Patent attributes
A technique reduces erroneous judgment due to effects of noise accompanying PWM control while using PWM control for brightness adjustment of light-emitting diodes disposed proximate of an electrode. An electrode is disposed proximate of operating portions that are subject to touch operations by unit of a conductive body. An operating portion of a light-emitting diode is lightened. A CPU performs brightness adjustment of the light-emitting diode through PWM control. A detecting circuit outputs detected values in accordance with electrostatic capacitances of the electrode. The CPU judges that a touch operation has been made when a difference between a detected value of the detecting circuit and a reference value stored in a RAM is not less than a prescribed value. The CPU stores a detected value that is first detected by the detecting circuit after transition of an executing state of PWM control in the RAM as a reference value.
