Ferromagnetic-ball sensor using a magnetic field detection element

• US 6,198,276 B1
• Filed: 02/19/1998
• Issued: 03/06/2001
• Est. Priority Date: 02/19/1997
• Status: Expired due to Term

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: NEC Corporation
• Inventors: Konno, Hideto
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US09/026,258
• Time in Patent Office: 1,111 Days
• Field of Search: 324/207.21, 324/207.26, 338/32.R, 273/121.A, 273/121.B, 273/118.A
• US Class Current: 324/207.22
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other

Abstract

The present invention relates to a ferromagnetic-article sensor comprises a pathway-forming means for defining a pathway for a ferromagnetic-article; a magnet disposed adjacent to the pathway, forming a magnetic field; and a magnetic field detection element for detecting a part of a magnetic field formed by the magnet, the part of the magnetic field extending parallel to the plane of the magnetic field detection element; wherein the pathway-forming means, the magnet, and the magnetic field detection element are arranged such that the magnetic field detection element detects modification of magnetic fields by the ferromagnetic-article when the ferromagnetic-article travels through the pathway, distorting the magnetic field.

Claims

1. A ferromagnetic-ball sensor, comprising:

a base having a pathway for a ferromagnetic-ball;

a magnet mounted on the base for forming a magnetic field between the magnet and ferromagnetic-ball passing through the pathway; and

a magnetic field detection element for detecting a part of the magnetic field formed by the magnet, wherein the magnetic field detection element has a magneto-resistive face responsive to a magnetic field parallel to the magneto-resistive face;

whereby the base, the magnet, and the magnetic field detection element are arranged such that the magnetic field detection element detects a modification of a part of the magnetic field when the ferromagnetic ball travels through the pathway;

an angle between the center of the magnet and the center of the magnetic field detection element with respect to the center of the ferromagnetic ball passing through the pathway is in a range of one of 42-80 degrees, 132-170 degrees, 222-260 degrees, and 312-350 degrees; and

an angle between the magneto-resistive face and a plane passing through the centers of the ferromagnetic ball and of the magnetic field detection element is in a range of one of 42-80 degrees, 132-170 degrees, 222-260 degrees, and 312-350 degrees.

2. The ferromagnetic-ball sensor according to claim 1, wherein pluralities of said magnet and said magnetic field detection element are provided so as to detect a rate of travel of said ferromagnetic-article traveling through said pathway.

3. The ferromagnetic-ball sensor according to claim 1, wherein said magnetic field detection element is formed of a thin film of at least one of Ni—

Fe, Ni—

Co, and Ni—

Fe—

Co.

4. The ferromagnetic-ball sensor according to claim 1, wherein said magnetic field detection element is arranged on a silicon substrate of an integrated circuit chip and is connected to a circuit in said integrated circuit chip.

5. The ferromagnetic-ball sensor according to claim 1, wherein said magnetic field detection element is at least one of an anisotropic magneto-resistive element, a giant magneto-resistive element, and a colossal magneto-resistive element.

6. The ferromagnetic-ball sensor according to claim 1, wherein said pathway-forming means comprises a base having a hole defining the pathway for allowing the movement of said ferromagnetic ball, said magnet being mounted on said base.

7. The ferromagnetic-ball sensor according to claim 1, wherein said magnet is a permanent magnet.

8. The ferromagnetic ball sensor according to claim 1, wherein the magnetic field direction element and the magnet are not connected by a ferromagnetic material.