Force detector and moment detector using resistance element

• US 4,905,523 A
• Filed: 12/19/1988
• Issued: 03/06/1990
• Est. Priority Date: 04/24/1987
• Status: Expired due to Fees

• Current Assignee: Wacoh Company
• Original Assignee: Wacoh Company
• Inventors: Okada, Kazuhiro
• Primary Examiner(s): Ruehl, Charles A.
• Application Number:
  US07/295,601
• Time in Patent Office: 442 Days
• Field of Search: 73/862.04, 73/862.05, 73/862.06, 73/862.67
• 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

Abstract

Force and moment exerted on the working point (P) on a semiconductor substrate (110; 210), on one surface of which resistance elements (r, R) having an electric resistance varying due to mechanical deformation are formed, are detected. A portion spaced from the working point of the semiconductor substrate is fixed. Since openings (113) or bridge portions (212 to 215) are formed in the semiconductor substrate, when a force or an angular moment in a fixed direction is applied to the working point, uneven stresses are produced on the semiconductor substrate. Such uneven stresses are detected as changes in electric resistances of the resistance elements. A measure is taken for an arrangement of resistance elements on the semiconductor substrate, thereby to constitute predetermined bridges. Thus, forces in three directions and angular moments in three directions in the three-dimensional space can be independently read as bridge voltages, respectively.

Claims

1. A detector for detecting forces exerted in respective axial directions and moments exerted around respective axes with an origin (P) being as a working point in an XYZ three-dimensional coordinate system,

wherein there are provided

first bridging portions (214, 215) formed along the X-axis on respective both sides of said origin, and

second bridging portions (212, 213) formed along the Y-axis on respective both sides of said origin,

both the ends of said first and second bridging portions being fixed as fixed portions so that strains are produced in said respective bridging portions by applying a force to said origin, respectively, and

wherein resistance element groups (R) comprising a plurality of resistance elements having a property such that electric resistance changes due to mechanical deformation are provided on the XY plane of said first and second bridging portions at principal positions of the following positions:

a pair of positions for resistance elements (R13, R15) arranged on both sides of the X-axis in respective positive and negative directions of the Y-axis in the vicinity of said origin in the positive direction of said X-axis,

a pair of positions for resistance elements (R10, R12) arranged on both sides of said X-axis in respective positive and negative directions of said Y-axis in the vicinity of said origin in the negative direction of said X-axis,

a pair of positions for resistance elements (R14, R16) arranged on both sides of said X-axis in respective positive and negative directions of said Y-axis in the vicinity of said fixed portion in the positive direction of said X-axis,

a pair of positions for resistance elements (R9, R11) arranged on both sides of said X-axis in respective positive and negative directions of said Y-axis in the vicinity of said fixed portion in the negative direction of said X-axis,

a pair of positions for resistance elements (R5, R7) arranged on both sides of said Y-axis in respective positive and negative directions of said X-axis in the vicinity of said origin in the positive direction of said Y-axis,

a pair of positions for resistance elements (R2, R4) arranged on both sides of said Y-axis in respective positive and negative directions of said X-axis in the vicinity of said origin in the negative direction of said Y-axis,

a pair of positions for resistance elements (R6, R8) arranged on both sides of said Y-axis in respective positive and negative directions of said X-axis in the vicinity of said fixed portion in the positive direction of said Y-axis, and

a pair of positions for resistance elements (R1, R3) arranged on both sides of said Y-axis in respective positive and negative directions of said X-axis in the vicinity of said fixed portion in the negative direction of said Y-axis,

thus to detect a change in the force exerted on said origin on the basis of changes in electric resistances of respective resistance elements.

2. A detector as set forth in claim 1, wherein a bridge assembly is constructed by resistance elements to make a detection:

said bridge assembly comprising;

(1) a bridge provided at one opposite sides with two resistor pairs, one resistor pair being obtained by connecting in series two resistance elements (R15, R16) positioned in the positive direction of said X-axis and on the positive side of said Y-axis with respect to said X-axis, and the other resistor pair being obtained by connecting in series two resistance elements (R13, R14) positioned in the positive direction of said X-axis and on the negative side of said Y-axis with respect to said X-axis, respectively,

said bridge further provided at the other opposite sides with two resistor pairs, one resistor pair being obtained by connecting two resistance elements (R11, R12) positioned in the negative direction of said X-axis and on the positive side of said Y-axis with respect to said X-axis, and the other resistor pair being obtained by connecting in series two resistance elements (R9, R10) positioned in the negative direction of said X-axis and on the negative side of said Y-axis with respect to said X-axis, respectively, thus to detect a force in the X-axis direction on the basis of a bridge voltage of said bridge,

(2) a bridge provided at one opposite sides with two resistor pairs, one resistor pair being obtained by connecting in series two resistance elements (R5, R6) positioned in the positive direction of said Y-axis and on the positive side of said X-axis with respect to said Y-axis, and the other resistor pair being obtained by connecting in series two resistance elements (R7, R8) positioned in the positive direction of said Y-axis and on the negative side of said X-axis with respect to said Y-axis, respectively,

said bridge further provided at the other opposite sides with two resistor pairs, one resistor pair being obtained by connecting in series two resistance elements (R1, R2) positioned in the negative direction of said Y-axis and on the positive side of said X-axis with respect to said Y-axis, and the other resistor pair being obtained by connecting in series two resistance elements (R3, R4) positioned in the negative direction of said Y-axis and on the negative side of said X-axis with respect to said Y-axis, respectively, thus to detect a force in the Y-axis direction on the basis of a bridge voltage of said bridge,

(3) a bridge provided at one opposite sides with two resistor pairs, one resistor pair being obtained by connecting in series a resistance element (R16) positioned in the vicinity of said fixed portion in the positive direction of said X-axis and on the positive side of said Y-axis with respect to said X-axis and a resistance element (R9) positioned in the vicinity of said fixed portion in the negative direction of said X-axis and on the negative side of said Y-axis with respect to said X-axis, and

the other resistor pair being obtained by connecting in series a resistance element (R14) positioned in the vicinity of said fixed portion in the positive direction of said X-axis and on the negative side of said Y-axis with respect to said X-axis and a resistance element (R11) positioned in the vicinity of said fixed portion in the negative direction of said X-axis and on the positive side of said Y-axis with respect to said X-axis, respectively,

said bridge further provided at the other opposite sides with two resistor pairs, one resistor pair being obtained by connecting in series a resistance element (R15) positioned in the vicinity of said origin in the positive direction of said X-axis and on the positive side of said Y-axis with respect to said X-axis and a resistance element (R10) positioned in the vicinity of said origin and on the negative side of said Y-axis with respect to said X-axis, and

the other resistor pair being obtained by connecting in series a resistance element (R13) in the vicinity of said origin in the positive direction of said X-axis and a resistance element (R12) in the vicinity of said origin in the negative direction of said X-axis and on the positive side of said Y-axis with respect to said X-axis, respectively, thus to detect a force in the Z-axis direction on the basis of a bridge voltage of said bridge,

(4) a bridge provided atone opposite sides with two resistor pairs, one resistor pair being obtained by connecting in series two resistance elements (R6, R8) in the vicinity of said fixed portion in the positive direction of said Y-axis, and the other resistor pair being obtained by connecting in series two resistance elements (R2, R4) in the vicinity of said fixed portion in the negative direction of said Y-axis, respectively,

said bridge further provided at the other opposite sides with two resistor pairs, one resistor pair being obtained by connecting in series two resistance elements (R5, R7) positioned in the vicinity of said origin in the positive direction of said Y-axis, and the other resistor pair being obtained by connecting in series two resistance elements (R1, R3) positioned in the vicinity of said fixed portion in the negative direction of said Y-axis, respectively, thus to detect a moment around said X-axis on the basis of a bridge voltage of said bridge,

(5) a bridge provided at one opposite sides with two resistor pairs, one resistor pair being obtained by connecting in series two resistance elements (R14, R16) positioned in the vicinity of said fixed portion in the positive direction of said X-axis, and the other resistor pair being obtained by connecting two resistance elements (R10, R12) positioned in the vicinity of said origin in the negative direction of said X-axis, respectively,

said bridge further provided at the other opposite sides with two resistor pairs, one resistor pair being obtained by connecting in series two resistance elements (R13, R15) positioned in the vicinity of said origin in the positive direction of said X-axis, and the other resistor pair being obtained by connecting in series two resistance elements (R9, R11) positioned in the vicinity of said fixed portion in the negative direction of said X-axis, respectively, thus to detect a moment around said Y-axis on the basis of a bridge voltage of said bridge, and

(6) a bridge provided at one opposite sides with two resistor pairs, one resistor pair being obtained by connecting in series a resistance element (R15, R16) positioned in the vicinity of said origin or said fixed portion in the positive direction of said X-axis and on the positive side of said Y-axis with respect to said X-axis and a resistance element (R9, R10) positioned in the vicinity of said origin or said fixed portion in the negative direction of said X-axis and on the negative side of said Y-axis with respect to said X-axis, and

the other resistor pair being obtained by a resistance element (R7, R8) positioned in the vicinity of said origin or said fixed portion in the positive direction of said Y-axis and on the negative side of said Y-axis with respect to said Y-axis and a resistance element (R1, R2) positioned in the vicinity of said origin or said fixed portion in the negative direction of said Y-axis and on the positive side of said X-axis with respect to said Y-axis, respectively,

said bridge further provided at the other opposite sides with two resistor pairs, one resistor pair being obtained by connecting in series a resistance element (R11, R12) positioned in the vicinity of said origin or said fixed portion in the negative direction of said X-axis and on the positive side of said Y-axis with respect to said X-axis and a resistance element (R13, R14) positioned in the vicinity of said origin or said fixed portion in the positive direction of said X-axis and on the negative side of said Y-axis with respect to said X-axis, and

the other resistor pair being obtained by a resistance element (R3, R4) positioned in the vicinity of said origin or said fixed portion in the negative direction of said Y-axis and on the negative side of said X-axis with respect to said Y-axis and a resistance element (R5, R6) positioned in the vicinity of said origin or said fixed portion in the positive direction of said Y-axis and on the positive side of said X-axis with respect to said Y-axis, respectively, thus to detect a moment around said Z-axis on the basis of a bridge voltage of said bridge.

3. A detector as set forth in claim 1, wherein, under condition where no force or moment is exerted, respective resistance elements all have substantially the same resistance value, and changes in electric resistance based on strains produced in said bridging portions are substantially equal to each other for respective resistance elements.

4. A detector as set forth in claim 1, which further comprises a supporting substrate (223) adjoining each bridging portion.