STATIC CAPACITANCE SWITCH

摘要

PURPOSE:To detect surely the presence or absence of depression of a switch without malfunction by detecting the change in the capacitance of a variable capacitor depending on the change in the signal width due to the change in the charging time of the variable capacitor. CONSTITUTION:The variable capacitor 2 is charged through a prescribed charging circuit. Then a switching means 3 is turned on/off depending on the length of the charging time of the said capacitor 2 to output a charging time detection signal with different signal width. The signal width is detected by a signal width detection circuit 10 and when the signal width reaches a signal width or over corresponding to a prescribed charging time, a switch depression detection signal is outputted.