Mechanical shock sensor

• US 5,811,910 A
• Filed: 01/30/1997
• Issued: 09/22/1998
• Est. Priority Date: 01/30/1997
• Status: Expired due to Fees

• Current Assignee: Graham P. Cameron, Jeffrey S. Haviland
• Original Assignee: Graham P. Cameron, Jeffrey S. Haviland
• Inventors: Cameron, Graham P., Haviland, Jeffrey S.
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US08/790,814
• Time in Patent Office: 600 Days
• Field of Search: 310/324, 310/328, 310/329, 310/338, 73/514.01
• US Class Current: 310/324
• CPC Class Codes: G01P 15/0922 of the bending or flexing mode type
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/084 the mass being suspended at more than one of its sides, e.g. membrane-type suspension, so as to permit multi-axis movement of the mass
• CPC Class Codes: H10N 30/302 Sensors

Abstract

A mechanical shock sensor including a diaphragm suspended about its edge to an elevated pedestal and a pattern of piezoelectric material attached to the diaphragm surface. A proof mass is attached beneath the diaphragm surface and centered along a vertical axis passing through the diaphragm and the concentric piezoelectric materials. Electrical conductors are attached to the first and second concentric electrically conductive layers on piezoelectric material and are connected to a circuit capable of responding to the piezoelectric signals developed thereby.

Claims

1. An omnidirectional shock sensor for measuring acceleration in X, Y, Z axes, the sensor comprising:

a) a base having a opening aligned along the Z axis;

b) a diaphragm attached to said base over said opening and parallel to the X and Y axes, said diaphragm having a top and bottom surface;

c) contiguous piezoelectric material attached to the top surface of said diaphragm;

d) a proof mass attached to the bottom surface of said diaphragm and aligned along said Z axis; and

e) a first electrically conductive layer centrally positioned on the piezoelectric material, and a second electrically conductive layer deposited on the piezoelectric material, the second electrically conductive layer being ring-shaped, concentric with, and extending around the first electrically conductive, the first and second conductive layers electrically connectable to a circuit whereby acceleration in any one of the X, Y, and Z axis generates an electrical signal whereby said acceleration may be detected.

2. The apparatus of claim 1, wherein said base further comprises a thickness along said Z axis at least as great as the Z axial dimension of said proof mass.

3. The apparatus of claim 2, wherein said diaphragm further comprises a metal diaphragm.

4. The apparatus of claim 3, wherein said diaphragm has a thickness of from 0.1 millimeters to 0.4 millimeters.

5. The apparatus of claim 1, wherein said piezoelectric material further comprises polyvinylidene fluoride.

6. The apparatus of claim 1, wherein said piezoelectric material further comprises copolymers of vinylidene fluoride.

7. The apparatus of claim 1, wherein said piezoelectric material further comprises copolymers of trifluoroethylene.

8. The apparatus of claim 1, wherein said piezoelectric material further comprises a polycrystalline ceramic.

9. The apparatus of claim 1, wherein said piezoelectric material further comprises a crystalline ceramic and lead metal oxide.

10. The apparatus of claim 1, further comprising conductive tabs on said base for forming a connection between said electrical conductors and said electric circuit.

11. The apparatus of claim 1, wherein said proof mass is a solid, cylindrically-shaped member.

12. The apparatus of claim one wherein the proof mass is attached to the bottom surface of the diaphragm and the piezoelectric material is attached to the top surface.

13. A shock sensor for measuring acceleration in X, Y, Z axes, the sensor comprising:

a) a base having a circular opening extending along the Z axis;

b) a diaphragm attached to said base over said opening and parallel to the X and Y axes, said diaphragm having a top and bottom surface;

c) piezoelectric material attached to the top surface of said diaphragm;

d) a proof mass attached to the bottom surface of said diaphragm and aligned along said Z axis, no symmetrical proof mass being attached to the top surface; and

e) a first electrically conductive layer centrally positioned on the piezoelectric material, a second electrically conductive layer deposited on the piezoelectric material, the second electrically conductive layer being concentric with the first, the first and second conductive layers electrically connectable to a circuit whereby acceleration of the apparatus in any one of the X, Y, and Z axis generates an electrical signal whereby said acceleration may be detected.