Large area sensing cell

• US 5,563,354 A
• Filed: 04/03/1995
• Issued: 10/08/1996
• Est. Priority Date: 04/03/1995
• Status: Expired due to Term

• Current Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Force Imaging Technologies, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Kropp, Harry C.
• Primary Examiner(s): Chilcot, Richard
• Assistant Examiner(s): BIEGEL, RONALD L
• Application Number:
  US08/415,484
• Time in Patent Office: 554 Days
• Field of Search: 280/731, 280/732, 200/61.54, 200/511, 324/446, 324/724, 73/862.041, 73/862.044, 73/862.046, 73/862.54, 73/862.637, 73/862.642, 73/862.68
• US Class Current: 73/862.473
• CPC Class Codes: B60Q 5/003 mounted on the steering wheel
• CPC Class Codes: B60R 21/21658 with integrated switches, e.g. horn switches
• CPC Class Codes: G01L 1/18 using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
• CPC Class Codes: G01L 1/20 by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids of piezo-resistive materials G01L1/18; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress

Abstract

A thin film force sensor designed to sense application of a force over a wide area. In one embodiment, a large area sensing cell is provided that comprises a first planar electrode configured as a perimetric conductive portion circumscribing at least one additional perimetric conductive portion, with the conductive portions electrically connected together through at least one conductive path and a second planar electrode configured as a perimetric conductive portion circumscribing at least one additional perimetric conductive portion, with the conductive portions electrically connected together through at least one conductive path. The second planar electrode confronts the first planar electrode, with a pressure sensitive resistive material interposed between the first planar electrode and the second planar electrode. The conductive portions of the first planar electrode are substantially coextensive with the conductive portions of the second planar electrode, such that application of a broad force applying means anywhere within the perimeter of the perimetric conductive portion is electrically discernible, and a conductive lead extends from each electrode for providing an electrical termination for the electrode.

Claims

1. A large area sensing cell comprising:

a first planar electrode configured as a perimetric conductive portion substantially circumscribing at least one additional perimetric conductive portion, with said conductive portions electrically connected together through at least one conductive path;

a second planar electrode configured as a perimetric conductive portion substantially circumscribing at least one additional perimetric conductive portion, with said conductive portions electrically connected together through at least one conductive path, said second planar electrode confronting said first planar electrode;

a pressure sensitive resistive material interposed between said first planar electrode and said second planar electrode; and

said conductive portions of said first planar electrode being substantially coextensive with said conductive portions of said second planar electrode, such that application of a broad force applying means anywhere within the perimeter of said perimetric conductive portion is electrically discernible; and

a conductive lead extending from each electrode for providing an electrical termination for said electrode.

2. The large area sensing cell of claim 1, further comprising adhesive disposed in laterally spaced, adjacent relationship to said electrodes to restrain lateral movement of said electrodes relative to each other.

3. The large area sensing cell of claim 1, wherein said perimetric conductive portions are generally circular.

4. The large area sensing cell of claim 1, wherein said perimetric conductive portions are rectangular.

5. The large area sensing cell of claim 4, wherein said rectangular perimetric conductive portions are square.

6. The large area sensing cell of claim 1, wherein said perimetric conductive portions are triangular.

7. The large area sensing cell of claim 1, wherein said perimetric conductive portions are star shaped.

8. The large area sensing cell of claim 1, wherein said perimetric conductive portions are continuous.

9. The large area sensing cell of claim 1, wherein said perimetric conductive portions are discontinuous.

10. A large area sensing cell comprising:

a first planar electrode configured as a spiral-form conductive portion with a first end near a predetermined central point and a second end distal from said central point, and having an outermost conductive circumscribing segment;

a second planar electrode configured as a spiral-form conductive portion with a third end near a predetermined central point and a fourth end distal from said central point, said first planar electrode confronting said second planar electrode;

a pressure sensitive resistive material interposed between said first planar electrode and said second planar electrode; and

said conductive portion of said first planar electrode being substantially coextensive with said conductive portion of said second planar electrode, such that application of a broad force applying means anywhere within a boundary defined by said outermost conductive circumscribing segment is electrically discernible; and

a conductive lead extending from each electrode for providing an electrical termination for said electrode.

11. The large area sensing cell of claim 10, wherein said spiral-form conductive portions are disposed in the form of a smooth curve from said first end to said second end.

12. The large area sensing cell of claim 10, wherein said spiral-form conductive portions are disposed in the form of a rectangle comprising a series of linear conductive portions electrically connected and perpendicular to adjacent conductive portions.

13. The large area sensing cell of claim 10, wherein said spiral form conductive portions are disposed in the form of a triangle comprising a series of linear conductive portions electrically connected to adjacent conductive portions, and meeting said adjacent conductive portions at angles that are less than 90°

.

14. A large area sensing cell comprising:

a first conductor having a perimetric configuration with a plurality of internal conductor portions extending therefrom and circumscribed thereby;

a second conductor having a perimetric configuration with a plurality of internal conductor portions extending therefrom and circumscribed thereby, said second conductor and internal conductor portions confronting said first conductor and internal conductor portions;

a pressure sensitive resistive material interposed between said first conductor and said second conductor, such that application of force within the perimetric configuration of said first conductor is electrically discernible; and

a conductive lead extending from each of said first and second conductors for providing an electrical termination for each of said conductors.

15. The large area sensing cell of claim 14, wherein said internal conductor portions extend across spaced apart portions of said first and second conductors.

16. A large area sensing cell comprising:

a first conductor arranged as a group of spaced, elongated conductive portions, each conductive portion electrically connected to adjacent conductive portions through at least one conductive path, with exterior conductive portions and conductive portion end-points defining a first conductor perimeter;

a second conductor arranged as a group of spaced, elongated, conductive portions, each conductive portion electrically connected to adjacent conductive portions through at least one conductive path, with exterior conductive portions and conductive portion end-points defining a second conductor perimeter, and said second conductor confronting said first conductor;

a pressure sensitive resistive material interposed between said first conductor and said second conductor, such that application of force within said first conductor perimeter or said second conductor perimeter is electrically discernible; and

a conductive lead extending from each of said first conductor and said second conductor for providing an electrical termination for each of said conductors.

17. The large area sensing cell of claim 16, wherein said conductive portions are parallel, linear, and of substantially equal length.

18. A large area sensor cell comprising:

a first conductor having a first conductive portion and a plurality of spaced, elongated conductive segments, each having first and second ends and being electrically connected to said first conductive portion at said first ends only, with said second ends and said first conductive portion defining a first conductor perimeter;

a second conductor having a second conductive portion and a plurality of spaced, elongated conductive segments, each having third and fourth ends and being electrically connected to said second conductive portion at said third ends only, with said fourth ends and said second conductive portion defining a second conductor perimeter, said second conductor confronting said first conductor;

a pressure sensitive resistive material interposed between said first conductor and said second conductor, such that application of force within said first conductor perimeter or said second conductor perimeter is electrically discernible; and

a conductive lead extending from each of said first conductor and said second conductor for providing an electrical termination for each of said conductors.

19. The large area sensing cell of claim 18, wherein said conductive segments are parallel, linear, and of substantially equal length.