Samsung UA40ES6200R E-Manual page 218

This function removes after-images on
the screen by illuminating all the pixels
on the screen according to a pattern.
Use this function when there are after
images or symbols on the screen,
especially when you displayed a still
image on the screen for a long time.
N
The after-image removal function
has to be executed for a long time
(approximately 1 hour) to effectively
remove after-images on the screen.