A PCAP touch screen consists of two layers of transparent electrodes (usually ITO or metal grids) arranged in a crosswise pattern, forming a matrix of X and Y axes. The touch controller detects the touch position by scanning the mutual capacitance change between the electrodes: the X electrode transmits the signal, the Y electrode receives the signal, the finger touch will change the electric field coupling between the electrodes, which will change the size of the capacitance, and the chip detects the change in capacitance value, and then outputs the signal.
Projected Capacitive Touch Panel(PCAP) can not only achieve touch control in the display area (window area), but also through customized design in the non-display area (such as bezel, bottom) to add buttons (on/off key, function keys, etc.). The core principle is still based on capacitive sensing, but it requires targeted optimization on the FPC line.
How touch buttons work:
Any two conductive objects exist between the inductive capacitance, a key and the earth can also constitute an inductive capacitance, in the case of the surrounding environment is unchanged, the value of the inductive capacitance is a fixed and unchanged tiny value.
When there is a human finger close to the touch button, it will make the total inductive capacitance value increase.
Capacitive touch key IC detects a change in the value of the inductive capacitance of a key, and then outputs an OK signal that a key has been pressed. Capacitive touch key because there is no mechanical structure, all the detection is a small change in the amount of electricity, so the various interferences will be more sensitive, so the touch key design, touch panel design and the choice of touch IC is very critical.
If you have a project that needs to add touch keys, please feel free to contact us (sales03@wiwotouch.com) to get the optimal solution.