Touchpad (English touchpad - touch panel) - an input device that is present on all modern laptops. It was invented back in 1988. and has since remained the most common cursor control device on a laptop. The principle of operation of the touchpad is quite simple, making it very reliable and easy to use.
Inside the touchpad, horizontally and vertically, there are many inductive-capacitive sensors that determine the location of the finger by changing the electrical capacitance. If you disassemble the touchpad and examine it at high magnification, you can see a grid of metal conductors (capacitors), which are separated by a non-conductive polyester film. Due to the fact that a person conducts an electric current well enough, when a finger touches the touch panel, the electric field changes, and therefore the capacitance of the capacitors. By measuring the capacitance of each capacitor, the computer can accurately find out the coordinates of the finger on the touchpad.
In addition, it is possible to determine the approximate pressure applied to the touchpad. This is possible due to an increase in electrical capacity with increasing pressure and an increase in the number of fingers on the panel.
The capacitance of capacitors in the grid is also influenced by external electric fields and other physical effects. In this regard, a jittering change in the measured capacitance "jitter" appears. To neutralize it, "filtering" algorithms are used. They transform "jitter" into smooth positioning. There are many such algorithms, but the most common one is a simple one called the "averaging window" algorithm.
As you can see, the principle of operation of the touchpad is very simple, which is why it became so widespread. In terms of its reliability, it surpasses any other manipulators.
