The concept of capacitive touch-screen

- Jul 19, 2018 -

Capacitive touch screen technology is the use of the human body's current induction work. Capacitive touch screen is a four-layer composite glass screen, the inner surface and interlayer of the glass screen are coated with Ito, the outermost layer is a thin silica glass protective layer, interlayer ito coating as the working face, four angles to draw out four electrodes, the inner Ito as shielding layer to ensure a good working environment. When the fingers touch on the metal layer, because the human electric field, the user and touch screen surface formed with a coupling capacitor, for high-frequency current, the capacitor is a direct conductor, so the finger from the contact point suction a very small current.

The current flows out from the electrodes on the four corners of the touchscreen, and the current flowing through the four electrodes is directly proportional to the distance between the fingers and the corners, and the controller obtains the position of the touch point by calculating the ratio of these four currents accurately.