There are two types of capacitive touch screens: surface capacitive touch screens and projected capacitive touch screens. The surface capacitive touch screen has a simple working principle, low price, and simple circuit design, but it is difficult to realize multi-touch. Capacitive screen expert, number 183, the middle four digits are 2005, and the last four digits are 9375. Full touch.
The projected capacitive touch screen, but the projected capacitive touch screen has the function of multi-finger touch. This kind of capacitive touch screen has the advantages of high light transmittance, fast response speed, and long life. The disadvantage is: with the change of temperature and humidity, the capacitance value will change, resulting in poor working stability and frequent drift phenomenon. Check the screen frequently, and do not wear ordinary gloves for touch positioning. Projected capacitive screens can be divided into two types: self-capacitance screen and mutual-capacitance screen. The more common mutual-capacitance screen, for example, is composed of driving electrodes and receiving electrodes. The driving electrodes emit low-voltage and high-frequency signals that are projected to the receiving electrodes to form a stable Electric current, when the human body touches the capacitive screen, because the human body is grounded, the finger and the capacitive screen form an equivalent capacitance, and high-frequency signals can flow into the ground through this equivalent capacitance. In this way, the amount of charge received by the receiving end is reduced. When the finger is closer to the transmitting terminal, the electric charge decreases more obviously. Finally, the touched point is determined according to the current intensity received by the receiving terminal.
The horizontal and vertical electrode arrays are made of ITO on the glass surface. These horizontal and vertical electrodes respectively form a capacitor with the ground. This capacitor is commonly referred to as self-capacitance, that is, the capacitance of the electrode to the ground. When the finger touches the capacitive screen, the capacitance of the finger will be superimposed on the capacitance of the screen body, which increases the capacitance of the screen body.
