LED panels used in the X220 system use In Plane Switching (IPS) technology to provide optimum viewing angles and clarity. Some users have reported an image persistence phenomenon; they are able to create the image persistence by disabling screen savers and leaving a fixed image on their screen for extended periods of time - the persistent image is viewed only with a very light grey or off white background. Our testing indicates that the persistent images completely dissipated in a short time period.
The persistent image is caused by the discharging of residual electromagnetic charges internal to the LCD panel; when this charge has decayed or dissipated the persistent image is gone. This persistence image is not similar to previous generation CRT and monitor issues where the image was "burnt in" on the screen. Any persistent image is not permanent or damaging to the LCD panel.
Any of the following ThinkPad with the following Machine Types (MT):
- X220 and X220i MT: 4286, 4287, 4289, 4290, 4291, 4292, and 4293
- X220 Tablet and X220i Tablet MT: 4294, 4296, 4297, 4298, 4299, 4300, and 4301
Image persistence can be prevented by using screen savers and other power management tools to turn off LCD display when the screen is inactive.
Comparison between IPS and TN style LED panels.
IPS (In Plane Switching) LCD driving method and characteristic
Generally (Twisted Nematic- TN type) LCDs have a parallel electrical field, so all of the display area can be symmetrically controlled. By comparison, IPS LCDs have asymmetrical electrical fields in some small areas, the image persistence phenomenon will occur at the asymmetrical electric fields. The image will dissipate during power off or by an image change in a short amount of time. This phenomenon is a natural characteristic of an IPS LCD.
TN (Twisted Nematic LCD)
Liquid crystal is symmetrically controlled in the entire area.
IPS (In Plane Switching LCD)
Liquid Crystal is symmetrically controlled in almost the entire area but some small areas are controlled asymmetrically.