US 11,841,357 B2
Measurement apparatus and method of paper web
Markku Mäntylä, Kangasala (FI); and Pekka Suopajärvi, Oulu (FI)
Assigned to VALMET AUTOMATION OY, Espoo (FI)
Filed by VALMET AUTOMATION OY, Espoo (FI)
Filed on Aug. 27, 2020, as Appl. No. 17/004,697.
Claims priority of application No. 20195795 (FI), filed on Sep. 23, 2019.
Prior Publication US 2021/0088500 A1, Mar. 25, 2021
Int. Cl. G01N 21/3559 (2014.01); G01N 33/34 (2006.01); G01N 21/86 (2006.01); D21F 7/00 (2006.01); D21F 7/06 (2006.01)
CPC G01N 33/346 (2013.01) [D21F 7/003 (2013.01); D21F 7/06 (2013.01); G01N 21/3559 (2013.01); G01N 21/86 (2013.01); G01N 2021/8663 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A measurement apparatus of a moving paper web, wherein:
the apparatus comprises an optical radiation source that is configured to output optical radiation toward a scattering element of the measurement apparatus;
the scattering element is configured to scatter the optical radiation, and a transmitting surface of the scattering element is configured to direct the optical radiation in a scattered manner toward the moving paper web;
a distance between said transmitting surface of the scattering element and a surface of the paper web is known, and the transmitting surface and a detector of the apparatus are on opposite sides of the paper web;
the detector is configured to receive at least a part of the optical radiation, which is side-scattered from the moving paper web, the side-scattered optical radiation deviating by a predetermined angle from a direction that extends from the scattering element to the paper web, and reject the optical radiation that has passed directly through the moving paper web without scattering;
the detector is configured determine a moisture value and a dry weight of the paper web on a basis of spectral information on the received optical radiation and the known distance.
 
13. A method of measuring a moving paper web, comprising:
outputting, by an optical radiation source, optical radiation toward a scattering element;
scattering the optical radiation by the scattering element;
directing the optical radiation, by a transmitting surface of the scattering element, in a scattered manner toward the moving paper web, where a distance between said transmitting surface of the scattering element and a surface of the paper web is known, and the transmitting surface and a detector of a measurement apparatus are on opposite sides of the paper web;
receiving, by the detector, at least a part of the optical radiation, which is side-scattered from the moving paper web and rejecting the optical radiation that has passed directly through the moving paper web without scattering, the side-scattered optical radiation deviating by a predetermined angle that extends from a direction from the scattering element to the paper web; and
determining, by the detector, a moisture value and a dry weight of the paper web on the basis of spectral information on the received optical radiation and the known distance.