The surface of the capacitive screen is coated with a transparent conductive layer ITO, the voltage is connected to the four corners, and the electric charge is distributed on the surface of the screen to form a uniform electric field. When the screen is touched by the hand, the human body acts as a pole of the coupling capacitor, and the current is collected from the four corners of the screen to form another coupling capacitor. The pole, the controller calculates the relative distance of the current to the touch position to obtain the coordinate value at the touch