Method and system for evaluating paper dust on copy paper surface

Abstract

The present invention relates to a method and system for evaluating paper dust on the surface of copy paper. The method comprises: selecting a copy paper sample; using a surface paper dust collecting device to collect paper dust on the surface of the copy paper sample; obtaining a printed strip showing the amount of paper dust on high-gloss coated paper by printing; scanning the printed strip to obtain a first image of the printed strip with grayscale gradations; binarizing the first image to obtain a second image, that is, processing pixel points with grayscale values ​​less than or equal to the grayscale threshold into pure black, and processing pixel points with grayscale values ​​greater than the grayscale threshold into pure white; digitally calculating the proportion of white points in the second image to the total image to obtain the density of paper dust on the copy paper surface. The present invention can achieve the following beneficial technical effects: accurately evaluating the grade of paper dust on the surface of copy paper, and digitally and objectively evaluating the content of paper dust on the surface of copy paper.

Description

Technical Field

[0001] The invention relates to a method and system for evaluating paper dust on the surface of copy paper. Background Art

[0002] In order to evaluate the grade of paper dust on the copy paper surface, the existing test method QB / T 2897 Determination of loose matter on the surface of paper and paperboard is mainly based on the principle of rolling a steel printing disc with transparent roughened ink on the surface of the IGT (Institute of Graphic Technology) printability tester on the test surface of the sample for 25 weeks to collect loose matter (paper dust) on the paper surface, and then rolling a rubber-coated printing disc with black ink on the surface face to face for one week to transfer the ink to the surface of the steel printing disc, and then using the steel printing disc to print a high-gloss coated paper strip on the IGT printing proofer. The number of white spots on the printed strip reflects the amount of loose matter on the paper surface collected by the steel disc. The printed strip is compared with the number of white spots on the sample strip in the standard method to determine the visual grade.

[0003] However, the IGT surface loose matter results are determined by comparing the IGT loose matter grading chart, which is divided into grades 1 to 6. Since there is less paper dust on the surface of copy paper, it is basically between 2 and 3 according to the subjective judgment of the grading chart, and it is difficult to distinguish, which is not conducive to the quality evaluation and production improvement of copy paper.

[0004] In addition, the surface loose material collection device has a two-wheel structure, and the rear wheel is fixed and can only rotate in place. The handle uses the rear wheel as a fulcrum to drive the front wheel to rotate to collect paper powder. When collecting surface loose materials, the experimenter pushes the handle to move the collection wheel on the sample surface. Because different experimenters or the same experimenter use different forces and angles when pushing the handle each time, the steel printing disc is subject to different forces and directions in multiple experiments, which affects the steel printing disc's collection of paper powder based on its own gravity, resulting in different amounts of collected surface loose materials, and ultimately leading to deviations in the results. In particular, due to inertia, the handle is easily pressed down, causing the front wheel to press the paper surface too lightly, and the collected paper powder cannot reflect the actual situation. Summary of the invention

[0005] An object of the present invention is to provide a method for evaluating paper dust on the surface of copy paper, which can at least partially solve the problems existing in the prior art, accurately evaluate the grade of paper dust on the surface of copy paper, and conduct a digital and objective evaluation of the paper dust content on the surface of copy paper.

[0006] The above object of the present invention is achieved by a method for evaluating paper powder on the surface of copy paper, the method comprising:

[0007] Select a copy paper sample;

[0008] Using a surface paper dust collecting device to collect paper dust on the surface of the copy paper sample;

[0009] Printing is used to obtain a printed strip showing the amount of paper powder on high-gloss coated paper;

[0010] Scanning the printed strip to obtain a first image of the printed strip having grayscale levels;

[0011] Binarizing the first image to obtain a second image, that is, processing pixels whose grayscale values ​​are less than or equal to the grayscale threshold into pure black, and processing pixels whose grayscale values ​​are greater than the grayscale threshold into pure white;

[0012] The proportion of white spots in the second image to the total image is digitally calculated to obtain the paper dust density on the copy paper surface.

[0013] According to the above technical scheme, the copy paper surface dust evaluation method of the present invention can achieve the following beneficial technical effects: it can accurately evaluate the copy paper surface dust grade and conduct a digital and objective evaluation of the copy paper surface dust content.

[0014] Preferably, the grayscale is a 256-level grayscale, and the grayscale threshold is 35-45.

[0015] According to the above technical scheme, the copy paper surface dust evaluation method of the present invention can achieve the following beneficial technical effects: through an appropriate grayscale threshold, the copy paper surface dust grade can be more accurately evaluated, and the copy paper surface dust content can be digitally and objectively evaluated.

[0016] More preferably, the grayscale threshold is 40.

[0017] According to the above technical scheme, the copy paper surface dust evaluation method of the present invention can achieve the following beneficial technical effects: through a better grayscale threshold, the copy paper surface dust grade can be more accurately evaluated, and the copy paper surface dust content can be digitally and objectively evaluated.

[0018] Preferably, the method further comprises: converting white dots in the second image into green dots, and compounding the green dots with the first image to obtain a third image.

[0019] According to the above technical scheme, the copy paper surface paper dust evaluation method of the present invention can achieve the following beneficial technical effects: the grayscale threshold value can be verified, so that by selecting an appropriate grayscale threshold value, the copy paper surface paper dust grade can be more accurately evaluated, and the copy paper surface paper dust content can be digitally and objectively evaluated.

[0020] Preferably, the method further comprises: classifying the copy paper into corresponding copy paper powder grades according to the obtained copy paper surface powder density;

[0021] Among them, the grade of copy paper powder is divided into five levels, with paper powder density of 0-0.1% as level 1, 0.1-0.3% as level 2, 0.3-0.7% as level 3, 0.7-1% as level 4, and 1-2% as level 5.

[0022] According to the above technical solution, the copy paper surface dust evaluation method of the present invention can achieve the following beneficial technical effects: it can more appropriately classify the copy paper surface dust grades, facilitating effective distinction.

[0023] Another object of the present invention is to provide a copy paper surface dust evaluation system, which can at least partially solve the problems existing in the prior art, accurately evaluate the copy paper surface dust grade, and conduct a digital and objective evaluation of the copy paper surface dust content.

[0024] The above objects of the present invention are achieved by a copy paper surface paper powder evaluation system, the system comprising a surface paper powder collecting device, a printability meter, a scanning device, and an image processing and computing device;

[0025] The surface paper dust collecting device is configured to collect paper dust on the surface of the selected copy paper sample;

[0026] The printability meter is configured to obtain a printed strip showing the amount of paper powder on high-gloss coated paper by printing;

[0027] The scanning device is configured to scan the printed strip to obtain a first image of the printed strip having grayscale levels;

[0028] The image processing and computing device includes an image processing module and a computing module. The image processing module is configured to perform binarization processing on the first image to obtain a second image, that is, to process pixel points with grayscale values ​​less than or equal to the grayscale threshold into pure black, and to process pixel points with grayscale values ​​greater than the grayscale threshold into pure white. The computing module is configured to digitally calculate the proportion of white points in the second image to the total image to obtain the paper powder density on the surface of the copy paper.

[0029] According to the above technical scheme, the copy paper surface dust evaluation system of the present invention can achieve the following beneficial technical effects: it can accurately evaluate the copy paper surface dust grade and conduct digital and objective evaluation of the copy paper surface dust content.

[0030] Preferably, the grayscale is a 256-level grayscale, and the grayscale threshold is 35-45.

[0031] According to the above technical scheme, the copy paper surface dust evaluation system of the present invention can achieve the following beneficial technical effects: through appropriate grayscale thresholds, the copy paper surface dust grade can be more accurately evaluated, and the copy paper surface dust content can be digitally and objectively evaluated.

[0032] More preferably, the grayscale threshold is 40.

[0033] According to the above technical scheme, the copy paper surface dust evaluation system of the present invention can achieve the following beneficial technical effects: through a better grayscale threshold, it can more accurately evaluate the copy paper surface dust grade and conduct a digital and objective evaluation of the copy paper surface dust content.

[0034] Preferably, the image processing module is further configured to: convert white dots in the second image into green dots, and composite them with the first image to obtain a third image.

[0035] According to the above technical scheme, the copy paper surface paper dust evaluation system of the present invention can achieve the following beneficial technical effects: it can verify the value of the grayscale threshold, so that by selecting an appropriate grayscale threshold, it can more accurately evaluate the copy paper surface paper dust grade and conduct a digital and objective evaluation of the copy paper surface paper dust content.

[0036] Preferably, the surface paper powder collecting device comprises a surface paper powder collecting wheel placement shaft, a surface paper powder collecting wheel, a collecting wheel pivot shaft, a connecting bracket, a transfer wheel placement shaft, a supporting component, a limiting component, a handle, a first connecting rod, and a second connecting rod;

[0037] The surface paper dust collecting wheel placement shaft is installed at the lower front part of the surface paper dust collecting device by means of the collection wheel pivot shaft, the surface paper dust collecting wheel is detachably installed on the surface paper dust collecting wheel placement shaft, the transfer wheel placement shaft and the support component are respectively installed at the upper middle part and the lower middle part of the surface paper dust collecting device by means of the connecting bracket, and are connected to the second connecting rod, the first connecting rod is connected to the rear of the second connecting rod, and the handle is connected to the rear of the first connecting rod;

[0038] The limiting component is installed below the rear portion of the surface paper dust collecting device and is connected to the rear portion of the handle.

[0039] According to the above technical scheme, the copy paper surface paper dust evaluation system of the present invention can achieve the following beneficial technical effects: limiting the up and down movement of the surface paper dust collecting device during the pushing process, especially limiting the downward pressure, solving the problem of result deviation caused by different pushing force sizes and directions, and ensuring that the printed strip truly reflects the paper dust content or grade.

[0040] Preferably, the surface paper dust collecting device further comprises a horizontal pushing component, which is installed above the rear of the surface paper dust collecting device and connected to the rear of the handle.

[0041] According to the above technical scheme, the copy paper surface paper powder evaluation system of the present invention can achieve the following beneficial technical effects: it ensures that the friction force of the collection wheel is the same during 25 rotations, thereby ensuring that the paper powder collection conditions of different paper samples and different paths are consistent, reducing human errors.

[0042] Preferably, the supporting member is a supporting wheel.

[0043] According to the above technical solution, the copy paper surface dust evaluation system of the present invention can achieve the following beneficial technical effects: the support wheel is more conducive to rolling along with the surface dust collecting wheel. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The figure is a flow chart of a method for evaluating paper dust on the surface of copy paper according to an embodiment of the present invention.

[0045] Figure 2 Schematic diagram of a system for evaluating paper dust on the surface of copy paper according to an embodiment of the present invention.

[0046] Figure 3A Schematic diagram of a surface dust collecting device in a copy paper surface dust evaluation system according to an embodiment of the present invention.

[0047] Figure 3B The figure is a schematic diagram of the position of the placement axis of the surface paper dust collecting wheel in the surface paper dust collecting device in the copy paper surface paper dust evaluation system according to an embodiment of the present invention.

[0048] Figure 3C The figure is a schematic diagram of the position of the transfer wheel placement shaft in the surface paper dust collecting device in the copy paper surface paper dust evaluation system according to an embodiment of the present invention.

[0049] Figure 4 These are the first image, the second image and the third image of the five-level copy paper of the present invention.

[0050] Reference numerals list

[0051] 101. Surface paper powder collecting wheel;

[0052] 102. Collection wheel pivot shaft;

[0053] 103. Connecting bracket;

[0054] 104. transfer wheel;

[0055] 105. Supporting components;

[0056] 106. Limiting components;

[0057] 107. Pushing parts;

[0058] 108. Handle;

[0059] 109. a first connecting rod;

[0060] 110. second connecting rod;

[0061] 111. Surface paper powder collecting wheel placement shaft;

[0062] 112. Transfer wheel placement shaft;

[0063] G1, first image;

[0064] G2, second image;

[0065] G3, third image. DETAILED DESCRIPTION

[0066] The specific embodiments of the present invention will be described below. It should be noted that in the specific description of these embodiments, in order to be concise and clear, this specification cannot provide a detailed description of all the features of the actual embodiments. It should be understood that in the actual implementation of any embodiment, just as in the process of any engineering project or design project, in order to achieve the specific goals of the developer and to meet system-related or business-related restrictions, various specific decisions are often made, and this will also change from one embodiment to another. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the content disclosed by the present invention, some changes in design, manufacturing or production based on the technical content disclosed in this disclosure are just conventional technical means, and should not be understood as insufficient content of this disclosure.

[0067] Unless otherwise defined, the technical or scientific terms used in the claims and the specification shall have the usual meaning understood by persons with ordinary skills in the technical field to which the invention belongs. The words "first", "second" and similar words used in the patent application specification and the claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "One" or "one" and other similar words do not indicate a quantitative limitation, but indicate the existence of at least one. "Include" or "comprises" and other similar words mean that the elements or objects appearing before "include" or "comprises" include the elements or objects listed after "include" or "comprises" and their equivalent elements, and do not exclude other elements or objects. "Connected" or "connected" and other similar words are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0068] Figure 1 The figure is a flow chart of a method for evaluating paper dust on the surface of copy paper according to an embodiment of the present invention. Figure 2 Schematic diagram of a system for evaluating paper dust on the surface of copy paper according to an embodiment of the present invention.

[0069] like Figure 1 As shown, according to one embodiment of the present invention, a method for evaluating paper dust on the surface of copy paper includes:

[0070] Select a copy paper sample;

[0071] A surface paper powder collecting device is used to collect paper powder on the surface of the copy paper sample;

[0072] A printed strip showing the amount of paper dust (i.e., the paper dust collected by the surface paper dust collecting device) is obtained on the high-gloss coated paper by printing;

[0073] Scanning the printed strip to obtain a first image G1 of the printed strip with grayscale;

[0074] Binarization is performed on the first image G1 to obtain a second image G2, that is, pixels whose grayscale values ​​are less than or equal to the grayscale threshold are processed into pure black (that is, the grayscale value is 0), and pixels whose grayscale values ​​are greater than the grayscale threshold are processed into pure white (that is, the grayscale value is 255);

[0075] The proportion of white dots in the second image G2 to the total image (ie, the proportion of white pixels to the total image pixels, also referred to as white dot density) is digitally calculated to obtain the paper dust density on the copy paper surface.

[0076] According to the above technical scheme, the copy paper surface dust evaluation method of the present invention can achieve the following beneficial technical effects: it can accurately evaluate the copy paper surface dust grade and conduct a digital and objective evaluation of the copy paper surface dust content.

[0077] It should be noted that the printed strip showing the amount of paper dust obtained on high-gloss coated paper by printing specifically means that black ink is transferred to the surface paper dust collecting wheel, and there is no black ink where there is paper dust. Then the coated paper is printed on the printability tester, so that black ink cannot be provided where there is paper dust, forming white spots.

[0078] Preferably, the grayscale is a 256-level grayscale, and the grayscale threshold is 35-45.

[0079] According to the above technical scheme, the copy paper surface dust evaluation method of the present invention can achieve the following beneficial technical effects: through an appropriate grayscale threshold, the copy paper surface dust grade can be more accurately evaluated, and the copy paper surface dust content can be digitally and objectively evaluated.

[0080] It should be noted that 256 levels of grayscale are the optimal grayscale levels. Under different scanning conditions and software settings, grayscale levels lower than 256 are possible, such as 64 levels, 128 levels, etc., and grayscale levels higher than 256 are also possible, such as 512 levels, etc.

[0081] More preferably, the grayscale threshold is 40.

[0082] According to the above technical scheme, the copy paper surface dust evaluation method of the present invention can achieve the following beneficial technical effects: through a better grayscale threshold, the copy paper surface dust grade can be more accurately evaluated, and the copy paper surface dust content can be digitally and objectively evaluated.

[0083] Preferably, the method for evaluating paper dust on the surface of copy paper further comprises: converting white dots in the second image G2 into green dots, and combining the green dots with the first image G1 to obtain a third image G3.

[0084] According to the above technical scheme, the copy paper surface dust evaluation method of the present invention can achieve the following beneficial technical effects: the grayscale threshold value can be verified, so that by selecting an appropriate grayscale threshold value, the copy paper surface dust grade can be more accurately evaluated, and the copy paper surface dust content can be digitally and objectively evaluated. In other words, the green dots cover the white dots, so that the missing (if any) white dots can be seen more clearly; then by fine-tuning the grayscale threshold value, the white dots in the first image are basically covered by the green dots, and the grayscale threshold value at this time is more appropriate.

[0085] Preferably, the copy paper surface dust evaluation method further comprises: classifying the copy paper into corresponding copy paper dust grades according to the obtained copy paper surface dust density;

[0086] Among them, the grade of copy paper powder is divided into five grades (for example, see Figure 4 ), paper powder density 0-0.1% is level 1, 0.1-0.3% is level 2, 0.3-0.7% is level 3, 0.7-1% is level 4, and 1-2% is level 5.

[0087] According to the above technical solution, the copy paper surface dust evaluation method of the present invention can achieve the following beneficial technical effects: it can more appropriately classify the copy paper surface dust grades, facilitating effective distinction.

[0088] like Figure 2 As shown, according to one embodiment of the present invention, a system for evaluating the surface paper dust of copy paper includes a surface paper dust collecting device, a printability meter, a scanning device, and an image processing and computing device;

[0089] The surface paper dust collecting device is configured to collect paper dust on the surface of the selected copy paper sample;

[0090] The printability meter is configured to obtain a printed strip showing the amount of paper dust (i.e., the paper dust collected by the surface paper dust collecting device) on the high gloss coated paper by printing;

[0091] The scanning device is configured to scan the printed strip to obtain a first image G1 of the printed strip having grayscale levels;

[0092] The image processing and computing device includes an image processing module and a computing module. The image processing module is configured to perform binarization processing on the first image G1 to obtain a second image G2, that is, to process pixel points with grayscale values ​​less than or equal to the grayscale threshold as pure black, and to process pixel points with grayscale values ​​greater than the grayscale threshold as pure white. The computing module is configured to digitally calculate the proportion of white points in the second image G2 to the total image to obtain the paper powder density on the surface of the copy paper.

[0093] According to the above technical scheme, the copy paper surface dust evaluation system of the present invention can achieve the following beneficial technical effects: it can accurately evaluate the copy paper surface dust grade and conduct digital and objective evaluation of the copy paper surface dust content.

[0094] Preferably, the grayscale is a 256-level grayscale, and the grayscale threshold is 35-45.

[0095] According to the above technical scheme, the copy paper surface dust evaluation system of the present invention can achieve the following beneficial technical effects: through appropriate grayscale thresholds, the copy paper surface dust grade can be more accurately evaluated, and the copy paper surface dust content can be digitally and objectively evaluated.

[0096] More preferably, the grayscale threshold is 40.

[0097] According to the above technical scheme, the copy paper surface dust evaluation system of the present invention can achieve the following beneficial technical effects: through a better grayscale threshold, it can more accurately evaluate the copy paper surface dust grade and conduct a digital and objective evaluation of the copy paper surface dust content.

[0098] Preferably, the image processing module is further configured to: convert white dots in the second image G2 into green dots, and combine them with the first image G1 to obtain a third image G3.

[0099] According to the above technical scheme, the paper dust evaluation system of the copy paper surface of the present invention can achieve the following beneficial technical effects: the grayscale threshold value can be verified, so that by selecting an appropriate grayscale threshold value, the paper dust level of the copy paper surface can be more accurately evaluated, and the paper dust content of the copy paper surface can be digitally and objectively evaluated. In other words, the green dots cover the white dots, so that the missing (if any) white dots can be seen more clearly; then by fine-tuning the grayscale threshold value, the white dots in the first image are basically covered by the green dots, and the grayscale threshold value at this time is more appropriate.

[0100] Figure 3A Schematic diagram of a surface dust collecting device in a copy paper surface dust evaluation system according to an embodiment of the present invention. Figure 3B The figure is a schematic diagram of the position of the placement axis of the surface paper dust collecting wheel in the surface paper dust collecting device in the copy paper surface paper dust evaluation system according to an embodiment of the present invention. Figure 3C The figure is a schematic diagram of the position of the transfer wheel placement shaft in the surface paper dust collection device in the copy paper surface paper dust evaluation system according to an embodiment of the present invention. Preferably, the surface paper dust collection device comprises a surface paper dust collection wheel placement shaft 111 (front end shaft), a collection wheel pivot shaft 102, a connecting bracket 103, a transfer wheel placement shaft 112 (rear end shaft), a supporting component 105, a limiting component 106, a handle 108, a first connecting rod 109, and a second connecting rod 110;

[0101] The surface paper dust collecting wheel placement shaft 111 is installed at the front lower part of the surface paper dust collecting device by means of the collecting wheel pivot shaft 102, the transfer wheel placement shaft 112 and the support component 105 are installed at the upper middle part and the lower middle part of the surface paper dust collecting device by means of the connecting bracket 103, and are connected to the second connecting rod 110, the first connecting rod 109 is connected to the rear of the second connecting rod 110, and the handle 108 is connected to the rear of the first connecting rod 109;

[0102] The limiting component 106 is installed at the lower rear portion of the surface paper dust collecting device and is connected to the rear portion of the handle 108 .

[0103] According to the above technical scheme, the copy paper surface paper dust evaluation system of the present invention can achieve the following beneficial technical effects: limiting the up and down movement of the surface paper dust collecting device during the pushing process, especially limiting the downward pressure, solving the problem of result deviation caused by different pushing force sizes and directions, and ensuring that the printed strip truly reflects the paper dust content or grade.

[0104] Preferably, the limiting component 106 includes a 3 cm long bracket and a cylindrical wheel with a diameter of 4 cm and a weight of 1 kg installed below the bracket. After adding the limiting component, the wheel of the limiting component and the wheel of the collecting device itself form a straight line, limiting the downward movement of the original handle. The wheel of the limiting component is relatively heavy, so it also prevents the original handle from moving upward unconsciously.

[0105] Preferably, the surface paper dust collecting device further comprises a horizontal pushing component 107 , which is installed above the rear portion of the surface paper dust collecting device and connected to the rear portion of the handle 108 .

[0106] According to the above technical scheme, the copy paper surface paper powder evaluation system of the present invention can achieve the following beneficial technical effects: it ensures that the friction force of the collection wheel is the same during 25 rotations, thereby ensuring that the paper powder collection conditions of different paper samples and different paths are consistent, reducing human errors.

[0107] Preferably, the horizontal push component 107 includes a horizontal push handle with a length of 10 cm. The horizontal push component is designed as a vertical horizontal push handle. The experimenter holds the handle and pushes the collecting wheel horizontally under the guidance of the limiting component. Even if different experimenters use different forces, the friction force of the collecting wheel during the 25 rotations is the same, thus ensuring that the collection conditions of paper powder of different paper samples and different paths are consistent, reducing human errors.

[0108] Preferably, the support member 105 is a support wheel.

[0109] According to the above technical solution, the copy paper surface dust evaluation system of the present invention can achieve the following beneficial technical effects: the support wheel is more conducive to rolling along with the surface dust collecting wheel.

[0110] Preferably, the surface paper dust collecting device further comprises a surface paper dust collecting wheel 101 , and the surface paper dust collecting wheel 101 is detachably mounted on the surface paper dust collecting wheel placement shaft 111 .

[0111] According to the above technical scheme, the copy paper surface paper dust evaluation system of the present invention can achieve the following beneficial technical effects: the surface paper dust collecting wheel can be detachably installed on the surface paper dust collecting wheel placement shaft, so it is convenient to remove the surface paper dust collecting wheel before collecting paper dust to apply transparent roughened ink, and then install it on the surface paper dust collecting wheel placement shaft after coating.

[0112] Preferably, the transfer wheel 104 is detachably mounted on the transfer wheel placement shaft 112 , and the surface paper powder collecting wheel 101 connected to the collecting wheel pivot shaft 102 is pivoted around the pivot axis to contact the transfer wheel 104 , so as to transfer the black ink coated on the transfer wheel 104 to the surface paper powder collecting wheel 101 .

[0113] Specific implementation steps

[0114] 1.Paper pattern selection steps

[0115] 1.1 Before testing, the paper samples must be treated at a constant temperature of (23.0±1.0)℃ and a constant humidity of (50±2)RH% for more than 4 hours.

[0116] 1.2 Sampling: After opening the package of 500 pages of copy paper, remove about 100 sheets of paper from the top, take out about 10 sheets of paper, then remove about 100 sheets of paper, take out about 10 sheets of paper, then remove about 100 sheets of paper, take out about 10 sheets of paper. During the sampling process, avoid slipping between the pages.

[0117] 2. Paper powder collection steps

[0118] 2.1 According to the IGT operating procedures, a steel printing disc (i.e., a surface paper powder collecting wheel) is evenly coated with transparent roughened ink, wherein the diameter of the steel printing disc is 4 cm, the width is 2 cm, and the thickness of the transparent roughened ink is 0.32 μm.

[0119] 2.2 Put the IGT steel printing plate on the front end shaft of the surface loose material collection rack, and gently push it flat along the long side (vertical direction) in the middle of an A4 paper to ensure that the steel printing plate rolls one circle on the paper to collect paper powder on the paper surface.

[0120] 25 sheets of paper were tested, and the middle area of ​​each A4 paper was rolled one circle along the length direction, and a total of 25 cycles of paper dust were collected. (If there is more or less paper dust on the surface of the copy paper, the number of collection cycles can be reduced or increased, but it must be consistent between the compared samples)

[0121] 3. Printing strip operation steps

[0122] 3.1 According to the IGT operating steps, black ink is evenly applied to the rubber-coated printing disc (i.e., the transfer wheel), wherein the rubber-coated printing disc has a diameter of 4 cm, a width of 2 cm, and a thickness of 1.2 μm.

[0123] 3.2 Place the rubber-coated printing disc on the rear end shaft of the surface loose material collection rack. According to the IGT operating steps, the steel printing disc that has collected paper powder is tightly rotated with the rubber-coated printing disc for one circle, and the black ink on the rubber-coated printing disc is transferred to the steel printing disc.

[0124] 3.3 According to the IGT operating steps, the steel printing disc was placed on the printing frame and printed on the high-gloss coated paper to obtain a printing strip (25 cm long and 2 cm wide). The printing parameters were: printing pressure was 250 N, speed mode was uniform, and the final printing speed was 0.2 m / s.

[0125] 4. Scanning steps

[0126] The printed sample strip was scanned with a FUJI XEROX ApeosPort-VI C5571 printer, and the parameters were set as follows: 256 grayscale levels were selected for color mode, dark (+3) for scanning density, strong for clarity, photo for original image quality, yes for background removal, normal for contrast, no for photo paper scanning, no for reverse printing prevention, 600 dpi for scanning resolution, automatic detection for scanning size, 100% for scanning magnification, single-sided for double-sided original transport, no for mixed-size original transport, text up for original placement direction, no for book and periodical paging, 2mm, 2mm and 0mm for border removal, highest quality for image quality, large for file size, and PDF for output file format. Thus, a first image with 256 grayscale levels of the printed strip was obtained.

[0127] 5. Image processing steps

[0128] 5.1 Open the digital analysis software (image processing computing device) of the present invention, import the scanned image of the printed strip (first image), set the grayscale threshold (for copy paper, the grayscale threshold is preferably set to 35-45, more preferably set to 40), and binarize the first image to obtain the second image, that is, process the pixels with grayscale values ​​less than or equal to the grayscale threshold 40 into pure black, and process the pixels with grayscale values ​​greater than the grayscale threshold 40 into pure white.

[0129] 5.2 Convert the white dots in the second image to green dots and combine them with the first image to obtain the third image, thereby verifying the value of the grayscale threshold. After testing, when the grayscale threshold is set to 40, the white dots on the third image are all covered by green dots, indicating that the grayscale threshold value is appropriate. If necessary, the grayscale threshold value can be fine-tuned.

[0130] 6. Paper powder density calculation steps

[0131] The proportion of white dots in the second image to the total image (ie, the proportion of the number of white pixels to the total number of image pixels, also referred to as white dot density) is digitally calculated to obtain the paper dust density on the copy paper surface.

[0132] First embodiment

[0133] For two types of copy paper (copy paper A and copy paper B), during the actual printing process, copy paper A has more paper dust than copy paper B. Using the existing IGT surface loose matter test method and system, the visual surface paper dust level of the two copy papers is both level 2, and it is impossible to digitally evaluate the paper dust density and accurately distinguish the paper dust level.

[0134] Similarly, for these two types of copy paper (copy paper A and copy paper B), the copy paper surface paper powder evaluation method and system of the present invention were used to test and evaluate the paper powder density on the copy paper surface. Moreover, for each copy paper (copy paper A and copy paper B), two situations were distinguished: one without a limit component and a push component, and the other with a limit component and a push component, and the two situations were tested and evaluated respectively. The copy paper powder classification was based on the copy paper grade 1 to 5 standard of the present invention. The results are as follows:

[0135]

[0136] It can be seen from this that, compared with the visual surface paper dust grade of the prior art, after adopting the copy paper surface paper dust assessment method and system of the present invention, regardless of whether the limiting component and the push component are added, the copy paper surface paper dust grade can be accurately assessed, and the copy paper surface paper dust content can be digitally and objectively evaluated. Especially in the case of adding the limiting component and the push component, the paper dust on the copy paper surface can be obtained more accurately, reflecting the actual printing powder loss phenomenon, and better distinguishing copy papers with different paper dust grades. In addition, for the same type of copy paper, the paper dust density is smaller without the limiting component and the push component, which also reflects that the handle is easy to press down, thereby reducing the friction between the collection wheel and the paper surface, and reducing the amount of paper dust that should be collected.

[0137] The above describes the specific embodiments of the present invention, but those skilled in the art will understand that the above specific embodiments do not constitute a limitation of the present invention. Those skilled in the art can make various modifications based on the above disclosure without exceeding the scope of the present invention.

Claims

1. A method for evaluating paper dust on the surface of copy paper, characterized in that: The method comprises: Select a copy paper sample; Using a surface paper dust collecting device to collect paper dust on the surface of the copy paper sample; Printing is used to obtain a printed strip showing the amount of paper powder on high-gloss coated paper; Scanning the printed strip to obtain a first image of the printed strip having grayscale levels; Binarizing the first image to obtain a second image, that is, processing pixels whose grayscale values ​​are less than or equal to the grayscale threshold into pure black, and processing pixels whose grayscale values ​​are greater than the grayscale threshold into pure white; The proportion of white spots in the second image to the total image is digitally calculated to obtain the paper dust density on the copy paper surface.

2. The method for evaluating paper dust on the surface of copy paper according to claim 1, characterized in that: The grayscale is 256 levels, and the grayscale threshold is 35-45.

3. The method for evaluating paper dust on the surface of copy paper according to claim 2, characterized in that: The grayscale threshold is 40.

4. The method for evaluating paper dust on the surface of copy paper according to claim 1, characterized in that: The method further includes: converting white dots in the second image into green dots and combining the second image with the first image to obtain a third image.

5. The method for evaluating paper dust on the surface of copy paper according to claim 1, characterized in that: The method further comprises: classifying the copy paper into corresponding copy paper powder grades according to the obtained copy paper surface paper powder density; Among them, the grade of copy paper powder is divided into five levels, with paper powder density of 0-0.1% as level 1, 0.1-0.3% as level 2, 0.3-0.7% as level 3, 0.7-1% as level 4, and 1-2% as level 5.

6. A system for evaluating paper dust on the surface of copy paper, characterized in that: The system includes a surface paper powder collecting device, a printability meter, a scanning device, and an image processing and computing device; The surface paper dust collecting device is configured to collect paper dust on the surface of the selected copy paper sample; The printability meter is configured to obtain a printed strip showing the amount of paper powder on high-gloss coated paper by printing; The scanning device is configured to scan the printed strip to obtain a first image of the printed strip having grayscale levels; The image processing and computing device includes an image processing module and a computing module. The image processing module is configured to perform binarization processing on the first image to obtain a second image, that is, to process pixel points with grayscale values ​​less than or equal to the grayscale threshold into pure black, and to process pixel points with grayscale values ​​greater than the grayscale threshold into pure white. The computing module is configured to digitally calculate the proportion of white points in the second image to the total image to obtain the paper powder density on the surface of the copy paper.

7. The system for evaluating the surface dust of copy paper according to claim 6, characterized in that: The grayscale is 256 levels, and the grayscale threshold is 35-45.

8. The system for evaluating the surface dust of copy paper according to claim 7, characterized in that: The grayscale threshold is 40.

9. The system for evaluating the surface dust of copy paper according to claim 6, characterized in that: The image processing module is further configured to: convert white dots in the second image into green dots, and composite the second image with the first image to obtain a third image.

10. The system for evaluating the surface dust of copy paper according to claim 6, characterized in that: The surface paper powder collecting device comprises a surface paper powder collecting wheel placement shaft (111), a surface paper powder collecting wheel (101), a collecting wheel pivot shaft (102), a connecting bracket (103), a transfer wheel placement shaft (112), a supporting component (105), a limiting component (106), a handle (108), a first connecting rod (109), and a second connecting rod (110); The surface paper dust collecting wheel placement shaft (111) is installed at the lower front part of the surface paper dust collecting device by means of the collection wheel pivot shaft (102); the surface paper dust collecting wheel (101) is detachably installed on the surface paper dust collecting wheel placement shaft (111); the transfer wheel placement shaft (112) and the support component (105) are installed at the upper middle part and the lower middle part of the surface paper dust collecting device respectively by means of the connecting bracket (103), and are connected to the second connecting rod (110); the first connecting rod (109) is connected to the rear of the second connecting rod (110); and the handle (108) is connected to the rear of the first connecting rod (109); The limiting component (106) is installed below the rear of the surface paper powder collecting device and is connected to the rear of the handle (108).

11. The system for evaluating the surface dust of copy paper according to claim 10, characterized in that: The surface paper dust collecting device further comprises a horizontal pushing component (107), which is installed above the rear of the surface paper dust collecting device and connected to the rear of the handle (108).

12. The system for evaluating the surface dust of copy paper according to claim 10, characterized in that: The supporting component (105) is a supporting wheel.

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