A resistive touch screen is basically comprised of a layer of ITO Film and a layer of ITO Glass. The two layers are separated by DOT. A 5V electrical current is introduced to the ITO Film and ITO Glass. When a user touches the ITO Film with his finger or stylus, the indentation will result in contact with the ITO Glass at the bottom layer to result in a change of voltage.
The signal is converted into a digital one by the A/D controller in order for the PC to compute the coordinates (X and Y axis) of the touch event to achieve positioning.
Projected capacitive touch panel is use capacitor sensing. By using many etched ITO stips, when finger approaches surface, controller IC will detect the varied of capacitance then to quickly calculate position of finger. Due to this action is only sensing varied of capacitance, so finger can be sensed without actually touch surface.