How does the pointer movement wad work on laptop computers?

Answer:

TouchPad sensors work by using an electrical phenomenon call capacitance. Whenever two electrically conductive objects come near respectively other without certainly touching, their electric fields interact to form a capacitance. The surface of a TouchPad is a grid of conductive metal wires covered by a plastic insulator, usually a facesheet made of Mylar(R). The human finger is also a fitting electrical conductor. When you place your finger on a TouchPad, a capacitance forms between your finger and the metal wires in the TouchPad. In Synaptics TouchPad, the "wires" are if truth be told shaped as diamond chains to maximize capacitive contact with your finger. The Mylar(R) insulator keep your finger from actually touching the wires and is also textured to assist your finger move smoothly across the surface.



By measuring the swing in capacitance, the application specific integrated circuit (ASIC) can describe when your finger is touching, to an accuracy of more than 1/1000th of an inch. The sensing electronics are inside the ASIC, which includes a microprocessor that computes the finger's position and speed and reports them to the biggest computer in the form of cursor motion.



http://www.synaptics.com/products/touchp...



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