Measurement of moisture-stratified sheet material
AssigneeAccuray Incorporated
InventorSteven P. Sturm
Life of this patent
Estimating the term…
Abstract
A process and apparatus for measuring moisture content of moisture-stratified sheet material such as paper is disclosed. The effective reflectivities of two areas of an infrared moisture sensor that generally face opposite surfaces of the sheet are made significantly different, so that the sensitivity of the measurement to conditions prevailing in a high-moisture stratum of the sheet is increased.
Claims14
Apparatus for measuring the moisture content of sheet material, such as paper, comprising:
- (a) a source unit having a first area adapted to generally face a first surface of the sheet, the first area having an effective reflectivity;
- (b) means, disposed within the source unit, for directing infrared radiation onto the first surface;
- (c) a detector unit having a second area adapted to generally face a second surface of the sheet, the second area having an effective reflectivity, and the detector unit being spaced apart from the source unit to form a pass gap of sufficient width to allow substantially free movement of the sheet therethrough;
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- (d) means, disposed within the detector unit, for detecting infrared radiation that has emitted from the directing means and repeatedly interacted with the sheet and the first and second areas, and for producing detector responses from which measurements of the moisture content of the sheet can be derived, wherein the effective reflectivity of the second area is significantly greater than the effective reflectivity of the first area, the apparatus thereby being adapted to yield greater measurement sensitivity to moisture conditions prevailing in the sheet near the second surface than to those conditions prevailing near the first surface.
Apparatus for measuring the moisture content of sheet material such as paper, comprising:
- (a) a source unit having a first area adapted to generally face a first surface of the sheet, the first area having an effective reflectivity;
- (b) means, disposed within the source unit, for directing infrared radiation onto the first surface;
- (c) a detector unit having a second area adapted to generally face a second surface of the sheet, the second area having an effective reflectivity, and the detector unit being spaced apart from the source unit to form a pass gap of sufficient width to allow substantially free movement of the sheet therethrough;
- and
- (d) means, disposed within the detector unit, for detecting infrared radiation that has emitted from the directing means and repeatedly interacted with the sheet and the first and second areas, and for producing detector responses from which measurements of the moisture content of the sheet can be derived, wherein the effective reflectivity of the first area is significantly greater than the effective reflectivity of the second area, the apparatus thereby being adapted to yield greater measurement sensitivity to moisture conditions prevailing in the sheet near the first surface than to those conditions prevailing near the second surface.
A process for measuring the moisture content of sheet material, whereby moisture measurements are made via a traversing infrared moisture sensor, comprising the steps of:
- (a) directing infrared radiation from a source unit of the sensor onto a first surface of the sheet material to initiate multiple interactions of the radiation with the sheet material, with a first area of the source unit which first area has an effective relectivity, and with a second area of a detector unit of the sensor which second area has an effective reflectivity differing significantly from the effective reflectivity of the first area;
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- (b) detecting, within the detector unit, selected wavelengths of the radiation to produce detector responses from which the measurements are derived.
Dependencies are inferred from the claim text.