Patent ID: 7834645
Filing Date: 2010-11-16
Classification: G01R

Abstract:
1. A voltage measuring apparatus that measures the voltage of a measured object, comprising: a detection electrode capable of being disposed facing the measured object; and a variable capacitance circuit comprising a capacitance changing structure constructed by connecting a first construction unit, a second construction unit, a third construction unit, and a fourth construction unit, which each include a first electric element that hinders transmission of a direct current (DC) signal and has a capacitance that changes in accordance with the magnitude of an absolute value of an applied voltage, in the mentioned order in a ring; a driving circuit that changes the electrostatic capacitance of the capacitance changing structure by applying an AC voltage between a connection point of the first construction unit and the second construction unit and a connection point of the third construction unit and the fourth construction unit; wherein the variable capacitance circuit is connected between the detection electrode and a reference potential so that a connection point of the first construction unit and the fourth construction unit is positioned on a detection electrode side of the variable capacitance circuit and a connection point of the second construction unit and the third construction unit is positioned on a reference potential side of the variable capacitance circuit.