General displacement sensor
First Claim
Patent Images
1. Apparatus for sensing level of pourable material in a container, the apparatus comprising:
- pulse generation means for producing a sequence of voltage pulses, spaced in time, of substantially identical magnitude and duration;
resistive-capacitive circuit means, operatively associated with the pulse generation means, and having a probe which includes at least one probe capacitor immersed in the pourable material, for producing a signal indicative of level of pourable material in the container;
second resistive-capacitive circuit means, operatively associated with the pulse generation means, for producing a reference signal indicative of a reference level in the container;
amplification means for amplifying the pourable material level signal and the reference signal, producing an amplified pourable material level signal and an amplified reference signal;
integration means for generating a time-integrated difference signal of the amplified pourable material level signal and the amplified reference signal;
output means, operatively associated with the integration means, for producing an output signal proportional to a mathematical function of the pourable material level in the container;
shield driver means for reducing the effects of extraneous capacitance developed by the probe of the first resistive-capacitive circuit means, the shield driver being operatively associated with the probe of the first resistive-capacitive circuit means; and
the probe including a three-conductor cable, with one conductor electrically connected to the probe capacitor immersed in the pourable material, with a second conductor surrounding the first conductor and being electrically connected to the shield driver means, and with a third conductor surrounding the second conductor and being electrically grounded.
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Accused Products
Abstract
General resistive and capacitive circuitry for sensing and displaying liquid or powder level in a container, linear or rotational displacement of a body, ambient moisture content of the atmosphere, and similar physical quantities, using substantially the same circuitry for each such quantity.
54 Citations
40 Claims
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1. Apparatus for sensing level of pourable material in a container, the apparatus comprising:
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pulse generation means for producing a sequence of voltage pulses, spaced in time, of substantially identical magnitude and duration; resistive-capacitive circuit means, operatively associated with the pulse generation means, and having a probe which includes at least one probe capacitor immersed in the pourable material, for producing a signal indicative of level of pourable material in the container; second resistive-capacitive circuit means, operatively associated with the pulse generation means, for producing a reference signal indicative of a reference level in the container; amplification means for amplifying the pourable material level signal and the reference signal, producing an amplified pourable material level signal and an amplified reference signal; integration means for generating a time-integrated difference signal of the amplified pourable material level signal and the amplified reference signal; output means, operatively associated with the integration means, for producing an output signal proportional to a mathematical function of the pourable material level in the container; shield driver means for reducing the effects of extraneous capacitance developed by the probe of the first resistive-capacitive circuit means, the shield driver being operatively associated with the probe of the first resistive-capacitive circuit means; and the probe including a three-conductor cable, with one conductor electrically connected to the probe capacitor immersed in the pourable material, with a second conductor surrounding the first conductor and being electrically connected to the shield driver means, and with a third conductor surrounding the second conductor and being electrically grounded. - View Dependent Claims (2, 3, 4, 5, 6, 7, 36)
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36. Apparatus according to claim 1, wherein said shield driver means is circuit means for causing the electric potential on the second conductor on the probe to be substantially equal to the electric potential across said probe capacitor immersed in the pourable material.
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8. Apparatus for sensing ambient moisture content, the apparatus comprising:
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pulse generation means for producing a sequence of voltage pulses, spaced in time, of substantially identical magnitude and duration; resistive-capacitive means, operatively associated with the pulse generation means, having a probe which includes at least one moisture-sensing probe capacitor with its two plates separated by a moisture-absorbent, moisture-sensitive dielectric, for producing a signal indicative of moisture content of the dielectric; second resistive-capacitive means, operatively associated with the pulse generation means, for producing a reference signal indicative of a reference level of ambient moisture content; amplification means for amplifying the dielectric moisture content signal and the reference signal to produce an amplified dielectric moisture content signal and an amplified reference signal; integration means for generating a time-integrated difference signal of the amplified dielectric moisture content signal and the amplified reference signal; output means, operatively associated with the amplifying means, for producing a signal proportional to a mathematical function of the dielectric moisture content; shield driver means for reducing the effects of extraneous capacitance developed by the probe of the first resistive-capacitive circuit means, the shield driver being operatively associated with the probe of the first resistive-capacitive circuit means; and the probe including a three-conductor cable, with one conductor electrically connected to the probe capacitor with moisture-sensitive dielectric, with a second conductor surrounding the first conductor and being electrically connected to the shield driver means, and with a third conductor surrounding the second conductor and being electrically grounded. - View Dependent Claims (9, 10, 11, 12, 13, 14, 37)
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37. Apparatus according to claim 8, wherein said shield driver means is circuit means for causing the electric potential on the second conductor on the probe to be substantially equal to the electric potential across said probe capacitor with the moisture-sensitive dielectric.
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15. Apparatus for sensing rotational displacement of an object which is constrained to rotate in a plane about a fixed axis, the apparatus comprising:
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pulse generation means for producing a sequence of voltage pulses, spaced in time, of substantially identical magnitude and duration; resistive-capacitive circuit means, operatively associated with the pulse generation means, for producing a signal indicative of an angle of rotation of the object, and having a probe which includes at least one probe capacitor having two capacitor plates which are coaxial annular segments, the plates being radially spaced apart by a gap with one capacitor plate being mechanically connected with the object and disposed to rotate about the fixed axis with the object so as to maintain the gap between the two capacitor plates while allowing the angle of rotation between the two capacitor plates to vary; second resistive-capacitive means, operatively associated with the pulse generation means, for producing a reference signal indicative of a reference level of angular rotation of the object; amplification means for amplifying the object angular rotation signal and the reference signal to produce an amplified dielectric moisture content signal and an amplified reference signal; integration means for generating a time-integrated difference signal of the amplified object angular rotation signal and amplified reference signal; output means, operatively associated with the amplifying means, for producing an output signal proportional to a mathematical function of the angle of rotation of the object; shield driver means for reducing the effects of extraneous capacitance developed by the probe of the first resistive-capacitance circuit means, the shield driver being operatively associated with the probe of the first resistive-capacitive circuit means; and the probe including a three-conductor cable, with one conductor electrically connected to the probe capacitor which senses angular rotation, with a second conductor surrounding the first conductor and being electrically connected to the shield driver means, and with a third conductor surrounding the second conductor and being electrically grounded. - View Dependent Claims (16, 17, 18, 19, 20, 21, 38)
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38. Apparatus according to claim 15, wherein said shield driver means is circuit means for causing the electric potential on the second conductor on the probe to be substantially equal to the electric potential across said probe capacitor which senses angular rotation.
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22. Apparatus for sensing linear displacement of an object which is constrained to move only in one linear direction, the apparatus comprising:
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pulse generation means for producing a sequence of voltage pulses, spaced in time, of substantially identical magnitude and duration; resistive-capacitive circuit means, operatively associated with the pulse generation means, for producing a signal indicative of a linear displacement of the object, and having a probe which includes at least one probe capacitor having two capacitor plates, spaced apart by a gap, with one capacitor plate mechanically connected to the object and disposed to move linearly with the object so as to maintain the gap between the two capacitor plates while allowing linear displacement between the two capacitor plates to vary; second resistive-capacitive circuit means, operatively associated with the pulse generation means, for producing a reference signal indicative of a reference level of linear displacement of the object; amplification means for amplifying the object linear displacement signal and the reference signal, producing an amplified object linear displacement signal and an amplified reference signal; integration means for generating a time-integrated difference signal of the amplified object linear displacement signal and amplified reference signal; output means, operatively associated with the amplifying means, for producing an output signal proportional to a mathematical functional of the linear displacement of the object; shield driver means for reducing the effects of extraneous capacitance developed by the probe of the first resistive-capacitive circuit means, the shield driver being operatively associated with the probe of the first resistive-capacitive circuit means; and the probe including a three-conductor cable, with one conductor electrically connected to the probe capacitor which moves with the object, with a second conductor surrounding the first conductor and being electrically connected to the shield driver means, and with a third conductor surrounding the second conductor and being electrically grounded. - View Dependent Claims (23, 24, 25, 26, 27, 28, 39)
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39. Apparatus according to claim 22, wherein said shield driver means is circuit means for causing the electric potential on the second conductor on the probe to be substantially equal to the electric potential across said probe capacitor which moves with the object.
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29. Apparatus for sensing linear displacement of an object which is constrained to move in only one linear direction, the apparatus comprising:
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pulse generation means for producing a sequence of voltage pulses, spaced in time, of substantially identical magnitude and duration; current generator-capacitive circuit means, operatively associated with the pulse generation means, having a probe which includes at least one probe capacitor with two capacitor plates separated by a gap, one capacitor plate being mechanically connected with the object so as to allow the distance across the capacitor gap to change and to move in a linear direction in response to linear displacement of the object, for producing a signal indicative of the reciprocal of linear displacement of the object; second current generator-capacitive circuit means, operatively associated with the pulse generation means, for producing a reference signal indicative of a reference level of the reciprocal of linear displacement of the object; amplification means for amplifying the object linear displacement signal and the reference signal to produce an amplified object linear displacement signal and an amplified reference signal. integration means for generating a time-integrated difference signal of the amplified object linear displacement signal and the amplified reference signal; output means, operatively associated with the amplifying means, for producing an output signal proportional to a mathematical function of the magnitude of the linear displacement of the object; shield driver means, operatively associated with the probe of the first current generator-capacitive circuit means, for reducing the effects of extraneous capacitance developed by the probe of the first current generator-capacitive circuit means; and the probe including a three-conductor cable, with one conductor electrically connected to the probe capacitor which moves with the object with a second conductor surrounding the first conductor and being electrically connected to the shield driver means, and with a third conductor surrounding the second conductor and being electrically grounded. - View Dependent Claims (30, 31, 32, 33, 34, 35, 40)
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40. Apparatus according to claim 29, wherein said shield driver means is circuit means for causing the electric potential on the second conductor on the probe to be substantially equal to the electric potential across said probe capacitor which moves with the object.
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Specification