Research and Implementation of Multi-touch Algorithm for Resistive Touch Screen

- Nov 16, 2019-

Multi-touch refers to a technology that can correctly identify and locate two or more touch operations at the same time, can independently determine the operational significance of each touch point, and implement corresponding functions. This is a simple and convenient human-computer interaction mode that is free from traditional input devices. There are two types of multi-touch technology [1]: multi-touch gesture recognition and multi-touch position recognition.


At present, there are more ways to identify multi-touch gestures on the market. When the finger touches the screen at multiple points at the same time, the direction in which each finger moves can be recognized, and operations such as rotation, zooming, and panning can be performed, but the specific position of each finger cannot be determined. However, when two-touch or even multi-touch, multiple maxima will be generated on the X and Y axes, and the system cannot judge the exact position of the touched point. Usually the point that is not really touched is called "ghost point".


Multi-touch position recognition is a true multi-touch technology that can recognize the specific location of touch points without the phenomenon of "ghost points". This touch technology is based on the mutual capacitance detection method, and the touch point is judged by the change of the coupling capacitance Cm at the intersection of the rows and columns. When the finger touches, the mutual capacitance between the rows and columns decreases, and it is possible to judge the presence of the touched point and accurately determine the position of each touched point.