Patent ID: 7768272
Filing Date: 2010-08-03
Classification: H03K

Abstract:
1. A capacitance detecting apparatus comprising: a first variable capacitor having a first sensor electrode at one end, the first sensor electrode being adapted to face a measured object and storing an electric charge at an amount corresponding to an electric potential of the first sensor electrode, the first capacitor being configured to output a first capacitance which varies in response to a distance between the first sensor electrode and the measured object; a second variable capacitor having a second sensor electrode at one end, the second sensor electrode being adapted to face the measured object and storing an electric charge at an amount corresponding to an electric potential of the second sensor electrode, the second capacitor being configured to output a second capacitance which varies in response to a distance between the second sensor electrode and the measured object; a first reference capacitor configured to be connected to the first variable capacitor; and a second reference capacitor configured to be connected to the second variable capacitor; wherein the electric charge stored at the first sensor electrode is discharged and stored at the first reference capacitor, the electric charge stored at the second sensor electrode is discharged and stored at the second reference capacitor, so that the first capacitance of the first variable capacitor and the second capacitance of the second variable capacitor are detected based upon a difference between an electric potential at one end of the first reference capacitor and an electric potential at one end of the second reference capacitor, and wherein the electric potential of the first sensor electrode and the electric potential of the second sensor electrode change at an identical increment/decrement and in opposite directions.