Capacitive force sensing device
First Claim
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1. An apparatus comprising:
- an upper surface and a lower surface that are substantially parallel to each other, one of the said surfaces being fixed and the other surface being moveable relative to the fixed surface in response to applied force;
electrodes attached to each of the said upper and lower surfaces;
a variable capacitor attached to the electrodes which measures the capacitance between the two surfaces;
electric circuitry to provide an electrical output in response to changed capacitance; and
a plurality of conical washers stacked to form a spring assembly positioned between the upper surface and the lower surface to form a capacitive force sensing device.
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Abstract
An exemplary capacitive force sensing device using metallic springs of certain shapes as spacers between the dielectric plates.
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Citations
20 Claims
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1. An apparatus comprising:
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an upper surface and a lower surface that are substantially parallel to each other, one of the said surfaces being fixed and the other surface being moveable relative to the fixed surface in response to applied force; electrodes attached to each of the said upper and lower surfaces; a variable capacitor attached to the electrodes which measures the capacitance between the two surfaces; electric circuitry to provide an electrical output in response to changed capacitance; and a plurality of conical washers stacked to form a spring assembly positioned between the upper surface and the lower surface to form a capacitive force sensing device. - View Dependent Claims (17, 18, 19, 20)
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2. An apparatus comprising:
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an upper surface and a lower surface that are substantially parallel to each other, one of the said surfaces being fixed and the other surface being moveable relative to the fixed surface in response to applied force; electrodes attached to each of the said upper and lower surfaces; a variable capacitor attached to the electrodes which measures the capacitance between the two surfaces; electric circuitry to provide an electrical output in response to changed capacitance; and a spring assembly which deflects longitudinally in the direction of an applied force, and transversely to the direction of the applied force such that the transverse deflection does not touch any portion of the upper surface and the lower surface; and
a plurality of conical washers stacked to form the spring assembly positioned between the upper surface and the lower surface to form a capacitive force sensing device. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method comprising:
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placing a fixed surface and a moveable surface substantially parallel to each other; permitting the moveable surface to move in response to a force applied perpendicular to the moveable surface; attaching electrodes to both the fixed and the moveable surfaces; attaching a variable capacitor which measures the capacitance between the two surfaces; positioning a plurality of conical washers stacked to form a spring assembly which deflects longitudinally in the direction of an applied force, and transversely to the direction of the applied force such that the transverse deflection does not touch any portion of the upper surface and the lower surface; and measuring the applied force by measuring the capacitance using the variable capacitor. - View Dependent Claims (13, 14, 15, 16)
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Specification