A currently available full-in-cell touch panel has a surface on which a high-resistance transparent film is formed. In this type of panel, in a case where a resistance value of the transparent film becomes smaller than a normal value, a touch signal becomes weaker and consequently, touch sensitivity of the panel deteriorates.
Such deterioration in touch sensitivity of the touch panel can be detected, for example, by checking whether or not a signal value is not smaller than a predetermined value in a case where a testing conductor brought into contact with a panel surface is slid over the panel surface. According to the above method, however, it is likely that the number of inspection steps increases and the testing conductor cannot uniformly come into contact with the panel surface. This disadvantageously leads to unstable inspection and hinders accurate inspection. There is another concern that, for example, the panel surface may be scratched due to contact with the testing conductor.
Note that Patent Literature 1 discloses an inspection device, which is configured to measure an electrostatic capacitance of a touch panel, so as to determine whether the touch panel is good or defective.