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:
Feb. 27, 2001
Filed:
Oct. 06, 1998
Kazuo Fukunaga, Ichikawa, JP;
TDK Corporation, Tokyo, JP;
Abstract
The present invention relates to a magnetic sensor apparatus which is capable of detecting a very weak magnetic field even when the DC bias magnetic field is at zero and greatly reducing detection output occurring due to factors such as inconsistency of a magnetic body, temperature fluctuations, distortional fluctuations and drift. A magnetic sensor element S generates a pulse-type signal which is in proportion to a rate of change of the magnetic permeability of a magnetic body M and the size of an external magnetic field at a detection winding Wd. A drive circuit 11 cyclically changes the magnetic permeability of the magnetic body by supplying a pulse-type drive current for sampling to the magnetic body. A peak value detection unit 12 detects a positive peak value and a negative peak value of the pulse-type signal. A feedback circuit supplies an AC current which is in synchronization with the pulse-type drive current to the detection winding and also superimposes a DC current component on the AC current to set the absolute values of the positive peak value and the negative peak value equal to each other. The size of a magnetic field to be detected is detected based upon a DC current component at the detection winding.