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:
Apr. 27, 1993
Filed:
Apr. 27, 1989
Gernot Thorn, Hanau, DE;
Leybold Aktiengesellschaft, Hanau, DE;
Abstract
The invention concerns apparatus and a process for the non-destructive measurement of the ohmic resistance of thin layers according to the eddy-current principle. Here an inductor (2) is fed with a high frequency voltage (U.sub.osz) and the magnetic field of this inductor (2) is directed at the thin layer to be measured, whereby an eddy current flows in this layer the magnetic field of which weakens the magnetic field of the inductor (2). The inductor (2) is here part of an oscillating circuit (3) which is held always at resonance by means of a phase-correcting arrangement (14). Under these resonance conditions the reactive values of the oscillating circuit (3) may be neglected so that the current flowing into the oscillating circuit (3) depends solely on the ohmic resistance of this oscillating circuit (3), which in turn is determined by the ohmic resistance of the layer to be measured.