EP0279743A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Temperature compensated moisture sensor
Assignee: Honeywell Measurex Corp
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Filing: 1988-02-16
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Granted: —
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Expires: 2008-02-16
Abstract
Abstract An infrared paper web moisture sensor is described which comprises a source of infrared radiation for directing an infrared beam through the web and an infrared detecting unit disposed on the opposite side of the web from the infrared source. The infrared detecting unit measures the transmission of the infrared beam through the web at three separate wavelength regions of the infrared spectrum. The transmission through the web in one wavelength region is primarily sensitive to the moisture content of the web, the transmission of infrared through the web in the second wavelength region is primarily sensitive to the basis weight of the web and the transmission of infrared wavelengths through the web in the third wavelength region of the spectrum provides an indication of the web temperature. Signals are developed indicative of the transmission of infrared through the web in each of these regions, digitized, and fed to the process control computer for the paper mill. The computer combines the values of the digitized signals, via an empirically derived equation, to produce a value indicative of the percentage of moisture in the web. The process control computer utilizes this result to control devices which selectively add moisture to portions of the web or selectively dry portions of the web to thereby produce a web having a uniform moisture content.
Inventors
- 👤 John Howarth
- 👤 Leonard M. Anderson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 18:34
CPC Classifications
G; G01; G01N; G01N21/00; D; D21; D21F; D21F7/00; D21F7/003; G01N21/17; G01N21/25; G01N21/31; G01N21/35; G01N21/3554; G01N21/3559; G01N21/314; G01N2021/3148; G01N2021/3166
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
136 words
A paper web moisture sensor, comprising: an infrared radiation source for directing a beam of infrared radiation through a sheet of paper; and detecting means for detecting the amount of infrared radiation from the beam which passes through the sheet in a first, second and third separate wavelength regions of the infrared spectrum, wherein said first region is selected to detect infrared radiation which is primarily sensitive to the amount of moisture in the path of the infrared beam, the second region is selected to detect infrared radiation which is primarily sensitive to the amount of paper fiber in the path of the infrared beam, and the third region is selected so that the amount of infrared radiation in the third region transmitted throught the paper web from the source is dependent upon the web temperature.
Claim 2
Dependent Claim
136 words
A paper web moisture sensor, comprising: an infrared radiation source for directing a beam of infrared radiation through a sheet of paper; and detecting means for detecting the amount of infrared radiation from the beam which passes through the sheet in a first, second and third separate wavelength regions of the infrared spectrum, wherein said first region is selected to detect infrared radiation which is primarily sensitive to the amount of moisture in the path of the infrared beam, the second region is selected to detect infrared radiation which is primarily sensitive to the amount of paper fiber in the path of the infrared beam, and the third region is selected so that the amount of infrared radiation in the third region transmitted throught the paper web from the source is dependent upon the web temperature.
Claim 3
Dependent Claim
58 words
The paper sheet moisture sensor of claim 1, wherein the first region is positioned along the absorption spectrum in the range of from about 1.85 - 1.93 microns, the second region is positioned within the wavelength region from about 1.83 - 1.85 microns and the third region is located in the range of about 1.94 - 1.98 microns.
Claim 4
Dependent Claim
60 words
The paper sheet moisture sensor of claim 1, wherein the first region is positioned along the absorption spectrum in the wavelength range of from about 1.85 - 1.93 microns, the second region is positioned within the wavelength region from about 1.83 - 1.85 microns and the third region is located in the range of from about 1.55 - 1.67 microns.
Claim 5
Dependent Claim
110 words
A process for measuring the moisture content of a paper web, comprising the steps of: (a) directing a beam of infrared radiation, having a known intensity and band width characteristics, through the web; (b) determining, to a first approximation, the amount of moisture in the web in the path of the beam by measuring the intensity of a first portion of the infrared spectrum of the beam after said beam is transmitted through the web; (c) correcting the moisture determination of step (b) for changes in web temperature utilizing a measurement of the intensity of said beam transmitted through the web in a second separate portion of the infrared spectrum.
Claim 6
Dependent Claim
110 words
A process for measuring the moisture content of a paper web, comprising the steps of: (a) directing a beam of infrared radiation, having a known intensity and band width characteristics, through the web; (b) determining, to a first approximation, the amount of moisture in the web in the path of the beam by measuring the intensity of a first portion of the infrared spectrum of the beam after said beam is transmitted through the web; (c) correcting the moisture determination of step (b) for changes in web temperature utilizing a measurement of the intensity of said beam transmitted through the web in a second separate portion of the infrared spectrum.
Claim 7
Dependent Claim
31 words
The process of claim 4, wherein said second portion of the infrared spectrum is positioned on a slope of the infrared transmission spectrum between a transmission peak and a transmission valley.
Claim 8
Dependent Claim
20 words
The process of claim 5, wherein said second portion of the infrared spectrum includes the infrared wavelength of 1.97 microns.
Claim 9
Dependent Claim
23 words
The process of claim 5, wherein said second portion of the infrared spectrum includes the infrared wavelength range of 1.55 - 1.67 microns.
Claim 10
Dependent Claim
38 words
The process of claim 4, further comprising the step of utilizing the corrected moisture determination of step (c) to selectively activate at least one device for altering the moisture content of at least a portion of the web.
Claim 11
Dependent Claim
170 words
A process for adjusting the moisture content of a paper web, comprising the steps of: (a) directing a beam of infrared radiation through the web; (b) moving the beam relative to the web; (c) measuring the amount of infrared radiation from the beam which passes through the web in a first, second and third separate regions of the infrared spectrum, wherein said first region is located at a part of the infrared transmission spectrum absorbed primarily by paper fibers, the second region is located on a slope of the transmission spectrum adjacent to the water absorption peak, and the third region is located on a slope of the transmission spectrum separate from the first and second regions; (d) calculating, with a computer, the moisture content of different portions of the web using the measurements of infrared transmission for each of the first, second and third regions of the infrared spectrum; and (e) altering the moisture content of at least a portion of the web based upon the moisture content calculations.
Claim 12
Dependent Claim
170 words
A process for adjusting the moisture content of a paper web, comprising the steps of: (a) directing a beam of infrared radiation through the web; (b) moving the beam relative to the web; (c) measuring the amount of infrared radiation from the beam which passes through the web in a first, second and third separate regions of the infrared spectrum, wherein said first region is located at a part of the infrared transmission spectrum absorbed primarily by paper fibers, the second region is located on a slope of the transmission spectrum adjacent to the water absorption peak, and the third region is located on a slope of the transmission spectrum separate from the first and second regions; (d) calculating, with a computer, the moisture content of different portions of the web using the measurements of infrared transmission for each of the first, second and third regions of the infrared spectrum; and (e) altering the moisture content of at least a portion of the web based upon the moisture content calculations.
Claim 13
Dependent Claim
66 words
The process of claim 9, wherein the computer calculates the moisture content using the formula: RT=R1+C1*(R2-C2), wherein R1=REF/MES, R2=REF/CORR, C1 and C2 are constants, and wherein the REF value is indicative of the infrared measurement in the first region, the MES value is indicative of the infrared measurement in the second region and the CORR value is indicative of the infrared measurement in the third region.
Claim 14
Dependent Claim
66 words
The process of claim 9, wherein the computer calculates the moisture content using the formula: RT=R1*(1+C1(R2-C2)), wherein R1=REF/MES, R2=REF/CORR, C1 and C2 are constants, and wherein the REF value is indicative of the infrared measurement in the first region, the MES value is indicative of the infrared measurement in the second region and the CORR value is indicative of the infrared measurement in the third region.
Claim 15
Dependent Claim
53 words
The process of claim 10, further comprising the step of calculating, with the computer, the weight of the water in the web using the linear equation WW=A*RT+D, wherein A and D are the slope and intercept of the linear equation, respectively, and WW is the water weight per unit area of the web.
Claim 16
Dependent Claim
53 words
The process of claim 11, further comprising the step of calculating, with the computer, the weight of the water in the web using the linear equation WW=A*RT+D, wherein A and D are the slope and intercept of the linear equation, respectively, and WW is the water weight per unit area of the web.
Claim 17
Dependent Claim
68 words
The process of claim 9, wherein the computer calculates the moisture content using the formula: RT=1/2[C1(R1-D1)+C2(R2-D2)], wherein R1=REF/MES, R2=REF/COR, C1, C2, D1 and D2 are constants, and wherein the REF value is indicative of the infrared measurement in the first region, the MES value is indicative of the infrared measurement in the second region and the CORR value is indicative of the infrared measurement in the third region.
Claim 18
Dependent Claim
96 words
A paper web moisture sensor insensitive to web temperature, comprising: an infrared radiation source for directing a beam of infrared radiation through a sheet of paper; and detecting means for detecting the amount of infrared radiation from the beam which passes through the sheet in first and second separate wavelength regions of the infrared spectrum, wherein said first region is approximately centered around the infrared absorption peak for water and the second region is selected to detect infrared radiation which is primarily sensitive to the amount of paper fiber in the path of the infrared beam.
Claim 19
Dependent Claim
96 words
A paper web moisture sensor insensitive to web temperature, comprising: an infrared radiation source for directing a beam of infrared radiation through a sheet of paper; and detecting means for detecting the amount of infrared radiation from the beam which passes through the sheet in first and second separate wavelength regions of the infrared spectrum, wherein said first region is approximately centered around the infrared absorption peak for water and the second region is selected to detect infrared radiation which is primarily sensitive to the amount of paper fiber in the path of the infrared beam.
Claim 20
Dependent Claim
31 words
The paper sheet moisture sensor of claim 15, wherein the first region is centered around 1.93 microns and the second region is positioned within the wavelength region from about 1.83-1.85 microns.
Claim 21
Dependent Claim
187 words
A process for adjusting the moisture content of a paper web, comprising the steps of: (a) directing a beam of infrared radiation through the web; (b) moving the beam relative to the web; (c) measuring, at a pluality of locations along the web, the amount of infrared energy transmitted through the web in first and second separate regions of the infrared spectrum, wherein the first region is approximately centered around the infrared absorption peak for water and the long and short wavelength boundaries of the first region are so chosen that the amount of infrared energy transmitted through the web in the first region is independent of the web temperature, and the second region is located at a part of the infrared transmission spectrum absorbed primarily by paper fibers; (d) calculating, with a computer, the moisture content of different portions of the web using the measurements of the infrared transmission for the first and second regions of the infrared band; and (e) altering the moisture content of at least a portion of the web based upon the calculated moisture content of the different portions of the web.
Claim 22
Dependent Claim
187 words
A process for adjusting the moisture content of a paper web, comprising the steps of: (a) directing a beam of infrared radiation through the web; (b) moving the beam relative to the web; (c) measuring, at a pluality of locations along the web, the amount of infrared energy transmitted through the web in first and second separate regions of the infrared spectrum, wherein the first region is approximately centered around the infrared absorption peak for water and the long and short wavelength boundaries of the first region are so chosen that the amount of infrared energy transmitted through the web in the first region is independent of the web temperature, and the second region is located at a part of the infrared transmission spectrum absorbed primarily by paper fibers; (d) calculating, with a computer, the moisture content of different portions of the web using the measurements of the infrared transmission for the first and second regions of the infrared band; and (e) altering the moisture content of at least a portion of the web based upon the calculated moisture content of the different portions of the web.
References Cited (Backward Citations)
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