Capacitive measuring assembly for determining forces and pressures

• US 4,836,033 A
• Filed: 09/30/1987
• Issued: 06/06/1989
• Est. Priority Date: 10/13/1986
• Status: Expired due to Term

• Current Assignee: Peter Seitz
• Original Assignee: Peter Seitz
• Inventors: Seitz, Peter
• Primary Examiner(s): MYRACLE, JERRY
• Application Number:
  US07/102,722
• Time in Patent Office: 615 Days
• Field of Search: 73/862.04, 73/862.64, 73/862.68, 73/172, 901/33, 901/46, 361/280, 361/283, 361/291, 361/324
• US Class Current: 73/862.046
• CPC Class Codes: A61B 5/1036 Measuring load distribution, e.g. podologic studies
• CPC Class Codes: G01D 5/2412 by varying overlap
• CPC Class Codes: G01L 1/146 for measuring force distributions, e.g. using force arrays G01L1/148 takes precedence

Abstract

A capacitive measuring assembly for determining forces and/or pressures includes at least three plane parallel capacitor surfaces with intercalation of a dielectric therebetween. The capacitor surfaces being movable relative to each other against elastic resetting forces of the dielectric, a main surface being in opposing relation to all remaining surfaces and partly covering them with intercalation of the dielectric therebetween. The main surface being movable both perpendicular and parallel relative to the remaining surfaces so that from the individual capacity values between the main and remaining surfaces, there can be measured or eliminated both the forces that act perpendicularly between the main and remaining surfaces and the forces that act parallel with the capacitor surfaces.

Claims

1. An assembly for producing signals corresponding to forces and pressures, comprising:

at least three capacitor surfaces situated in two planes substantially opposite to each other;

a dielectric material between the surfaces in the two planes;

the surfaces in one plane being movable relative to the surfaces in the other plane against elastic resetting elements;

one main capacitor surface in one plane lying opposite to all remaining capacitor surfaces in the other plane with intercalation of said dielectric material therebetween and said main surface at least partly covering said remaining surfaces;

said main surface being movable both normally and parallel relative to said remaining surfaces so that forces that act both normally between said main surface and said remaining surfaces and parallel with said capacitor surfaces can be measured or eliminated from separate capacity valves between said main and remaining surfaces; and

said remaining surfaces include a smaller surface situated opposite to and completely covered by the main surface and a surrounding surface surrounding said smaller surface, said surrounding surface having an outer edge projecting beyond said main surface so that a differential between capacities of said surrounding surface and said main surface gives a standard for horizontal forces which can be compensated by means of the capacity value between said main surface and said smaller surface in relation to the vertical force component, or vice versa.

2. A measuring assembly according to claim 1, further comprising capacity measuring elements interconnecting said main surface and said remaining surfaces and means for calculating the sum of individual capacities (C₁₃ +C₁₄ +C₁₅ +C₁₆ =K_Z) of the capacity measuring elements corresponding to a vertical force (K_z) and the sums or differentials of said individual capacities (C₁₃ +C₁₄ -C₁₅ -C₁₆ =K_x ;

C₁₆ +C₁₃ -C₁₄ -C₁₅ =K_y) corresponding horizontal forces (K_x,K_y) computed on the total capacity or vertical force (K_x /K_z ;

K_y /K_z).

3. An assembly according to claim 1, wherein there is provided a multiplicity of main surfaces and a multiplicity of remaining surfaces that are similarly designed and equidistantly disposed in a matrix arrangement.

4. An assembly according to claim 3, wherein matrix outputs are connected via multiplexer/demultiplexer arrangements with measuring apparatus for determining the individual capacity values.

5. An assembly according to claim 3, wherein said capacitor surfaces are thin layers mounted upon plastic sheets that are joined to each other with intercalation of an elastomeric dielectric material therebetween, said plastic sheets between said capacitor surfaces being separated by notches.

6. An assembly according to claim 1, wherein said dielectric material comprises at least one foamed elastomer.

7. An assembly according to claim 1, wherein said dielectric material comprises at least two planar layers parallel with said surfaces having oppositely directed temperature coefficients and having a thickness such that a total temperature coefficient of the assembly becomes essentially zero.

8. An assembly according to claim 1, further comprising shields above and below said capacitor surfaces with intercalation of a dielectric material therebetween.

9. An assembly for producing signals corresponding to forces and pressures, comprising:

at least three capacitor surfaces situated in two planes substantially opposite to each other;

a dielectric material between the surface in the two planes;

the surfaces in one plane being movable relative to the surfaces in the other plane against elastic resetting elements;

one main capacitor surface in one plane lying opposite to all remaining capacitor surfaces in the other plane with intercalation of said dielectric material therebetween and said main surface at least partly covering said remaining surfaces;

said main surface being movable both normally and parallel relative to said remaining surfaces so that forces that act both normally between said main surface and said remaining surfaces and parallel with said capacitor surfaces can be measured or eliminated from separate capacity valves between said main and retaining surfaces; and

said remaining surfaces including at least three substantially congruous smaller surfaces situated opposite to the main surface, separated from each other and having outer edges projecting beyond the outer edge of said main surface.

10. An assembly according to claim 9, further comprising capacity measuring elements interconnecting said main surface and said remaining surfaces;

and

means for calculating the sum of individual capacities (C₁₃ +C₁₄ +C₁₅ +C₁₆ =K_Z) of the capacity measuring elements corresponding to a vertical force (k_z) and the sums or differentials of said individual capacities C₁₃ +C₁₄ -C₁₅ -C16=K_x, C₁₆ +C₁₃ -C₁₄ -C₁₅ =K_y) corresponding to horizontal forces (K_x,K_y) computed on the total capacity of vertical force (K_x /K_z ;

K_y /K_z).

11. An assembly according to claim 9, wherein there is provided a multiplicity of main surfaces and a multiplicity of remaining surfaces that are similarly designed and equidistantly disposed in a matrix arrangement.

12. An assembly according to claim 11, wherein matrix outputs are connected via multiplexer/demultiplexer arrangements with measuring apparatus for determining the individual capacity values.

13. An assembly according to claim 11, wherein said capacitor surfaces are thin layers mounted upon plastic sheets that are joined to each other with intercalation of an elastomeric dielectric material therebetween, said plastic sheets between said capacitor surfaces being separated by notches.

14. An assembly according to claim 9, wherein said dielectric material comprises at least one foamed elastomer.

15. A measuring assembly according to claim 9, wherein said dielectric material comprises at least two planar layers parallel with said surfaces having oppositely directed temperature coefficients and having a thickness such that a total temperature coefficient of the assembly becomes essentially zero.

16. An assembly according to claim 9, further comprising shields above and below said capacitor surfaces with intercalation of a dielectric material therebetween.

17. An assembly for producing signals corresponding to forces and pressures, comprising:

at least three capacitor surfaces situated in two planes substantially opposite to each other;

a dielectric material between the surfaces in the two planes;

the surface in one plane being movable relative to the surfaces in the other plane against elastic resetting elements;

one main capacitor surface in one plane lying opposite to all remaining capacitor surfaces in the other plane with intercalation of said dielectric material therebetween and said main surface at least partly covering said remaining surfaces;

said main surface being movable both normally and parallel relative to said remaining surfaces so that forces that act both normally between said main surface and said remaining surfaces and parallel with said capacitor surfaces can be measured or eliminated from separate capacity valves between said main and remaining surfaces;

capacity measuring elements interconnecting said main surface and said remaining surfaces; and

means for calculating the sum of individual capacities (C₁₃ +C₁₄ +C₁₅ +C₁₆ =K_z) of the capacity measuring elements corresponding to a vertical force (K_z) and the sums or differentials of said individual capacities (C₁₃ +C₁₄ -C15-C16=K_x, C₁₆ +C₁₃ -C₁₄ -C₁₅ =K_y) corresponding to horizontal forces (K_x,K_y) computed on the total capacity or vertical force (K_x /K_z ;

K_y /K_z).

18. An assembly according to claim 17, wherein there is provided a multiplicity of main surfaces and a multiplicity of remaining surfaces that are similarly designed and equidistantly disposed in a matrix arrangement.

19. An assembly according to claim 18, wherein matrix outputs are connected via multiplexer/demultiplexer arrangements with measuring apparatus for determining the individual capacity values.

20. An assembly according to claim 18, wherein said capacitor surfaces are thin layers mounted upon plastic sheets that are joined to each other with intercalation of an elastomeric dielectric material therebetween, said plastic sheets between said capacitor surfaces being separated by notches.

21. An assembly according to claim 17, wherein said dielectric material comprises at least one foamed elastomer.

22. A measuring assembly according to claim 17, wherein said dielectric material comprises at least two planar layers parallel with said surfaces having oppositely directed temperature coefficients and having thickness such that a total temperature coefficient of the assembly becomes essentially zero.

23. An assembly according to claim 17, further comprising shields above and below said capacitor surfaces with intercalation of a dielectric material therebetween.