Accurate overprinting system for intaglio printing

Abstract

The invention relates to the technical field of intaglio printing error detection, in particular to an accurate overprinting system for intaglio printing, which comprises a scanning module, a data preprocessing module, a curve drawing module, a curve analysis module and an adjusting module, and is characterized in that hue data obtained by a printed product and time data corresponding to the hue data are obtained through scanning of the scanning module; the method comprises the following steps of: processing hue data, drawing a broken line graph about the hue data and time, determining overprinting deviation through the broken line graph, and adjusting the position of a printing cylinder according to the overprinting deviation so as to ensure the accuracy of overprinting, so that a novel overprinting alignment deviation detection technology is provided; according to the technology, the accuracy of overprinting is guaranteed by analyzing the hue data, the limitation of overprinting marks is avoided, the stability and reliability of detection are improved, meanwhile, the overprinting deviation of each color can be independently detected through innovative hue data analysis, accumulation of errors is avoided, and the accuracy of overprinting is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of gravure printing error detection, in particular to a precise overprinting system for gravure printing. Background Art

[0002] Gravure printing involves engraving or etching the printing plate to create recessed areas for the image or text. These recessed areas are then filled with ink and transferred to the substrate. Gravure overprinting refers to the process in which each printing unit (each consisting of a plate cylinder, impression cylinder, and inking system) sequentially prints each color onto the substrate, precisely superimposing them to create a complete, color-coded printed product. During the overprinting process, color registration / registration deviations can occur for various reasons. The magnitude of these deviations is variable, necessitating monitoring and adjustment of the overprint of each color group to ensure print quality.

[0003] Existing technologies mostly use sensors or cameras to detect the position of the overprint mark in real time or track the previous color to perform overprinting, ensuring that the marks of each color completely overlap, thereby achieving overprint alignment. For example, Chinese patent application publication number CN116852855A discloses a multi-color overprinting method for an electronic axis gravure printing machine. By establishing a preset acceleration formula, a target acceleration curve is obtained. In the acceleration stage at the early stage of overprinting, each printing color group except the first printing color group is controlled to track the previous color for overprinting to maintain the tracking response speed of the early printing. After entering the steady-speed stage, each printing color group except the first printing color group is controlled to track the first color for overprinting. In order to maintain the overprinting speed in the early stage and avoid the cumulative error between colors after the steady speed and maintain the overprinting speed, the target acceleration curve is divided into an acceleration stage and a steady-speed stage. In the acceleration stage, overprinting is performed by tracking the previous color. In the steady-speed stage, each printing color group has obtained the overprinting color code signal corresponding to the first printing color group. In this case, overprinting is performed by tracking the first color, which can maintain a high overprinting speed and improve the overprinting accuracy. As can be seen from the above, the prior art uses the methods of detecting the overprint mark and tracking the previous color for overprinting. On the one hand, the registration by detecting the position of the overprint mark is highly dependent on the overprint mark, and this method is completely dependent on the clarity and visibility of the overprint mark. If the overprint mark is blurred, covered by ink, or affected by the surface characteristics of the material (such as reflective, transparent, etc.), it may cause detection failure or error. On the other hand, if the previous color itself has an error, the subsequent color will follow the previous color and produce cumulative errors, which may cause the subsequent color errors to become larger and larger, thereby reducing the printing quality. Summary of the Invention

[0004] To this end, the present invention provides a precise overprinting system for gravure printing, which is used to overcome the problem in the prior art of detecting the position of the overprint mark or tracking the previous color for overprinting, which is highly dependent on the overprint mark and produces cumulative errors, thereby reducing printing quality.

[0005] To achieve the above object, the present invention provides a precise register system for gravure printing, comprising:

[0006] a scanning module configured to scan a target printed product point by point along a set scanning path to obtain hue data and time data corresponding to the scanning path, wherein the scanning path includes at least a first scanning path and a second scanning path having scanning directions perpendicular to each other, the hue data includes at least first hue data and second hue data, and the time data includes at least first time data corresponding to the first hue data and second time data corresponding to the second hue data;

[0007] a data preprocessing module connected to the scanning module, configured to determine third hue data and third time data corresponding to the third hue data based on the first hue data and the first time data, and to obtain fourth hue data and fourth time data corresponding to the fourth hue data based on the second hue data and the second time data;

[0008] a curve drawing module connected to the data preprocessing module, for drawing a first hue-time broken line graph based on the third hue data and third time data corresponding to the third hue data, and drawing a second hue-time broken line graph based on the fourth hue data and fourth time data corresponding to the fourth hue data;

[0009] a curve analysis module connected to the curve drawing module, configured to determine a deviation value based on the first hue-time broken line graph and the second hue-time broken line graph, and determine an overprint deviation of gravure printing based on the deviation value, a scanning path, and a scanning speed;

[0010] An adjustment module is connected to the curve analysis module and is used to control the mechanical arm to adjust the position of the printing cylinder according to the overprint deviation.

[0011] Furthermore, the first scanning path and the second scanning path both traverse each monochrome printed pattern of the target printed product.

[0012] Furthermore, the data preprocessing module is also preset with first reference hue data and second reference hue data. The data preprocessing module determines the third hue data and the third time data corresponding to the third hue data based on the first hue data and the first reference hue data, and determines the fourth hue data and the fourth time data corresponding to the fourth hue data based on the second hue data and the second reference hue data.

[0013] Furthermore, the data preprocessing module is also used to determine a first change rate based on the first hue data, determine third hue data and third time data corresponding to the third hue data based on the first change rate, determine a second change rate based on the second hue data, and determine fourth hue data and fourth time data corresponding to the fourth hue data based on the second change rate.

[0014] Furthermore, the curve analysis module is also used to determine a first deviation value based on the first hue-time line graph, and determine a first overprint deviation based on the first deviation value, the first scanning path and the scanning speed; determine a second deviation value based on the second hue-time line graph, and determine a second overprint deviation based on the second deviation value, the second scanning path and the scanning speed.

[0015] Furthermore, the curve analysis module is also preset with a first standard line graph and a second standard line graph, and the first deviation value is determined according to the first hue-time line graph and the first standard line graph, and the second deviation value is determined according to the second hue-time line graph and the second standard line graph.

[0016] Furthermore, the adjustment module controls the mechanical arm to adjust the position of the printing cylinder according to the overprint deviation, including:

[0017] The adjustment module controls the robotic arm to adjust the position of the printing cylinder according to the first overprint deviation and the second overprint deviation.

[0018] Furthermore, the system of the present invention also includes an adaptive determination module, which is respectively connected to the curve analysis module and the adjustment module, for determining the current deviation trend based on the historical adjustment direction of the printing roller, and determining the potential overprint deviation based on the current deviation trend, the historical first overprint deviation data and the second overprint deviation data.

[0019] Furthermore, the adaptive determination module determines the current deviation trend according to the historical adjustment direction of the printing cylinder, and determines the potential overprint deviation according to the current deviation trend, the historical first overprint deviation data, and the second overprint deviation data, including:

[0020] Statistics are made on the adjustment directions of the printing rollers for the most recent several times. If the adjustment directions of the printing rollers for the most recent several times are the same, statistics are made on the first overprint deviation data and the second overprint deviation data corresponding to the most recent several times of printing roller adjustments. The minimum value of the first overprint deviation data corresponding to the most recent several times of printing roller adjustments and the minimum value of the second overprint deviation data corresponding to the most recent several times of printing roller adjustments are taken as potential overprint deviations.

[0021] Furthermore, the adjustment module controls the robotic arm to adjust the position of the printing cylinder according to the potential overprint deviation.

[0022] Furthermore, the number of the scanning modules is twice the number of the monochrome printing units of the gravure printing press, and each monochrome printing unit is provided with two scanning modules, and the two scanning modules scan the target printed product according to the first scanning path and the second scanning path respectively.

[0023] Compared with the prior art, the beneficial effect of the present invention lies in that a precise overprinting system for gravure printing of the present invention obtains hue data and time data corresponding to the hue data by scanning the printed product through a scanning module, draws a line graph of the hue data and time after processing the hue data, determines the deviation value through the line graph, determines the overprinting deviation according to the deviation value, the scanning path and the scanning speed, adjusts the position of the printing roller according to the overprinting deviation to ensure the accuracy of the overprinting, and provides a new technology for detecting overprinting alignment deviation. This technology ensures the accuracy of overprinting by analyzing hue data, avoids the limitations of overprinting marks, improves the stability and reliability of detection, and at the same time, through innovative hue data analysis, can independently detect the overprinting deviation of each color, avoids the accumulation of errors, and ensures the accuracy of overprinting.

[0024] Furthermore, the data preprocessing module of the present invention preprocesses the first hue data, the first time data, the second hue data, and the second time data to obtain the third hue data, the third time data, the fourth hue data, and the fourth time data, which greatly reduces the amount of hue data and time data. When drawing a line graph based on the third hue data, the third time data, the fourth hue data, and the fourth time data, it significantly reduces resource consumption and improves drawing efficiency, while avoiding excessive data congestion and improving the visualization effect of the line graph.

[0025] Furthermore, the present invention continuously tracks and compiles statistics on the recent adjustment directions of the printing rollers and the corresponding first and second overprint deviation data through a dynamic feedback mechanism. When it detects that the adjustment directions are consistent for multiple consecutive times, it automatically extracts the minimum value of the two types of deviations as the potential overprint error benchmark, and drives the robotic arm to accurately position and correct the printing roller. Based on the predictive model of historical adjustment trends and real-time deviation analysis, the system can identify and pre-correct potential errors in advance, effectively suppress error accumulation, and enhance overprint stability and accuracy. At the same time, combined with intelligent algorithms and automated control, it can achieve autonomous optimization of the printing process, significantly reduce the frequency of manual intervention, shorten downtime for maintenance, and reduce waste loss, thereby comprehensively improving printing efficiency and finished product quality, and providing the industry with an advanced overprint control solution that combines high precision, strong stability, and intelligent adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the structure of the system of the present invention;

[0027] Figure 2 A schematic diagram of a first scanning path provided by an embodiment of the present invention;

[0028] Figure 3 A schematic diagram of a second scanning path provided by an embodiment of the present invention;

[0029] Figure 4 A schematic diagram of a third scanning path provided by an embodiment of the present invention;

[0030] Figure 5 This is a schematic diagram of a first standard line graph according to an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of a first hue-time line graph according to an embodiment of the present invention;

[0032] Figure 7 Schematic diagram comparing the first standard line graph and the first hue-time line graph according to an embodiment of the present invention.

[0033] In the figure: 1. target printed product (printing material); 2. first scanning path; 3. second scanning path. DETAILED DESCRIPTION

[0034] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0035] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0036] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0037] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0038] See also Figure 1 As shown, an embodiment of the present invention provides a precise overprinting system for gravure printing, comprising:

[0039] A scanning module, configured to scan a target printed product point by point along a set scanning path, taking a scanning start time as a time origin, to obtain hue data and time data corresponding to the scanning path, wherein the scanning path includes at least a first scanning path and a second scanning path having scanning directions perpendicular to each other, the hue data includes at least first hue data and second hue data, and the time data includes at least first time data corresponding to the first hue data and second time data corresponding to the second hue data;

[0040] a data preprocessing module connected to the scanning module, for determining third hue data and third time data corresponding to the third hue data according to the first hue data and the first time data, and

[0041] Obtain fourth hue data and fourth time data corresponding to the fourth hue data according to the second hue data and the second time data;

[0042] a curve drawing module connected to the data preprocessing module, for drawing a first hue-time broken line graph based on the third hue data and third time data corresponding to the third hue data, and drawing a second hue-time broken line graph based on the fourth hue data and fourth time data corresponding to the fourth hue data;

[0043] a curve analysis module connected to the curve drawing module, configured to determine a deviation value based on the first hue-time broken line graph and the second hue-time broken line graph, and determine an overprint deviation of gravure printing based on the deviation value, a scanning path, and a scanning speed;

[0044] An adjustment module is connected to the curve analysis module and is used to control the mechanical arm to adjust the position of the printing cylinder according to the overprint deviation.

[0045] It can be understood that the first hue data and the first time data corresponding to the first hue data are obtained by scanning the target printed product according to the first scanning path, and the second hue data and the second time data corresponding to the second hue data are obtained by scanning the target printed product according to the second scanning path.

[0046] The present invention provides a precise overprint system for gravure printing, which obtains hue data and time data corresponding to the hue data by scanning a printed product through a scanning module, draws a line graph of the hue data and time after processing the hue data, determines the deviation value through the line graph, determines the overprint deviation according to the deviation value, the scanning path and the scanning speed, and adjusts the position of the printing roller according to the overprint deviation to ensure the accuracy of the overprint, providing a new technology for detecting overprint alignment deviation, which ensures the accuracy of the overprint by analyzing the hue data, avoids the limitations of the overprint mark, and improves the stability and reliability of the detection, and at the same time, through the innovative hue data analysis method, can independently detect the overprint deviation of each color, avoid the accumulation of errors, and ensure the accuracy of the overprint.

[0047] Specifically, the first scanning path and the second scanning path both traverse each monochrome printing pattern of the target printed product.

[0048] It can be understood that the first scanning path and the second scanning path are two virtual lines and do not actually exist on the target printed product. After the virtual first scanning path and the second scanning path are determined by the system program, the scanning module scans according to the virtual first scanning path and the second scanning path.

[0049] It can be understood that the first scanning path and the second scanning path both traverse the specific patterns of each monochrome printing of the target printed product: for example, there are three monochrome printing units, the pattern printed by the first monochrome printing unit is the first pattern, the pattern printed by the second monochrome printing unit is the second pattern, and the pattern printed by the third monochrome printing unit is the third pattern. The first scanning path needs to pass through / through all the patterns, that is, pass through / through the first pattern, the second pattern and the third pattern, and the second scanning path also needs to pass through / through all the patterns, that is, pass through / through the first pattern, the second pattern and the third pattern, so that the scanning module can fully obtain the hue data of the color of each monochrome printing of the target printed product or the hue data of the superimposed colors of multiple printings when scanning to obtain hue data.

[0050] like Figure 2 、 Figure 3 and Figure 4 FIG. 2 shows the first scanning path and the second scanning path in several different situations provided by the embodiment of the present invention.

[0051] When determining the first scanning path and the second scanning path, two mutually perpendicular virtual lines can be determined on the target printed product, and the two mutually perpendicular virtual lines can be arbitrarily translated ( Figure 2-Figure 3 state) or rotation ( Figure 2-Figure 4 or Figure 3-Figure 4state), until both the first scanning path and the second scanning path traverse the pattern of each single-color printing of the target printed product.

[0052] As an embodiment, if the target printed product is a square as a whole, the first scanning path and the second scanning path can be two diagonals of the square target printed product, provided that the two diagonals of the square target printed product traverse or pass through each monochrome printed pattern.

[0053] See also Figure 2 As an embodiment, if the target printed product is a rectangle as a whole, the first scanning path and the second scanning path can be parallel to two adjacent sides of the rectangular target printed product respectively.

[0054] The first scanning path and the second scanning path both traverse each monochrome printed pattern of the target printed product, which can ensure that the scanning module can completely obtain the hue data of the target printed product when scanning and obtaining the hue data.

[0055] It is understandable that the first scanning path and the second scanning path are predetermined by the standard typesetting product, and are not determined during the printing and registration detection process.

[0056] It can be understood that when determining the first scanning path and the second scanning path, there may be multiple groups of paths for the first scanning path and the second scanning path that meet the requirements that the first scanning path is perpendicular to the second scanning path and the first scanning path and the second scanning path traverse each monochrome printing pattern of the target printed product. The first scanning path and the second scanning path combination with the shortest longer path among all combinations of the first scanning path and the second scanning path is preferentially selected, so that the scanning module can take the shortest time when scanning according to the scanning path.

[0057] In gravure printing, the ink or color printed by each printing unit is different. Different colors have different hue data. Hue is the primary characteristic of color and the most accurate standard for distinguishing different colors. The present invention scans the printed product during the printing process to collect hue data and time data, and draws a hue-time line graph after processing the hue data and time data. If the gravure printing is accurate, that is, there is no overprint deviation, the drawn hue-time line graph should be exactly the same as the standard line graph (the hue data is the same, and the time data corresponding to the hue data is the same). The data are also the same), if there is a deviation in the gravure printing overprint, that is, the front and rear printing units are not accurately superimposed on the substrate during the overprint process, then the hue data collected by scanning the printed product is also the same (or exists), but due to the overprint deviation (the position deviation between the two different colors before and after), the time data corresponding to the hue data is different, and the drawn hue-time line graph is also different from the standard line graph. The present invention recognizes and calculates the overprint deviation based on the scanned hue data and time data, adjusts the position of the printing roller according to the overprint deviation, and ensures the accuracy of the overprint.

[0058] Specifically, the data preprocessing module is also preset with first reference hue data and second reference hue data. The data preprocessing module determines the third hue data and the third time data corresponding to the third hue data based on the first hue data and the first reference hue data, and determines the fourth hue data and the fourth time data corresponding to the fourth hue data based on the second hue data and the second reference hue data.

[0059] It can be understood that the first reference hue data and the second reference hue data are obtained by pre-processing the first standard hue data and the second standard hue data obtained by scanning the standard typesetting product according to the determined first scanning path and the second scanning path. Taking the first standard hue data obtained by scanning the first scanning path as an example, the specific processing method is as follows:

[0060] There are multiple first standard hue data sets, each collected at a specific time step. Each standard hue data set corresponds to first standard time data. Based on the first standard hue data and the first standard time data, the rate of change between two adjacent first standard hue data sets is calculated: (next first standard hue data set - previous first standard hue data set) / time step. Therefore, if there are N first standard hue data sets, there are N-1 rates of change. These N-1 rates of change are each compared to a rate of change threshold. If a rate of change exceeds the rate of change threshold, the two first standard hue data sets corresponding to that rate of change are retained. This yields n first reference hue data sets and the corresponding time data for the first reference hue data sets, where n is less than or equal to N.

[0061] The change rate threshold can be determined based on the hue of the specific color of monochrome printing. For example, if there are two monochrome printing units and the hue data of the two colors are red with a hue of 0° and green with a hue of 120°, then the change rate threshold is the absolute value of the difference between the two hues / number of monochrome printing units / time step = 120° / 2 / time step.

[0062] Specifically, the third hue data and the third time data corresponding to the third hue data are determined based on the first hue data and the first reference hue data: the first hue data is compared with the first reference hue data, and the time data in the first hue data that is the same as the first reference hue data and the first time data corresponding to the first reference hue data is retained closest to obtain the third hue data and the third time data corresponding to the third hue data.

[0063] The process of determining the fourth hue data and the fourth time data corresponding to the fourth hue data based on the second hue data and the second time data is the same as the process of determining the third hue data and the third time data corresponding to the third hue data based on the first hue data and the first reference hue data, and will not be repeated here.

[0064] The data preprocessing module of the present invention preprocesses the first hue data, the first time data, the second hue data, and the second time data to obtain the third hue data, the third time data, the fourth hue data, and the fourth time data, thereby greatly reducing the amount of hue data and time data. When drawing a curve based on the third hue data, the third time data, the fourth hue data, and the fourth time data, it significantly reduces resource consumption and improves drawing efficiency, while avoiding excessive data congestion and improving the visualization effect of the curve / line graph.

[0065] Specifically, the data preprocessing module is also used to determine a first change rate based on the first hue data, determine the third hue data and the third time data corresponding to the third hue data based on the first change rate, determine a second change rate based on the second hue data, and determine the fourth hue data and the fourth time data corresponding to the fourth hue data based on the second change rate.

[0066] As an embodiment, the data preprocessing module determines a first change rate based on the first hue data, and determines the third hue data and the third time data corresponding to the third hue data based on the first change rate, including: there are a plurality of first hue data, the plurality of first hue data are collected according to a specific time step, each hue data corresponds to first time data, and the first change rate of each two adjacent first hue data is calculated based on the first hue data and the first time data, that is, (latter first hue data - previous first hue data) / time step. Therefore, if there are N first hue data, there are N-1 first change rates, and the N-1 first change rates are respectively compared with the change rate threshold. If a first change rate is greater than the change rate threshold, the two first hue data corresponding to the first change rate are retained, thereby obtaining n third hue data, where n is less than or equal to N, and the time data corresponding to the n third hue data is the third time data.

[0067] The change rate threshold can be determined based on the hue of the specific color of monochrome printing. For example, if there are two monochrome printing units and the hue data of the two colors are red with a hue of 0° and green with a hue of 120°, then the change rate threshold is the absolute value of the difference between the two hues / number of monochrome printing units / time step = 120° / 2 / time step.

[0068] It can be understood that the process / method in which the data preprocessing module determines the second change rate based on the second hue data, and determines the fourth hue data and the fourth time data corresponding to the fourth hue data based on the second change rate is the same as the process / method in which the data preprocessing module determines the first change rate based on the first hue data, and determines the third hue data and the third time data corresponding to the third hue data based on the first change rate, and will not be repeated here.

[0069] The data preprocessing module of the present invention preprocesses the first hue data, the first time data, the second hue data, and the second time data to obtain the third hue data, the third time data, the fourth hue data, and the fourth time data, thereby greatly reducing the amount of hue data and time data. When drawing a curve based on the third hue data, the third time data, the fourth hue data, and the fourth time data, it significantly reduces resource consumption and improves drawing efficiency, while avoiding excessive data congestion and improving the visualization effect of the curve / line chart.

[0070] See also Figure 6 As an implementation manner, in the first hue-time line graph and the second hue-time line graph, the first time data / the second time data are the horizontal coordinates, and the third hue data / the fourth hue data are the vertical coordinates.

[0071] Specifically, the curve analysis module is also used to determine the first deviation value based on the first hue-time line graph, and determine the first overprint deviation based on the first deviation value, the first scanning path and the scanning speed; determine the second deviation value based on the second hue-time line graph, and determine the second overprint deviation based on the second deviation value, the second scanning path and the scanning speed.

[0072] Specifically, the curve analysis module is also preset with a first standard line graph and a second standard line graph, and the first deviation value is determined according to the first hue-time line graph and the first standard line graph, and the second deviation value is determined according to the second hue-time line graph and the second standard line graph.

[0073] In one embodiment, determining the first register deviation includes:

[0074] If the first hue-time line graph is completely identical to or coincides with the first standard line graph, the first overprint deviation is 0;

[0075] If the first hue-time line graph is not completely the same as or overlaps with the first standard line graph, such as Figure 7 As shown, a first deviation value is determined according to the first hue-time broken line graph and the first standard broken line graph, and a first overprint deviation is determined according to the first deviation value, the first scanning path, and the scanning speed.

[0076] Specifically, determining the first deviation value according to the first hue-time broken line graph and the first standard broken line graph, and determining the first overprint deviation according to the first deviation value, the first scanning path, and the scanning speed includes:

[0077] Count the horizontal coordinate deviation values ​​of all deviation points in the first hue-time line graph and the standard line graph, subtract the horizontal coordinates of the deviation points in the first hue-time line graph from the horizontal coordinates of the deviation points in the standard line graph, and determine the first overprint deviation based on the deviation value, the angle between the first scanning path and the boundary of the target printed product, and the scanning speed.

[0078] For ease of description, Figure 2 、 Figure 3 and Figure 4 As shown, A and B are the two end points of the first scanning path, which are also the intersection points of the first scanning path and the boundary of the target printed product (printing material); C and D are the two end points of the second scanning path, which are also the intersection points of the second scanning path and the boundary of the target printed product (printing material); O is the intersection point of the first scanning path and the second scanning path on the target printed product (printing material); and E is a vertex of the target printed product (printing material).

[0079] See also Figure 7In one embodiment, point (t1, a2) coincides with (T1, a2), point (t2, a3) coincides with (T2, a3), point (t3, a1) does not coincide with (T3, a1), and there is a deviation; point (t4, a4) does not coincide with (T4, a4), and there is a deviation.

[0080] The angle between the first scanning path and the boundary of the target printed product is the smaller angle between the first scanning path and the boundary line of the target printed product (ie, the boundary of the printing material).

[0081] See also Figure 4 Taking the first scanning path as an example, the angles between the first scanning path and the boundary of the target printed product are angle ABC and angle BAE respectively, and the smaller angle between the first scanning path and the boundary line of the target printed product (i.e., the boundary of the printing material) is angle ABC.

[0082] Specifically, determining the first overprint deviation according to the deviation value, the angle between the first scanning path and the boundary of the target printed product, and the scanning speed includes:

[0083] The average of the horizontal coordinate deviation values ​​of all deviation points is calculated, and the first overprint deviation = the average of the horizontal coordinate deviation values ​​× the linear speed of the scanning module × the cosine value of the angle between the first scanning path and the boundary of the target printed product.

[0084] In one embodiment, see Figure 7 , there is a deviation between point (t3, a1) and (T3, a1), there is a deviation between point (t4, a4) and (T4, a4), and the average of the horizontal coordinate deviation values ​​of all deviation points is [(t3-T3)+(t4-T4)] / 2.

[0085] The curve analysis module determines the second deviation value based on the second hue-time line graph, and determines the second overprint deviation based on the second deviation value, the second scanning path and the scanning speed in the same way as determining the first deviation value based on the first hue-time line graph, and determining the first overprint deviation based on the first deviation value, the first scanning path and the scanning speed, and will not be repeated here.

[0086] Specifically, the adjustment module controls the mechanical arm to adjust the position of the printing cylinder according to the overprint deviation, including:

[0087] The adjustment module controls the robotic arm to adjust the position of the printing cylinder according to the first overprint deviation and the second overprint deviation.

[0088] Specifically, the adjustment module controls the robotic arm to adjust the printing roller according to the first overprint deviation and the second overprint deviation, respectively. The first overprint deviation and the second overprint deviation represent the adjustment amounts in two directions, that is, the adjustment direction of the first overprint deviation and the second overprint deviation is determined to be horizontal or vertical according to the scanning path, and whether the adjustment is to the left or right in the horizontal direction, and whether the adjustment is to the upward (front) or downward (back) in the vertical direction is determined according to the positive or negative values ​​of the first overprint deviation and the second overprint deviation.

[0089] See also Figure 4 , the angle between the first scanning path and the boundary line of the target printed product (i.e., the boundary of the printing material) in the longitudinal direction (EB direction) is small, and the obtained first overprint deviation is the deviation in the longitudinal direction (EB direction); the longitudinal offset of the printing roller is adjusted according to the first overprint deviation. If the scanning module scans from A to B along the first scanning path and the first overprint deviation is a negative value, the printing roller is adjusted upward in the longitudinal direction (from B→E direction); if the scanning module scans from A to B along the first scanning path and the first overprint deviation is a positive value, the printing roller is adjusted downward in the longitudinal direction (from E→B direction); if the scanning module scans from B to A along the first scanning path and the first overprint deviation is a negative value, the printing roller is adjusted downward in the longitudinal direction (from B→E); if the scanning module scans from B to A along the first scanning path and the first overprint deviation is a positive value, the printing roller is adjusted downward in the longitudinal direction (from E→B), and the adjustment distance is the absolute value of the first overprint deviation.

[0090] See also Figure 4 , the angle between the second scanning path and the boundary line of the target printed product (i.e., the boundary of the printing material) in the horizontal direction (EA direction) is smaller, and the obtained second overprint deviation is the deviation in the horizontal direction (EA direction); the lateral offset of the printing cylinder is adjusted according to the second overprint deviation. If the scanning module scans from C to D along the second scanning path and the second overprint deviation is a negative value, the printing cylinder is adjusted to the left in the horizontal direction (from A→E direction); if the scanning module scans from C to D along the second scanning path and the second overprint deviation is a positive value, the printing cylinder is adjusted to the right in the horizontal direction (from E→A direction); if the scanning module scans from D to C along the second scanning path and the second overprint deviation is a negative value, the printing cylinder is adjusted to the right in the horizontal direction (from E→A direction); if the scanning module scans from D to C along the second scanning path and the second overprint deviation is a positive value, the printing cylinder is adjusted to the left in the horizontal direction (from A→E direction), and the adjustment distance is the absolute value of the second overprint deviation.

[0091] Specifically, the precise overprinting system for gravure printing of the present invention also includes an adaptive determination module, which is respectively connected to the curve analysis module and the adjustment module, for determining the current deviation trend based on the historical adjustment direction of the printing roller, and determining the potential overprinting deviation based on the current deviation trend, the historical first overprinting deviation data and the second overprinting deviation data.

[0092] Specifically, the adaptive determination module determines the current deviation trend according to the historical adjustment direction of the printing cylinder, and determines the potential overprint deviation according to the current deviation trend, the historical first overprint deviation data and the second overprint deviation data, including:

[0093] Statistics are made on the adjustment directions of the printing rollers for the most recent several times. If the adjustment directions of the printing rollers for the most recent several times are the same, statistics are made on the first overprint deviation data and the second overprint deviation data corresponding to the most recent several times of printing roller adjustments. The minimum value of the first overprint deviation data corresponding to the most recent several times of printing roller adjustments and the minimum value of the second overprint deviation data corresponding to the most recent several times of printing roller adjustments are taken as potential overprint deviations.

[0094] Specifically, the adjustment directions of the ten most recent printing rollers are counted. If the adjustment directions of the ten most recent printing rollers are all to the left (or right) in the horizontal direction and to the upward (or downward) direction in the vertical direction, then it is determined that the current deviation trend is to shift to the right (or left) in the horizontal direction and to shift downward (or upward) in the vertical direction. The minimum value of the first overprint deviation data corresponding to the ten most recent printing roller adjustments and the minimum value of the second overprint deviation data corresponding to the ten most recent printing roller adjustments are taken as potential overprint deviations.

[0095] Specifically, the adjustment module controls the robot arm to adjust the position of the printing cylinder according to the potential overprint deviation.

[0096] Specifically, the method for determining the direction and magnitude of adjusting the position of the printing cylinder based on the potential overprint deviation data is the same as the aforementioned method for determining the direction and magnitude based on the first and second overprint deviations. The difference lies in the timing of the adjustment and the number of adjustments. The aforementioned method for controlling the mechanical arm to adjust the position of the printing cylinder based on the first and second overprint deviations is to control the mechanical arm to adjust the position of the printing cylinder once immediately after determining the first and second overprint deviations before the next overprint begins. However, the potential overprint deviation is generated over time, so the adjustment amount needs to be determined in combination with the number of adjustments and time. This embodiment provides a method for controlling the mechanical arm to adjust the position of the printing cylinder based on the potential overprint deviation as follows:

[0097] Count the time when the printing roller was adjusted according to the hue data for the most recent times, calculate the time interval between two adjacent adjustments and take the average of all time intervals, determine the number of adjustments based on the average time interval and the overprint interval period (that is, the time interval between the previous printing and the next printing of the printing unit), and determine the amount of adjustment each time based on the number of adjustments and the potential overprint deviation. Specifically, the number of adjustments = the average time interval / the overprint interval period. If the number of adjustments is a decimal, round it up by truncation. The amount of adjustment each time = the absolute value of the potential overprint deviation / the number of adjustments. The specific adjustment time point is between the previous printing and the next printing of the printing unit.

[0098] The present invention continuously tracks and compiles statistics on the recent adjustment directions of the printing roller and the corresponding first and second overprint deviation data through a dynamic feedback mechanism. When it detects that the adjustment directions are consistent for multiple consecutive times, it automatically extracts the minimum value of the two types of deviations as the potential overprint error benchmark, and drives the robotic arm to accurately position and correct the printing roller. Based on a predictive model based on historical adjustment trends and real-time deviation analysis, the system can identify and pre-correct potential errors in advance, effectively suppress error accumulation, and enhance overprint stability and accuracy. At the same time, combined with intelligent algorithms and automated control, it achieves autonomous optimization of the printing process, significantly reduces the frequency of manual intervention, shortens downtime for maintenance, and reduces waste loss, thereby comprehensively improving printing efficiency and finished product quality, and providing the industry with an advanced overprint control solution that combines high precision, strong stability, and intelligent adaptability.

[0099] Specifically, the number of the scanning modules is twice the number of the monochrome printing units of the gravure printing press, and each monochrome printing unit is provided with two scanning modules. The two scanning modules scan the target printed product according to the first scanning path and the second scanning path respectively.

[0100] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

[0101] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A precise register system for gravure printing, characterized in that include: a scanning module configured to scan a target printed product point by point along a set scanning path to obtain hue data and time data corresponding to the scanning path, wherein the scanning path includes at least a first scanning path and a second scanning path having scanning directions perpendicular to each other, the hue data includes at least first hue data and second hue data, and the time data includes at least first time data corresponding to the first hue data and second time data corresponding to the second hue data; a data preprocessing module connected to the scanning module, configured to determine third hue data and third time data corresponding to the third hue data based on the first hue data and the first time data, and to obtain fourth hue data and fourth time data corresponding to the fourth hue data based on the second hue data and the second time data; a curve drawing module connected to the data preprocessing module, for drawing a first hue-time broken line graph based on the third hue data and third time data corresponding to the third hue data, and drawing a second hue-time broken line graph based on the fourth hue data and fourth time data corresponding to the fourth hue data; a curve analysis module connected to the curve drawing module, configured to determine a deviation value based on the first hue-time broken line graph and the second hue-time broken line graph, and determine an overprint deviation of gravure printing based on the deviation value, a scanning path, and a scanning speed; An adjustment module is connected to the curve analysis module and is used to control the mechanical arm to adjust the position of the printing cylinder according to the overprint deviation.

2. The precise register system for gravure printing according to claim 1, characterized in that The first scanning path and the second scanning path both traverse each single-color printed pattern of the target printed product.

3. The precise register system for gravure printing according to claim 2, characterized in that The data preprocessing module is also preset with first reference hue data and second reference hue data. The data preprocessing module determines third hue data and third time data corresponding to the third hue data based on the first hue data and the first reference hue data, and determines fourth hue data and fourth time data corresponding to the fourth hue data based on the second hue data and the second reference hue data.

4. The precise register system for gravure printing according to claim 2, characterized in that The data preprocessing module is also used to determine a first change rate based on the first hue data, determine third hue data and third time data corresponding to the third hue data based on the first change rate, determine a second change rate based on the second hue data, and determine fourth hue data and fourth time data corresponding to the fourth hue data based on the second change rate.

5. The precise register system for gravure printing according to claim 3 or 4, characterized in that The curve analysis module is also used to determine a first deviation value based on the first hue-time line graph, and determine a first overprint deviation based on the first deviation value, the first scanning path and the scanning speed; determine a second deviation value based on the second hue-time line graph, and determine a second overprint deviation based on the second deviation value, the second scanning path and the scanning speed.

6. The precise register system for gravure printing according to claim 5, characterized in that The curve analysis module is also preset with a first standard broken line graph and a second standard broken line graph, and the first deviation value is determined according to the first hue-time broken line graph and the first standard broken line graph, and the second deviation value is determined according to the second hue-time broken line graph and the second standard broken line graph.

7. The precise register system for gravure printing according to claim 5, characterized in that The adjustment module controls the mechanical arm to adjust the position of the printing cylinder according to the overprint deviation, including: The adjustment module controls the robotic arm to adjust the position of the printing cylinder according to the first overprint deviation and the second overprint deviation.

8. The precise register system for gravure printing according to claim 7, characterized in that It also includes an adaptive determination module, which is connected to the curve analysis module and the adjustment module respectively, and is used to determine the current deviation trend according to the historical adjustment direction of the printing roller, and determine the potential overprint deviation according to the current deviation trend, the historical first overprint deviation data and the second overprint deviation data.

9. The precise register system for gravure printing according to claim 8, characterized in that The adjustment module controls the robotic arm to adjust the position of the printing cylinder according to the potential overprint deviation.

10. The precise register system for gravure printing according to claim 1, characterized in that The number of the scanning modules is twice the number of the monochrome printing units of the gravure printing press. Each monochrome printing unit is provided with two scanning modules. The two scanning modules scan the target printed product according to the first scanning path and the second scanning path respectively.

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