US3879660A
Expired / Lapsed
US
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Capacitive measuring system
Assignee: Individual
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Filing: 1973-10-24
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Granted: 1975-04-22
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Expires: 1993-10-24
Abstract
Abstract A system for continuously measuring and monitoring physical or chemical changes in materials by detecting capacitive changes as the materials pass a sensor. In a specific application, threads, filaments, wires or tapes are passed at high speed through a sensor to provide continuous direct measure of capacitance. In the particular case of monitoring denier of synthetic yarns, the sensor is mounted directly upon a spin station superstructure and the newly formed fiber is drawn through the plates of capacitors in the sensor head. The capacitors in the sensor head are arranged in a bridge and the bridge unbalance output is differentially amplified and fed to a synchronously operated phase-sensitive detector, the direct current output of which may be amplified, compared with standards and utilized as a continuous display or feed-backs for alarm indicators, for quality control, or for process control.
Inventors
- 👤 John S Piso
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:11
CPC Classifications
B; B65; B65H; B65H63/00; B65H63/06; B65H63/062; B65H63/064; B29; B29C; B29C48/00; B29C48/03; B29C48/05; B29C48/06; B29C48/07; B29C48/08; B29C48/25; B29C48/92; D; D06; D06H; D06H3/00; D06H3/10; G; G01; G01B; G01B7/00; G01B7/12; G01B7/125; G01N; G01N27/00; G01N27/02; G01N27/22; G01N27/228; G01R; G01R17/00; B29C2948/00; B29C2948/92; B29C2948/92009; B29C2948/92019; B29C2948/92114; B29C2948/92123; B29C2948/92161; B65H2701/00; B65H2701/30; B65H2701/31; G01N33/00; G01N33/36; G01N33/365
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
165 words
In a capacitive bridge measuring system for continuously monitoring the characteristics of a moving length of material, the combination of a sensor head incorporating said capacitive bridge, a source of two electrical signals of a given frequency, equal amplitude and opposite phase connected to opposite inputs of said bridge whereby said bridge is in balance, means for passing said length of material through said sensor head in proximity to two oppositely disposed individual capacitors of said bridge whereby said bridge is unbalanced and an unbalance output signal is produced, means for differentially amplifying said unbalance output signal, a demodulator having two inputs, means for applying one of said two electrical signals from said source to one of the inputs of said demodulator, means connecting said differential amplifying means to the other input of said demodulator whereby said unbalance output signal is demodulated to produce a second output signal proportional to unbalance of said bridge caused by said length of material passing through said sensor head.
Claim 2
Dependent Claim
165 words
In a capacitive bridge measuring system for continuously monitoring the characteristics of a moving length of material, the combination of a sensor head incorporating said capacitive bridge, a source of two electrical signals of a given frequency, equal amplitude and opposite phase connected to opposite inputs of said bridge whereby said bridge is in balance, means for passing said length of material through said sensor head in proximity to two oppositely disposed individual capacitors of said bridge whereby said bridge is unbalanced and an unbalance output signal is produced, means for differentially amplifying said unbalance output signal, a demodulator having two inputs, means for applying one of said two electrical signals from said source to one of the inputs of said demodulator, means connecting said differential amplifying means to the other input of said demodulator whereby said unbalance output signal is demodulated to produce a second output signal proportional to unbalance of said bridge caused by said length of material passing through said sensor head.
Claim 3
Dependent Claim
165 words
In a capacitive bridge measuring system for continuously monitoring the characteristics of a moving length of material, the combination of a sensor head incorporating said capacitive bridge, a source of two electrical signals of a given frequency, equal amplitude and opposite phase connected to opposite inputs of said bridge whereby said bridge is in balance, means for passing said length of material through said sensor head in proximity to two oppositely disposed individual capacitors of said bridge whereby said bridge is unbalanced and an unbalance output signal is produced, means for differentially amplifying said unbalance output signal, a demodulator having two inputs, means for applying one of said two electrical signals from said source to one of the inputs of said demodulator, means connecting said differential amplifying means to the other input of said demodulator whereby said unbalance output signal is demodulated to produce a second output signal proportional to unbalance of said bridge caused by said length of material passing through said sensor head.
Claim 4
Dependent Claim
165 words
In a capacitive bridge measuring system for continuously monitoring the characteristics of a moving length of material, the combination of a sensor head incorporating said capacitive bridge, a source of two electrical signals of a given frequency, equal amplitude and opposite phase connected to opposite inputs of said bridge whereby said bridge is in balance, means for passing said length of material through said sensor head in proximity to two oppositely disposed individual capacitors of said bridge whereby said bridge is unbalanced and an unbalance output signal is produced, means for differentially amplifying said unbalance output signal, a demodulator having two inputs, means for applying one of said two electrical signals from said source to one of the inputs of said demodulator, means connecting said differential amplifying means to the other input of said demodulator whereby said unbalance output signal is demodulated to produce a second output signal proportional to unbalance of said bridge caused by said length of material passing through said sensor head.
Claim 5
Dependent Claim
79 words
In a capacitive bridge measuring system as defined in claim 1, the combination in which said sensor head comprises an outer shell, a plurality of conductive segments disposed in said shell and insulated from each other and from said shell, pairs of said segments forming said individual capacitors, said shell having at least an opening formed therein adjacent said two oppositely disposed individual capacitors to permit passage of said length of material therethrough in proximity to said two capacitors.
Claim 6
Dependent Claim
55 words
In a capacitive bridge measuring system as defined in claim 2, the combination in which one segment of each of said two capacitors has an opening formed therein, a transistor being disposed in each opening and in direct electrical connection therewith, each said transistor forming a part of an amplifier of said unbalance output signal.
Claim 7
Dependent Claim
92 words
In a capacitive bridge measuring system as defined in claim 2, the combination in which said sensor head has two parallel slotted openings formed therein defining three similar portions, each said portion including two of said conductive segments, the two conductive segments of the central portion having openings formed therein, a transistor being disposed in each said opening in said conductive segments of said central portion and having its input directly connected to its associated conductive segment, each of said transistor forming a part of an amplifier of said unbalance output signal.
Claim 8
Dependent Claim
95 words
In a capacitive bridge measuring system as defined in claim 4, the further combination therewith of a low pass filter connected to and receiving said second output signal, a reference comparator connected to and receiving the output of said low pass filter, said reference comparator including a low limit reference and a high limit reference, means for producing a first warning signal in response to said second output signal exceeding said high limit reference and means for producing a second warning signal in response to said second output signal falling below said low limit reference.
Claim 9
Dependent Claim
43 words
In a capacitive bridge measuring system as defined in claim 5, the combination in which said sensor head further includes a high denier indicator and a low denier indicator operable in response to said first warning signal and said second warning signal respectively.
Claim 10
Independent Claim
252 words
A system for continuously monitoring the characteristics of a moving length of material compressing a sensor head, a capacitive bridge composed of first, second, third and fourth serially connected capacitors of equal value, a first input terminal at the junction of said first and fourth capacitors, a second input terminal at the junction of said second and third capacitors, a first output terminal at the junction of said fiRst and second capacitors, a second output terminal at the junction of said third and fourth capacitors, a source of a first alternating signal of a given frequency, predetermined amplitude and a first phase connected to said first input terminal, a source of a second alternating signal of said given frequency, predetermined amplitude and a second phase opposite to said first phase connected to said second input terminal, means for passing said length of material through said head adjacent said first and third capacitors whereby the capacitance thereof is modified and output signals corresponding to said modified capacitance are produced at said output terminals, a differential amplifier connected to said output terminal for differentially amplifying said output signals, a demodulator connected to and synchronously responsive in operation to said source of a second alternating signal of said given frequency, means connecting the output of said differential amplifier to said demodulator, said demodulator producing a d. c. output corresponding to the instanteous value of said modified capacitance, and utilization means for continuously displaying the value of said modified capacitance in response to said d.c. output.
Claim 11
Independent Claim
252 words
A system for continuously monitoring the characteristics of a moving length of material compressing a sensor head, a capacitive bridge composed of first, second, third and fourth serially connected capacitors of equal value, a first input terminal at the junction of said first and fourth capacitors, a second input terminal at the junction of said second and third capacitors, a first output terminal at the junction of said fiRst and second capacitors, a second output terminal at the junction of said third and fourth capacitors, a source of a first alternating signal of a given frequency, predetermined amplitude and a first phase connected to said first input terminal, a source of a second alternating signal of said given frequency, predetermined amplitude and a second phase opposite to said first phase connected to said second input terminal, means for passing said length of material through said head adjacent said first and third capacitors whereby the capacitance thereof is modified and output signals corresponding to said modified capacitance are produced at said output terminals, a differential amplifier connected to said output terminal for differentially amplifying said output signals, a demodulator connected to and synchronously responsive in operation to said source of a second alternating signal of said given frequency, means connecting the output of said differential amplifier to said demodulator, said demodulator producing a d. c. output corresponding to the instanteous value of said modified capacitance, and utilization means for continuously displaying the value of said modified capacitance in response to said d.c. output.
Claim 12
Dependent Claim
43 words
A system as defined in claim 7 and further comprising a low pass filter connected to said demodulator to receive the output thereof, said low pass filter including a resistance-capacitance network and switch means for changing the amount of resistance in said network.
Claim 13
Independent Claim
131 words
The method of continuously monitoring the characteristics of a moving length of material utilizing a bridge composed of four joined capacitive elements which comprises the steps of applying a first signal to a first junction of said bridge, applying a second signal to a second junction opposite said first junction of said bridge, said first and second signals being substantially identical alternating signals but opposite in phase to one another, passing said material in proximity to two oppositely disposed capacitive elements of said bridge whereby said bridge is unbalanced and an output signal is produced at third and fourth junctions of said bridge, differentially amplifying said output signal, and synchronously demodulating said differentially amplified output signal to produce an output voltage varying with the characteristics of said moving length of material.
Claim 14
Independent Claim
131 words
The method of continuously monitoring the characteristics of a moving length of material utilizing a bridge composed of four joined capacitive elements which comprises the steps of applying a first signal to a first junction of said bridge, applying a second signal to a second junction opposite said first junction of said bridge, said first and second signals being substantially identical alternating signals but opposite in phase to one another, passing said material in proximity to two oppositely disposed capacitive elements of said bridge whereby said bridge is unbalanced and an output signal is produced at third and fourth junctions of said bridge, differentially amplifying said output signal, and synchronously demodulating said differentially amplified output signal to produce an output voltage varying with the characteristics of said moving length of material.
Claim 15
Dependent Claim
96 words
In a capacitive measuring system for monitoring the characteristics of material, the combination of four capacitive elements joined at four junction points to form a bridge, means for energizing said bridge at a first pair of opposite junction points, means for normally balancing said bridge to produce no signals at a second pair of opposite junction points, and means for bringing said material into proximity to two of said capacitive elements to affect the capacity thereof and produce an unbalance output signal representative of characteristics of said material at said second pair of opposite junction points.
Claim 16
Dependent Claim
96 words
In a capacitive measuring system for monitoring the characteristics of material, the combination of four capacitive elements joined at four junction points to form a bridge, means for energizing said bridge at a first pair of opposite junction points, means for normally balancing said bridge to produce no signals at a second pair of opposite junction points, and means for bringing said material into proximity to two of said capacitive elements to affect the capacity thereof and produce an unbalance output signal representative of characteristics of said material at said second pair of opposite junction points.
Claim 17
Dependent Claim
51 words
In a system as defined in claim 10, the combination wherein said two capacitive elements are in oppositely disposed arms of said bridge, each said capacitive element having two plates and means are provided whereby said material is continuously passed between the two plates of each of said two capacitive elements.
References Cited (Backward Citations)
US3757211A
Cited
US3742347A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |