The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 26, 1998
Filed:
Sep. 26, 1996
Gustav Wetzel, Lorrach, DE;
Werner Thoren, Steinen, DE;
Endress + Hauser GmbH + Co., Maulberg, DE;
Abstract
The capacitive level limit switch used for monitoring the level of a material in a container has a capacitive probe fitted at the height of the level to be monitored so that it is covered by the material when the level has attained this height. The capacitance of the probe is compared to a threshold value determining the switching point, for establishing whether the probe is covered by material or not. For setting the switching point, the capacitance of the probe measured in one condition of the probe is stored as a first reference value and a provisional second reference value is calculated from the first reference value by addition or subtraction of a predetermined amount and is also stored. From the stored reference values the threshold value is calculated according to a prescribed function so that it lies between the two reference values. If it is determined in operation that the measured capacitance value deviates by a certain amount from the second reference value, this measured capacitance value is stored as a new second reference value, and from the reference values now stored a new threshold value is calculated according to the prescribed function.