The capacitive touch screen is composed of a driving electrode and a receiving electrode. The driving electrode sends a low voltage and high frequency signal to the receiving electrode to form a stable current. When the human body contacts the capacitive screen, the fingers and the capacitive screen form an equivalent capacitance because the human body is grounded.
High frequency signals can flow into the ground through this equivalent capacitance, so the amount of charge received by the receiver is reduced. When the finger is close to the emitter, the charge drops more obviously. Finally, the contact point is determined according to the current intensity received by the receiving end. As for multi touch, simply put, the screen is partitioned. Each group of mutual capacitance modules in each area works independently. The capacitive screen can independently detect the touch condition of each area, and can realize multi-point touch after processing.
Touch screen ctp (capacitive touch screen) uses current sensor from human body. The capacitive screen is a four layer composite glass screen. The inner surface and the middle layer of the glass screen are respectively coated with ito (nano indium tin oxide). The outer layer is 0.0015 mm thick quartz glass protective layer, the middle layer is coated with ito working surface, four electrodes are formed at four corners, and the inner layer is a shielding layer to ensure the working environment.
When the user touches the capacitive screen, due to the electric field, the user's finger forms a coupling capacitance with the working face. Because there is a high-frequency signal on the working face, the finger absorbs a very small current and flows out from the electrodes at the four corners of the screen. The current flowing through the four electrodes is theoretically proportional to the distance from the finger to the four corners. The response speed is less than 3ms, and the accuracy can reach 99%.