Apparatus and method for sensing multiple parameters of sheet material

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.

A method for simultaneously sensing a plurality of characteristics of sheet material, comprising the steps of:

• generating a plurality of beams of coherent electromagnetic radiation, each of said beams having a different frequency;
• directing said plurality of beams against the material at a area of incidence;
• generating separate reflectance and transmittance signals for each of said beams proportional to the amount of each of said beams reflected from and transmitted through said material, respectively;
• and
• calculating moisture content and thickness from said reflectance and transmittance signals.

A method for simultaneously sensing a plurality of characteristics of sheet material, comprising the steps of:

• generating a plurality of groups of beams of coherent electromagnetic radiation, each beam in a group having a different frequency from the other beams of the group;
• directing each group of beams against the material at a different area of incidence;
• generating separate reflectance and transmittance signals for the beams proportional to the intensity of each of the beams reflected from and transmitted through the material, respectively;
• and
• calculating values representative of the moisture content and thickness of the said material from said reflectance and transmittance signals at each of said areas of incidence to generate a moisture content and thickness spatial profile of the material.

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.

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.

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.

A method for simultaneously sensing a plurality of characteristics of sheet material, comprising the steps of:

• generating a plurality of beams of coherent electromagnetic radiation, each of said beams having a different frequency;
• directing said plurality of beams against the material at a area of incidence;
• generating separate incident, reflectance, and transmittance signals for each of said beams proportional to the amount of each of said beams applied to, reflected from, and transmitted through said material, respectively;
• and
• calculating moisture content, thickness, and basis weight from said incident, reflectance, and transmittance signals.

A method for simultaneously sensing a plurality of characteristics of sheet material, comprising the steps of:

• generating a plurality of groups of beams of coherent electromagnetic radiation, each beam in a group having a different frequency from the other beams of the group;
• directing each group of beams against the material at a different area of incidence;
• generating separate incident, reflectance, and transmittance signals for the beams proportional to the intensity of each of the beams applied to, reflected from, and transmitted through the material, respectively;
• and
• calculating values representative of the moisture content, thickness, and basis weight of the said material from said incident, reflectance, and transmittance signals at each of said areas of incidence to generate a moisture content, thickness, and basis weight spatial profile of the material.