METHOD OF DETERMINING NON-UNIFORMITY OF PAPER SURFACE Russian patent published in 2025 - IPC G01N21/86 

FIELD: measuring.

SUBSTANCE: invention relates to an optical control system for measuring surface inhomogeneity of a fibrous composite material. Fixed sample is exposed to oblique light 2, which is supplied to non-uniform profile 3 of the paper at angle of 20-40°, light-and-shadow image 6 is obtained in the form of shadows 4 and protrusions 5 on the profile of surface 3 of the paper. Light-and-shadow image is divided into a matrix consisting of cells 8. Each cell contains points with different light intensity, wherein determining the light intensity in each cell of matrix 10, divided into pixels, determining the light intensity distribution mode in each cell of matrix 10, converting the light-and-shadow image into a table with the light intensity values of each cell of matrix 9, and according to the light intensity of each cell, light intensity distribution diagram 11 is plotted. To assess the surface of the front side of the paper, measurements are taken from two opposite sides for the machine direction I_{MD_front}, and then determining the average surface moulding index, and on two opposite sides for the transverse direction also with the determination of the average surface moulding index in the transverse direction I_{CD_front}, after which four measurements are carried out in a similar way over the back side of the paper I_{MD_back}, I_{CD_back}.

EFFECT: high accuracy of measuring non-uniformity of the surface of paper and cardboard.

1 cl, 2 dwg