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:
Jan. 28, 1986
Filed:
Feb. 23, 1984
Takeo Yamada, Yokohama, JP;
Tomohisa Yamamoto, Kawasaki, JP;
Seigo Ando, Yokohama, JP;
Yoshihiro Kawase, Kawasaki, JP;
Nippon Kokan Kabushiki Kaisha, Tokyo, JP;
Abstract
The distance between the tip of a probe and a high-temperature object of measurement is continuously and accurately measured by arranging the probe comprising a primary coil and a pair of secondary coils substantially vertically to the object of measurement; inducing an AC voltage (e.sub.1) and an AC voltage (e.sub.2) respectively in the pair of secondary coils by means of an AC magnetic field of the primary coil excited by an output voltage (e.sub.out) of a positive feedback amplifier; generating an eddy current in the object of measurement by means of the AC magnetic field of the primary coil to generate another AC magnetic field in the direction opposite to that of the AC magnetic field of the primary coil; impressing an equal DC voltage onto each of the pair of secondary coils to detect respectively a DC voltage (E.sub.1) and a DC voltage (E.sub.2) of the pair of secondary coils; calculating an error voltage (e.sub.4) corresponding to the difference in temperature between the pair of secondary coils, on the basis of the output voltage (e.sub.out) and a value of difference (E.sub.3) between the DC voltages (E.sub.1) and (E.sub.2); and feeding a value of difference (e.sub.3') between the error voltage (e.sub.4) and a value of difference (e.sub.3) between the AC voltages (e.sub.1) and (e.sub.2), back to the positive feedback amplifier, thereby determining the output voltage (e.sub.out) of the positive feedback amplifier, from which the influence of the difference in temperature between the pair of secondary coils has been eliminated.