What is LCD Image Persistence?
Major LCD manufacturers acknowledge that image persistence can occur even with today’s modern LCD televisions. The filaments in liquid crystals can become stuck in a non-neutral position if exposed to a static image for an extended period of time. This results in a semi-transparent residual image persisting in the screen. The LCD filaments must return to their neutral state in order for the persisted image to no longer be visible.
This is achieved by applying an alternating signal to the pixel field for a defined period of time. Major LCD manufacturers recommend that you “create a solid white image and display the image as a screen saver covering the entire display area for an extended period of time.” [Wikipedia] However, virtually none of the major manufacturers provide a built in mechanism for doing so.
PixelTuneup is the only portable solution that makes it easy to follow the manufacturer recommendation for removing image persistence using a safe, low voltage signal to reset LCD filaments. This is achieved by applying precisely controlled voltages to the video controller through the VGA connector. By controlling voltages at the hardware level, PixelTuneup is able to produce a perfectly balanced color signal — no other solution can make this claim! In addition, PixelTuneup’s horizontal and vertical synchronization signals are calibrated to ensure uniform pixel coverage regardless of aspect ratio.
Wikipedia defines image persistence in LCD displays as follows:
“Liquid crystals have a natural relaxed state. When a voltage is applied they rearrange themselves to block certain light waves. 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 coloroff by a slight degree, which causes the image to look like the traditional ‘burn-in’ on phosphor based displays. In fact, the root cause of LCD image persistence is the same as phosphor burn-in, namely, non-uniform usage of the display’s pixels.
“The cause of this tendency is unclear. It might be due to accumulation of ionic impurities inside the LCD, electric charge building up near the electrodes, parasitic capacitance, or a DC voltage component that occurs unavoidably in some display pixels owing to anisotropy in the dielectric constant of the liquid crystal.
“Usually the image persistence is temporary, but can become permanent. As a result, all major LCD display manufacturers exclude image persistence from their warranties.”
Note that LCD warranties do not cover image persistence. Therefore, it is the responsibility of the owner to maintain the screen and prevent image persistence from damaging the screen.
PixelTuneup both treats and prevents image persistence in LCD televisions. Here is a video demonstration of PixelTuneup in repairing an LCD panel with image persistence.