Working principle of capacitive touch screen

Principle Overview:
To achieve multi touch on a capacitive screen, it relies on adding electrodes with mutual capacitance. Simply put, the screen is divided into blocks and a set of mutual capacitance modules are set up in each area to work independently. Therefore, the capacitive screen can independently detect the touch situation in each area, process it, and easily achieve multi touch.
The Capacity Touch Panel (CTP) uses human current induction to operate. The capacitive screen is a four layer composite glass screen, with a layer of ITO (nano indium tin metal oxide) coated on the inner surface and interlayer of the glass screen. The outermost layer is a protective layer of silica glass with a thickness of only 0.0015mm, and the interlayer ITO coating serves as the working surface. Four electrodes are led out from the four corners, and the inner layer ITO serves as the screen layer to ensure the working environment.
When a user touches a capacitive screen, due to the electric field of the human body, a coupling capacitor is formed between the user's fingers and the working surface. As there is a high-frequency signal connected to the working surface, the fingers absorb a small current, which flows out from the electrodes at the four corners of the screen. Theoretically, the current flowing through the four electrodes is proportional to the distance from the fingers to the four corners. The controller calculates the position by accurately calculating the proportion of the four currents. It can achieve 99% accuracy and has a response speed of less than 3ms.