Apparatus and method for sensing multiple parameters of sheet material

Claim 2

Apparatus for sensing the characteristics of sheet material, comprising: radiating means for generating a plurality of beams of coherent electromagnetic radiation, each of said beams having a different frequency, and for directing said beams against said material at an area of incidence; first signal generating means for generating separate reflectance and transmittance signals for each of said beams, said signals being proportional to the intensity of each of said beams reflected from and transmitted through said material, respectively; and processing means for producing moisture and thickness signals calculated from said plurality of reflectance and transmittance signals.

Claim 3

Apparatus as recited in claim 1 wherein said beams are stationary.

Claim 4

Apparatus as recited in claim 2 comprising a plurality of said radiating means each directing its associated plurality of beams against a separate area of incidence, said separate areas of incidence being spatially distributed across said material, wherein said processing means produces separate moisture and thickness signals for each of said radiating means, and whereby spatial profiles of moisture and thickness characteristics are produced for said material.

Claim 5

Apparatus as recited in claim 3 wherein said radiating means comprises means for generating microwave radiation.

Claim 6

Apparatus as recited in claim 4 wherein said means for generating microwave radiation generates radiation having a wavelength greater than four times the thickness of said material.

Claim 7

Apparatus as recited in claim 4 comprising second generating means for generating a reference signal proportional to basis weight at a reference position and wherein said processing means generates a spatial profile of basis weight of said material calculated from said reference signal and said moisture and thickness signals.

Claim 8

Apparatus as recited in claim 6 wherein said radiating means comprises transmitting antennas and reflectance receiving antennas in a stationary position on one side of the plane of a moving web of said material and transmittance receiving antennas in a stationary position on the opposite side of said plane of a moving web of said material.

Claim 9

Apparatus as recited in claim 6 wherein said second generating means comprises means for generating a beam of particles.

Claim 10

Apparatus as recited in claim 8 wherein said second generating means comprises means for generating a beam of electrons.

Claim 11

Apparatus as recited in claim 9 wherein said second generating means comprises a radioactive source of beta radiation.

Claim 12

Apparatus as recited in claim 9 wherein said second generating means comprises an electron gun.

Claim 13

Apparatus as recited in claim 1 wherein said reflectance and transmittance signals are respectively proportional to the intensity of each of said beams reflected from and transmitted through said material.

Claim 14

Apparatus as recited in claim 1 wherein said processing means comprises means for solving simultaneous equations which include functions of moisture content, thickness, and complex index of refraction of said material.

Claim 15

Apparatus as recited in claim 4 wherein said processing means comprises means for solving a plurality of simultaneous equations including functions of moisture content, thickness, and complex index of refraction of said material at the frequencies of said beams.

Claim 16

Apparatus for sensing the characteristics of sheet material, comprising: a plurality of radiating means for generating coherent microwave electromagnetic radiation, each of said radiating means generating a plurality of beams having a different frequency, and, each of said radiating means directing its associated plurality of beams against a separate area of incidence, said separate areas of incidence being spatially distributed across said material; first signal generating means for generating separate reflectance and transmittance signals for each of said beams, said signals being proportional to the intensity of each of said beams reflected from and transmitted through said material, respectively; second generating means for generating a reference signal proportional to basis weight at a reference position; and processing means for producing separate moisture and thickness signals for each of said radiating means calculated from said plurality of reflectance and transmittance signals and from said reference signal; said processing means generating a spatial profile of moisture and thickness across said material.

Claim 17

Apparatus for sensing the characteristics of sheet material, comprising: a plurality of radiating means for generating coherent microwave electromagnetic radiation, each of said radiating means generating a plurality of beams having a different frequency, and, each of said radiating means directing its associated plurality of beams against a separate area of incidence, said separate areas of incidence being spatially distributed across said material; first signal generating means for generating separate reflectance and transmittance signals for each of said beams, said signals being proportional to the intensity of each of said beams reflected from and transmitted through said material, respectively; second generating means for generating a reference signal proportional to basis weight at a reference position; and processing means for producing separate moisture and thickness signals for each of said radiating means calculated from said plurality of reflectance and transmittance signals and from said reference signal; said processing means generating a spatial profile of moisture and thickness across said material.

Claim 22

A method as recited in claim 17 comprising the additional steps of: generating a reference signal proportional to basis weight of said material at one of the areas of incidence; and calculating a plurality of basis weight values from said reference signal and said values representative of moisture content and thickness to generate a basis weight spatial profile of said material.

Claim 23

A method as recited in claim 18 wherein said step of generating a reference signal comprises the steps of directing a beam of electrons through said material and measuring the amount of said electron beam energy transmitted through said material.

Claim 24

A method as recited in claim 18 comprising the step of generating a plurality of dry basis weight signals from said basis weight values and said moisture content values to generate a spatial profile of dry basis weight for said material.

Claim 25

A method as recited in claim 17 wherein the step of generating a plurality of groups of beams of electromagnetic radiation comprises the step of generating a plurality of microwave signals.

Claim 26

Apparatus for analyzing sheet material, comprising: a reflectance unit comprising: a first radiation source for generating a first beam of coherent electromagnetic radiation, a second radiation source for generating a second beam of coherent electromagnetic radiation having a frequency different from said first beam, first focusing means for collimating said first and second beams and for directing said first and second beams against the material to be analyzed, second focusing means for receiving said first and second beams reflected from the material to be analyzed; and first and second reflectance detector means for generating first and second reflectance signals responsive to the intensity of said reflected first and second beams, respectively; a transmittance unit adapted for mounting on the side of the material to be analyzed opposite from said reflectance unit, said transmittance unit comprising first and second transmittance detector means for generating first and second transmittance signals respectively responsive to the intensity of said first and second beams transmitted through the material to be analyzed; means for generating first and second incident signals indicative of the intensity of said first and second beams applied to said material; and means for processing said incident, reflectance, and transmittance signals to produce signals representative of characteristics of the material being analyzed.

Claim 27

Apparatus for analyzing sheet material, comprising: a reflectance unit comprising: a first radiation source for generating a first beam of coherent electromagnetic radiation, a second radiation source for generating a second beam of coherent electromagnetic radiation having a frequency different from said first beam, first focusing means for collimating said first and second beams and for directing said first and second beams against the material to be analyzed, second focusing means for receiving said first and second beams reflected from the material to be analyzed; and first and second reflectance detector means for generating first and second reflectance signals responsive to the intensity of said reflected first and second beams, respectively; a transmittance unit adapted for mounting on the side of the material to be analyzed opposite from said reflectance unit, said transmittance unit comprising first and second transmittance detector means for generating first and second transmittance signals respectively responsive to the intensity of said first and second beams transmitted through the material to be analyzed; means for generating first and second incident signals indicative of the intensity of said first and second beams applied to said material; and means for processing said incident, reflectance, and transmittance signals to produce signals representative of characteristics of the material being analyzed.

Claim 28

Apparatus for analyzing sheet material, comprising: a reflectance unit comprising: a first radiation source for generating a first beam of coherent electromagnetic radiation, a second radiation source for generating a second beam of coherent electromagnetic radiation having a frequency different from said first beam, first focusing means for collimating said first and second beams and for directing said first and second beams against the material to be analyzed, second focusing means for receiving said first and second beams reflected from the material to be analyzed; and first and second reflectance detector means for generating first and second reflectance signals responsive to the intensity of said reflected first and second beams, respectively; a transmittance unit adapted for mounting on the side of the material to be analyzed opposite from said reflectance unit, said transmittance unit comprising first and second transmittance detector means for generating first and second transmittance signals respectively responsive to the intensity of said first and second beams transmitted through the material to be analyzed; and means for processing said reflectance and transmittance signals to produce signals representative of characteristics of the material being analyzed.

Claim 29

Apparatus for analyzing sheet material, comprising: a reflectance unit comprising: a first radiation source for generating a first beam of coherent electromagnetic radiation, a second radiation source for generating a second beam of coherent electromagnetic radiation having a frequency different from said first beam, first focusing means for collimating said first and second beams and for directing said first and second beams against the material to be analyzed, second focusing means for receiving said first and second beams reflected from the material to be analyzed; and first and second reflectance detector means for generating first and second reflectance signals responsive to the intensity of said reflected first and second beams, respectively; a transmittance unit adapted for mounting on the side of the material to be analyzed opposite from said reflectance unit, said transmittance unit comprising first and second transmittance detector means for generating first and second transmittance signals respectively responsive to the intensity of said first and second beams transmitted through the material to be analyzed; and means for processing said reflectance and transmittance signals to produce signals representative of characteristics of the material being analyzed.

Claim 30

Apparatus as recited in claim 2 comprising a beam combiner downstream from said radiation sources directing said first and second beams of electromagnetic radiation along a common path.

Claim 31

Apparatus as recited in claim 24 comprising: a reflectance beam splitter downstream from said second focusing means directing said reflected first and second beams into said first and second reflectance detector means, respectively; and a transmittance beam splitter downstream from said transmittance focusing means directing said transmitted first and second beams into said first and second transmittance detector means, respectively.

Claim 32

Apparatus as recited in claim 25 wherein said reflectance unit comprises reflectance means for reflecting at least one of said first and second beams from its respective radiation source to said beam combiner.

Claim 33

Apparatus as recited in claim 26 wherein said reflectance means reflects said first and second beams from their respective radiation sources to said beam combiner.

Claim 34

Apparatus as recited in claim 27 wherein said reflectance means comprise an off-axis paraboloid mirror.

Claim 35

Apparatus as recited in claim 25 wherein said first and second reflectance focusing means each comprise a lens of dielectric material, said first reflectance focusing means lens having a different output beam waist size than the input beam waist size of said second reflectance focusing means lens.

Claim 36

Apparatus as recited in claim 29 wherein said first reflectance focusing means lens has a larger output beam waist size than the input beam waist size of said second reflectance focusing means lens.

Claim 37

Apparatus as recited in claim 25 comprising a transmittance mounting board and a pair of said transmittance units mounted on opposite sides of said transmittance mounting board to form a transmittance module.

Claim 38

Apparatus as recited in claim 31 comprising a reflectance mounting board and a pair of said reflectance units mounted on opposite sides of said reflectance mounting board to form a reflectance module.

Claim 39

Apparatus as recited in claim 32 comprising: a plurality of said transmittance modules, a plurality of said reflectance modules equal in number to the number of said transmittance modules, means for connecting each of said transmittance and reflectance detectors to said processing means, a transmittance frame supporting said transmittance modules juxtaposed in a horizontal plane, a reflectance frame supporting said reflectance modules juxtaposed parallel to said horizontal plane, and means for supporting said reflectance and transmittance frames in a manner so as to define an elongated opening therebetween parallel to said horizontal plane and adapted to receive a moving web of material to be analyzed, said supporting means supporting each of said reflectance modules in vertical alignment with a corresponding one of said transmittance modules.

Claim 40

Apparatus as recited in claim 33 wherein said transmittance modules are positioned above said elongated opening and said reflectance modules are positioned below said elongated opening.

Claim 41

Apparatus as recited in claim 32 wherein each of said reflectance units comprises a first modulator producing modulation of a first modulation type on said first beam and a second modulator producing a second modulation type on second beam.

Claim 42

Apparatus as recited in claim 35 wherein said first modulators of adjacent reflectance units produce modulation of different frequencies.

Claim 43

Apparatus as recited in claim 35 wherein said reflectance frame comprises a plurality of control devices, each of said control devices being removably connected to one of said reflectance units, and said modulators are responsive to said control devices to establish the modulation frequency of each of said modulators.

Claim 44

Apparatus for sensing the characteristics of sheet material, comprising: radiating means for generating a plurality of beams of coherent electromagnetic radiation, each of said beams having a different frequency, and for directing said beams against said material at an area of incidence; first signal generating means for generating separate reflectance and transmittance signals for each of said beams, said signals being proportional to the intensity of each of said beams reflected from and transmitted through said material, respectively; incident signal generating means for generating a separate incident signal for each of said beams, said incident signal being proportional to energy incident upon said material; and processing means for producing moisture, thickness, and basis weight signals calculated from said plurality of reflectance, transmittance, and incident signals.

Claim 45

Apparatus for sensing the characteristics of sheet material, comprising: radiating means for generating a plurality of beams of coherent electromagnetic radiation, each of said beams having a different frequency, and for directing said beams against said material at an area of incidence; first signal generating means for generating separate reflectance and transmittance signals for each of said beams, said signals being proportional to the intensity of each of said beams reflected from and transmitted through said material, respectively; incident signal generating means for generating a separate incident signal for each of said beams, said incident signal being proportional to energy incident upon said material; and processing means for producing moisture, thickness, and basis weight signals calculated from said plurality of reflectance, transmittance, and incident signals.

Claim 46

Apparatus as recited in claim 38 wherein said beams are stationary.

Claim 47

Apparatus as recited in claim 39 comprising a plurality of said radiating means each directing its associated plurality of beams against a separate area of incidence, said separate areas of incidence being spatially distributed across said material, wherein said processing means produces separate moisture, thickness, and basis weight signals for each of said radiating means, and whereby spatial profiles of moisture, thickness, and basis weight characteristics are produced for said material.

Claim 48

Apparatus as recited in claim 40 wherein said radiating means comprises means for generating microwave radiation.

Claim 49

Apparatus as recited in claim 41 wherein said means for generating microwave radiation generates radiation having a wavelength greater than four times the thickness of said material.

Claim 50

Apparatus as recited in claim 38 wherein said reflectance and transmittance signals are respectively proportional to the intensity of each of said beams reflected from and transmitted through said material.

Claim 51

Apparatus as recited in claim 38 wherein said processing means comprises means for solving simultaneous equations which include functions of moisture content, thickness, and complex index of refraction of said material.

Claim 52

Apparatus as recited in claim 41 wherein said processing means comprises means for solving a plurality of simultaneous equations including functions of moisture content, thickness, and complex index of refraction of said material at the frequencies of said beams.

Claim 53

Apparatus as recited in claim 38 wherein said beams have different polarization.

Claim 54

Apparatus as recited in claim 46 wherein said radiating means generates a pair of orthogonally polarized beams.

Claim 59

A method as recited in claim 49 wherein the step of generating a plurality of groups of beams of electromagnetic radiation comprises the step of generating a plurality of microwave signals.