Self-capacitance is based on measuring the capacitance of a single electrode to the ground. When the finger is close to the electrode, the capacitance of the body will change the self-capacitance of the electrode. In the self-capacitive touch screen, the transparent conductive material is etched into a specified pattern on one or two separate electrodes.
When the electrodes are on a layer, each electrode represents a different touch coordinate and is connected to the controller respectively. When the electrodes are on two layers, they are usually arranged as rows of one layer and columns of the other layer. The intersection of each row or column represents a unique group coordinate.
In any case, the controller of the self-contained touch screen cannot measure the coordinates of each intersection, it can only measure which row or column it is.
When there is only one finger touch, the touch screen will work normally. For example, as shown in the figure below, the single-point touch position X2, Y0 can be accurately sensed by detecting all X electrodes and Y electrodes in turn. Measuring a single electrode instead of a cross point is the main drawback of a double-layer self-capacitive touch screen-it cannot clearly detect multiple touches.
The touch of the two points X2, Y0, and X1, Y3 actually produced four-point coordinates. No matter what, the two-finger gesture operation defect cannot be completely solved when using the self-contained touch screen. The secret is in the software-I would rather use an ambiguous reporting method so that the software can identify the direction of the reporting point.
In this case, it doesn’t matter whether the two-point touch generates four-point coordinates, as long as it can accurately recognize that the two points are a gesture of moving away from each other or moving toward each other.