Patent ID: 6373263
Filing Date: 2002-04-16
Classification: B60S,G01N

Abstract:
A window provided with a temperature stable capacitive sensor deployed on an internal surface for sensing moisture on an external surface, the window comprising:(a) a window having an internal surface and an external surface; (b) a conductive pattern including at least three capacitive electrodes disposed on said internal surface, said at least three capacitive electrodes including at least a first pair of electrodes defining a sensing capacitor and at least a second pair of electrodes defining a compensation capacitor, wherein a spacing between said second pair of electrodes is smaller than a spacing between said first pair of electrodes such that said sensing capacitor is sensitive to moisture on said external surface of said window and such that said compensation capacitor is substantially insensitive to moisture on said external surface of said window; (c) a shield for electrically shielding at least part of said conductive pattern; and (d) circuitry associated with said at least three capacitive electrodes and configured to generate an output which varies as a function of a difference in capacitance between said sensing capacitor and said compensation capacitor.