Patent Literature 1: JP 2012-79661 A
Patent Literature 1 discloses a capacitive touch switch apparatus. This touch switch device includes a touch detecting electrode (touch electrode) whose capacitance changes when an operator performs a touch operation, and a detecting unit that detects changes in the capacitance based on the touch operation by applying an AC voltage to the touch detecting electrode. The touch detecting electrode is made of copper foil and formed as a circular pattern on a circuit substrate. The detecting unit detects presence or absence of a touch operation by detecting a change in the capacitance.