how does a touchpad system work?

[dpopiz]

can anybody explain to me in detail how a touchpad works?

first of all, how is the touch converted into electrical impulses and how is it represented?
what I'm most interested in though is how the impulses (however they are represented) outputted by the touchpad are translated into control of a pointer or the ipod menu system

 

[Mday]

http://www.synaptics.com/products/touchpad_faq.cfm

 

[dpopiz]

thanks mday.

it says the asic outputs position and speed. it also outputs direction of movement right? so:
x y coords for position
angle and magnitude for movement vector