Water weight sensor array imbedded in a sheetmaking machine roll

• US 6,341,522 B1
• Filed: 04/06/1998
• Issued: 01/29/2002
• Est. Priority Date: 12/13/1996
• Status: Expired due to Term

• Current Assignee: Measurex Corporation (Honeywell International Inc.)
• Original Assignee: Measurex Corporation (Honeywell International Inc.)
• Inventors: Chase, Lee, Goss, John D.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): CYGAN, MICHAEL T
• Application Number:
  US09/056,932
• Time in Patent Office: 1,394 Days
• Field of Search: 731/59, 73/73, 73/74, 737/45, 731/60, 162/198
• US Class Current: 73/159
• CPC Class Codes: D21F 7/06 Indicating or regulating the thickness of the layer; Signal devices
• CPC Class Codes: D21G 9/0009 Paper-making control systems
• CPC Class Codes: D21H 23/78 Controlling or regulating not limited to any particular process or apparatus
• CPC Class Codes: G01G 17/02 for weighing material of filamentary or sheet form
• CPC Class Codes: G01G 9/00 Methods of, or apparatus for, the determination of weight, not provided for in groups G01G1/00 - G01G7/00
• CPC Class Codes: G01N 33/346 paper sheets

Abstract

A sensor imbedded roller for detecting changes in properties of a material and a measurement apparatus including a fixed impedance element coupled in series with a variable impedance sensor imbedded roller between an input signal and a reference potential (e.g. ground) is described. The sensor, which includes an electrode configuration, is imbedded into a roller such that when it rotates it comes in contact with the material being measured and its impedance varies. The variable impedance of the sensor relates to changes in property of the material being sensed which can then be related to changes in other physical characteristics of the material such as weight, chemical composition, and temperature. Sensor imbedded rollers can be placed in a sheetmaking machine to measure the pre-formed and post-formed paper product.

Claims

1. An apparatus for use in the wet end of a sheetmaking machine including a moving conveyor for the moving and the drainage of a wetstock material that comprises an aqueous fibrous mixture, said apparatus comprising:

a rotatable roller having an outer surface of grounded metal in close proximity to a lower surface said wetstock material on said conveyor wherein the rotatable roller supports the wetstock material;

at least one sensor comprising an electrode configuration that is imbedded within said outer surface for detecting changes in conductivity of said wetstock material, said sensor having a variable resistive impedance such that changes in said conductivity causes changes in resistive impedance of said sensor wherein said electrode comprises a metal layer that is imbedded in said outer surface and a dielectric layer that is imbedded in said outer surface and a single segmented electrode imbedded into said dielectric layer so as to be insulated from said outer surface;

wherein when said roller rotates, said at least one sensor comes essentially in contact with said lower surface of said wetstock material causing said sensor to detect said changes in said conductivity that is proportional to changes in the weight of the wetstock material over said sensor.

2. The apparatus as described in claim 1 wherein said rotatable roller in said apparatus also functions as a roller in a sheetmaking system.

3. The apparatus as described in claim 1 wherein said rotatable roller has an inner region that includes means for processing measured values associated with said changes in resistive impedance received from said sensor and generating data associated with said conductivity.

4. The apparatus as described in claim 3 wherein said processing means serializes said data so as to provide serialized data from said roller.

5. The apparatus as described in claim 1 wherein said roller includes:

a rotatable outer shell including said outer surface and having an inner surface, said inner surface providing electrical connection to said sensor;

a stationary inner roller disposed within said shell and having an electrical contact assembly;

wherein when said outer shell rotates and said at least one sensor comes essentially in contact with said material, said contact assembly makes electrical contact with said electrical connection to said sensor.

6. The apparatus as described in claim 1 wherein said roller is cylindrical.

7. A measurement apparatus for detecting properties of wetstock material that comprises an aqueous fibrous mixture in the wet end of a sheetmaking machine including a moving conveyor for the moving and the drainage of a wetstock material, said apparatus comprising:

a fixed impedance portion;

a sensor coupled to said fixed impedance portion between a signal source and a reference potential, said sensor having a variable resistive impedance such that changes in conductivity of said wetstock material causes changes in resistive impedance of said sensor, said sensor including;

a rotatable roller having an outer surface wherein the rotatable roller supports the wetstock material; and

at least one means for detecting said changes in conductivity of said wetstock material by sensing said changes in resistive impedance, said detecting means comprises an electrode configuration that is imbedded within said outer surface of said rotatable roller and in close proximity a lower surface of to said wetstock material on said conveyor wherein said electrode configuration includes (i) a first elongated electrode coupled to said reference potential and a segmented elongated electrode coupled to said fixed impedance portion and (ii) a second elongated electrode couples to said reference potential;

wherein when said roller rotates, said detecting means comes essentially in contact with said lower surface of said wetstock material causing said detecting means to detect said changes in said conductivity that is proportional to changes in the weight of the wetstock material over said detecting means.

8. The apparatus as described in claim 7 wherein said segmented electrode is spaced-apart and centered between said first and second electrodes.

9. The apparatus as described in claim 7 wherein said rotatable roller in said apparatus also functions as a roller in a sheetmaking system.

10. The apparatus as described in claim 7 wherein said outer surface is grounded metal and said electrode configuration comprises a dielectric layer imbedded in said outer surface and a single segmented electrode imbedded in said dielectric layer so as to be insulated from said outer surface, said single segmented electrode being coupled to said fixed impedance portion.

11. The apparatus as described in claim 7 wherein said roller includes:

a rotatable outer shell including said outer surface and having an inner surface, said inner surface providing electrical connection to said detection means;

a stationary inner roller disposed within said shell and having an electrical contact assembly, said electrical contact assembly for electrically coupling with other elements of said measurement apparatus that are not included within said roller;

wherein when said outer shell rotates and said at least one sensor comes essentially in contact with said wetstock material, said contact assembly makes electrical contact with said electrical connection to said sensor.

12. The apparatus as described in claim 7 wherein said apparatus further comprises a means for correlating said changes in said conductivity to fluctuations in physical characteristics of said wetstock material including material weight, chemical composition, and temperature.

13. A system for producing a paper product from a wetstock material that comprises an aqueous fibrous mixture comprising:

a headbox for dispensing said stock material;

a water removal stage for receiving said dispensed stock material having at least one webbed conveyor belt, said at least one webbed conveyor belt having a first surface on which said stock material is dispensed and a second surface wherein said water is removed, wherein water is removed from said dispensed material through said belt to produce a web of material;

a drying stage for drying said web of material to form said paper product;

a measurement apparatus for detecting changes in conductivity of said wetstock material which includes a fixed impedance portion and sensor coupled to said fixed impedance portion between a signal source and a reference potential, said sensor having a variable impedance such that changes in conductivity of said wetstock material causes changes in impedance of said sensor, said sensor including;

at least one rotatable roller having an outer surface wherein the rotatable roller supports the wetstock material; and

at least one means for detecting said changes in conductivity of said wetstock material by sensing said changes in impedance, said detecting means comprising an electrode configuration that is imbedded within said outer surface of said at least one roller wherein said electrode configuration includes (i) a first elongated electrode coupled to said reference potential and a segmented elongated electrode coupled to said fixed impedance portion and (ii) a second elongated electrode couples to said reference potential;

wherein when said roller rotates, said detecting means comes essentially in close proximity to a lower surface of said wetstock material, causing said detecting means to detect said changes in conductivity that is proportional to changes in the weight of the wetstock material over said detection means.

14. The system as described in claim 13 wherein said system includes at least one sensor in said water removal stage.

15. The system as described in claim 14 wherein said at least one roller is positioned beneath said webbed conveyor belt.

16. The system as described in claim 14 wherein said at least one roller is part of a means for driving said webbed conveyor belt.

17. The system as described in claim 13 wherein said properties include dielectric constant, conductivity, and proximity of said material.

18. The system as described in claim 13 wherein said apparatus further comprises a means for correlating said changes in said properties to fluctuations in physical characteristics of said material including material weight, chemical composition, and temperature.

19. The system as described in claim 13 wherein said at least one roller directs said web of material'"'"'s movement through said system.