Measurement of tissue paper

• US 10,643,323 B2
• Filed: 04/09/2018
• Issued: 05/05/2020
• Est. Priority Date: 12/04/2012
• Status: Active Grant

• Current Assignee: Valmet Automation Oy
• Original Assignee: Valmet Automation Oy
• Inventors: Toskala, Marko, Makela, Ismo, Mantyla, Markku
• Primary Examiner(s): Thomas, Mia M
• Application Number:
  US15/948,701
• Publication Number:
  US 20180225819A1
• Time in Patent Office: 757 Days
• CPC Class Codes: B31F 1/12 Crêping
• CPC Class Codes: D21F 7/06 Indicating or regulating the thickness of the layer; Signal devices
• CPC Class Codes: D21G 9/0009 Paper-making control systems
• CPC Class Codes: G01B 11/0691 of objects while moving G01B11/0616 takes precedence
• CPC Class Codes: G01B 11/303 using photoelectric detection means
• CPC Class Codes: G01N 21/89 in moving material, e.g. running paper or textiles G01N21/90, G01N21/91, G01N21/94 take precedence
• CPC Class Codes: G06T 15/04 Texture mapping
• CPC Class Codes: G06T 2207/10012 Stereo images
• CPC Class Codes: G06T 2207/10028 Range image; Depth image; 3D point clouds
• CPC Class Codes: G06T 2207/30124 Fabrics; Textile; Paper
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: G06T 7/593 from stereo images

Abstract

A topographical imaging device is placable after a creping process which causes folds to the tissue sheet and the topographical imaging device provides image data having three-dimensional information on the tissue sheet. A data processing device determines, on the basis of a shape of a cross section of at least one fold of creping of the tissue sheet, at least one of the following: thickness of the tissue sheet, softness of the tissue sheet.

Claims

1. An apparatus, wherein the apparatus comprises:

at least one topographic imaging camera that captures at least one image of a creped tissue sheet moving from a roll to a spool for providing image data having three-dimensional information on the creped tissue sheet; and

a data processor that determines softness of the creped tissue sheet on the basis of a shape of a cross section of at least one fold of the creped tissue sheet in the image data of the at least one image and wherein the data processor is further configured to determine the softness of the creped tissue sheet on the basis of roundness and/or sharpness of at least one fold of the creping.

2. The apparatus of claim 1, wherein the data processor determines softness of the creped tissue sheet on the basis of a radius of curvature of the at least one fold;

and the data processor further generates a signal to (i) change a parameter of a blade, which detaches a tissue sheet from the roll and cause the tissue sheet to be creped, in order to produce the creped tissue sheet having a desired softness, and/or (ii) generate an alarm if the quality departs or is on the way to depart from what is desired.

3. The apparatus of claim 1, wherein the data processor determines the softness of the creped tissue sheet on the basis of tightness of the at least one fold of the creping.

4. The apparatus of claim 1, wherein the data processor determines the softness of the creped tissue sheet on the basis of a radius of curvature of the at least one fold.

5. The apparatus of claim 1, wherein the data processor determines the softness of the creped tissue sheet on the basis of a smallest radius of curvature of the at least one fold.

6. The apparatus of claim 1, wherein the data processor determines the softness of the tissue sheet on the basis of a number of subfolds in a fold.

7. The apparatus of claim 1, wherein the data processor determines the softness of the tissue sheet on the basis of at least one spatial wavelength of the sub folds in a fold.

8. The apparatus of claim 1, wherein the data processor determines the softness of the tissue sheet on the basis of roughness caused by the at least one fold of creping.

9. The apparatus of claim 1, wherein the data processor determines the softness of the tissue sheet additionally on the basis of at least one wavelength of the folds of creping.

10. The apparatus of claim 1, wherein the data processor determines the softness of the tissue sheet on the basis of the spatial power spectrum of Fourier analysis.

11. A data processing apparatus, comprising:

at least one processor;

and at least one memory including computer program code, wherein the at least one memory, with the at least one processor and the computer program code, cause the data processing apparatus to;

control at least one topographic imaging camera to capture of at least one image of a creped tissue sheet moving from a roll to a spool for providing image data having three-dimensional information on the creped tissue sheet; and

determine softness of the creped tissue sheet on the basis of a shape of a cross section of at least one fold of the creped tissue sheet in the image data of the at least one image and wherein the data processor is further configured to determine the softness of the creped tissue sheet on the basis of roundness and/or sharpness of at least one fold of the creping.

12. The data processing apparatus of claim 11, wherein the at least one processor and the at least one memory including the computer program code are configured to cause the data processing apparatus to obtain, from the at least one camera for capturing at least one image for providing image data having three-dimensional information;

the image data having three-dimensional information on a creped tissue sheet as the creped tissue sheet is moving from the roll to a spool, the creped tissue sheet having folds caused by a creping process, wherein the creped tissue sheet is caused to be creped when detached from the roll by a blade;

determine softness of the creped tissue sheet on the basis of a radius of curvature of the at least one fold, and generate a signal to (i) change a parameter of the blade based on the determined softness in order to produce the creped tissue sheet having a desired softness and/or (ii) alarm a user of the paper machine if the quality departs or is on the way to depart from what is desired.

13. The data processing apparatus of claim 11, wherein the at least one processor further comprises:

band-pass filtering spatial frequencies in the three-dimensional image data and determining softness of the creped tissue sheet on the basis of a frequency and the amplitude of the spatial frequencies.

14. The data processing apparatus of claim 11, wherein the at least one processor further determines the softness of the tissue sheet on the basis of the spatial power spectrum of Fourier analysis.