Hall effect displacement transducer using a bar magnet parallel to the plane of the Hall device

• US 4,107,604 A
• Filed: 12/01/1976
• Issued: 08/15/1978
• Est. Priority Date: 12/01/1976
• Status: Expired due to Term

• Current Assignee: Compunetics Inc. (Compunetix, Inc.)
• Original Assignee: Compunetics Inc. (Compunetix, Inc.)
• Inventors: Bernier, Donald R.
• Primary Examiner(s): Corcoran, Robert J.
• Application Number:
  US05/746,249
• Time in Patent Office: 622 Days
• Field of Search: 324/34 D, 324/34 PS, 324/45, 324/46, 338/32 R, 338/32 H, 340/365 L, 323/94 H, 335/1
• US Class Current: 324/207.2
• CPC Class Codes: G01R 33/07 Hall effect devices
• CPC Class Codes: G01V 3/08 operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices with electromagnetic waves G01V3/12

Abstract

A position indicating device for providing a generally linear output in response to displacement; the system includes a Hall effect device and apparatus for providing a response therein in accordance to displacement of a movable stylus or plunger and the method of making the same.

Claims

1. A position indicating device comprising:

a housing having a central bore, an electrical connector connected to one end of said housing in registry with said bore for providing electrical connection into and out of said housing, a guide and support tube having one end connected to said electrical connector and extending into said central bore at one end, said guide and support tube being generally rectangular in cross section, sensing means responsive to changes in magnitude of magnetic flux for providing an output signal varying in magnitude in accordance with the changes in magnitude of magnetic flux, said sensing means secured to the outer surface of said guide and support tube and magnet means located within said support tube for movement relative to said sensing means whereby the variations in magnitude of said output signal will be provided as a function of the relative position between said magnet means and said sensing means, display means operatively connected with said sensing means and responsive to said output signal for providing a display of the magnitude of the relative position between said magnet means and said sensing means, said magnet means comprising a bar magnet extending longitudinally along an axis and having a circular cross section and a support tube structure fixedly holding said bar magnet, said support tube structure having a generally rectangular cross section and being located within said guide and support tube for relative sliding movement therein, said magnet means including a return, coil spring connected with one end of said bar magnet and engageable with said electrical connector, a cap located in the opposite end of said central bore, a pin slidably supported in said cap and engageable with the opposite end of said bar magnet whereby axial movement of said pin will result in movement of said bar magnet relative to said sensing means, said sensing means comprising a Hall effect device secured to said guide and support tube with its Hall plate parallel to the axis of said bar magnet, said bar magnet having only one north magnetic pole located at one end and only one south magnetic pole located at the opposite end, said output signal indicating a null when said Hall plate is located substantially centrally of said north and south poles.

2. A position indicating device comprising:

a housing having a central bore, an electrical connector connected to one end of said housing in registry with said bore for providing electrical connection into and out of said housing, a guide and support tube having one end connected to said electrical connector and extending into said central bore at one end, Hall effect sensing means responsive to changes in magnitude of magnetic flux for providing an output signal varying in magnitude in accordance with the changes in magnitude of magnetic flux, said sensing means secured to said with the plane of said Hall effect device being parallel to the axis of said bore and magnet means connected with said support tube for movement relative to said sensing means whereby the variations in magnitude of said output signal will be provided as a function of the relative position between said magnet means and said sensing means, display means operatively connected with said sensing means and responsive to said output signal for providing a display of the magnitude of the relative position between said magnet means and said sensing means, said magnet means comprising a permanent bar magnet supported for relative, translational movement with said guide and support tube with the axis of the bar magnet being parallel to the axis of said bore, said magnet means including a spring member operable for biasing said permanent magnet, actuating means located in the opposite end of said central bore and operable with said permanent magnet for providing movement of said permanent magnet relative to said sensing means, said bar magnet having only one north magnetic pole located at one end and only one south magnetic pole located at the opposite end, said output signal indicating a null when said sensing means is located substantially centrally of said north and south poles.

3. The device of claim 2 with said magnet means including support surface means for holding said permanent magnet from rotation relative to said guide and support tube.

4. The device of claim 3 with said support surface means comprising non-circular engaging surfaces.

5. A position indicating device comprising:

sensing means responsive to changes in magnitude of magnetic flux for providing an output signal varying in magnitude in accordance with the changes in magnitude of magnetic flux, and magnet means supported for movement relative to said sensing means whereby the variations in magnitude of said output signal will be provided as a function of the relative position between said magnet means and said sensing means, display means operatively connected with said sensing means and responsive to said output signal for providing a display of the magnitude of the relative position between said magnet means and said sensing means, said magnet means comprising a longitudinally extending permanent bar magnet having a central axis with only one pair of opposite magnetic poles located at opposite ends and spaced along said central axis, and support means for supporting said magnet means for movement relative to said sensing means along said central axis and holding said permanent magnet and said sensing means from relative rotation about said central axis;

said sensing means comprising a Hall effect device having its Hall plate located adjacent to and parallel to said central axis, said output signal indicating a null when said Hall plate is located substantially centrally of said north and south poles.

6. The device of claim 5 with said support means including a guide and support tube, said sensing means secured to said guide and support tube, and said support means comprising an interfitting structure between said magnet and said guide and support tube permitting relative axial movement of said magnet along said support tube while preventing relative rotation.

7. The device of claim 6 with said interfitting structure comprising non-circular mating surfaces between said guide and support tube and said magnet.

8. In a position indicating device including a housing having a central bore, a guide and support tube located at one end of said housing and extending into said central bore, sensing means responsive to changes in magnitude of magnetic flux for providing an output signal varying in magnitude in accordance with the changes in magnitude of magnetic flux, said sensing means including a Hall effect device, and magnet means supported for providing the magnetic flux to said sensing means and including a permanent bar magnet for movement relative to said sensing means whereby the variations in magnitude of said output signal will be provided as a function of the magnitude of relative change in position between said bar magnet and said sensing means, the method comprising:

locating the Hall effect device on said guide and support tube at a preselected location with its plane parallel to the axis of the bore, connecting said permanent bar magnet with its axis parallel to the axis of the bore for movement along said guide and support tube and for movement relative to said Hall effect device, and varying the length of said bar magnet to vary the response and/or stroke of the position indicating device, said method further comprising the steps of;

locating said bar magnet relative to said Hall effect device with a preselected circumferential field orientation, and securing said bar magnet from rotational movement from said orientation.

9. In a position indicating device including a housing having a central bore, a guide and support tube located at one end of said housing and extending into said central bore, sensing means responsive to changes in magnitude of magnetic flux for providing an output signal varying in magnitude in accordance with the changes in magnitude flux, said sensing means including a Hall effect device and magnet means for providing the magnetic flux to said sensing means and including a longitudinally extending permanent bar magnet having a central axis and supported for movement relative to said sensing means along said central axis whereby the variations in magnitude of said output signal will be provided as a function of the magnitude of relative change in position between said bar magnet and said sensing means, the method comprising:

locating the Hall effect device on said guide and support tube at a preselected location with its plane parallel to said axis, connecting said permanent bar magnet for movement along said guide and support tube and for movement along said central axis relative to said Hall effect device, varying the coercive force of said bar magnet to vary the response and/or stroke of the position indicating device, and locating said bar magnet relative to said Hall effect device with a preselected circumferential field orientation, and securing said bar magnet from rotational movement from said orientation.