Capacitive touchscreens typically employ a multi-layer structure to achieve their functionality. Taking the F+F (Film+Film) structure as an example, it primarily consists of the following components:
Outer protective film: As the outermost layer, it provides scratch resistance, stain resistance, and enhanced durability;
Transparent conductive layer: Located beneath the protective film, it generally uses ITO (indium tin oxide) material, offering both excellent conductivity and light transmittance;
Insulating layer: Covering the conductive layer, it isolates and protects the inner and outer conductive structures;
Inner conductive layer: Also made of ITO material, it is the core component for sensing touch operations;
Base glass: Serving as the supporting substrate, it provides structural strength and stability.
Capacitive touchscreens determine positioning based on capacitance changes. Capacitance measures a physical quantity representing charge storage capacity, formed when a dielectric exists between two conductors. Its operational process is as follows:
In the untouched state, a uniformly distributed electric field exists between the conductive layers. When a conductive object like a finger contacts the screen, it forms a coupling capacitance with the surface conductive layer, altering the original electric field. Since the human body is conductive, the touch causes a redistribution of charge, resulting in the transfer of high-frequency current through this coupling capacitance.
Electrode sensors positioned at the screen's edges or corners continuously monitor changes in the electric field. The current generated by the touch flows out through these electrodes, producing four current signals proportional to the distance from the touch point. The controller analyzes the proportional relationship between these currents. Using algorithms, it calculates the precise coordinates of the touch point and transmits this data to the processing system for subsequent operations.