Capacitive touch screen drift theory oled module

Capacitive touch screen itself is actually a sophisticated leakage sensor, gloved hand can not touch, resulting in the use of capacitively drift. Capacitive screen and electric female screen are electrical schematic work, electrical work for multi-touch, no matter how many points, whether continuous or discontinuous are to take multi-touch the center point of judgment, because the current superimposed can not tell who is who, no way.Embedded LCD display
Proceed in accordance with the basic principles of the ideas, but ran into insurmountable obstacles: the transparent conductive material ITO - metal oxide is very fragile, and touch can be damaged, can not be directly used as the working layer. Material for a moment, difficult to resolve, had to make compromises: the increase in the external layer of very thin hard glass, it is clearly not conductive, DC is to die in favor of high-frequency AC signal by human fingers (separated by thin glass) and the face coupling capacitor sucked an AC current, which is the origin of the name "capacitor" capacitive screen.
The first is the "drift", because the way of the coupling capacitor is unstable, it is directly affected by the temperature, humidity, wet fingers, the body weight, the ground the degree of drying, affected by the interference of the large external area of ​​the object is also very large, brought no stable results, which are in direct contravention of the basic requirements of the touch screen as the absolute coordinate system, the inevitable drift, some capacitive touchscreen desire through a 25-point calibration method or even 96-point calibration method to solve the drift problem, in fact, is not may drift decision capacitor work this way, even if it is a in controller single procedure using dynamic calculation and experience the value of the look-up table, can only be a temporary solution. Multi-point calibration method first large-screen projection touchpad method used, the purpose is to eliminate the lines xing distortion of coordinates correspond capacitive touch screen line xing distortion is also very powerful, mainly because the calculation of the capacitive screen built in four of the amount of current and touch point to the ideal state of the four electrodes proportional to the distance on the actual due Setting capacitors, circuit parasitic capacitance and the use of different, That proportional relationship can not be completely linear, multi-point calibration method can only be resolved local assigned line xing the problem, not solve the overall drift.TFT display module