How does the TFT LCD touch screen work?

- Jul 30, 2018-

As a very common commercial LCD screen, TFT capacitor screen can be seen in all walks of life and various scenes.

Capacitive touch screen technology works by using the human body's current induction.Capacitive touch screen is a four-layer composite glass screen. The inner surface and interlayer of the glass screen are coated with one layer of ITO. The outermost layer is a thin layer of silica glass protective layer.

When the finger touches a metal layer, due to the human electric field, the user and the touch screen surface form a coupling capacitor. For high frequency current, the capacitor is a direct conductor, so the finger sucks a small current from the contact point.The current flows out of the four electrodes at the four corners of the touch screen, and the current flowing through the four electrodes is proportional to the distance between the fingers and the corners. The controller calculates the exact ratio of the four currents to determine the position of the touch point.

At present, the capacity bottleneck of Glass capacitor screen is the sputtering process. In the CF(color film) process of ordinary tft-lcd, the sputtering process only takes 24 seconds, but the Sputter of projectile capacitor screen takes 65-70 seconds, that is, the production capacity is almost half.

In addition, the purchase of sputtering equipment is time-consuming, the purchase cycle is at least half a year.Because of the time consuming of sputtering process, the production capacity expansion is slow.According to foxconn's forecast for OCA, apple's iPad orders are expected to be 40m next year.Touch screen factories are far from producing enough.