WO2004034041A1 - Method and apparatus for the optical evaluation of a paper surface - Google Patents

Method and apparatus for the optical evaluation of a paper surface Download PDF

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Publication number
WO2004034041A1
WO2004034041A1 PCT/PT2003/000014 PT0300014W WO2004034041A1 WO 2004034041 A1 WO2004034041 A1 WO 2004034041A1 PT 0300014 W PT0300014 W PT 0300014W WO 2004034041 A1 WO2004034041 A1 WO 2004034041A1
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WO
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Prior art keywords
paper
illumination
image
defects
analysis
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Application number
PCT/PT2003/000014
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French (fr)
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WO2004034041B1 (en
Inventor
Nuno José Reis Gomes de OLIVEIRA
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Soporcel -Sociedade Portuguesa De Papel, S.A.
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Application filed by Soporcel -Sociedade Portuguesa De Papel, S.A. filed Critical Soporcel -Sociedade Portuguesa De Papel, S.A.
Priority to AU2003267886A priority Critical patent/AU2003267886A1/en
Publication of WO2004034041A1 publication Critical patent/WO2004034041A1/en
Publication of WO2004034041B1 publication Critical patent/WO2004034041B1/en
Priority to SE0500761A priority patent/SE528526C2/en
Priority to FI20050383A priority patent/FI121033B/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
    • G01N21/8901—Optical details; Scanning details
    • G01N21/8903—Optical details; Scanning details using a multiple detector array
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/30—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces
    • G01B11/303—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces using photoelectric detection means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
    • G01N21/8914—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles characterised by the material examined
    • G01N2021/8917—Paper, also ondulated

Definitions

  • the present invention is included in the field of the evaluation of the paper quality and specifically refers to a method for the evaluation of the paper surface aspect and to automated equipment allowing the method to be performed.
  • the "whiteness” is characterized by the colorimetric description of the paper surface and it is not the object of the present invention, except in an indirect form on what the identification and location of significant local variations of fluorescence are concerned.
  • the most used mechanical method to measure the paper roughness is based on the flow of air on the paper surface.
  • Devices like for example Bendtsen, Parker Print Surf, Sheffield, Bekk and Gurley Hill are used.
  • a cylindrical element is pressed against the paper surface with a certain force.
  • a differential pressure is created on the element in relation to the atmosphere and the air that passes through the space between the edge of the cylindrical element and the paper surface is measured.
  • a disadvantage of this method is the error factor caused by the dependence between the result of the measurement and the force used to press the cylindrical element against the surface of the existing paper.
  • the scope of the measurement is a large area of the surface of the paper and for that reason, precise information of the detailed structure of the paper surface cannot be obtained.
  • Document WO 0068638 discloses a method that relies on the measurement of a paper surface defect based on the intensity of the light received at the pixels of a camera reflected from the light collimated in a manner substantially parallel to the normal of the paper.
  • Other examples of conventional equipments and techniques available in the state of art are "DOMAS (Digital Optical Measurement and Analysis System) analysing device", developed by PTS Heidenau and the “Eureka system” developed by IFP (Institut fur Pandafabrikation) .
  • DOMAS Digital Optical Measurement and Analysis System
  • IFP Institute fur Textilfabrikation
  • document OF 4230068 that describes a method wherein the acquisition of the image reflected on the paper surface and the treatment of the respective spectrum with the aid of the Fourier transform is done, its comparison being made afterwards with characteristic values of the surface roughness. It is therefore a comparative method that uses established and classified patterns, being hence limited to the detection of well-known pattern defects.
  • the present invention provides the necessary means to detect arbitrary "smoothness” detects with impact in the final user in real time (i.e., complying with the above-mentioned requirements for operation in an immediate control laboratory) , in order to allow the detection of "smoothness" defects that are not reflected in roughness determinations.
  • the present invention provides a method and automated installation for the evaluation of the paper surface aspect, whose foundations and operation are defined in the enclosed claims and that will be described in detail. To do this, illustrative figures will be shown, which should not be considered as limiting the scope of the invention which is defined by the enclosed claims, wherein:
  • Figure 1 schematically represents the functional blocks that constitute the automatic system for the evaluation of the paper surface aspect.
  • Figure 2 represents the illumination and image acquisition system configured for the evaluation of topography defects.
  • Figure 3 represents the illumination and image acquisition system configured for the evaluation of defects of starch application on the paper surface.
  • Figure 4 represents the illumination and image acquisition system configured for the evaluation of water-lines defects.
  • Figure 5 represents the system of paper transport and positioning.
  • Figure 6 diagrammatically represents the algorithm for the evaluation of paper topography defects.
  • Figure 7 also diagrammatically represents the algorithm for the evaluation of defects on the starch application to the paper surface.
  • Figure 8 still diagrammatically represents the algorithm for the evaluation of paper water-lines defects.
  • the present invention hence refers to a method and automated equipment for the optical evaluation of "smoothness" defects, namely topography defects of the streak type (periodic or approximately periodic variations of the topography essentially oriented according to a well-defined direction) , flaws in the surface application of starch (that, being applied jointly with a fluorescent optical bleach - OBA - result in the appearing of bands along the direction of the paper machine - MD direction - with significant variation of the paper fluorescence) and defects of the water-lines type (variations of the apparent glow of the paper with a structure essentially oriented according to MD) , of the obtained paper surface in an installation for paper production, which comprises a system 1 for the transport and positioning of the paper in a flat table, a system 2 of illumination and image acquisition, a computer based control system 3 for the positioning of the paper in the transport system and finally a system 4 for the analysis and processing of the obtained images .
  • the method for the optical evaluation of paper surface defects uses an equipment comprising a system 2 of illumination and image acquisition and a system 4 of analysis and processing of the obtained image, wherein: a) system 2 of illumination and image acquisition uses an illumination 5 with a grazing angle in relation to the surface of the paper in analysis, provided with a small opening light beam, and a digital camera 6 with the optical axis perpendicular to the surface of the paper, b) system 4 of image analysis and processing performs the steps described in the algorithm of Figure 6, namely:
  • the system 2 of illumination and image acquisition of the invention uses a grazing angle illumination 5 perpendicular to the machine direction.
  • the system 2 of illumination and image acquisition of the invention uses a grazing angle illumination 5 parallel to the machine direction.
  • the paper surface to be analysed is scrolled in a flat table 7 from a sample collected at full width of the paper reel in analysis (roll 8).
  • the method of the invention allows the optical evaluation of defects in the paper surface starch application, using an equipment comprising a system 2 of illumination and image acquisition and a system 4 of analysis and processing of the obtained image, wherein: a) system 2 of illumination and image acquisition uses a diffuse illumination of ultraviolet light 9, b) system 4 of image analysis and processing performs the steps shown on Figure 7, namely:
  • the method of the invention also performs the optical evaluation of water-lines defects on the paper surface, using an equipment comprising a system 2 of illumination and image acquisition and a system 4 of analysis and processing of the obtained image, wherein: a) system 2 of illumination and image acquisition uses an illumination of a small opening light beam 10 with a low angle, adjustable, of incidence in the plane of the paper and the digital camera 11 is placed in a (adjustable) position approximately symmetrical to the lamp 10 in relation to an axis perpendicular to the paper, b) system 4 of analysis and image processing performs the steps represented in Figure 8, namely: • Acquisition of the image, • Reduction to one dimension, line along to the CD direction, of the obtained image, by means of calculation of the average of the MD values in each CD position, • Filtration of the low frequency components
  • the invention also refers to an equipment for the automatic and integrated optical evaluation of the "smoothness" defects, according to the above referred methods, that comprises a system 1 of transport and positioning of the paper on a flat table 7, a system 2 of illumination and image acquisition, a computer based control system 3 for the control of the positioning of the paper in the transport system and finally a system 4 of analysis and processing of the obtained image, that performs the following steps:
  • system 1 of transport and positioning of the paper on a plane table 7 of the of the invention equipment comprises a paper unwinder that allows to unwind a sample corresponding to the width of a reel of paper 8, 12 in order to be available on the plane table 7 an area 13 of the paper to be analysed whose distance to the end of the reel of paper 12 is controlled.
  • System 2 of illumination and image acquisition of the invention equipment comprises a light source 5, 9, 10 and a digital camera 6, 11, being the orientation of the light and of the camera in relation to the plane of the paper, as well as the light spectrum and opening of the emitted beam, chosen as a function of the type of defect to be detected. The choice is made among lamps and cameras available in the system.
  • the computer based control system 3 for the positioning of the paper in the system of transport of the invention equipment is totally automatic, not needing therefore any human intervention for its operation after loading the paper sample.
  • the equipment for the automatic and integrated optical evaluation of "smoothness" defects of the invention can be namely applied to the optical evaluation of:

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)

Abstract

The present invention relates to a method and automated equipment for the optical evaluation of smoothness defects, namely surface defects, starch application flaws and water-line defects, of the surface of the paper obtained in a paper production plant, which comprises a system (1) for the transportation and positioning of the paper in a planar table, a system (2) for the illumination and imaging, a computer based control system (3) for the control of the positioning of the paper in the transportation system and finally a system (4) for the analysis and processing of the obtained image. Image processing is performed through low-pass filtering, including through the use of Fourier or East Fourier (FFT) transforms. The image signal of defects is enhanced by averaging pixels along the machine direction (MD).

Description

METHOD AND APPARATUS FOR THE OPTICAL EVALUATION OF A PAPER SURFACE
SCOPE OF THE INVENTION
The present invention is included in the field of the evaluation of the paper quality and specifically refers to a method for the evaluation of the paper surface aspect and to automated equipment allowing the method to be performed.
BACKGROUND OF THE INVENTION
The visual impact of a paper sheet surface is a decisive parameter in the perception of its quality and consequently in its positioning in terms of market segmentation. This impact is translated, at the level of the user, in two empiric concepts: "whiteness" and "smoothness."
In a paper production process it is necessary to proceed to the systematic characterization of these parameters "whiteness" and "smoothness" at the end of the paper machine. The methods used in this quality control should be based on expedite and essentially autonomous analysis procedures (i.e., keeping the need for human intervention at a minimum level) , in order to be compatible with the rhythm and the degree of specialization of the operators of an immediate control laboratory.
The "whiteness" is characterized by the colorimetric description of the paper surface and it is not the object of the present invention, except in an indirect form on what the identification and location of significant local variations of fluorescence are concerned.
The concept of "smoothness" is traditionally quantified by mechanical methods, which measure a roughness indicator, i.e. the variability of the paper topography. These methods, however, are unable to differentiate periodic, isotropic and stochastic topographies. Since the physiologic answer of the human eye to these 3 topography forms is different, situations appear wherein the conventional previously referred methods do not detect flaws of "smoothness" that are penalized by the final consumer.
The most used mechanical method to measure the paper roughness is based on the flow of air on the paper surface. Devices like for example Bendtsen, Parker Print Surf, Sheffield, Bekk and Gurley Hill are used. In these devices, a cylindrical element is pressed against the paper surface with a certain force. A differential pressure is created on the element in relation to the atmosphere and the air that passes through the space between the edge of the cylindrical element and the paper surface is measured. A disadvantage of this method is the error factor caused by the dependence between the result of the measurement and the force used to press the cylindrical element against the surface of the existing paper. Also, the scope of the measurement is a large area of the surface of the paper and for that reason, precise information of the detailed structure of the paper surface cannot be obtained.
Optical methods to measure paper surface defects have been also developed. Document WO 0068638 discloses a method that relies on the measurement of a paper surface defect based on the intensity of the light received at the pixels of a camera reflected from the light collimated in a manner substantially parallel to the normal of the paper. Other examples of conventional equipments and techniques available in the state of art are "DOMAS (Digital Optical Measurement and Analysis System) analysing device", developed by PTS Heidenau and the "Eureka system" developed by IFP (Institut fur Papierfabrikation) . These systems are based on the Fourier spectral analysis of a paper surface image and in the identification of the intensity and wavelength of the periodic structures detected on the paper, for later analysis by a specialized operator. These systems do not allow, however, their use in an immediate control laboratory because they are not expedite nor autonomous .
It is worth mentioning, between the optical methods for evaluation of paper surface defects, document OF 4230068 that describes a method wherein the acquisition of the image reflected on the paper surface and the treatment of the respective spectrum with the aid of the Fourier transform is done, its comparison being made afterwards with characteristic values of the surface roughness. It is therefore a comparative method that uses established and classified patterns, being hence limited to the detection of well-known pattern defects.
It may then be concluded that techniques are available to detect roughness variations in real time in an immediate control laboratory, and to analyse subtler "smoothness" defects in full detail in a specialized back laboratory and with an extensive lag time. The need for a detection method in real time of arbitrary "smoothness" defects i.e. of not previously classified defects still exists in the present state of art. Therefore, there is presently a need for a system for the evaluation of the paper surface aspect that allows detecting, in real time, non-classified "smoothness" defects.
The present authors have found, quite unexpectedly, that by using a particular group of illumination geometries, reinforced with filtration of the thus obtained optical image of the paper surface in order to eliminate noise, an index of surface marking, namely the standard deviation of the grey levels, was obtained which characterizes the visual impact of the paper surface on the user, without the need to use known patterns, and so they made the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides the necessary means to detect arbitrary "smoothness" detects with impact in the final user in real time (i.e., complying with the above-mentioned requirements for operation in an immediate control laboratory) , in order to allow the detection of "smoothness" defects that are not reflected in roughness determinations.
Therefore, the present invention provides a method and automated installation for the evaluation of the paper surface aspect, whose foundations and operation are defined in the enclosed claims and that will be described in detail. To do this, illustrative figures will be shown, which should not be considered as limiting the scope of the invention which is defined by the enclosed claims, wherein:
Figure 1 schematically represents the functional blocks that constitute the automatic system for the evaluation of the paper surface aspect. Figure 2 represents the illumination and image acquisition system configured for the evaluation of topography defects.
Figure 3 represents the illumination and image acquisition system configured for the evaluation of defects of starch application on the paper surface.
Figure 4 represents the illumination and image acquisition system configured for the evaluation of water-lines defects.
Figure 5 represents the system of paper transport and positioning.
Figure 6 diagrammatically represents the algorithm for the evaluation of paper topography defects.
Figure 7 also diagrammatically represents the algorithm for the evaluation of defects on the starch application to the paper surface.
Figure 8 still diagrammatically represents the algorithm for the evaluation of paper water-lines defects.
The present invention hence refers to a method and automated equipment for the optical evaluation of "smoothness" defects, namely topography defects of the streak type (periodic or approximately periodic variations of the topography essentially oriented according to a well-defined direction) , flaws in the surface application of starch (that, being applied jointly with a fluorescent optical bleach - OBA - result in the appearing of bands along the direction of the paper machine - MD direction - with significant variation of the paper fluorescence) and defects of the water-lines type (variations of the apparent glow of the paper with a structure essentially oriented according to MD) , of the obtained paper surface in an installation for paper production, which comprises a system 1 for the transport and positioning of the paper in a flat table, a system 2 of illumination and image acquisition, a computer based control system 3 for the positioning of the paper in the transport system and finally a system 4 for the analysis and processing of the obtained images .
The method for the optical evaluation of paper surface defects, namely the existence of streaks caused by the paper production machine, uses an equipment comprising a system 2 of illumination and image acquisition and a system 4 of analysis and processing of the obtained image, wherein: a) system 2 of illumination and image acquisition uses an illumination 5 with a grazing angle in relation to the surface of the paper in analysis, provided with a small opening light beam, and a digital camera 6 with the optical axis perpendicular to the surface of the paper, b) system 4 of image analysis and processing performs the steps described in the algorithm of Figure 6, namely:
• Calculation of the spectrum of the acquired image, using an algorithm of FFT (Fourier Fast Transform),
• Application of a digital filter to eliminate part of the calculated spectrum that consists typically of low frequency components, such as lack of homogeneity of the illumination, and structures with preferential orientation parallel to the illumination direction,
• Calculation of the inverse Fourier transform of the filtered spectrum to obtain a filtered version of the original image, • Optical measurement of the roughness index defined as the standard deviation of the grey levels of the filtered image,
• Recording the roughness index and the CD position.
For the detection of structures essentially parallel to the direction of the machine of paper production (MD direction) , the system 2 of illumination and image acquisition of the invention uses a grazing angle illumination 5 perpendicular to the machine direction. For the detection of structures essentially perpendicular to the direction of the machine of paper production (CD direction) the system 2 of illumination and image acquisition of the invention uses a grazing angle illumination 5 parallel to the machine direction.
The paper surface to be analysed is scrolled in a flat table 7 from a sample collected at full width of the paper reel in analysis (roll 8).
In another embodiment, the method of the invention allows the optical evaluation of defects in the paper surface starch application, using an equipment comprising a system 2 of illumination and image acquisition and a system 4 of analysis and processing of the obtained image, wherein: a) system 2 of illumination and image acquisition uses a diffuse illumination of ultraviolet light 9, b) system 4 of image analysis and processing performs the steps shown on Figure 7, namely:
• Recording the absolute position of the origin of the coordinates in the frame on the digital camera in the moment of image acquisition,
• Conversion of the image to a binary image that differentiates zones with significant variations of fluorescence, that correspond to the zones where flaws in the superficial application of starch occurred,
1. Reduction to one dimension, CD direction, of the obtained image, by means of calculation of the average of the MD values in each CD position,
2. Filtration of low frequency components (subtraction to each pixel of the average value of its n neighbours) , 3. Recording the relative positions wherein the grey levels are out of the window defined as typical - relative position of the starch flaws.
• Calculation and recording of the absolute CD position of the starch flaws,
• Waiting until positioning in the adjacent frame,
• Repetition of the analysis cycle until completely unwinding the paper sample.
Still in another embodiment, the method of the invention also performs the optical evaluation of water-lines defects on the paper surface, using an equipment comprising a system 2 of illumination and image acquisition and a system 4 of analysis and processing of the obtained image, wherein: a) system 2 of illumination and image acquisition uses an illumination of a small opening light beam 10 with a low angle, adjustable, of incidence in the plane of the paper and the digital camera 11 is placed in a (adjustable) position approximately symmetrical to the lamp 10 in relation to an axis perpendicular to the paper, b) system 4 of analysis and image processing performs the steps represented in Figure 8, namely: • Acquisition of the image, • Reduction to one dimension, line along to the CD direction, of the obtained image, by means of calculation of the average of the MD values in each CD position, • Filtration of the low frequency components
(Subtraction from each pixel of the average value of its n neighbours),
• Measurement of the water-lines index defined as the standard deviation of the grey levels of the filtered image (line) ,
• Recording the calculated index and the CD position.
The invention also refers to an equipment for the automatic and integrated optical evaluation of the "smoothness" defects, according to the above referred methods, that comprises a system 1 of transport and positioning of the paper on a flat table 7, a system 2 of illumination and image acquisition, a computer based control system 3 for the control of the positioning of the paper in the transport system and finally a system 4 of analysis and processing of the obtained image, that performs the following steps:
• Loading the paper sample in the transport system 1,
• Transport of the paper in order that the first analysis position is under the digital cameras 6, 11,
• Application of the starch application flaws measurement algorithm according to claim 8, that remains active during all the measurement process,
• Application of the algorithm for topography measurement according to claim 5 for each illumination incidence direction, and for water-lines measurement according to claim 9, • Transport of the paper to the next position of measurement and return to the previous point, repeating the cycle until the paper sample is completely unwound.
In this equipment, system 1 of transport and positioning of the paper on a plane table 7 of the of the invention equipment comprises a paper unwinder that allows to unwind a sample corresponding to the width of a reel of paper 8, 12 in order to be available on the plane table 7 an area 13 of the paper to be analysed whose distance to the end of the reel of paper 12 is controlled.
System 2 of illumination and image acquisition of the invention equipment comprises a light source 5, 9, 10 and a digital camera 6, 11, being the orientation of the light and of the camera in relation to the plane of the paper, as well as the light spectrum and opening of the emitted beam, chosen as a function of the type of defect to be detected. The choice is made among lamps and cameras available in the system.
The computer based control system 3 for the positioning of the paper in the system of transport of the invention equipment is totally automatic, not needing therefore any human intervention for its operation after loading the paper sample.
The equipment for the automatic and integrated optical evaluation of "smoothness" defects of the invention can be namely applied to the optical evaluation of:
a. topography defects of the streak type, b. starch application defects, c. water-lines defects.

Claims

CLAIMSA method for the optical evaluation of paper surface defects, using an equipment comprising a system (2) of illumination and image acquisition and a system (4) of analysis and processing of the obtained image, characterized in that:a) system (2) of illumination and image acquisition uses an illumination (5) with a grazing angle to the surface of the paper in analysis, provided with a small opening light beam, and a digital camera (6) with an optical axis perpendicular to the surface of the paper, b) system (4) of image analysis and processing performs the following steps, in agreement with Figure 6:• Calculation of the spectrum of the acquired image, using a FFT algorithm (Fourier Fast Transform) ,• Application of a digital filter to eliminate the part of the calculated spectrum that consists typically of low frequency components, such as lack of homogeneity of the illumination, and the structures with preferential orientation parallel to the illumination direction, • Calculation of the inverse Fourier transform of the filtered spectrum to obtain a filtered version of the original image,• Optical measurement of the roughness index defined as the standard deviation of the grey levels.A method according to claim 1 characterized in that the system (2) of illumination and image acquisition uses a grazing angle illumination (5) perpendicular to the machine direction for the detection of structures essentially parallel to the machine direction.A method according to claim 1 characterized in that the system (2) of illumination and image acquisition uses a grazing angle illumination (5) parallel to the machine direction for the detection of structures essentially perpendicular to the machine direction.A method for the optical evaluation of defects in the application of starch to the paper surface, using an equipment comprising a system (2) of illumination and image acquisition and a system (4) of analysis and processing of the obtained image, characterized in that: a) system (2) of illumination and image acquisition uses a diffuse illumination of ultraviolet light (9), b) system (4) of image analysis and processing performs the following steps, according to Figure 7: • Recording the absolute position of the origin of the coordinates in the picture of the digital camera at the moment of the image acquisition,• Conversion of the image to a binary image that differentiates zones with significant variations of fluorescence, that correspond to the faulty areas in the surface application of starch,
1. Reduction to one dimension, CD direction, of the obtained image, by means of calculation of the average MD values, in each CD position, 2. Filtration of the low frequency components
(subtraction from each pixel of the average value of its n neighbours),
• Calculation and recording the absolute position of the starch application flaws, • Waiting for the positioning in the adjacent frame,
• Repetition of the analysis cycle until complete unwinding of the paper sample.
5. A method for the optical evaluation of water-lines defects on the paper surface, using an equipment comprising a system (2) of illumination and image acquisition and a system (4) of analysis and processing of the obtained image, characterized in that: a) system (2) of illumination and image acquisition uses an illumination of an adjustable small opening light beam (10) , with incidence in the plane of the paper and the digital camera (11) is placed in a (adjustable) position approximately symmetrical to the lamp (10) in relation to an axis perpendicular to the paper surface, b) system (4) of analysis and processing of image performs the following steps, according to Figure 8:
• Acquisition of the image, • Reduction to one dimension, line along the CD direction, of the obtained image, by means of calculation of the average of the MD values in each CD position,
• Filtration of the one-dimensional image, • Measurement of the water-lines index defined as the standard deviation of the grey levels of the filtered image (line) ,
• Recording the calculated index and CD position.
β. An equipment for the automatic and integrated optical evaluation of the "smoothness" defects, according to the methods described in claims 1 to 5, characterized in that it comprises a system (1) of transport and positioning of the paper on a plane table (7), a system (2) of illumination and image acquisition, a computer based control system (3) for the control of the positioning of the paper in the transport system and finally a system (4) of analysis and processing of the obtained image, that performs the following steps:
• Loading the paper sample in the equipment's system (1) for paper transport,
• Transport of the paper in order to place the first for position CD analysis under the digital cameras (6, 11), • Application of the starch application flaw measurement algorithm according to claim 8, that stays active during the whole measurement process,
• Application of the topography measurement algorithm according to claim 5 for each direction of incidence of the illumination, and water-lines measurement according to claim 9,
• Transport of the paper to the next position of measurement and return to the previous point repeating the cycle until the paper sample is completely unwound.
The equipment for the automatic and integrated optical evaluation of the "smoothness" defects according to claim 6, characterized in that the system (1) of transport and positioning of the paper on a flat table (7) comprises a unwinder of the paper that allows to unwind a sample corresponding to the width of a paper reel (8, 12) in order to be available on the plane table (7) an area (13) of the paper to be analysed whose distance to the end of the paper reel (12) is controlled.
The equipment for the automatic and integrated optical evaluation of the "smoothness" defects according to claim 6, characterized in that the system (2) of illumination and image acquisition comprises a light source (5, 9, 10) and a digital camera (6, 11), and also in that the orientation of the light and of the camera in relation to the plane of the paper, as well as the light spectrum and beam opening, can be chosen as a function of the defect to be detected.
The equipment for the automatic and integrated optical evaluation of the "smoothness" defects according to claim 6, characterized in that the computer based control system (3) for the positioning of the paper in the transport system, is totally automatic, therefore without the need of any human intervention for its operation after loading the paper sample .
The use of the equipment for the automatic and integrated optical evaluation of "smoothness" defects according to claims 6 to 9, characterized in that it is applied namely to the optical evaluation of: a. topography defects of the streak type, b. flaws of starch surface application, c. water-lines defects.
PCT/PT2003/000014 2002-10-08 2003-10-08 Method and apparatus for the optical evaluation of a paper surface WO2004034041A1 (en)

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Application Number Priority Date Filing Date Title
AU2003267886A AU2003267886A1 (en) 2002-10-08 2003-10-08 Method and apparatus for the optical evaluation of a paper surface
SE0500761A SE528526C2 (en) 2002-10-08 2005-04-07 Method and apparatus for optical evaluation of a paper surface
FI20050383A FI121033B (en) 2002-10-08 2005-04-14 Method and devices for optical evaluation of paper surface

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PT102849 2002-10-08
PT102849A PT102849B (en) 2002-10-08 2002-10-08 AUTOMATIC METHOD AND INSTALLATION OF OPTICAL ASSESSMENT OF THE ASPECT OF THE PAPER SURFACE

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WO2004034041A1 true WO2004034041A1 (en) 2004-04-22
WO2004034041B1 WO2004034041B1 (en) 2004-05-27

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Publication number Priority date Publication date Assignee Title
DE102004061951A1 (en) * 2004-12-23 2006-07-06 Man Roland Druckmaschinen Ag Quality control device for use in sheet offset printing machine, has camera for analysing printed sheet by recording light reflection, light emission and shadowing effects with respect to image units embossed in areas of printed sheet
EP1898207A1 (en) * 2006-09-06 2008-03-12 ABB Oy Method and apparatus for measuring intensity of laid lines in a strip-like product
WO2009015934A1 (en) * 2007-08-02 2009-02-05 Voith Patent Gmbh Method and device for identifying structures in a fibrous material web or in a fibrous material suspension jet
US8174690B2 (en) 2007-05-11 2012-05-08 Argos Solutions As Apparatus for characterizing a surface structure
CN103672589A (en) * 2013-10-14 2014-03-26 中科院成都信息技术股份有限公司 Image detection lighting equipment
CN104458750A (en) * 2013-09-25 2015-03-25 中国科学院沈阳自动化研究所 Automatic aluminum profile surface defect detecting equipment based on machine vision
CN117387473A (en) * 2023-12-12 2024-01-12 维达纸业（中国）有限公司 Full-automatic intelligent smoothness measuring device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105651783A (en) * 2016-01-08 2016-06-08 深圳控石智能系统有限公司 Dynamic picture detection machine tool and using method thereof

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4222064A (en) * 1977-03-07 1980-09-09 Nekoosa Papers Inc. Optical property measurement system and method
FR2631112A1 (en) * 1988-05-04 1989-11-10 Cattarino Yvan Method and device for automatically detecting, visually displaying and measuring the position of the water line of a paper-making machine
US5068799A (en) * 1985-04-24 1991-11-26 Jarrett Jr Harold M System and method for detecting flaws in continuous web materials
EP1001249A1 (en) * 1997-03-28 2000-05-17 Newcreation Co., Ltd. Surface inspecting device and surface inspecting method
WO2000068638A1 (en) * 1999-05-10 2000-11-16 Metso Paper Automation Oy Method and measuring arrangement for measuring paper surface
WO2001086228A1 (en) * 2000-05-05 2001-11-15 Roger Tuomas A method to measure surface structure

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4222064A (en) * 1977-03-07 1980-09-09 Nekoosa Papers Inc. Optical property measurement system and method
US5068799A (en) * 1985-04-24 1991-11-26 Jarrett Jr Harold M System and method for detecting flaws in continuous web materials
FR2631112A1 (en) * 1988-05-04 1989-11-10 Cattarino Yvan Method and device for automatically detecting, visually displaying and measuring the position of the water line of a paper-making machine
EP1001249A1 (en) * 1997-03-28 2000-05-17 Newcreation Co., Ltd. Surface inspecting device and surface inspecting method
WO2000068638A1 (en) * 1999-05-10 2000-11-16 Metso Paper Automation Oy Method and measuring arrangement for measuring paper surface
WO2001086228A1 (en) * 2000-05-05 2001-11-15 Roger Tuomas A method to measure surface structure

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004061951A1 (en) * 2004-12-23 2006-07-06 Man Roland Druckmaschinen Ag Quality control device for use in sheet offset printing machine, has camera for analysing printed sheet by recording light reflection, light emission and shadowing effects with respect to image units embossed in areas of printed sheet
DE102004061951B4 (en) * 2004-12-23 2017-10-12 manroland sheetfed GmbH Quality control procedure for surface variable printed matter
EP1898207A1 (en) * 2006-09-06 2008-03-12 ABB Oy Method and apparatus for measuring intensity of laid lines in a strip-like product
US8174690B2 (en) 2007-05-11 2012-05-08 Argos Solutions As Apparatus for characterizing a surface structure
WO2009015934A1 (en) * 2007-08-02 2009-02-05 Voith Patent Gmbh Method and device for identifying structures in a fibrous material web or in a fibrous material suspension jet
CN104458750A (en) * 2013-09-25 2015-03-25 中国科学院沈阳自动化研究所 Automatic aluminum profile surface defect detecting equipment based on machine vision
CN103672589A (en) * 2013-10-14 2014-03-26 中科院成都信息技术股份有限公司 Image detection lighting equipment
CN117387473A (en) * 2023-12-12 2024-01-12 维达纸业（中国）有限公司 Full-automatic intelligent smoothness measuring device
CN117387473B (en) * 2023-12-12 2024-02-23 维达纸业（中国）有限公司 Full-automatic intelligent smoothness measuring device

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AU2003267886A1 (en) 2004-05-04
PT102849A (en) 2004-04-30

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