Patent ID: 8941391
Filing Date: 2015-01-27
Classification: H03K

Abstract:
1. A multi purpose capacitive sensor which is suitable for indicating close proximity of a person to a surface along a large-size truck as well as along a medium-size painting or a pocket-size mobile phone and in which a voltage measuring device is provided with a signal ground connected to a first pole of an oscillating voltage source that has a second pole connected to a signal input of the voltage measuring device, said signal input having a first capacitance to earth and a second capacitance to said signal ground, a third capacitance being exhibited to earth by said second pole of the voltage source, and said signal ground being connected to electrically conductive means extended along said surface and exhibiting a fourth capacitance to earth that is of at least the same order of magnitude as said third capacitance, characterized thereby that a prebias component is connected between said second pole of the voltage source and said signal input of the voltage measuring device and has an impedance of at least the same order of magnitude as the impedance exhibited between said signal input and said signal ground.