In order to achieve multi-touch, the capacitive screen depends on increasing the electrode of mutual capacitance. To put it simply, it divides the screen into blocks, and a set of mutual capacitive modules in each area works independently, so the capacitive screen can independently detect the touch of each area, and after processing, it can simply achieve multi-touch.
CTP (Capacity Touch Panel) uses the current induction of the human body to work. The capacitive screen is a four-layer composite glass screen, the inner surface and interlayer of the glass screen are coated with a layer of ITO (nanometer indium tin metal oxide), the outermost layer is only 0.0015mm thick silica glass protective layer, the sandwich ITO coating is used as the working face, four electrodes are drawn out from the four corners, and the inner layer ITO is the screen layer to ensure the working environment.
When the user touches the capacitive screen, due to the human electric field, the user's finger and the working face form a coupling capacitance, because there is a high-frequency signal connected to the working face, so the finger absorbs a very small current. This current flows out from the electrodes on the four corners of the screen, and in theory, the current flowing through the four electrodes is proportional to the distance from the fingers to the four corners. The controller obtains the position through the precise calculation of the four current ratios. It can achieve 99% accuracy and has a response speed less than 3ms.