A multi-color overprint real-time deviation correction method, device, medium and computer equipment

Abstract

The application provides a multi-color overprint real-time deviation correction method, device, medium and computer equipment. The deviation correction method comprises the following steps: a flexible printing plate passes through an Nth color group printing unit to superimpose and print an Nth color pattern on an N-1th color pattern, and an Nth color overprint register mark is printed in a preset area; an image of a first color overprint register mark and the Nth color overprint register mark is captured, a mark offset of the Nth color overprint register mark relative to the first color overprint register mark is calculated, a deviation correction signal is generated, and the deviation correction signal is used to drive a deviation correction roller to compensate the position of an N+1th color group printing unit in a second direction and a rotating direction. Independent of the identification of the printing pattern of the effective area of the flexible printing plate, the first color overprint register mark and the Nth color overprint register mark of the deviation correction mark are separately identified and calculated, have the advantages of independent image acquisition and independent calculation, and provide an implementation basis for the replacement of the domestic servo and mechanical deviation correction system for the foreign high-precision deviation correction system.

Description

TECHNICAL FIELD

[0001] The present application relates to a multi-color overprint real-time correction method, device, medium and computer equipment, belonging to the field of industrial printing. BACKGROUND

[0002] Overprint printing is an important printing process in industrial printing. Different colors of ink are printed layer by layer in the designed order through color separation, and stereoscopic visual effects are formed by color mixing or covering. When selecting multiple ink colors, more than 4 colors are usually used, and special colors such as metal color, fluorescent color, or special effect ink are included. The core technology is to decompose the design file into independent color separation plates, and each color separation plate is generated by film or CTP. After accurately calculating the color superposition order, the positioning mark (overmark) is used to realize the accurate alignment of each color plate.

[0003] The real-time correction deviation module of the printing equipment uses imported high-frame-rate industrial cameras and high-response servo systems, and the overall detection effect is good, but the cost of a single machine is more than 500,000. In the process of replacing imported products with domestic products, the domestic multi-color overprint correction system uses relatively low-precision servo systems and mechanical correction systems. In order to ensure the overall accuracy, the real-time correction algorithm is usually optimized to overcome the technical problem of error amplification of multi-color overprint after multiple color overprint corrections. SUMMARY

[0004] In view of the shortcomings of the prior art, the purpose of the present application is to provide a multi-color overprint real-time correction method, device, medium and computer equipment.

[0005] According to the embodiment of the present application, the first scheme is provided: a multi-color overprint real-time correction method, comprising the following steps:

[0006] S1: Obtain a flexible printing plate material, and continuously input the flexible printing plate material along a first direction to a multi-color printing unit group, wherein the multi-color printing unit group comprises a first color group printing unit and an Nth color group printing unit, and N is an integer greater than or equal to 2;

[0007] S2: The flexible printing plate material is printed by the first color group printing unit to obtain a first color pattern, and a first color overprint mark is printed in a preset area outside the effective area of the first color pattern;

[0008] S3: The flexible printing plate material is printed by the Nth color group printing unit to superimpose an Nth color pattern on the N-1 color pattern, and an Nth color overprint mark is printed in the preset area;

[0009] S4: image capture of the passed first color alignment mark and the Nth color alignment mark by a linear scanning industrial camera, and calculation of the mark offset of the Nth color alignment mark relative to the first color alignment mark by an edge positioning algorithm;

[0010] S6: generating a correction signal according to the mark offset, and driving the correction roller to compensate the position of the Nth color group printing unit in the second direction and the rotation direction by the correction signal.

[0011] Further, it further comprises:

[0012] S6: generating a correction signal according to the mark offset, and driving the correction roller to compensate the position of the Nth color group printing unit in the second direction and the rotation direction by the correction signal.

[0013] Further, the first color alignment mark comprises a cross center line and L-shaped marks distributed around the cross center line, and the Nth color alignment mark comprises a secondary cross line and / or a secondary L-shaped mark.

[0014] Further, the Nth color alignment mark is superimposed on the N-1th color alignment mark, the secondary cross line is superimposed on the cross center line, and the plurality of secondary L-shaped marks correspond to the L-shaped marks one by one.

[0015] The ink of the Nth color alignment mark is different in color from the ink of the N-1th color alignment mark, the translation offset and the rotation offset are calculated by the secondary cross line and the cross center line, and the local deformation offset is calculated by the secondary L-shaped mark and the L-shaped mark.

[0016] Further, if the flexible printing plate material is a dark plate material, the first color alignment mark is a negative film hollow or hollow recess generated on the flexible printing plate material, and the subsequent Nth color alignment mark fills the negative film hollow or negative film recess with positive film reflective ink, and the reflective ink of the Nth color alignment mark is darker in color than the N-1th color alignment mark.

[0017] Further, the Nth color alignment mark and the N-1th color alignment mark are distributed in a non-superimposed stepwise offset manner along the y-axis direction of the flexible printing plate material, the mark spacing between the Nth color alignment mark and the N-1th color alignment mark is ≥10mm, the Nth color alignment mark and the N-1th color alignment mark are aligned in the x-axis direction of the flexible printing plate material, and the alignment tolerance in the x-axis direction is ±0.1mm.

[0018] Further, the step of calculating the mark offset of the Nth color alignment mark relative to the first color alignment mark by the edge positioning algorithm comprises:

[0019] acquire a capture image of the first color register mark, calculate a first cross line edge value and a first L-shaped mark edge value according to the position of the primary cross line and the primary L-shaped edge in the planar model, and acquire a first longitudinal offset amount by comparing the first cross line edge value with the y-axis and a second longitudinal offset amount by comparing the first L-shaped mark edge value with the y-axis;

[0020] acquire a capture image of the first color register mark, calculate a first cross line edge value and a first L-shaped mark edge value according to the position of the primary cross line and the primary L-shaped edge in the planar model, and acquire a first longitudinal offset amount by comparing the first cross line edge value with the y-axis and a second longitudinal offset amount by comparing the first L-shaped mark edge value with the y-axis;

[0021] acquire a capture image of the first color register mark, calculate a first cross line edge value and a first L-shaped mark edge value according to the position of the primary cross line and the primary L-shaped edge in the planar model, and acquire a first longitudinal offset amount by comparing the first cross line edge value with the y-axis and a second longitudinal offset amount by comparing the first L-shaped mark edge value with the y-axis;

[0022] calculate an Nth absolute offset amount of the Nth color register mark relative to the first color register mark according to the Nth mark offset amount, calculate an Nth relative offset amount of the Nth color register mark relative to the N-1th color register mark according to the Nth mark offset amount and the N-1th mark offset amount, pre-correct the Nth relative offset amount with the Nth absolute offset amount to obtain an Nth corrected offset amount, and generate a correction signal according to the Nth corrected offset amount.

[0023] According to an embodiment of the present application, the first scheme provided by the present application is used to provide a real-time multi-color register printing correction method, and the second scheme is provided as follows:

[0024] A real-time multi-color register printing correction device, comprising:

[0025] a system module, configured to acquire a flexible printing plate, and continuously input the flexible printing plate to a multi-color printing unit group along a first direction, the multi-color printing unit group comprising a first color group printing unit and an Nth color group printing unit, wherein N≥2 and N is an integer;

[0026] a first color module, configured to print a first color pattern on the flexible printing plate by the first color group printing unit, and print a first color register mark on a preset area outside the effective area of the first color pattern.

[0027] The N-color module is used to overlay and print the Nth color pattern on the N-1 color pattern through the Nth color group printing unit on the flexible printing plate, and at the same time, print and obtain the Nth color registration mark in the preset area.

[0028] The offset calculation module is used to capture images of the first color registration mark and the Nth color registration mark through a linear scanning industrial camera, and to calculate the mark offset of the Nth color registration mark relative to the first color registration mark through an edge positioning algorithm.

[0029] The correction module is used to generate a correction signal based on the mark offset, and drive the correction roller to perform position compensation on the N+1 color group printing unit in the second direction and rotation direction through the correction signal.

[0030] A computer device includes a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the following steps:

[0031] A flexible printing plate is obtained, and the flexible printing plate is continuously input into a multi-color printing unit group along a first direction. The multi-color printing unit group includes a first color group printing unit and an Nth color group printing unit, where N≥2 and N is an integer.

[0032] The flexible printing plate obtains the first color pattern by printing the first color pattern through the first color group printing unit. At the same time, the first color registration mark is obtained by printing in the preset area on the outer edge of the effective area containing the first color pattern.

[0033] The flexible printing plate overlays and prints the Nth color pattern on the N-1 color pattern through the Nth color group printing unit, and at the same time, prints and obtains the Nth color registration mark in the preset area.

[0034] The first color registration mark and the Nth color registration mark are captured by a linear scanning industrial camera, and the mark offset of the Nth color registration mark relative to the first color registration mark is calculated by an edge localization algorithm.

[0035] A correction signal is generated based on the mark offset, and the correction signal drives the correction roller to perform position compensation on the N+1 color group printing unit in the second direction and rotation direction.

[0036] A computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the following steps:

[0037] A flexible printing plate is obtained, and the flexible printing plate is continuously input into a multi-color printing unit group along a first direction. The multi-color printing unit group includes a first color group printing unit and an Nth color group printing unit, where N≥2 and N is an integer.

[0038] The flexible printing plate obtains the first color pattern by printing the first color pattern through the first color group printing unit. At the same time, the first color registration mark is obtained by printing in the preset area on the outer edge of the effective area containing the first color pattern.

[0039] The flexible printing plate overlays and prints the Nth color pattern on the N-1 color pattern through the Nth color group printing unit, and at the same time, prints and obtains the Nth color registration mark in the preset area.

[0040] The first color registration mark and the Nth color registration mark are captured by a linear scanning industrial camera, and the mark offset of the Nth color registration mark relative to the first color registration mark is calculated by an edge localization algorithm.

[0041] A correction signal is generated based on the mark offset, and the correction signal drives the correction roller to perform position compensation on the N+1 color group printing unit in the second direction and rotation direction.

[0042] Compared with the prior art, the unique advantages of the technical solution provided in this application are as follows: This solution pre-arranges a pre-examination area in the usable edge area of ​​the flexible printing plate. When passing through one color group printing unit in the preset area, a correction identification and correction compensation is performed once. Since the correction mark is set at the edge position, it can independently identify and calculate the first color registration mark and the Nth color registration mark of the correction mark, independently of the identification of the printed pattern in the effective area of ​​the flexible printing plate. The algorithm can be established and optimized independently. Therefore, it has the advantages of independent image acquisition and independent calculation for real-time correction of multi-color printing. Moreover, the algorithm upgrade operation is convenient, which greatly improves the correction effect and allows for easy updating or replacement of the correction algorithm according to different printing plates, without relying on the limitations of the traditional correction module attached to the whole printing press. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] in:

[0045] Figure 1 This is a flowchart of a real-time correction method for multi-color overprinting in one embodiment;

[0046] Figure 2 This is a structural block diagram of a real-time correction device for multi-color overprinting in one embodiment;

[0047] Figure 3 This is a structural block diagram of a computer device in one embodiment.

[0048] Figure label:

[0049] 100 - System module; 200 - Primary color module; 300 - N-color module; 400 - Offset calculation module; 500 - Correction module. Detailed Implementation

[0050] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0051] Example 1

[0052] The technical problem solved by this embodiment is that, in order to overcome the relatively insufficient accuracy caused by the low-level mechanical equipment, the existing domestic multi-color printing correction system with domestically produced alternative parts uses a real-time correction algorithm to improve the overall accuracy and overcome the technical problem of error amplification after multiple color corrections in multi-color printing.

[0053] To address the aforementioned technical problems, this embodiment provides a real-time correction method for multi-color overprinting, such as... Figure 1 As shown, it includes the following steps:

[0054] S1: Obtain a flexible printing plate and continuously input the flexible printing plate into a multi-color printing unit group along a first direction. The multi-color printing unit group includes a first color group printing unit and an Nth color group printing unit, where N≥2 and N is an integer.

[0055] S2: The flexible printing plate obtains the first color pattern by printing the first color pattern through the first color group printing unit. At the same time, the first color registration mark is obtained by printing in the preset area on the outer edge of the effective area containing the first color pattern.

[0056] S3: The flexible printing plate overlays and prints the Nth color pattern on the N-1 color pattern through the Nth color group printing unit, and at the same time, prints and obtains the Nth color registration mark in the preset area;

[0057] S4: Capture images of the first color registration mark and the Nth color registration mark using a linear scanning industrial camera, and calculate the mark offset of the Nth color registration mark relative to the first color registration mark using an edge localization algorithm;

[0058] S6: Generate a correction signal based on the mark offset, and drive the correction roller to perform position compensation on the N+1 color group printing unit in the second direction and rotation direction through the correction signal.

[0059] Step S1 involves the overall control method of flexible printing plates, that is, the flexible plate sequentially passes through the first color group printing unit, the second color group printing unit, ... to the Nth color group printing unit of the multi-color printing unit group. This process is usually the standard process of multi-color printing equipment. Flexible printing plates include paper such as offset paper, as well as deformable materials such as printing tape, plastic film and metal foil.

[0060] Steps S2-S6 execute the control method sequentially.

[0061] In step S2, the flexible printing plate passes through the first color group unit, prints the first color pattern through the first color group unit, and forms an effective area. The effective area includes at least one first color pattern. Typically, the effective area includes multiple first color patterns arranged in a matrix. The effective area is usually arranged in the internal area of ​​the flexible printing plate excluding the four edge border areas. A preset area is set in the four edge border areas. The preset area corresponds to the registration mark generation device and the image capture device. The generation device prints and generates the first color registration mark and the Nth color registration mark in the preset area. The image capture device captures the images of the generated first color registration mark and the Nth color registration mark.

[0062] Step S3 performs the same action as step S2 and finally obtains the Nth color registration mark.

[0063] Step S4 involves capturing images of the primary color registration mark and the Nth color registration mark, and calculating the mark offset of the Nth color registration mark relative to the primary color registration mark. This process is one of the core inventive points of this application. Image capture and analysis are performed at each step of multi-color printing. In traditional correction calculations, images of each printed pattern within the effective area are acquired and analyzed. However, since printed patterns are complex and it is not easy to directly set registration marks within the printed pattern (otherwise, it would destroy the original design of the printed pattern), existing low-precision domestic alternative servo systems and mechanical correction systems easily amplify errors after multiple multi-color printings, with correction trigger frequencies several times or even tens of times higher than high-precision systems. This solution can independently identify and calculate the primary color registration mark and the Nth color registration mark of the correction mark, independent of the identification of the printed pattern in the effective area of ​​the flexible printing plate. The generation of the registration marks is standardized, and the identification process is uniform; therefore, the identification accuracy can ensure that error amplification is effectively controlled. Furthermore, since it can independently identify the printing pattern of the effective area of ​​the flexible printing plate, and separately identify and calculate the first color registration mark and the Nth color registration mark of the correction mark, the real-time correction of multi-color printing has independent image acquisition and independent calculation. That is, this module interface can be processed independently, the algorithm is adjustable and upgradable, and can be independently designed based on different material scenarios. Compared with the traditional non-editable method, it has a large improvement space and does not rely on the limitations of the traditional correction module attached to the whole printing press.

[0064] In subsequent embodiments, we also provide different calculation methods for the marker offset in different scenarios. These different methods include not only different algorithms, but also different algorithms resulting from different methods of generating the Nth color registration mark. This is one of the technical advantages of the independent registration mark module.

[0065] Step S5: Generate a correction signal based on the mark offset. Use the correction signal to correct the Nth color pattern in real time to avoid the error amplification of the N+1 color pattern. This embodiment achieves this through a correction roller, which is also an important breakthrough. The correction roller is not a single-direction correction roller. It can perform correction in at least the second direction and the rotation direction. In fact, every time the flexible printing plate passes through one color group printing unit, it performs image capture, edge positioning algorithm to calculate the mark offset and generate a correction signal, and performs position compensation through the correction signal.

[0066] Through the above methodology, a domestically produced alternative servo system and mechanical correction system for low-precision printing was finally implemented, achieving high-precision multi-color printing. This effectively reduced printing costs, eliminated reliance on the correction module limitations of high-precision printing machines, and solved the problem of high-precision printing machine parts.

[0067] Example 2

[0068] This embodiment is an effective supplement to Embodiment 1. Specifically, the real-time correction process for multi-color printing involves the flexible printing plate performing a correction through the correction system every time it passes through a multi-color printing unit. The correction process includes acquiring an image of the Nth color registration mark corresponding to the Nth color pattern position, generating a correction signal based on the image, and performing position compensation for the N+1 color group printing unit. Furthermore, in addition to performing position compensation for the N+1 color group printing unit, this solution also performs position compensation for the Nth color group printing unit. That is, when a position offset exceeding the threshold is detected by identifying the image of the Nth color registration mark, the core issue is that the Nth color group printing unit has already deviated during the execution of this printing task. This deviation can be corrected and recovered by the N+1 color group printing unit, but it can also be corrected by the Nth color group printing unit itself to avoid the occurrence and accumulation of errors.

[0069] Specifically, the process of generating a correction signal based on the marker offset includes:

[0070] Obtain the mark offset of the Nth color registration mark relative to the first color registration mark, and the historical mark offset of the Nth color registration mark relative to the first color registration mark. The historical mark offset is the mark offset of the Nth color registration mark relative to the first color registration mark in the previous 5 times (or other preset number of times). If the mark offset of the previous 5 historical mark offsets all exceed the preset threshold, then position compensation is performed on the Nth color group printing unit to eliminate the cause of the error, instead of simply making up for it through subsequent correction. The correction principle is different, so the number of correction triggers is less for the overall correction system.

[0071] Example 3

[0072] This embodiment provides a real-time correction method for multi-color overprinting, including the following steps:

[0073] A flexible printing plate is obtained and continuously input into a multi-color printing unit group along a first direction. The multi-color printing unit group includes a first color group printing unit and an Nth color group printing unit, where N ≥ 2 and N is an integer. The flexible printing plate prints the first color pattern through the first color group printing unit and simultaneously prints a first color registration mark in a preset area on the outer edge of the effective area containing the first color pattern. The flexible printing plate overlays and prints the Nth color pattern on the N-1 color pattern through the Nth color group printing unit and simultaneously prints the Nth color registration mark in the preset area. The first color registration mark and the Nth color registration mark are captured by a linear scanning industrial camera, and the mark offset of the Nth color registration mark relative to the first color registration mark is calculated by an edge positioning algorithm. A correction signal is generated based on the mark offset, and the correction signal drives the correction roller to perform position compensation on the N+1th color group printing unit in the second direction and the rotation direction.

[0074] Specifically, the primary color registration mark includes a crosshair center line and L-shaped marks distributed around the crosshair center line, and the Nth color registration mark includes a secondary crosshair and / or a secondary L-shaped mark. The primary and Nth color registration marks use row-marker graphics to facilitate compatibility, identification, and calculation by the independent correction system. However, the specific generation and calculation methods for the primary and Nth color registration marks are specifically designed in this embodiment.

[0075] In the first design method, the Nth color registration mark is superimposed on the (N-1)th color registration mark, and the secondary crosshair is covered on the center line of the crosshair. The positions of multiple secondary L-shaped marks correspond one-to-one with the L-shaped marks. The ink color of the Nth color registration mark is different from that of the (N-1)th color registration mark. The translational and rotational offsets are calculated by the secondary crosshair and the center line of the crosshair, and the local deformation offsets are calculated by the secondary L-shaped marks and the L-shaped marks.

[0076] This design approach is primarily designed for scenarios where the flexible printing plate is dark-colored. Typically, both light and dark marking inks are affected by the dark background, leading to significant recognition errors. Even when using light-colored marking inks with large color differences, the need to identify multiple inks in different colors necessitates a progression from light to dark, causing recognition errors for subsequent dark inks. Therefore, conventional registration marking schemes for colored inks are significantly affected when recognizing multiple colors on a dark plate. This solution specifically addresses this issue by employing a combination of negative die-cutting and positive reflective ink. For example, within a pre-defined area on the dark flexible printing plate, the negative properties of photoresist are used to transfer the crosshair center line and L-shaped markings. Recognition is less affected by the color of the flexible printing plate, resulting in higher accuracy without affecting subsequent ink overlay. The positive reflective ink for the Nth color registration mark forms a highly reflective area using positive photoresist (or reflective materials), providing sufficient accuracy for offset calculations.

[0077] In the second design, the Nth color registration mark and the (N-1)th color registration mark are non-overlapping and steppedly offset along the y-axis direction of the flexible printing plate. The mark spacing between the Nth color registration mark and the (N-1)th color registration mark is ≥10mm. The Nth color registration mark and the (N-1)th color registration mark are aligned in the x-axis direction of the flexible printing plate, and the alignment tolerance range in the x-axis direction is ±0.1mm.

[0078] The step of calculating the offset of the Nth color registration mark relative to the first color registration mark using the edge positioning algorithm includes:

[0079] Acquire the captured image of the primary color registration mark, the crosshair center line and L-shaped mark of the captured image of the primary color registration mark, and the planar model of the primary color registration mark based on the center point of the crosshair center line and the x-axis and y-axis of the flexible printing plate;

[0080] Obtain the captured image of the (N-1)th color registration mark. Calculate the edge values ​​of the secondary crosshairs and secondary L-shaped marks based on the positions of the secondary crosshairs and secondary L-shaped edges in the captured image within the planar model. Compare the edge values ​​of the secondary crosshairs of the captured image with the y-axis to obtain the first vertical offset. Compare the edge values ​​of the secondary L-shaped marks with the y-axis to obtain the second vertical offset. Calculate the (N-1)th mark offset of the (N-1)th color registration mark based on the first vertical offset and at least one second vertical offset.

[0081] Obtain the captured image of the Nth color registration mark. Calculate the edge values ​​of the secondary crosshairs and secondary L-shaped marks based on the positions of the secondary crosshairs and secondary L-shaped edges in the captured image within the planar model. Compare the edge values ​​of the secondary crosshairs of the captured image of the Nth color registration mark with the y-axis to obtain the first vertical offset. Compare the edge values ​​of the secondary L-shaped marks with the y-axis to obtain the second vertical offset. Calculate the Nth mark offset of the (N-1)th color registration mark based on the first vertical offset and at least one second vertical offset.

[0082] Calculate the Nth absolute offset of the Nth mark relative to the first color registration mark based on the Nth mark offset. Calculate the Nth relative offset of the Nth color registration mark relative to the (N-1)th color registration mark based on the Nth mark offset and the (N-1)th mark offset. Pre-correct the Nth absolute offset with the Nth relative offset and obtain the Nth corrected offset. Generate a correction signal based on the Nth corrected offset.

[0083] Specifically, the correction roller can adjust the lateral movement (second direction) and rotation angle (rotation direction) of the flexible printing plate, and correct the lateral offset and angular deviation of the N+1 color group printing unit relative to the previous color group by changing the tension and path of the flexible printing plate.

[0084] The second direction of translation adjustment process: Usually, a domestic precision servo motor + ball screw or linear motor is arranged on the entrance side of the N+1 color group. Adjusting the position of the correction roller directly affects the lateral alignment of the flexible printing plate.

[0085] The process of adjusting the rotation direction: The tilting correction roller of the domestic precision servo motor + reducer or direct drive torque motor causes the flexible printing plate to generate a lateral displacement gradient when it passes through, and gradually corrects the angle deviation.

[0086] This step specifically includes:

[0087] Obtain the mark offset of the Nth color registration mark relative to the first color registration mark: lateral deviation ΔY and rotation angle deviation Δθ, with a sampling frequency higher than the dynamic response requirements of the flexible printing plate running speed;

[0088] Based on the feedforward control model, the lateral deviation ΔY and the rotation angle deviation Δθ are decomposed into the second-direction translation amount ΔYe and the rotation angle adjustment amount θe of the correction roller, where:

[0089] ΔYe = L·ΔY / D (L is the distance from the correction roller to the edge of the N+1th color group entrance, and D is the transmission ratio);

[0090] (Δθ·W / 2πR) (W is the width of the substrate of the flexible printing plate, and R is the radius of the correction roller);

[0091] The second-direction translation and rotation angle adjustment amount of the correction signal drive the correction roller to synchronously perform translation and rotation in the second direction. The translation is driven by a servo motor and a ball screw, and its response speed matches the linear speed of the flexible printing plate. The rotation is driven by a rotary motor (servo) and a reducer, and its angular resolution is ≤0.01°.

[0092] The encoder verifies the actual displacement and angle of the correction roller in real time until the lateral deviation ΔY and the rotation angle deviation Δθ converge to the preset tolerance range.

[0093] Example 4

[0094] This embodiment provides a real-time correction device for multi-color overprinting, including:

[0095] System module 100 is used to acquire flexible printing plate and continuously input the flexible printing plate into a multi-color printing unit group along a first direction. The multi-color printing unit group includes a first color group printing unit and an Nth color group printing unit, where N≥2 and N is an integer.

[0096] The first color module 200 is used to print the first color pattern on the flexible printing plate through the first color group printing unit, and at the same time, print the first color registration mark in a preset area on the outer edge of the effective area containing the first color pattern.

[0097] The N-color module 300 is used to overlay and print the Nth color pattern on the N-1 color pattern through the Nth color group printing unit on the flexible printing plate, and at the same time, print and obtain the Nth color registration mark in the preset area.

[0098] The offset calculation module 400 is used to capture images of the first color registration mark and the Nth color registration mark through a linear scanning industrial camera, and to calculate the mark offset of the Nth color registration mark relative to the first color registration mark through an edge positioning algorithm.

[0099] The correction module 500 is used to generate a correction signal based on the mark offset, and drive the correction roller to perform position compensation on the N+1 color group printing unit in the second direction and rotation direction through the correction signal.

[0100] This solution pre-deploys a pre-screening area in the usable edge region of the flexible printing plate. When the plate passes through one color printing unit within the pre-set area, a correction identification and compensation is performed. Since the correction markers are positioned at the edges, the identification of the printed pattern in the effective area of ​​the flexible printing plate can be independent of the identification of the first color registration mark and the Nth color registration mark. The algorithm can be independently established and optimized. Therefore, it has the advantages of independent image acquisition and independent calculation for real-time correction of multi-color printing. Furthermore, the algorithm upgrade operation is convenient, greatly improving the correction effect. The correction algorithm can be easily updated or replaced according to different printing plates, without relying on the limitations of traditional correction modules attached to the entire printing press.

[0101] Example 5

[0102] Figure 3 An internal structural diagram of a computer device in one embodiment is shown. This computer device can specifically be a terminal or a server. Figure 3 As shown, the computer device includes a processor, memory, and a network interface connected via a system bus. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and may also store a computer program. When executed by the processor, this computer program enables the processor to implement a correction method. The memory may also store a computer program, which, when executed by the processor, enables the processor to implement a correction method. Those skilled in the art will understand that... Figure 3 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0103] In one embodiment, a computer device is provided, including a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the following steps:

[0104] S1: Obtain a flexible printing plate and continuously input the flexible printing plate into a multi-color printing unit group along a first direction. The multi-color printing unit group includes a first color group printing unit and an Nth color group printing unit, where N≥2 and N is an integer.

[0105] S2: The flexible printing plate obtains the first color pattern by printing the first color pattern through the first color group printing unit. At the same time, the first color registration mark is obtained by printing in the preset area on the outer edge of the effective area containing the first color pattern.

[0106] S3: The flexible printing plate overlays and prints the Nth color pattern on the N-1 color pattern through the Nth color group printing unit, and at the same time, prints and obtains the Nth color registration mark in the preset area;

[0107] S4: Capture images of the first color registration mark and the Nth color registration mark using a linear scanning industrial camera, and calculate the mark offset of the Nth color registration mark relative to the first color registration mark using an edge localization algorithm;

[0108] S6: Generate a correction signal based on the mark offset, and drive the correction roller to perform position compensation on the N+1 color group printing unit in the second direction and rotation direction through the correction signal.

[0109] In one embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, causes the processor to perform the following steps:

[0110] S1: Obtain a flexible printing plate and continuously input the flexible printing plate into a multi-color printing unit group along a first direction. The multi-color printing unit group includes a first color group printing unit and an Nth color group printing unit, where N≥2 and N is an integer.

[0111] S2: The flexible printing plate obtains the first color pattern by printing the first color pattern through the first color group printing unit. At the same time, the first color registration mark is obtained by printing in the preset area on the outer edge of the effective area containing the first color pattern.

[0112] S3: The flexible printing plate overlays and prints the Nth color pattern on the N-1 color pattern through the Nth color group printing unit, and at the same time, prints and obtains the Nth color registration mark in the preset area;

[0113] S4: Capture images of the first color registration mark and the Nth color registration mark using a linear scanning industrial camera, and calculate the mark offset of the Nth color registration mark relative to the first color registration mark using an edge localization algorithm;

[0114] S6: Generate a correction signal based on the mark offset, and drive the correction roller to perform position compensation on the N+1 color group printing unit in the second direction and rotation direction through the correction signal.

[0115] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0116] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A real-time correction method for multi-color overprinting, characterized in that, Includes the following steps: A flexible printing plate is obtained, and the flexible printing plate is continuously input into a multi-color printing unit group along a first direction. The multi-color printing unit group includes a first color group printing unit and an Nth color group printing unit, where N≥2 and N is an integer. The flexible printing plate obtains the first color pattern by printing the first color pattern through the first color group printing unit. At the same time, the first color registration mark is obtained by printing in the preset area on the outer edge of the effective area containing the first color pattern. The flexible printing plate overlays and prints the Nth color pattern on the N-1 color pattern through the Nth color group printing unit, and at the same time, prints and obtains the Nth color registration mark in the preset area. The first color registration mark and the Nth color registration mark are captured by a linear scanning industrial camera, and the mark offset of the Nth color registration mark relative to the first color registration mark is calculated by an edge localization algorithm. Based on the mark offset, a correction signal is generated, and the correction signal drives the correction roller to perform position compensation on the N+1 color group printing unit in the second direction and the rotation direction. The primary color registration mark includes a crosshair center line and L-shaped marks distributed around the crosshair center line; the Nth color registration mark includes a secondary crosshair and / or a secondary L-shaped mark. The Nth color registration mark is superimposed on the (N-1)th color registration mark, the secondary crosshair is covered on the center line of the crosshair, and the positions of the multiple secondary L-shaped marks correspond one-to-one with the L-shaped marks; The ink color difference between the Nth color registration mark and the N-1th color registration mark is calculated by the translational and rotational offsets through the secondary crosshair and the crosshair center line, and by the local deformation offsets through the secondary L-shaped mark and the L-shaped mark.

2. The real-time correction method for multi-color overprinting according to claim 1, characterized in that, Also includes: A correction signal is generated based on the mark offset, and the correction roller is driven by the correction signal to perform position compensation in the Nth color group printing unit in the second direction and rotation direction.

3. The real-time correction method for multi-color overprinting according to claim 1, characterized in that, If the flexographic printing plate is a dark-colored plate, the first color registration mark is a negative cutout or cutout recess generated on the flexographic printing plate. The subsequent Nth color registration mark is filled with positive reflective ink on the negative cutout or negative recess. The reflective ink color of the Nth color registration mark is darker than that of the N-1th color registration mark.

4. The real-time correction method for multi-color overprinting according to claim 1, characterized in that, The Nth color registration mark and the (N-1)th color registration mark are non-overlapping and steppedly offset along the y-axis direction of the flexible printing plate. The mark spacing between the Nth color registration mark and the (N-1)th color registration mark is ≥10mm. The Nth color registration mark and the (N-1)th color registration mark are aligned in the x-axis direction of the flexible printing plate, and the alignment tolerance range in the x-axis direction is ±0.1mm.

5. The real-time correction method for multi-color overprinting according to claim 4, characterized in that, The step of calculating the offset of the Nth color registration mark relative to the first color registration mark using the edge positioning algorithm includes: Acquire the captured image of the primary color registration mark, the crosshair center line and L-shaped mark of the captured image of the primary color registration mark, and the planar model of the primary color registration mark based on the center point of the crosshair center line and the x-axis and y-axis of the flexible printing plate; Obtain the captured image of the (N-1)th color registration mark. Calculate the edge values ​​of the secondary crosshairs and secondary L-shaped marks based on the positions of the secondary crosshairs and secondary L-shaped edges in the captured image within the planar model. Compare the edge values ​​of the secondary crosshairs of the captured image with the y-axis to obtain the first vertical offset. Compare the edge values ​​of the secondary L-shaped marks with the y-axis to obtain the second vertical offset. Calculate the (N-1)th mark offset of the (N-1)th color registration mark based on the first vertical offset and at least one second vertical offset. Obtain the captured image of the Nth color registration mark. Calculate the edge values ​​of the secondary crosshairs and secondary L-shaped marks based on the positions of the secondary crosshairs and secondary L-shaped edges in the captured image within the planar model. Compare the edge values ​​of the secondary crosshairs of the captured image of the Nth color registration mark with the y-axis to obtain the first vertical offset. Compare the edge values ​​of the secondary L-shaped marks with the y-axis to obtain the second vertical offset. Calculate the Nth mark offset of the (N-1)th color registration mark based on the first vertical offset and at least one second vertical offset. Calculate the Nth absolute offset of the Nth mark relative to the first color registration mark based on the Nth mark offset. Calculate the Nth relative offset of the Nth color registration mark relative to the (N-1)th color registration mark based on the Nth mark offset and the (N-1)th mark offset. Pre-correct the Nth absolute offset with the Nth relative offset and obtain the Nth corrected offset. Generate a correction signal based on the Nth corrected offset.

6. A real-time correction device for multi-color overprinting, characterized in that, The apparatus for applying the real-time correction method for multi-color printing according to any one of claims 1 to 5, the apparatus comprising: The system module is used to acquire flexible printing plates and continuously input the flexible printing plates into a multi-color printing unit group along a first direction. The multi-color printing unit group includes a first color group printing unit and an Nth color group printing unit, where N≥2 and N is an integer. The first color module is used to print the first color pattern on the flexible printing plate through the first color group printing unit, and at the same time, print the first color registration mark in a preset area on the outer edge of the effective area containing the first color pattern. The N-color module is used to overlay and print the Nth color pattern on the N-1 color pattern through the Nth color group printing unit on the flexible printing plate, and at the same time, print and obtain the Nth color registration mark in the preset area. The offset calculation module is used to capture images of the first color registration mark and the Nth color registration mark through a linear scanning industrial camera, and to calculate the mark offset of the Nth color registration mark relative to the first color registration mark through an edge positioning algorithm. The correction module is used to generate a correction signal based on the mark offset, and drive the correction roller to perform position compensation on the N+1 color group printing unit in the second direction and rotation direction through the correction signal.

7. A computer-readable storage medium storing a computer program that, when executed by a processor, causes the processor to perform the steps of the method as claimed in any one of claims 1 to 5.

8. A computer device comprising a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the steps of the method as claimed in any one of claims 1 to 5.

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