MAGNETIC CIRCUIT DEVICE FOR A CONTACTLESS SWITCH OR THE LIKE

• US 3,858,145 A
• Filed: 05/04/1973
• Issued: 12/31/1974
• Est. Priority Date: 06/19/1972
• Status: Expired due to Term

• Current Assignee: Albert W. Vinal, Michael Sulich
• Original Assignee: Albert W. Vinal, Michael Sulich
• Inventors: Vinal, Albert W., Sulich, Michael
• Primary Examiner(s): Albritton, C. L.
• Application Number:
  US05/357,284
• Time in Patent Office: 606 Days
• Field of Search: 338/32H,32R 335/2,205,215 324/45,46 323/94H 340/365L
• US Class Current: 338/32.00H
• CPC Class Codes: H01F 7/0252 PM holding devices H01F7/021, H01F7/0215, H01F7/0226 take precedence
• CPC Class Codes: H03K 17/90 by the use, as active elements, of galvano-magnetic devices, e.g. Hall-effect devices H03K17/95, H03K17/97 take precedence

Abstract

A magnetic circuit comprises a cylindrical disk permanent magnet having oppositely polarized end surfaces and a keeper of soft magnetic material. The permanent magnet has an axial aperture which is cylindrical. The keeper comprises a disk portion which bears on one end surface of the permanent magnet and a cylindrical pin which occupies the aperture of the magnet. The pin terminates in a flat surface which is substantially co-planar with the second opposite surface of the disk magnet. The magnetic circuit provides a high intensity localized magnetic field having field reversal properties for switching magnetic sensor devices such as a Hall effect cell.

Claims

1. In an electric pushbutton switch, a key mechanism comprising, a first member, a second member movable relative to said first member between first and second switch positions, a Hall element mounted on said first member and having a sensing surface, said Hall element being operable for detecting changes in the direction of magnetic field for producing a switching signal, and a switching magnet mounted on said second member for relative movement therewith between said first and second switch positions, said switching magnet comprising a cylindrical permanent magnet having parallel faces of opposite polarity, said permanent magnet having one of said faces proximate said sensing surface of said Hall element and movable transversely thereto during relative movement of said second member from said first to said second switch positions, said permanent magnet having a cylindrical aperture connecting said parallel faces and parallel with the axis of magnetization thereof, said aperture having an axis perpendicular with said sensing surface of said Hall element and parallel with the direction of relative motion of said first and second members between said first and second switch positions, said aperture producing a concentrated magmetic field with a field reversal region extending beyond said face of said magnet in the vicinity of said sensing surface, said field reversal region of said magnetic field being located within the distance of relative movement between said first and second switch positions, whereby said Hall element is subjected to a reversing magnetic field to produce said switching signal during said relative movement between said first and second switch positions.

2. In an electric pushbutton switch, a key mechanism in accordance with claim 1 in which said switching magnet further includes a keeper of soft magnetic material having a disk-like portion bearing against the parallel face of said permanent magnet remote from said Hall element and a cylindrical core portion extending through said cylindrical aperture of said permanent magnet said core portion terminating in a surface substantially co-planar with said face of said permanent magnet proximate said sensing surface of said Hall element.