Pivotal magnetic coupling and position sensor

• US 5,168,221 A
• Filed: 03/25/1991
• Issued: 12/01/1992
• Est. Priority Date: 08/28/1987
• Status: Expired due to Fees

• Current Assignee: Houston, John S.
• Original Assignee: Houston, John S.
• Inventors: Houston, John S.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US07/671,685
• Time in Patent Office: 617 Days
• Field of Search: 324/207.13, 324/207.20, 324/207.21, 324/207.22, 324/207.25, 324/207.26, 324/235, 324/251, 33/1 M, 73/DIG. 3, 73/517 R, 73/779, 74/471 XY, 200/6 A, 200/61.45 R, 200/61.45 M, 200/61.52, 304/870.33, 304/709, 304/710, 901/2, 901/15, 901/46, 464/29
• US Class Current: 324/207.13
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01B 7/004 for measuring coordinates of points
• CPC Class Codes: G05G 2009/04755 Magnetic sensor, e.g. hall generator, pick-up coil
• CPC Class Codes: Y10T 74/20201 Control moves in two planes

Abstract

Two toroidal magnets (221, 22) are coupled to each other by a ferrous spherical spacer (23). The spacer (23) partially engages openings (24, 25) provided in the two magnet surfaces facing each other. The facing magnet surfaces have the same polarity, repelling each other. The configuration creates a stable equilibrium by conduction of the magnetic flux through the spacer and the repulsive forces at the periphery of the magnets. This structure forms a resilient pivot joint which when capped by a spherical handle (30) attached to the upper magnet (21) becomes a multiple-axis pointng device or a tactile sensor (20).

Claims

1. A multi-axes position and movement sensing device which comprises:

a first magnet element having a first magnetic field;

a magnetically permeable second element;

means for holding said elements in a modifiable spatial relationship to each other;

said means for holding comprising a magnetically permeable spacer having each of two opposite sides contiguous to one of same first and second elements, said first magnet element being rockingly and swivelingly coupled to one side of said spacer and having a central opening engaging one side of said spacer;

wherein said first magnetic field interacts with the second element through the spacer to resiliently keep the first element into an equilibrium position in relation to the second element, whereby any movement imparted upon the first element in relation to the second element creates a measurable variation in said first magnetic field.

2. The device of claim 1, wherein:

said first element is a toroidal magnet

having a circular central opening; and

one side of said spacer defines a semi-spherical head partially engaged into said opening.

3. The device of claim 2, wherein said spacer comprises a sphere having a diameter larger than the diameter of said circular opening.

4. The device of claim 3, wherein said second element is a toroidal magnet having a circular central opening generally commensurate with the central opening of said first element.

5. The device of claim 4, wherein poles of same polarity of said first and second elements are facing each other separated by said spacer.

6. The device of claim 5, wherein said spacer comprises at least two spheres.

7. The device of claim 5 which further comprises a third toroidal magnet element and a second spherical spacer between said second and third elements.

8. The device of claim 1 which further comprises at least one detector supported, positioned and oriented so as to sense changes in the relative positions of said first and second elements.

9. The device of claim 8, wherein said sensor is responsive to changes in ambient magnetic fields.

10. The device of claim 9, wherein said sensor is a Hall-effect magnetic sensor.

11. The device of claim 1, wherein each of said first and second elements has a non-circular cross-section about a plane perpendicular to an axis passing through said first and second sensor and spacer.

12. The device of claim 1, wherein each of said first and second elements has a magnetic field which varies circumferentially about an axis passing through said first and second element and spacer.

13. The device of claim 12, wherein each of said first and second elements has a contoured face, said face having variable distances from a plane perpendicular to said axis.

14. The device of claim 9 which further comprises a manipulating handle attached to said first element.

15. The device of claim 14 which further comprises:

a third element having a third magnetic field and a central opening;

a magnetically-permeable shaft concentrically attached to and extending from a side of said second element opposite a side facing said first element;

said shaft being slidingly engaged into the central opening of said third element;

wherein poles of the same polarity of said second and third elements are facing each other; and

at least one detector supported, positioned and oriented so as to sense changes in the relative positions of said second and third elements.

16. The device of claim 12 which further comprises:

a third element having a third magnetic field and a central opening;

a magnetically-permeable shaft concentrically attached to and extending from a side of said second element opposite a side facing said first element;

said shaft being slidingly engaged into the central opening of said third element;

wherein poles of the same polarity of said second and third elements are facing each other; and

at least one detector supported, positioned and oriented so as to sense changes in the relative positions of said second and third elements.