanent. It does go away if you leave the monitor off for a while. The burn-in also doesn’t seem to get as bad as it does on a CRT – but on the other hand, it can set in quicker.
As I understand it the process is a little different though. On CRT monitors, burn-in happens because the cathode gun imprints an image on the tube’s phosphors, which subsequently breaks them down causing them to become permanently “burned” in the areas where parts of images contrasted with the background. LCD burn-in – more appropriately called “image persistence” – happens differently.
Modern LCD monitors work via a matrix of thin film transistors (TFTs) that supply an electrical current to specific grid coordinates through a controller. The amount of current applied to a specific coordinate activates, or “twists” the liquid crystal element at that location to produce a point of colour. The amount of current determines how much the crystal twists, which determines the colour of that pixel. If an image is left on the monitor for a long period of time, the crystals can form a kind of memory of their current state. So charged with this memory, their twist becomes a little off kilter, which is what causes the image persistence. Liquid crystals do have a natural resting state though, and if allowed to rest long enough (by turning the monitor off for several hours to a day) they will eventually return to that state, eliminating the persistence. At least, until you let another image burn-in.
