A resistive touchscreen panel comprises two transparent electrically resistive layers facing each other with a thin gap between.
The bottom is the LCD screen.
One layer has conductive connections along its sides, the other along top and bottom. Thus, edge electrodes of the upper layer are rotated 90° with respect to those of the lower layer.
If a DC voltage is applied between the two electrodes of the lower layer, while the upper layer floats, the touch brings the upper layer to the same voltage as the touch point.
The touch coordinate in the direction of the lower layer is identified by measuring the voltage on the upper layer to determine the ratio of the resistance at the touch point to the total resistance. Then, electrical connections for the layers are swapped, and the coordinate of the touch point on the other axis is obtained.
- 电容屏 -
- Capacitive Touchscreen -
A capacitive touchscreen panel consists of an insulator coated with a transparent conductor.
As the human body is also an electrical conductor, touching the surface of the screen results in a distortion of the screen's electrostatic field, measurable as a change in capacitance.
In one basic technology, a small voltage is applied to the layer, resulting in a uniform electrostatic field. When a conductor, such as a human finger, touches the uncoated surface, a capacitor is dynamically formed.
The sensor's controller can determine the location of the touch indirectly from the change in the capacitance as measured from the four corners of the panel. The larger the change in capacitance, the closer the touch is to that corner.