Patent ID: 8076948

Claim:
A method to read out capacitive sensors for distance measurement used by a position control system having a high accuracy and low noise comprising the following steps: (1) providing two sensor capacitors, wherein at least one plate of said sensor capacitor is fastened on an object whose position is to be controlled, a sense amplifier stage, a digital controller controlling a motor, a digital-to-analog converter and a comparator; (2) setting a reference voltage dependent upon a target position to be reached; (3) measuring sequentially voltages across said two sensor capacitors using said reference voltage as input voltage on a first terminal of each sensor capacitor; (4) checking if both voltages are equal and, if positive go to step (7), otherwise go to step (5); (5) moving said object in a direction according to difference of the voltages measured across both sensor capacitors; (6) measuring sequentially voltages across said two sensor capacitors using last voltage measured across each sensor capacitor as input voltage on a first terminal of each correspondent sensor capacitor and go to step (4); and (7) target position is reached.