Tunable magnetic device for use in a proximity sensor

• US 6,703,830 B2
• Filed: 02/18/2002
• Issued: 03/09/2004
• Est. Priority Date: 02/18/2002
• Status: Expired due to Fees

• Current Assignee: Phoenix America Inc. (discoverIE Group Plc)
• Original Assignee: Phoenix America Inc. (discoverIE Group Plc)
• Inventors: Kaste, John M.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US10/078,905
• Publication Number:
  US 20030155911A1
• Time in Patent Office: 750 Days
• Field of Search: 324/202, 324/207.2, 324/207.21, 324/207.25, 324/207.26, 324/235, 324/173, 324/174, 324/251, 324/252, 307/116, 307/117, 335/205, 335/298, 327/510, 327/511
• US Class Current: 324/207.26
• 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
• CPC Class Codes: H01H 36/002 Actuation by moving ferromagnetic material, switch and magnet being fixed
• CPC Class Codes: H03K 17/9517 using galvanomagnetic devices
• CPC Class Codes: H03K 2217/94015 Mechanical, e.g. by displacement of a body, a shielding element, or a magnet, in or out of the sensing area

Abstract

A tunable magnetic device which includes a permanent magnet in the shape of a ring, an inner aperture, a tuning member, and a field sensor secured to the permanent magnet. The tuning member may be a ferrous or magnetic material and may be secured to a non-magnetic tuning device. The inner aperture is preferably small compared to the permanent magnet. The magnetic device provides a magnetic field that is sensitive to the proximity of a ferrous object and provides a tunable mechanism to locally balance the magnetic field where the field sensor is located.

Claims

1. A tunable magnetic device comprising:

a magnet structure comprising a permanent magnet and a ferrous tuning element physically connected with and movable relative to said magnet to tune said magnetic device, said magnet structure lacking pole pieces; and

a magnetic field sensor secured to said magnet structure in proximity to said ferrous tuning element.

2. The device according to claim 1 wherein said ferrous tuning element forms a line fit with said permanent magnet.

3. The device according to claim 1 wherein said ferrous tuning element comprises a ferrous tuning element which is directly threaded into said permanent magnet.

4. The device according to claim 1 wherein said ferrous tuning element is bonded to a non-magnetic tuning element.

5. The device according to claim 4 wherein said non-magnetic tuning element is threadedly associated with said permanent magnet.

6. The device according to claim 1 wherein said permanent magnet is ring-shaped.

7. The device according to claim 1 wherein said ferrous tuning element is located within said permanent magnet.

8. The device according to claim 1 wherein said ferrous tuning element is magnetized in a direction opposite to the direction of magnetization of said permanent magnet.