The Working Principle Of Capacitive Touch Screen

To achieve multi-touch on the capacitive screen, we need to increase mutual capacitance electrodes. In a word, we need to block the screen and set a group of mutual capacitance modules in each area to work independently, so the capacitive screen can independently detect the touch situation in each area. After processing, we can simply achieve multi-touch.
The Capacity Touch Panel (CTP) uses human current sensing to operate. A capacitive screen is a four layer composite glass screen, with an ITO (nano indium tin metal oxide) coating on the inner surface and interlayer. The outermost layer is a protective layer of silica glass with a thickness of only 0.0015mm. The interlayer ITO coating serves as the working surface, and four electrodes are introduced from the four corners. The inner layer ITO serves as the screen layer to ensure the working environment.
When a user touches a capacitive screen, due to the human electric field, a coupling capacitor is formed between the user's fingers and the working surface. Due to the high-frequency signal connected to the working surface, the fingers absorb a small amount of current, which flows out from the electrodes at the four corners of the screen. In theory, the current flowing through the four electrodes is proportional to the distance from the finger to the four corners. The controller calculates the position of the four current ratios accurately. It can achieve 99% accuracy and has a response speed of less than 3ms.