Why does static charge accumulate on TV or monitor ??

The picture on your computer monitor or your television set is drawn with an electron beam. So it is no surprise that the screen builds up a static electric charge. Most screens build up a static charge when you turn them on; this gradually goes away. Then, when you turn them off, you get another static charge - the opposite sign of charge this time. You will get a uniform charge over the surface of the screen. The dust particles on the screen will get charged up, and will be attracted to your finger.
 

 If you watch, you can see the dust particles migrating toward your finger - and away from each other. They also migrate toward clear regions of the screen. It seems like the dust particles, which are all charged the same way, will repel each other and attract your finger. And once you have cleared some dust particles from the screen, the remaining particles will be attracted to this region - but once they start moving, they might keep moving all the way to your finger, leaving a trail of clear screen.