Patent ID: 8547113

Claim:
A capacitive touch panel for detecting an input operation made at a position of a sensing electrode based on elapsed time that increases as a result of increase of a stray capacitance, the capacitive touch panel comprising: a sensing electrode arranged on an insulating panel, the sensing electrode increasing in stray capacitance in response to approach of an input unit; a resistive element forming a CR time constant circuit between the resistive element and a value of the stray capacitance of the sensing electrode; a charge and discharge switch for raising an electric potential of the sensing electrode from a ground potential to a predetermined charge potential or reducing the electric potential of the sensing electrode from the charge potential to the ground potential by connecting a common terminal on one side of the resistive element to a switching terminal that is either at the charge potential or at the ground potential from a base point in time to charge or discharge the stray capacitance with the time constant of the CR time constant circuit; and time measuring means for measuring elapsed time for the electric potential of the sensing electrode at the charge potential or ground potential to become the same as a predetermined threshold potential between the charge potential and the ground potential by charging or discharging the stray capacitance from the base point in time, wherein the switching of the charge and discharge switch is controlled by a PWM modulated signal obtained by pulse-width modulating a rectangular wave pulse signal at a fixed frequency by a predetermined modulation value, and the common terminal on one side of the resistive element is connected with or separated from the switching terminal in response to a binary signal value of the PWM modulated signal.