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:
Nov. 12, 1996
Filed:
Sep. 02, 1993
Applicant:
Inventor:
Friedhelm Joost, Essen, DE;
Assignee:
Tiefenbach GmbH, Essen, DE;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01B / ;
U.S. Cl.
CPC ...
32420726 ; 324225 ; 32420712 ; 32420716 ; 34087031 ; 331 65 ;
Abstract
A proximity switch for determining the approach of a metal object includes an oscillating circuit which has a coil and a capacitor, and which produces a high-frequency field at the poles of the coil. A sensing resistor is connected to the oscillating circuit and serves to determine and evaluate the damping of the oscillating circuit by the object. Also, the sensing resistor is controlled as a function of the current measured in the sensing resistor such that the total resistance of the evaluation circuit remains constant. The voltage drop across the sensing resistor is measured and the measured voltage drop may be used to signal the approach of the metal object.