US4873407A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dielectric cross machine moisture control
Assignee: Devron Hercules Inc
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Filing: 1989-02-17
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Granted: 1989-10-10
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Expires: 2009-02-17
Abstract
Abstract In a method for applying heat to a web, the web is subjected to dielectric heating in discrete segments, arranged transverse to the web, by modules containing pairs of electrodes. The heat thus generated can be used to vary the moisture and/or temperature profile. Each module has a built-in self modulating moisture leveler. Other properties of the web, which are varied by such process operations as wet pressing, drying, calendering, etc. and which themselves are influenced by the moisture/temperature of the web can thereby be also controlled by said dielectric heating in closed-loop fashion.
Inventors
- 👤 Douglas W. P. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:18
CPC Classifications
D; D21; D21F; D21F7/00; D21F7/003; D21F5/00; D21F5/16; D21F5/165; H; H05; H05B; H05B6/00; H05B6/46; H05B6/60
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
178 words
A method of applying heat to a paper web by subjecting the web to dielectric heating in discrete segments, comprising the steps of: providing a plurality of discrete heating modules distributed transverse to the width of the web and all opposite one major surface of the web to control moisture in the web in the cross-machine direction; providing in each of said heating modules a plurality of pairs of equally-spaced heating electrodes, with said heating electrodes extending over a respective one of said discrete segments in a spaced-apart array facing said surface of the web and with said heating electrodes being equally spaced from the web; connecting one electrode of each of said pairs together to a first current supply conductor and the other electrode of each of said pairs together to a second current supply conductor; and energizing said heating modules by supplying an electrical current through said conductors to effect dielectric heating of said web so that the web is heated by current flow between said electrodes in accordance with the moisture profile of said web.
Claim 2
Independent Claim
178 words
A method of applying heat to a paper web by subjecting the web to dielectric heating in discrete segments, comprising the steps of: providing a plurality of discrete heating modules distributed transverse to the width of the web and all opposite one major surface of the web to control moisture in the web in the cross-machine direction; providing in each of said heating modules a plurality of pairs of equally-spaced heating electrodes, with said heating electrodes extending over a respective one of said discrete segments in a spaced-apart array facing said surface of the web and with said heating electrodes being equally spaced from the web; connecting one electrode of each of said pairs together to a first current supply conductor and the other electrode of each of said pairs together to a second current supply conductor; and energizing said heating modules by supplying an electrical current through said conductors to effect dielectric heating of said web so that the web is heated by current flow between said electrodes in accordance with the moisture profile of said web.
Claim 3
Dependent Claim
28 words
A method as claimed in claim 1 in which the input power to the discrete heater modules is set by duty cycle control for each discrete heater module.
Claim 4
Dependent Claim
27 words
A method as claimed in claim 1 in which the input power to the discrete heater module is set by variable voltage control at each heater module.
Claim 5
Dependent Claim
30 words
A method as claimed in claim 1 in which the input power to each discrete heater module is set by thyristor control of incoming alternating current to each heater module.
Claim 6
Dependent Claim
41 words
A method as claimed in claim 1 in which input power to the discrete heater modules is set by varying the distance of the web in each discrete segment from the electrodes of the dielectric heating unit for each heater module.
Claim 7
Dependent Claim
32 words
A method as claimed in claim 1 in which the input power to the discrete heater modules is set by varying the frequency of the dielectric heating unit in each heater module.
Claim 8
Dependent Claim
34 words
A method as claimed in claim 1 in which the input power levels to the discrete heater modules is decided by a computer in response to a signal from a sensor, sensing the web.
Claim 9
Dependent Claim
20 words
A method as claimed in claim 1 in which the web is a paper web on a paper making machine.
Claim 10
Dependent Claim
22 words
A method as claimed in claim 1 in which the electrodes are rods arranged with their longitudinal axes in the machine direction.
Claim 11
Dependent Claim
16 words
A method as claimed in claim 7 in which the sensor is able to sense moisture.
Claim 12
Dependent Claim
14 words
A method as claimed in claim 7 in which the sensor measures the temperature.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-10-09 | 1993-04-10 | 1993-10-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-09 | 1997-04-10 | 1997-10-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-09 | 2001-04-10 | 2001-10-10 | $7700.00 | Window Closed / Lapsed |