Capacitive touch screen technology uses the current sensing of the human body to work. The capacitive touch screen is a four-layer composite glass screen. The inner surface and the interlayer of the glass screen are each coated with a layer of ITO. The outer layer is a thin layer of silica glass protective layer. The interlayer ITO coating is used as the working surface. The four corners lead out four Electrodes, the inner layer of ITO as a shielding layer to ensure a good working environment. When the finger touches the metal layer, due to the electric field of the human body, a coupling capacitor is formed between the user and the touch screen surface. For high-frequency current, the capacitor is a direct conductor, so the finger draws a small current from the contact point. This current flows from the electrodes on 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 proportion of these four currents accurately to get the position of the touch point .
At present, the capacity bottleneck of the Glass capacitive screen is the sputtering (Sputtering) process. In the CF (color film) process of the ordinary TFT-LCD, the sputtering process only takes 24 seconds, but the Sputter made by the projected capacitive screen requires 65-70 seconds, that is, the production capacity is almost half.
In addition, the purchase of sputtering equipment is also relatively time-consuming, with a purchase cycle of at least six months. Due to the time-consuming expansion of the sputtering process, the expansion of production capacity is slow, and various manufacturers cannot increase output based on the original production capacity. According to Foxconn’s demand for OCA film, next year’s Apple iPad order is expected to be 40 million units; the capacity of the touch screen factory is far from enough.
Post time: Jul-06-2020