Force sensor for electrical measuring of forces, torques, acceleration pressures and mechanical stresses
First Claim
1. A force sensor for electric measuring of forces, torques, acceleration, pressures and/or mechanical stresses applied to said force sensor in the form of a distributed mechanical stress field comprising:
- (a) an electrically insulating carrier body;
(b) a piezo-resistive transducer comprising a first pattern of filaments firmly attached to said carrier body and at least one further pattern of filaments upon said first pattern, said patterns being separated by insulating layers, said filaments consisting of resistive material, said filaments of said first pattern having a direction transverse to that of said filaments of said further pattern;
(c) a force transmission means for applying said distributed mechanical stress field in normal direction onto said piezo-resistive transducer;
(d) plane elements formed by the projection of two adjacent of the said patterns in the direction of the lines of force of said stress field, said elements being of equal area and completely subjected to any strain of the carrier body caused by said distributed mechanical stress field, said strain having first and second strain components in the direction of said filaments of said first and said further patterns respectively; and
(e) a bridge circuit arrangement having branches consisting of said first and said further patterns, an electric current flowing through said first pattern in said direction of said first strain component and through said further pattern in said direction of said second strain component.
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Accused Products
Abstract
Force sensor for electric measuring of forces, mechanical stress or the like, which are converted in the interior of the force sensor into a mechanical normal stress field and then into an electric resistance change. Transverse to the normal stress σj a piezo-resistive measuring element (17) consisting of at least one layer of resistance material is applied whose material constant c is selected such that a mechanical strain of the measuring element resulting from the strain of a carrier body (1) does not influence the measurement. The resistance layers may be overlying crossing patterns M1, M2 forming area elements (13) of equal area size which completely exhibits the mutually perpendicular strains εx, εy of the carrier body (1). For compensating disturbing influences exterior of the normal stress field a compensation element (18) is provided corresponding to the measuring element (17).
32 Citations
22 Claims
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1. A force sensor for electric measuring of forces, torques, acceleration, pressures and/or mechanical stresses applied to said force sensor in the form of a distributed mechanical stress field comprising:
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(a) an electrically insulating carrier body; (b) a piezo-resistive transducer comprising a first pattern of filaments firmly attached to said carrier body and at least one further pattern of filaments upon said first pattern, said patterns being separated by insulating layers, said filaments consisting of resistive material, said filaments of said first pattern having a direction transverse to that of said filaments of said further pattern; (c) a force transmission means for applying said distributed mechanical stress field in normal direction onto said piezo-resistive transducer; (d) plane elements formed by the projection of two adjacent of the said patterns in the direction of the lines of force of said stress field, said elements being of equal area and completely subjected to any strain of the carrier body caused by said distributed mechanical stress field, said strain having first and second strain components in the direction of said filaments of said first and said further patterns respectively; and (e) a bridge circuit arrangement having branches consisting of said first and said further patterns, an electric current flowing through said first pattern in said direction of said first strain component and through said further pattern in said direction of said second strain component. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A force sensor for electric measuring of forces, torques, accelerations, pressures and/or mechanical stresses acting in the form of a distributed mechanical stress field comprising:
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(a) an electrically insulating carrier body, (b) a piezo-resistive transducer comprising at least one two-dimensional pattern of filaments consisting of resistive material and firmly attached to said carrier body, (c) a force transmission means for applying said distributed mechanical stress field normal to said piezo-resistive transducer; wherein a material constant c of said resistive material is selected such that any change in resistance of the piezo-resistive transducer due to said stress field to be measured remains essentially uninfluenced by mechanical strain acting on said transducer and caused by mechanical strain caused in said carrier body upon application of said distributed mechanical stress field. - View Dependent Claims (18, 19, 20)
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21. A force sensor for electrical measuring of forces, torques, acceleration, pressures and/or mechanical stresses applied to said force sensor in the form of a distributed mechanical stress field, comprising:
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(a) an electrically insulating carrier body; (b) a piezo-resistive transducer means comprising at least one pattern of filaments consisting of resistive material and firmly attached to said carrier body, (c) a force transmission means for applying said distributed mechanical stress field in normal direction to said piezo-resistive transducer, (d) a piezo-resistive compensation element having a design corresponding to said piezo-resistive transducer and being attached to a surface of said insulating carrier body, said compensation element being free from said distributed mechanical stress field, said piezo-resistive compensation element being electrically connected in branches of a bridge circuit arrangement;
wherein a material constant c of said resistive material is selected such that any change in resistance of the piezo-resistive transducer due to said stress field to be measured remains essentially uninfluenced by mechanical strain acting on said transducer and caused by mechanical strain caused in said carried body upon application of said distributed mechanical stress field. - View Dependent Claims (22)
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Specification