Patent US3704412A successfully refreshed from Google Patents.
US3704412A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Scanning impedance measuring system employing a spiral sensing element
Assignee: MOISTURE REGISTER CO
•
Filing: 1971-02-11
•
Granted: 1972-11-28
•
Expires: 1991-02-11
Abstract
Abstract Apparatus for periodically scanning the impedance across a web of material and displaying the impedance variations. A sensing element having a pair of parallel, spaced metallic strips spirally mounted on the external surface of a carrier cylinder is positioned across the web for minimal surface contact therewith. A small section of the width of the web is in surface contact with the spaced parallel strips and forms an impedance therebetween to be measured. The section of the web being measured moves, in affect, across the web as the cylinder rotates. The measuring circuitry includes a periodically balanced impedance bridge circuit and a triggering mechanism for the measuring and display systems which generates simultaneous isolated trigger pulses.
Inventors
- 👤 John W Lundstrom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 11:59
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/048
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
135 words
A system for measuring impedance as a function of position across a web of material, said system comprising: a cylinder having its longitudinal axis across said web, said cylinder having minimal surface contact with said web; a sensing element having a pair of relatively narrow parallel strips spaced a relatively short distance apart and spirally positioned around the external surface of said cylinder, whereby said sensing element may make contact with said web over a minimal section of the width of said web, said section moving over the width of said web as said cylinder rotates; means for generating an alternating voltage between said spaced parallel strips, said section of said web being in contact with said strips forming an impedance between said strips; and means for measuring said impedance to produce an impedance signal.
Claim 2
Independent Claim
135 words
A system for measuring impedance as a function of position across a web of material, said system comprising: a cylinder having its longitudinal axis across said web, said cylinder having minimal surface contact with said web; a sensing element having a pair of relatively narrow parallel strips spaced a relatively short distance apart and spirally positioned around the external surface of said cylinder, whereby said sensing element may make contact with said web over a minimal section of the width of said web, said section moving over the width of said web as said cylinder rotates; means for generating an alternating voltage between said spaced parallel strips, said section of said web being in contact with said strips forming an impedance between said strips; and means for measuring said impedance to produce an impedance signal.
Claim 3
Dependent Claim
38 words
The system defined in claim 1 wherein said means for measuring includes a bridge having said strips in a first branch and a variable capacitance in a second branch, said variable capacitance being controlled to balance said bridge.
Claim 4
Dependent Claim
54 words
The system defined in claim 2 wherein said strips are spirally positioned around said cylinder for a circumferential distance less than the total circumference of said cylinder, said variable capacitance is controlled to balance said bridge when said web is in contact with the portion of said cylinder which does not carry said strips.
Claim 5
Dependent Claim
28 words
The system defined in claim 1 including means for displaying said impedance signal as a function of the position of said section across the width of said web.
Claim 6
Dependent Claim
43 words
The system defined in claim 4 including triggering means for generating two simultaneous, electrically isolated trigger pulses for each revolution of said cylinder, said means for displaying being synchronized with the rotation of said cylinder by a first one of said trigger pulses.
Claim 7
Dependent Claim
33 words
The system defined in claim 5 wherein said trigger pulses are generated when said web is in contact with a portion of the circumference of said cylinder which does not carry said strips.
Claim 8
Dependent Claim
30 words
A system defined in claim 5 including balancing means for balancing said measuring means, the operation of said balancing means being initiated by a second one of said trigger pulses.
Claim 9
Independent Claim
212 words
A system for measuring impedance as a function of position across a web of material, said system comprising: a cylinder having its longitudinal axis across said web, said cylinder having minimal surface contact with said web; a sensing element having a pair of spaced parallel strips spirally positioned around the external surface of said cylinder, whereby said sensing element may make contact with said web over a minimal section of the width of said web, said section moving over the width of said web as said cylinder rotates; means for generating an alternating voltage between said spaced parallel strips, said section of said web being in contact with said strips forming an impedance beTween said strips; and means for measuring said impedance to produce an impedance signal; triggering means for generating two simultaneous, electrically isolated trigger pulses for each revolution of said cylinder, said means for displaying being synchronized with the rotation of said cylinder by a first one of said trigger pulses; balancing means for controlling said variable capacitance to balance the said bridge, the operation of said balancing means being initiated by a first one of said trigger pulses; and wherein said means displaying is synchronized with the rotation of said cylinder by a second one of said trigger pulses.
Claim 10
Independent Claim
212 words
A system for measuring impedance as a function of position across a web of material, said system comprising: a cylinder having its longitudinal axis across said web, said cylinder having minimal surface contact with said web; a sensing element having a pair of spaced parallel strips spirally positioned around the external surface of said cylinder, whereby said sensing element may make contact with said web over a minimal section of the width of said web, said section moving over the width of said web as said cylinder rotates; means for generating an alternating voltage between said spaced parallel strips, said section of said web being in contact with said strips forming an impedance beTween said strips; and means for measuring said impedance to produce an impedance signal; triggering means for generating two simultaneous, electrically isolated trigger pulses for each revolution of said cylinder, said means for displaying being synchronized with the rotation of said cylinder by a first one of said trigger pulses; balancing means for controlling said variable capacitance to balance the said bridge, the operation of said balancing means being initiated by a first one of said trigger pulses; and wherein said means displaying is synchronized with the rotation of said cylinder by a second one of said trigger pulses.
Claim 11
Independent Claim
254 words
A system for measuring impedance as a function of position across a web of material, said system comprising: a cylinder having its longitudinal axis across said web, said cylinder having minimal surface contact with said web; a sensing element having a pair of spaced parallel strips spirally positioned around the external surface of said cylinder, whereby said sensing element may make contact with said web over a minimal section of the width of said web, said section moving over the width of said web as said cylinder rotates; means for generating an alternating voltage between said spaced parallel strips, said section of said web being in contact with said strips forming an impedance between said strips; means for measuring said impedance to produce an impedance signal; triggering means for generating two simultaneous electrically isolated trigger pulses for each revolution of said cylinder; display means for visually displaying said impedance signal as a function of the position of said section across the width of said web, said impedance signal being applied to a vertical control section of said display means, said display means having a horizontal coordinate generator for moving a horizontal coordinate position in accordance with the rotational position of said cylinder, said horizontal coordinator generator being synchronized with a rotation of said cylinder by a first one of said trigger pulses; and balancing means for balancing said measuring means prior to measuring said impedance, said balancing means being synchronized with the rotation of said cylinder by a second one of said trigger pulses.
Claim 12
Independent Claim
254 words
A system for measuring impedance as a function of position across a web of material, said system comprising: a cylinder having its longitudinal axis across said web, said cylinder having minimal surface contact with said web; a sensing element having a pair of spaced parallel strips spirally positioned around the external surface of said cylinder, whereby said sensing element may make contact with said web over a minimal section of the width of said web, said section moving over the width of said web as said cylinder rotates; means for generating an alternating voltage between said spaced parallel strips, said section of said web being in contact with said strips forming an impedance between said strips; means for measuring said impedance to produce an impedance signal; triggering means for generating two simultaneous electrically isolated trigger pulses for each revolution of said cylinder; display means for visually displaying said impedance signal as a function of the position of said section across the width of said web, said impedance signal being applied to a vertical control section of said display means, said display means having a horizontal coordinate generator for moving a horizontal coordinate position in accordance with the rotational position of said cylinder, said horizontal coordinator generator being synchronized with a rotation of said cylinder by a first one of said trigger pulses; and balancing means for balancing said measuring means prior to measuring said impedance, said balancing means being synchronized with the rotation of said cylinder by a second one of said trigger pulses.
Claim 13
Independent Claim
142 words
A system for measuring impedance as a function of position across a web of material, said system comprising: a cylinder having its longitudinal axis across said web, said cylinder having minimal surface contact with said web; a sensing element having a pair of spaced parallel strips spirally positioned around the external surface of said cylinder for a circumferential distance of approximately four-fifths of the total circumference of said cylinder, whereby said sensing element may make contact with said web over a minimal section of the width of said web, said section moving over the width of said web as said cylinder rotates; means for generating an alternating voltage between said spaced parallel strips, said section of said web being in contact with said strips and forming an impedance between said strips; and means for measuring said impedance to produce an impedance signal.
Claim 14
Independent Claim
142 words
A system for measuring impedance as a function of position across a web of material, said system comprising: a cylinder having its longitudinal axis across said web, said cylinder having minimal surface contact with said web; a sensing element having a pair of spaced parallel strips spirally positioned around the external surface of said cylinder for a circumferential distance of approximately four-fifths of the total circumference of said cylinder, whereby said sensing element may make contact with said web over a minimal section of the width of said web, said section moving over the width of said web as said cylinder rotates; means for generating an alternating voltage between said spaced parallel strips, said section of said web being in contact with said strips and forming an impedance between said strips; and means for measuring said impedance to produce an impedance signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-11-28 | 1976-05-29 | 1976-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-28 | 1980-05-29 | 1980-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-28 | 1984-05-29 | 1984-11-28 | $7700.00 | Window Closed / Lapsed |