Patent ID: 7127943

Claim:
A capacitive sensor for detecting a level of a viscous fluid in a container having an interior volume, the sensor comprising mutually cooperative, mutually electrically isolated first, upper and second, lower electrodes arranged for placement on a wall of the container in isolation from the interior volume of the container, wherein each of the first and second electrodes exhibits a two-dimensional area having a vertical dimension and a horizontal dimension, and wherein the first and second electrodes are arranged in mutual proximity such that at least a majority of each of their respective areas are both vertically and horizontally offset from each other and to an extent at least sufficient to enable rapid detection of a decreasing level of the viscous fluid in the container when the viscous fluid has reached a level proximate a lower edge of the first, upper electrode and a residual film of the viscous fluid remains on an inner surface of the wall of the container above the level of the viscous fluid and adjacent at least a portion of the first, upper electrode.