Do I build up static charge from using a capacitive touchscreen?

[Evertje]

Hi guys,

As I've tried to convey using the topic title, I would like to know if (and how large the effect would be) one gets charged by using an ordinary capacitive touchscreen.

From what I've understood, the projective capacitive touchscreens have the conductive layers (the wires I mean) sandwiched in between non-conductive transparent layers (e.g. the layer you touch). So from these devices there would not be any direct contact to charged layers. The 'normal' capacitive touchscreens have a voltage on the upper layer (by this I again mean the layer you touch) which is also coated by a conductive material. The sensing is done essentially because you drain charge from this layer upon touching. Am I right in thinking this means that every time one touches such a screen there is a small build-up of charge? And would this mean that if you just keep your finger pressed against the screen, you would pretty soon be able to get a 'nice' shock from touching a doorknob? :)

 

[berkeman]

Most touchscreens work with capacitive sensing now, so you are not in contact with anything conductive. They try not to have the outer material that you touch build up much charge, because that confuses the touchscreen sensor's output. Most folks now have had the negative experience of their laptop touchpad going nuts sometimes and doing false moves and clicks on dry days...