Detector for force and acceleration using resistance element

• US 4,967,605 A
• Filed: 12/19/1988
• Issued: 11/06/1990
• Est. Priority Date: 04/24/1987
• Status: Expired due to Term

• Current Assignee: Wacoh Company
• Original Assignee: Wacoh Company
• Inventors: Okada, Kazuhiro
• Primary Examiner(s): Ruehl, Charles A.
• Application Number:
  US07/295,210
• Time in Patent Office: 687 Days
• Field of Search: 73/517 R, 73/510, 73/721, 73/727, 73/777, 73/862.04, 73/862.67, 73/862.65, 338/5, 338/47
• US Class Current: 73/862.044
• 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 5/162 of piezoresistors
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• 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: G01R 1/203 Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts resistors in general H01C; microwave or radiowave terminations H01P1/26; coupling devices H01R
• CPC Class Codes: G01R 33/038 using permanent magnets, e.g. balances, torsion devices
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/10253 Silicon [Si]

Abstract

A force detector is comprised of resistance elements having a piezo resistance effect such that electric resistance varies due to mechanical deformation, and formed on a single crystal substrate (10), and a strain generative body (20) having a supporting portion (21) and a working portion (23), thus allowing the resistance elements to produce a mechanical deformation on the basis of a displacement with respect to the supporting portion of the working portion. This force detector can detect a force applied to the working portion as changes in resistance values of the resistance elements. The plane on which resistance elements are to be formed on the single crystal substrate is selected so that piezo resistance coefficients in two directions perpendicular to each other exhibit peak. When a weight body (30) is connected to the working portion, it is possible to detect an acceleration acting on the weight body. Moreover, when a magnetic body (330) is connected to be working portion, it is possible to detect a magnetic force acting on the magnetic body. By using the detector system for acceleration in common to the detector system for magnetic force to perform a compensation computation, detection of a magnetic force which is not influenced by acceleration can be made. By devising an arrangement of resistance elements in either detector, it is possible to independently determine magnitudes of objects to be measured with respect to directions of the three-dimensional coordinate system, respectively.

Claims

1. A force detector detecting three-dimensional components of force in a three-dimensional coordinate system expressed by three axes of X, Y and Z, comprising:

resistance elements having a piezo resistance effect such that electric resistance of the elements varies due to mechanical deformation, and formed on a single crystal substrate, and

a strain generative body having a supporting portion connected to a part of said substrate and working portion connected to another part of said substrate, wherein a displacement is made between said supporting portion and said working portion by adding force to said working portion, thus allowing said resistance elements to experience mechanical deformation on the basis of said displacement,

wherein a different set each comprising four resistance elements is provided for detecting the component of force along each of said three axes, respectively, and three bridges are formed each of which comprises a different one of said sets of resistance elements, thus to detect all of said three-dimensional components of force.

2. A force detector detecting three-dimensional components of force in a three-dimensional coordinate system expressed by three axes of X, Y and Z, comprising:

resistance elements having a piezo resistance effect such that electric resistance of the elements varies due to mechanical deformation, and formed on a single crystal substrate, a first set of four resistance elements being formed along a first line which lies on a surface of the substrate, a second set of four resistance elements being formed along a second line which lies on said surface and is substantially perpendicular to said first line, and a third est of four resistance elements being formed along a third line which lies on said surface, and

a strain generative body having a supporting portion connected to a part of said substrate and a working portion connected to another part of said substrate, wherein a displacement is made between said supporting portion and said working portion by adding force to said working portion, thus allowing said resistance elements to experience mechanical deformation on the basis of said displacement,

wherein three bridges are formed to detect all of said components, a first bridge formed by said first set of resistance elements in such a way that, in the order of sequence of said elements along said first line, a first element is opposite to a third element and a second element is opposite to a fourth element, a second bridge being formed by said second set of resistance elements in such a way that a first element of the sequence of elements is opposite to a third element and a second element is opposite to a fourth element, and a third bridge being formed by said third set of resistance elements in such a way that a first element of the sequence of elements is opposite to a fourth element and a third element is opposite to a second element.

3. An acceleration detector detecting three-dimensional components of acceleration in a three-dimensional coordinate system expressed by three axes of X, Y, and Z, comprising:

resistance elements having a piezo resistance effect such that electric resistance of the elements varies due to mechanical deformation, and formed on a single crystal substrate, and

a strain generative body having a supporting portion connected to a part of said substrate and a working portion connected to another part of said substrate, wherein a displacement is made between said supporting portion and said working portion by adding force to said working portion, thus allowing said resistance elements to experience mechanical deformation on the basis of said displacement,

a weight body connected to said working portion of said strain generative body, thus allowing said working portion to produce a displacement corresponding to an acceleration of said strain generative body,

wherein a different set each comprising four resistance elements is provided for detecting the component of force along each of said three axes, respectively, and three bridges are formed each of which comprises a different one of said sets of resistance elements, thus to detect all of said three-dimensional components of acceleration.

4. An acceleration detector as set forth in claim 3, wherein either one of the central portion of said strain generative body and the peripheral portion thereof is used as said supporting portion, and the other portion is used as said working portion.

5. An acceleration detector as set forth in claim 3, wherein said resistance elements, said strain generative body, and said weight body are integrally formed within the same substrate.

6. An acceleration detector as set forth in claim 3, which further comprises a displacement limiting member formed with a predetermined space between said displacement limiting member and said weight body so as to limit displacements in three-dimensional directions of said weight body produced by an external force that said weight body undergoes.

7. An acceleration detector as set forth in claim 3 wherein said resistance elements and said strain generative body are integrally formed within the same substrate.

8. An acceleration detector detecting three-dimensional components of acceleration in a three-dimensional coordinate system expressed by three axes of X, Y and Z, comprising:

resistance elements having a piezo resistance effect such that electric resistance of the elements varies due to mechanical deformation, and formed on a single crystal substrate, a first set of four resistance elements being formed along a first line which lies on a surface of the substrate, a second set of four resistance elements being formed along a second line which lies on said surface and is substantially perpendicular to said first line, and a third set of four resistance elements being formed along a third line which lies on said surface, and

a strain generative body having a supporting portion connected to a part of said substate and a working portion connected to another part of said substrate, wherein a displacement is made between said supporting portion and said working portion by adding force to said working portion, thus allowing said resistance elements to experience mechanical deformation on the basis of said displacement,

a weight body connected to said working portion of said strain generative body, thus allowing said working portion to produce a displacement corresponding to an acceleration of said strain generative body,

wherein three bridges are formed to detect all of said components, a first bridge formed by said first set of resistance elements in such a way that, in the order of sequence of said elements along said first line, a first element is opposite to a third element and a second element is opposite to a fourth element, a second bridge being formed by said second set of resistance elements in such a way that a first element of the sequence of elements is opposite to a third element and a second element is opposite to a fourth element, and a third bridge being formed by said third set of resistance elements in such a way that a first element of the sequence of elements is opposite to a fourth element and a third element is opposite to a second element.

9. An acceleration detector detecting two-dimensional components of acceleration in a two-dimensional coordinate system expressed by two axes of X and Y, comprising:

resistance elements having a piezo resistance effect such that electric resistance of the elements varies due to mechanical deformation, and formed on a single crystal substrate, and

a strain generative body having a supporting portion connected to a part of said substrate and a working portion connected to another part of said substrate, wherein a displacement is made between said supporting portion and said working portion by adding force to said working portion thus allowing said resistance elements to experience mechanical deformation on the basis of said displacement,

a weight body connected to said working portion of said strain generative body, thus allowing said working portion to produce a displacement corresponding to an acceleration of said strain generative body,

wherein two sets each comprising four resistance elements are provided for detecting the component of force along each of said two axes, respectively, and two bridges are formed each of which comprises a different one of said sets of said resistance elements, thus to detect both of said two-dimensional components of acceleration.

10. An acceleration detector as set forth in claim 9, wherein said resistance elements, said strain generative body, and said weight body are integrally formed within the same substrate.

11. An acceleration detector as set forth in claim 9 wherein said resistance elements and said strain generator body are integrally formed within the same substrate.