Biaxial capacitance strain transducer
First Claim
1. A multiaxial capacitance strain transducer comprising:
- a stack of at least three support wafers defining at least two slots therebetween, a first capacitance strain transducer formed in one of said slots including at least one capacitance varying element slidably carried in said one slot and extending outwardly therefrom, a second capacitance strain transducer formed in the other of said slots including at least one capacitance varying element slidably carried in said other slot and extending outwardly therefrom, said second capacitance strain transducer being angularly offset with respect to said first capacitance strain transducer by a predetermined angle and coupling means connecting the outwardly extending portions of said capacitance varying elements with the surface wherein strain is to be measured.
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Abstract
A biaxial capacitance strain transducer in the form of a laminated structure defining two capacitance strain transducers in orthogonal orientation. Each capacitance strain transducer comprises driven capacitance plates which are excited by an oscillator and a sensing capacitance plate disposed in spaced parallel relation to the driven capacitance plates. A shutter mechanism in the form of a pair of apertured plates is provided between the driven plates and the sensing plates. The ends of the apertured plates extend out of the laminated structure and are attached to the surface wherein strain is to be measured. Strain will produce relative displacement of the apertured plates, resulting in variation in the capacitive coupling between the sensing and driven plates through the apertures. This differential capacitance, which is thus related to the strain to be measured, is detected and measured by suitable electronic instrumentation.
44 Citations
26 Claims
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1. A multiaxial capacitance strain transducer comprising:
- a stack of at least three support wafers defining at least two slots therebetween, a first capacitance strain transducer formed in one of said slots including at least one capacitance varying element slidably carried in said one slot and extending outwardly therefrom, a second capacitance strain transducer formed in the other of said slots including at least one capacitance varying element slidably carried in said other slot and extending outwardly therefrom, said second capacitance strain transducer being angularly offset with respect to said first capacitance strain transducer by a predetermined angle and coupling means connecting the outwardly extending portions of said capacitance varying elements with the surface wherein strain is to be measured.
- View Dependent Claims (2, 3, 4, 5)
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6. A multiaxial capacitance strain transducer comprising:
- a stack of at least three support wafers defining at least two slots therebetween, a first capacitance strain transducer formed in one of said slots, a second capacitance strain transducer formed in the other of said slots, each of said first and second capacitance strain transducers comprising a pair of driven capacitance plates carried on the surface of one of said support wafers interior of said slot, a sensing capacitance plate carried on the surface of the other of said support wafers interior of said slot in parallel spaced relation to said driven capacitance plates and shutter means disposed between said driven capacitance plates and said sensing capacitance plates for varying the differential capacitance therebetween in response to the displacement of said shutter means, said first capacitance strain transducer being oriented orthogonally with respect to said second capacitance strain transducer.
- View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
- 17. A capacitance strain transducer comprising at least two support wafers defining a slot therebetween, a pair of driven capacitance plates carried on the surface of one of said support wafers interior of said slot, a sensing capacitance plate carried on the surface of the other of said support wafers interior of said slot in parallel spaced relation to said driven capacitance plates and shutter means disposed between said driven capacitance plates and said sensing capacitance plate, said shutter means comprising a pair of apertured plates each having at least one aperture, the apertures of one of said apertured plates partially overlapping the apertures of the other of said apertured plates to define capacitance slots therethrough, the dimensions of said capacitance slots varying upon relative displacement of said apertured plates for varying the differential capacitance therebetween in response to displacement to said shutter means, said apertured plates extending outwardly from said slot on opposite sides thereof, and means for coupling the outwardly extending portions of said apertured plates with the surface wherein strain is to be measured.
- 19. A capacitance strain transducer comprising at least two support wafers defining a slot therebetween, a pair of driven capacitance plates carried on the surface of one of said support wafers interior of said slot, said driven capacitance plates comprising a plurality of elongate parallel spaced-apart projections, the projections of one of said driven capacitance plates being interposed between the projections of the other of said driven capacitance plates, a sensing capacitance plate carried on the surface of the other of said support wafers interior of said slot in parallel spaced relation to said driven capacitance plates and shutter means disposed between said driven capacitance plates and said sensing capacitance plate, said shutter means comprising a pair of apertured plates each having at least one aperture, the apertures of one of said apertured plates partially overlapping the apertures of the other of said apertured plates to define capacitance slots therethrough, the dimensions of said capacitance slot varying upon relative displacement of said apertured plates for varying the differential capacitance therebetween in response to displacement of said shutter means.
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22. A capacitive strain transducer comprising:
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a pair of differentially driven capacitance plates; a sensing capacitance plate spaced parallel to said driven plates to define a channel therebetween; first and second shutter plates disposed between said driven plates and said sensing plate in said channel, each shutter plate having therethrough at least one aperture partially overlapping an aperture in the other shutter plate to define a pair of capacitance slots through said first and second shutter plates, one of said pair of slots being aligned with the first of said driven plate pair and the other of said pair of slots being aligned with a second of said driven plate pair, the displacement of said shutter plates relative to one another varying the ratio of areas of said pair of slots upon relative displacement of said shutter plates for varying the differential capacitance between said driven capacitance plates relative to said sensing capacitance plate. - View Dependent Claims (23, 24, 25, 26)
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Specification