A capacitive touch panel is a substrate on which transparent electrode patterns are coated. When a finger is closes to or contacts the touch panel, a coupling capacitor is formed between the finger and the transparent electrode patterns because the finger is a conductor and has static electricity. Meanwhile, electrical capacitance of the electrode positioned at a touch point on the touch panel will change, thus making voltage or current on the electrode change. And then by comparing the voltage difference between the electrode and adjacent electrodes, a position of the touch point can be calculated.
However, although the touch input by the fingers is convenient, it is obviously difficult to achieve the following requirements of depicting lines with various thicknesses on a touchscreen, or realizing touch recognition for fine locations by the fingers. Therefore, in order to increase the accuracy of the touch and have a function of pressure sensing, a solution by using an electromagnetic stylus/pen has been proposed. However, the conventional touch panel, which is used with the electromagnetic pen, needs to be equipped with an induction coil for interacting with the electromagnetic pen so as to generate a pressure sensitive signal.
At present, there are three solutions to dispose the induction coil on the touch panel. The first is to wind wires around the touch panel manually. However, not only is the manual winding labor-intensive, but it is inconsistent with a requirement of automated production. The second is to arrange the induction coil on a circuit board and then to assemble the circuit board and the original touch panel. However, this solution has a drawback of increasing a thickness of the entire touch module. The third is to coat a pattern of the induction coil with transparent metal on a substrate of the capacitive touch panel. However, this solution needs to change the design of a photomask, so it will greatly increase the cost.