Capacitive position sensor
First Claim
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1. A method for measuring position, the method comprising:
- arranging a dielectric shuttle such that it is at least partially between a common electrode and a first sensing electrode, the dielectric shuttle having a first dielectric constant portion and a second dielectric constant portion with different relative permittivities, and being arranged with a first percentage of the first dielectric constant portion and a second percentage of the second dielectric constant portion located between the common electrode and the first sensing electrode;
sensing a first capacitance of the common electrode in combination with the first sensing electrode, the first capacitance being based on the first percentage and the second percentage;
moving the dielectric shuttle relative to the first sensing electrode such that it passes between the common electrode and a second sensing electrode, with a third percentage of the first dielectric constant portion and a fourth percentage of the second dielectric constant portion located between the common electrode and the second sensing electrode;
sensing a second capacitance of the common electrode in combination with the second sensing electrode, the second capacitance being based on the third percentage and the fourth percentage; and
measuring the position of the dielectric shuttle based on the sensed first and second capacitances.
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Abstract
A transducer includes a plurality of electrodes and a dielectric shuttle. The dielectric shuttle passes between a subset of the electrodes, modifying the capacitance between them. By measuring the capacitance of subsets of the electrodes, the position of the dielectric shuttle may be determined.
10 Citations
17 Claims
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1. A method for measuring position, the method comprising:
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arranging a dielectric shuttle such that it is at least partially between a common electrode and a first sensing electrode, the dielectric shuttle having a first dielectric constant portion and a second dielectric constant portion with different relative permittivities, and being arranged with a first percentage of the first dielectric constant portion and a second percentage of the second dielectric constant portion located between the common electrode and the first sensing electrode; sensing a first capacitance of the common electrode in combination with the first sensing electrode, the first capacitance being based on the first percentage and the second percentage; moving the dielectric shuttle relative to the first sensing electrode such that it passes between the common electrode and a second sensing electrode, with a third percentage of the first dielectric constant portion and a fourth percentage of the second dielectric constant portion located between the common electrode and the second sensing electrode; sensing a second capacitance of the common electrode in combination with the second sensing electrode, the second capacitance being based on the third percentage and the fourth percentage; and measuring the position of the dielectric shuttle based on the sensed first and second capacitances. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A transducer comprising:
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an insulating material; a first sensing electrode disposed on the insulating material; a second sensing electrode disposed on the insulating material; a common electrode; and a dielectric shuttle, movable in a direction substantially parallel to a surface of the common electrode, arranged with a first part of the dielectric shuttle between the first sensing electrode and the common electrode and a second part of the dielectric shuttle between the second sensing electrode and the common electrode, wherein the dielectric shuttle comprises; a first portion with a first dielectric constant; and a second portion with a second dielectric constant that is not equal to the first dielectric constant; wherein a first capacitance between the first sensing electrode and the common electrode is based on a first percentage of the first portion that makes up the first part of the dielectric shuttle and a second percentage of the second portion that makes up the first part of the dielectric shuttle; and wherein a second capacitance between the second sensing electrode and the common electrode is based on a third percentage of the first portion that makes up the second part of the dielectric shuttle and a fourth percentage of the second portion that makes up the second part of the dielectric shuttle. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for measuring position, the method comprising:
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arranging a dielectric shuttle such that it is at least partially between a common electrode and a first sensing electrode, the dielectric shuttle having a first dielectric constant portion and a second dielectric constant portion with different relative permittivities; sensing a capacitance of the common electrode in combination with the first sensing electrode; moving the dielectric shuttle relative to the first sensing electrode such that it passes between the common electrode and a second sensing electrode by rotating the dielectric shuttle around the common electrode; sensing the capacitance of the common electrode in combination with the second sensing electrode; and measuring the position of the dielectric shuttle based on the sensed capacitances, including counting the number of full rotations of the dielectric shuttle.
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Specification