Peter T Campbell

US Patent:

55459854, Aug 13, 1996

Filed:

Mar 16, 1994

Appl. No.:

8/214142

Inventors:

Peter Campbell - Boca Raton FL

International Classification:

G01B 714
G01B 730

US Classification:

32420721

Abstract:

In a preferred embodiment, a magnetoresistive (MR) position sensor, including: a rotatable cylindrical encoder wheel having a plurality of alternating N and S magnetic poles spaced a constant pole pitch around the circumferential surface of the encoder wheel, adjacent ones of the N and S poles having interfacing edges parallel to the axis of rotation of the encoder wheel; a first MR sensing array disposed on an insulative substrate in proximity to the circumferential surface of the encoder wheel, such as to sense rotating magnetic fields produced by the N and S poles as they pass the first MR sensing array as the encoder wheel rotates, the first MR sensing array including at least a first section comprising at least two legs extending parallel to the interfacing edges, the at least two legs being joined in series so as to form a serpentine shape; apparatus to apply a constant DC voltage across terminal ends of the serpentine shape.

US Patent:

55200583, May 28, 1996

Filed:

Apr 5, 1995

Appl. No.:

8/417106

Inventors:

Peter Campbell - Boca Raton FL
Robert A. Seto - Crystal Lake IL
Alex G. Bersin - Long Grove IL

Assignee:

Cole-Parmer Instrument Company - Niles IL

International Classification:

G01F 156

US Classification:

7386108

Abstract:

A magnetic reluctance flowmeter having a magnetic float in which a permanent magnet and soft iron pole pieces are arranged in such a manner that the resulting magnetic field passes directly through the yoke which is also made of soft iron. The shape of the yoke is such that, as the magnetic float is progressively displaced from its neutral position within the yoke, the magnetic field progressively saturates regions of the yoke causing some of this field to emanate into the space surrounding the yoke, in which locations this emanating field interacts with the magnetic field sensors in such a way as to modify the electrical signal produced by a sensing circuit.