Capacitive screen manufacturers explained that capacitive touch screen is the use of the human body's current induction to work.Capacitive touch screen is a four-layer composite glass screen. The inner surface and interlayer of the glass screen are each coated with a layer of ITO(transparent conductive film). The outermost layer is a thin layer of silica glass protective layer.
When the finger touches the metal layer, due to the human body electric field, the user and the touch screen surface form a coupling capacitor. For the high-frequency current, the capacitor is a direct conductor, so the finger absorbs a small current from the contact point.This current flows out from the electrodes at the four corners of the touch screen, and the current flowing through the four electrodes is proportional to the distance from the fingers to the four corners. The controller accurately calculates the ratio of these four currents to get the position of the touch point.It is this working principle of capacitor screen that leads to the existence of "drift" phenomenon.