What is capacitive touch screen and how does it work?

- Mar 03, 2020-


Capacitive touch screen technology works by using the body's current induction. The capacitive touch screen is a four-layer composite glass screen. The inner surface of the glass screen and the interlayer are coated with ITO. The outermost layer is a thin layer of silica glass protective layer. When the finger touches the metal layer, the user and the touch screen surface form a coupling capacitance due to the human electric field. For high-frequency current, the capacitance is a direct conductor, so the finger sucks a small current away from the contact point. This current flows from the electrodes at the four corners of the touch screen, and the current flowing through these four electrodes is proportional to the distance from the finger to the four corners. The controller calculates the precise ratio of these four currents to obtain the position of the touch point.

 

Capacitive screen to achieve multi-touch, rely on the increase of mutual capacitance electrode, simply speaking, is the screen block, set a set of mutual capacitance module in each area are independent work, so capacitive screen can independently detect the touch situation in each area, after processing, simple multi-touch.

 

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How does capacitive touch screen work

 

The Capacity Touch Panel, or CTP, USES the body's induction of current to work. The capacitive screen is a four-layer composite glass screen. The inner surface of the glass screen and the interlayer are coated with ITO(oxide of indium sikgold). The outermost layer is a protective layer of silica glass only 0.0015mm thick.

 

When a user capacitive touch screen, the electric field due to the human body, your fingers and face form a coupling capacitance, because the working plane to have a high frequency signal, so the fingers on a very small current, respectively from the current screen in the four corners of the electrode, and theoretically through the four electrodes with the finger to the four corners of the current is proportional to the distance, the controller through the precise calculation of the four current ratio, it is concluded that location. Can achieve 99% accuracy, with response speed of less than 3ms.