Accurate overprinting and anti-diffusion compensation system for digital jet printing

Abstract

The invention relates to the technical field of digital jet printing, in particular to a precise overprinting and anti-diffusion compensation system for digital jet printing, which comprises a data processing module for processing code pattern data to be printed; the jet printing module is used for overprinting the first color surface data and the second color surface data by using a printer so as to output a code pattern; the detection module is connected with the jet printing module and comprises a photoelectric sensor which is connected with the adaptive frame and is used for determining a printing position and a visual sensor which is connected with the adaptive frame and is used for collecting the overprinting image; and the control module is respectively connected with the data processing module, the jet printing module and the detection module, and is used for determining the ink jet pressure of the first nozzle according to the deviation value between the target position and the actual position of the first nozzle, or determining the exposure time of the overprinted image according to the overprinting failure rate of the code pattern. According to the invention, the overprinting accuracy of the printer is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of digital inkjet printing, and in particular to a precise overprinting and anti-diffusion compensation system for digital inkjet printing. Background Art

[0002] In the tobacco packaging industry, QR codes carry key information such as product traceability, authenticity identification, and marketing interaction, and their printing quality cannot be compromised. With a high-speed operating efficiency of 120m / min-240m / min, paper feeding equipment is widely used in the field of high-speed printing. For example: the main frequency limit of the nozzle (theoretical speed of a single nozzle is 120m / min). In order to achieve high-speed printing (above 200m / min), the current mainstream technology is to place two or more nozzles side by side, and increase the speed by reducing the resolution in the paper feeding direction while keeping the main frequency unchanged. That is, the working speed of a single nozzle at a resolution of 600*600dpi is 120m / min, and in the case of double-row nozzles, the speed of each 600*300dpi reaches 240m / min. This technical application not only increases the speed but also ensures the ink coverage per unit area. Since the data of the two copies must be printed at the same physical position at high speed, and inaccurate overprinting occurs during high-speed printing, the strokes of the QR code will become thicker, affecting the grade. This solution uses a software algorithm to reduce the corresponding pixels on both sides of the print content of one of the nozzles. Even if deviations occur during the overprinting process, the overprinting error will be reduced under this technology because one pattern is larger than the other, similar to trapping in traditional printing.

[0003] Chinese Patent Publication No.: CN108016127A discloses a method for compensating for overprint errors of a combined device of rotary screen printing and digital printing, comprising the following steps: 1) determining a rotary screen printing pattern and a digital printing pattern; 2) aligning the starting positions of the rotary screen printing and the digital printing; 3) after a digital printing of a pattern is completed, a shooting signal is generated to drive the image acquisition unit to collect again, note: after the completion of step 2), a job printing is completed, and the printing control generates a trigger signal to trigger the camera to shoot; 4) the pattern of the pattern after the rotary screen printing is obtained through the image acquisition unit, and the pattern error between the rotary screen printing patterns is obtained through the information processing unit; 5) the information processing unit controls the digital printing unit to control the size of the digital pattern by drawing points when printing the digital pattern according to the pattern error, so as to ensure that the position of the digital pattern and the rotary screen printing pattern is always consistent; the above steps 3) to 5) are repeated. It can be seen that the overprint error compensation method of the rotary screen printing and digital printing combined device has the problem that the guide rail where the nozzle is located is worn after long-term use, resulting in increased surface roughness, inaccurate positioning, and thus causing the overprint accuracy of the printer to decrease. Summary of the invention

[0004] To this end, the present invention provides a precise overprinting and anti-diffusion compensation system for digital inkjet printing, which is used to overcome the problem in the prior art that the guide rail where the nozzle is located is worn after long-term use, resulting in increased surface roughness, inaccurate positioning, and thus reduced overprinting accuracy of the printer.

[0005] To achieve the above-mentioned purpose, the present invention provides a precise overprinting and anti-diffusion compensation system for digital printing, comprising: a data processing module for processing code graphic data to be printed, comprising a data segmentation unit for segmenting the code graphic data through an overprinting algorithm to output first color plane data and second color plane data, and a data transmission unit connected to the data segmentation unit for transmitting the first color plane data and the second color plane data to a printing position; a printing module, which is connected to the data processing module, for overprinting the first color plane data and the second color plane data using a printer to output a code graphic, comprising a first nozzle for printing an original code graphic according to the first color plane data, a second nozzle for printing an overprinted image according to the second color plane data Two nozzles and an adapter frame for respectively fixing the positions of the first nozzle and the second nozzle; a detection module, which is connected to the printing module, including a photoelectric sensor connected to the adapter frame for determining the printing position, a visual sensor connected to the adapter frame for collecting the overprint image, and a temperature sensor connected to the drive motor in the printer for detecting the surface temperature of the drive motor; a control module, which is respectively connected to the data processing module, the printing module and the detection module, and is used to determine the ink injection pressure of the first nozzle according to the deviation between the target position and the actual position of the first nozzle, or determine the exposure time of the overprint image according to the overprint failure rate of the code pattern, and determine the printing speed of the printer according to the rate of increase of the surface temperature of the drive motor.

[0006] Furthermore, the control module is used to determine whether the overprinting accuracy of the printer meets the requirements based on the deviation between the target position and the actual position of the first nozzle. If the deviation between the target position and the actual position of the first nozzle is greater than a preset first deviation, it is determined that the overprinting accuracy of the printer does not meet the requirements.

[0007] Furthermore, the control module is used to preliminarily determine that the operating stability of the overprinting algorithm does not meet the requirements when the deviation between the target position and the actual position of the first nozzle is greater than the preset first deviation and less than or equal to the preset second deviation, and determine whether the operating stability of the overprinting algorithm meets the requirements based on the overprinting failure rate of the code graphic.

[0008] Furthermore, the control module is used to increase the ink ejection pressure of the first nozzle when the deviation between the target position and the actual position of the first nozzle is greater than the preset second deviation;

[0009] The increase range of the ink ejection pressure of the first nozzle is determined by the difference between the deviation between the target position and the actual position of the first nozzle and a preset second deviation.

[0010] Furthermore, the control module is used to determine whether the operating stability of the overprinting algorithm meets the requirements according to the overprinting failure rate of the code pattern. If the overprinting failure rate of the code pattern is greater than a preset first failure rate, it is determined that the operating stability of the overprinting algorithm does not meet the requirements.

[0011] Furthermore, the control module is used to preliminarily determine that the environmental stability of the printer's overprinting does not meet the requirements when the overprint failure rate of the code graphic is greater than a preset second failure rate, and determine whether the environmental stability of the printer's overprinting meets the requirements based on the rate of increase of the surface temperature of the drive motor.

[0012] Furthermore, the control module is used to increase the exposure time of the overprint image when the overprint failure rate of the code pattern is greater than the preset first failure rate and less than or equal to the preset second failure rate.

[0013] Furthermore, the increase range of the exposure time of the overprint image is determined by the difference between the overprint failure rate of the code pattern and a preset first failure rate.

[0014] Furthermore, the control module is used to determine whether the environmental stability of the printer overprinting meets the requirements based on the rate of increase of the surface temperature of the drive motor. If the rate of increase of the surface temperature of the drive motor is greater than the preset rate of increase, it is determined that the environmental stability of the printer overprinting does not meet the requirements, and the printing speed of the printer is reduced.

[0015] Furthermore, the reduction range of the printing speed of the printer is determined by the difference between the increase rate of the surface temperature of the driving motor and a preset increase rate.

[0016] Compared with the prior art, the beneficial effect of the present invention lies in that the system of the present invention determines the ink injection pressure of the first nozzle according to the deviation between the target position and the actual position of the first nozzle by setting a data processing module, a printing module, a detection module and a control module. Since the guide rail where the nozzle is located is worn after long-term use, the surface roughness increases, thereby affecting the movement accuracy of the nozzle on the guide rail, resulting in inaccurate positioning. By increasing the ink injection pressure of the first nozzle, the ink can be ejected more forcefully, to a certain extent offset the influence of the nozzle movement deviation on the ink landing point, so that the ink is closer to the target position, and the accuracy of overprinting is improved. The exposure time of the overprinted image is determined according to the overprint failure rate of the code pattern. Since the mechanical parts in the printing equipment vibrate during operation, these vibrations will cause the sensor to vibrate slightly, thereby generating noise interference, affecting The inaccurate collection of position data will be affected, resulting in inaccurate data calibration, which will cause defects in the overprint algorithm. By increasing the exposure time of the overprint image, the overall brightness of the image can be increased, and the signal-to-noise ratio of the image can be improved to a certain extent, making the effective information in the image easier to identify and extract, providing more accurate data for the overprint algorithm. The printing speed of the printer is determined according to the rate of increase of the surface temperature of the drive motor. When the motor and drive system of the printing equipment are in operation, heat will be generated due to current flow and mechanical friction. The longer the running time, the more heat will be generated, which may cause the ink to dry too quickly, causing the nozzle to be blocked and affecting the printing quality. By reducing the printing speed of the printer, the number of ink discharges per unit time can be reduced, allowing the nozzle to have more time to wait for the natural replenishment of ink, reducing the possibility of ink drying and clogging at the nozzle, and improving the overprint accuracy of the printer.

[0017] Furthermore, the system of the present invention determines the ink injection pressure of the first nozzle by setting a preset first deviation and a preset second deviation. Since the guide rail where the nozzle is located is worn after long-term use, the surface roughness increases, which affects the movement accuracy of the nozzle on the guide rail and causes inaccurate positioning. By increasing the ink injection pressure of the first nozzle, the ink can be ejected more forcefully, which to a certain extent offsets the effect of the nozzle movement deviation on the ink landing point, making the ink closer to the target position, improving the accuracy of overprinting, and further improving the overprinting accuracy of the printer.

[0018] Furthermore, the system of the present invention determines the exposure time of the overprint image by setting a preset first failure rate and a preset second failure rate. Since the mechanical parts in the printing equipment vibrate during operation, these vibrations will cause the sensor to vibrate slightly, thereby generating noise interference, affecting the accurate collection of position data, resulting in inaccurate data calibration, and thus causing defects in the overprint algorithm. By increasing the exposure time of the overprint image, the overall brightness of the image can be increased, and the signal-to-noise ratio of the image can be improved to a certain extent, making the effective information in the image easier to identify and extract, providing more accurate data for the overprint algorithm, and further improving the overprint accuracy of the printer.

[0019] Furthermore, the system of the present invention determines the printing speed of the printer by setting a preset increase rate. When the motor and drive system of the printing equipment are in operation, heat will be generated due to the passage of current and mechanical friction. The longer the operation time, the more heat will be generated, which may cause the ink to dry too quickly, resulting in clogging of the nozzle and affecting the printing quality. By reducing the printing speed of the printer, the number of ink discharges by the nozzle per unit time can be reduced, allowing the nozzle to have more time to wait for the natural replenishment of ink, reducing the possibility of ink drying and clogging at the nozzle, and further improving the printer's overprinting accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is an overall structural block diagram of the precise overprinting and anti-diffusion compensation system for digital printing according to an embodiment of the present invention;

[0021] Figure 2 A logic flow chart for determining the ink jetting pressure of the first nozzle in the precise overprinting and anti-diffusion compensation system for digital inkjet printing according to an embodiment of the present invention;

[0022] Figure 3 A logic flow chart of determining the exposure time of an overprint image in a precise overprint and anti-diffusion compensation system for digital inkjet printing according to an embodiment of the present invention;

[0023] Figure 4 The present invention is a logic flow chart for determining the printing speed of a printer in a precise overprinting and anti-diffusion compensation system for digital printing according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] 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 only used to explain the present invention and are not used to limit the present invention.

[0025] 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 protection scope of the present invention.

[0026] 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 drawings. This is merely 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.

[0027] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] See also Figure 1 , Figure 2 , Figure 3 as well as Figure 4 As shown, they are respectively an overall structural block diagram of the precise overprinting and anti-diffusion compensation system for digital printing according to an embodiment of the present invention, a logic flow chart for determining the ink jetting pressure of the first nozzle, a logic flow chart for determining the exposure time of the overprinted image, and a logic flow chart for determining the printing speed of the printer. The precise overprinting and anti-diffusion compensation system for digital printing according to the present invention comprises:

[0029] A data processing module, for processing the code graphic data to be printed, comprising a data segmentation unit for segmenting the code graphic data by an overprint algorithm to output first color plane data and second color plane data, and a data transmission unit connected to the data segmentation unit for transmitting the first color plane data and the second color plane data to a printing position;

[0030] A printing module, connected to the data processing module, for overprinting the first color plane data and the second color plane data using a printer to output a code pattern, comprising a first nozzle for printing an original code pattern according to the first color plane data, a second nozzle for printing an overprint image according to the second color plane data, and an adapter frame for fixing the positions of the first nozzle and the second nozzle respectively;

[0031] A detection module connected to the printing module, comprising a photoelectric sensor connected to the adapter frame for determining the printing position, a visual sensor connected to the adapter frame for collecting the overprint image, and a temperature sensor connected to the drive motor in the printer for detecting the surface temperature of the drive motor;

[0032] A control module is respectively connected to the data processing module, the printing module and the detection module, and is used to determine the ink injection pressure of the first nozzle according to the deviation between the target position and the actual position of the first nozzle, or to determine the exposure time of the overprint image according to the overprint failure rate of the code pattern, and to determine the printing speed of the printer according to the rate of increase of the surface temperature of the drive motor.

[0033] Specifically, the code graphic data includes product number, product name, and website link.

[0034] Specifically, code graphics include QR codes, bar codes, and dot matrix codes.

[0035] Specifically, the overprint algorithm includes an edge detection algorithm, an error compensation algorithm, and a position control algorithm.

[0036] Specifically, the first color plane data is part of the coding information, part of the positioning pattern data, and color correction data.

[0037] Specifically, the second color plane data includes other coding information, other positioning pattern data, and transparency data.

[0038] Specifically, the overprinting process is: divide the complete code graphic data into two color plane data, the first color plane data drives the first nozzle to print the original code image, follows the standard code design size and high resolution, and ensures that the initial recognition features of the QR code are intact; the second color plane data drives the second nozzle to print the optimized overprint image, which is completely consistent with the original image in terms of content.

[0039] Specifically, when overprinting, there are three situations:

[0040] When color blocks are adjacent to each other: use the single-color line overprint method or the composite line method. For example, when the cyan block is adjacent to the magenta block, you can use the single-color line overprint method to change the line of the magenta block to 0.4mm magenta, and select the attribute as overprint line. In this case, the magenta block will expand 0.2mm into the cyan block. If the composite line method is used, the magenta block and the cyan block will each expand 0.1mm toward each other.

[0041] When the gradient is adjacent to the color block: trapping needs to be arranged according to the printing color sequence. For example, when the cyan gradient is adjacent to the magenta block, the magenta block needs to be extended 0.2mm into the cyan gradient. When the yellow gradient is adjacent to the cyan and magenta blocks, the cyan and magenta blocks need to be extended 0.2mm into the yellow gradient respectively.

[0042] When a continuous tone image is adjacent to a color block: you can extend the color block into the image or extend the image edge into the color block. For example, when a four-color image is adjacent to one or several primary colors, trapping is generally not required; however, if the hue of the color block is significantly different from the hue of the image, trapping is required.

[0043] Specifically, trapping, also known as white leakage or expansion and contraction, is mainly used to compensate for the problem of color leakage caused by inaccurate overprinting during the printing process. During the printing process, due to various factors, inaccurate color overprinting may cause white edges or color aliasing at the intersection of two colors, affecting the visual effect. Trapping technology avoids these problems by allowing the two colors to penetrate each other a little at the intersection of colors.

[0044] In implementation, the system of the present invention determines the ink injection pressure of the first nozzle according to the deviation between the target position and the actual position of the first nozzle by setting a data processing module, a printing module, a detection module and a control module. Since the guide rail where the nozzle is located is worn after long-term use, the surface roughness increases, thereby affecting the movement accuracy of the nozzle on the guide rail, resulting in inaccurate positioning. By increasing the ink injection pressure of the first nozzle, the ink can be ejected more forcefully, to a certain extent offset the influence of the nozzle movement deviation on the ink landing point, so that the ink is closer to the target position, and the accuracy of overprinting is improved. The exposure time of the overprinted image is determined according to the overprint failure rate of the code pattern. Since the mechanical parts in the printing equipment vibrate during operation, these vibrations will cause the sensor to vibrate slightly, thereby generating noise interference, affecting the accuracy of the position data. Inaccurate data collection leads to inaccurate data calibration, which in turn causes defects in the overprint algorithm. By increasing the exposure time of the overprint image, the overall brightness of the image can be increased, and the signal-to-noise ratio of the image can be improved to a certain extent, making the effective information in the image easier to identify and extract, providing more accurate data for the overprint algorithm. The printing speed of the printer is determined according to the rate of increase of the surface temperature of the drive motor. When the motor and drive system of the printing equipment are in operation, heat will be generated due to current flow and mechanical friction. The longer the running time, the more heat will be generated, which may cause the ink to dry too quickly, causing the nozzle to be blocked and affecting the printing quality. By reducing the printing speed of the printer, the number of ink discharges per unit time can be reduced, allowing the nozzle to have more time to wait for the natural replenishment of ink, reducing the possibility of ink drying and clogging at the nozzle, and improving the overprint accuracy of the printer.

[0045] Specifically, the control module is used to respectively obtain the target position and actual position of the first nozzle, and calculate the deviation between the target position and the actual position of the first nozzle. If the deviation between the target position and the actual position of the first nozzle is greater than the preset first deviation, it is determined that the overprinting accuracy of the printer does not meet the requirements.

[0046] Specifically, the control module is used to preliminarily determine that the operating stability of the overprinting algorithm does not meet the requirements when the deviation between the target position and the actual position of the first nozzle is greater than the preset first deviation and less than or equal to the preset second deviation, and to determine whether the operating stability of the overprinting algorithm meets the requirements based on the overprinting failure rate of the code graphic.

[0047] It can be understood that the three intervals divided by the preset first deviation amount and the preset second deviation amount correspond to three situations respectively:

[0048] The first interval is that the deviation between the target position and the actual position of the first nozzle is less than or equal to the preset first deviation, and the corresponding situation is: determining that the overprint accuracy of the printer meets the requirements;

[0049] The second interval is when the deviation between the target position and the actual position of the first nozzle is greater than the preset first deviation and less than or equal to the preset second deviation. The corresponding situation is: since the mechanical parts in the printing device vibrate during operation, these vibrations will cause the sensor to vibrate slightly, thereby generating noise interference, affecting the accurate collection of position data, resulting in inaccurate data calibration, and thus causing defects in the overprinting algorithm;

[0050] The third interval is that the deviation between the target position and the actual position of the first nozzle is greater than the preset second deviation. The corresponding situation is: the guide rail where the nozzle is located is worn after long-term use, resulting in increased surface roughness, which affects the movement accuracy of the nozzle on the guide rail and causes inaccurate positioning.

[0051] In practice, the preset first deviation is generally selected in the range of [0.1 mm, 0.3 mm], and the preset second deviation is generally selected in the range of [0.4 mm, 0.6 mm].

[0052] Preferably, the preferred embodiment of the preset first deviation is 0.2 mm, and the preferred embodiment of the preset second deviation is 0.5 mm.

[0053] Specifically, the deviation between the target position and the actual position of the first nozzle is a straight-line distance between the target position and the actual position of the first nozzle.

[0054] In implementation, the system of the present invention determines the overprint accuracy of the printer by setting a preset first deviation and a preset second deviation, thereby reducing the impact of the printer's overprint stability caused by inaccurate determination of the printer's overprint accuracy, and further improving the printer's overprint accuracy.

[0055] Specifically, the control module is used to increase the ink ejection pressure of the first nozzle when the deviation between the target position and the actual position of the first nozzle is greater than the preset second deviation;

[0056] The increase range of the ink ejection pressure of the first nozzle is determined by the difference between the deviation between the target position and the actual position of the first nozzle and a preset second deviation.

[0057] Specifically, when the difference between the deviation amount of the target position and actual position of the first nozzle and the preset second deviation amount is within 0.2mm, the ink injection pressure of the first nozzle increases to 1.1 times of the original value; when the difference between the deviation amount of the target position and actual position of the first nozzle and the preset second deviation amount exceeds 0.2mm, on the basis of being increased to 1.1 times of the original value, the ink injection pressure of the first nozzle increases by 20kPa for every 0.01mm exceeding the value. For example, the difference between the deviation amount of the target position and actual position of the first nozzle and the preset second deviation amount is 0.4mm, the current ink injection pressure of the first nozzle is 100kPa, and the increased ink injection pressure of the first nozzle is 100×1.1+20×2=150kPa.

[0058] In implementation, the system of the present invention determines the ink injection pressure of the first nozzle by setting a preset first deviation and a preset second deviation. Since the guide rail where the nozzle is located is worn after long-term use, the surface roughness increases, which affects the movement accuracy of the nozzle on the guide rail and causes inaccurate positioning. By increasing the ink injection pressure of the first nozzle, the ink can be ejected more forcefully, which to a certain extent offsets the effect of the nozzle movement deviation on the ink landing point, making the ink closer to the target position, improving the accuracy of overprinting, and further improving the overprinting accuracy of the printer.

[0059] Specifically, the control module is used to obtain the number of failed overprints of the code pattern and the total number of overprints of the code pattern respectively, and calculate the overprint failure rate of the code pattern. If the overprint failure rate of the code pattern is greater than the preset first failure rate, it is determined that the operating stability of the overprint algorithm does not meet the requirements.

[0060] Specifically, the control module is used to preliminarily determine that the environmental stability of the printer's overprinting does not meet the requirements when the overprint failure rate of the code graphic is greater than a preset second failure rate, and to determine whether the environmental stability of the printer's overprinting meets the requirements based on the rate of increase of the surface temperature of the drive motor.

[0061] It can be understood that the three intervals divided by the preset first failure rate and the preset second failure rate correspond to three situations respectively:

[0062] The first interval is that the overprint failure rate of the code pattern is less than or equal to the preset first failure rate, and the corresponding situation is: determining that the operation stability of the overprint algorithm meets the requirements;

[0063] The second interval is when the overprint failure rate of the code pattern is greater than the preset first failure rate and less than or equal to the preset second failure rate. The corresponding situation is: since the mechanical parts in the printing equipment vibrate during operation, these vibrations will cause the sensor to vibrate slightly, thereby generating noise interference, affecting the accurate collection of position data, resulting in inaccurate data calibration, and thus causing overprint algorithm defects;

[0064] The third interval is when the overprint failure rate of the code graphics is greater than the preset second failure rate. The corresponding situation is: due to the passage of current and mechanical friction, heat will be generated. The longer the running time, the more heat will be generated, which may cause the ink to dry too quickly, causing the nozzle to be blocked and affecting the printing quality.

[0065] In practice, the preset first failure rate is generally selected in the range of [0.2%, 0.4%], and the preset second failure rate is generally selected in the range of [0.5%, 0.7%].

[0066] Preferably, the preferred embodiment of the preset first failure rate is 0.3%, and the preferred embodiment of the preset second failure rate is 0.6%.

[0067] Specifically, the overprint failure rate of the code pattern is the ratio of the number of overprint failures of the code pattern to the total number of overprints of the code pattern.

[0068] In implementation, the system of the present invention determines the operating stability of the overprinting algorithm by setting a preset first failure rate and a preset second failure rate, thereby reducing the impact of the printer's overprinting accuracy caused by inaccurate determination of the overprinting algorithm's operating stability, and further improving the printer's overprinting accuracy.

[0069] Specifically, the control module is used to increase the exposure time of the overprint image when the overprint failure rate of the code pattern is greater than the preset first failure rate and less than or equal to the preset second failure rate.

[0070] Specifically, the increase range of the exposure time of the overprint image is determined by the difference between the overprint failure rate of the code pattern and a preset first failure rate.

[0071] Specifically, when the difference between the overprint failure rate of the code graphic and the preset first failure rate is within 0.1%, the exposure time of the overprint image is increased to 1.2 times of the original; when the difference between the overprint failure rate of the code graphic and the preset first failure rate exceeds 0.1%, on the basis of being increased to 1.2 times of the original, the exposure time of the overprint image is increased by 10ms for every 0.1% exceeding it. For example, the difference between the overprint failure rate of the code graphic and the preset first failure rate is 0.3%, the current exposure time of the overprint image is 50ms, and the increased exposure time of the overprint image is 50×1.2+10×2=80ms.

[0072] In implementation, the system of the present invention determines the exposure time of the overprint image by setting a preset first failure rate and a preset second failure rate. Since the mechanical parts in the printing equipment vibrate during operation, these vibrations will cause the sensor to vibrate slightly, thereby generating noise interference, affecting the accurate collection of position data, resulting in inaccurate data calibration, and thus causing defects in the overprint algorithm. By increasing the exposure time of the overprint image, the overall brightness of the image can be increased, and the signal-to-noise ratio of the image can be improved to a certain extent, making the effective information in the image easier to identify and extract, providing more accurate data for the overprint algorithm, and further improving the overprint accuracy of the printer.

[0073] Specifically, the control module is used to obtain the surface temperature of the drive motor per unit time and calculate the rate of increase of the surface temperature of the drive motor. If the rate of increase of the surface temperature of the drive motor is greater than the preset rate of increase, it is determined that the environmental stability of the printer overprinting does not meet the requirements, and the printing speed of the printer is reduced.

[0074] It can be understood that the two intervals divided by the preset increase rate correspond to two situations:

[0075] The first interval is when the rate of increase of the surface temperature of the drive motor is less than or equal to the preset rate of increase, and the corresponding situation is: determining that the environmental stability of the printer overprinting meets the requirements;

[0076] The second interval is when the rate of increase of the surface temperature of the drive motor is greater than the preset rate of increase. The corresponding situation is: due to the passage of current and mechanical friction, heat will be generated. The longer the running time, the more heat will be generated, which may cause the ink to dry too quickly, causing the nozzle to be blocked and affecting the printing quality.

[0077] In practice, the preset temperature increase rate is generally selected in the range of [1°C / min, 3°C / min].

[0078] Preferably, the preset increasing rate is preferably 2° C. / min.

[0079] Specifically, the rate of increase of the surface temperature of the drive motor is the ratio of the difference between the surface temperature of the drive motor at the end time of the unit time and the surface temperature of the drive motor at the initial time of the unit time to the duration of the unit time.

[0080] In implementation, the system of the present invention determines the environmental stability of the printer overprinting by setting a preset increase rate, thereby reducing the impact of the printer's overprinting accuracy caused by inaccurate determination of the environmental stability of the printer overprinting, and further improving the printer's overprinting accuracy.

[0081] Specifically, the reduction range of the printing speed of the printer is determined by the difference between the increase rate of the surface temperature of the driving motor and a preset increase rate.

[0082] Specifically, when the difference between the increase rate of the driving motor surface temperature and the preset increase rate is within 2°C / min, the printing speed of the printer is reduced to 0.9 times the original speed; when the difference between the increase rate of the driving motor surface temperature and the preset increase rate exceeds 2°C / min, on the basis of being reduced to 0.9 times the original speed, the printing speed of the printer is reduced by 5m / min for every 0.5°C / min exceeding the original speed. For example, the difference between the increase rate of the driving motor surface temperature and the preset increase rate is 3°C / min, the current printing speed of the printer is 200m / min, and the reduced printing speed of the printer is 200×0.9-5×2=170m / min.

[0083] In implementation, the system of the present invention determines the printing speed of the printer by setting a preset increase rate. When the motor and drive system of the printing equipment are in operation, heat will be generated due to the passage of current and mechanical friction. The longer the operation time, the more heat will be generated, which may cause the ink to dry too quickly, resulting in clogging of the nozzle and affecting the printing quality. By reducing the printing speed of the printer, the number of ink discharges by the nozzle per unit time can be reduced, allowing the nozzle to have more time to wait for the natural replenishment of ink, reducing the possibility of ink drying and clogging at the nozzle, and further improving the printer's overprinting accuracy.

[0084] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A precise overprinting and anti-diffusion compensation system for digital printing, characterized in that: include: A data processing module, for processing the code graphic data to be printed, comprising a data segmentation unit for segmenting the code graphic data by an overprint algorithm to output first color plane data and second color plane data, and a data transmission unit connected to the data segmentation unit for transmitting the first color plane data and the second color plane data to a printing position; A printing module, connected to the data processing module, for overprinting the first color plane data and the second color plane data using a printer to output a code pattern, comprising a first nozzle for printing an original code pattern according to the first color plane data, a second nozzle for printing an overprint image according to the second color plane data, and an adapter frame for fixing the positions of the first nozzle and the second nozzle respectively; A detection module connected to the printing module, comprising a photoelectric sensor connected to the adapter frame for determining the printing position, a visual sensor connected to the adapter frame for collecting the overprint image, and a temperature sensor connected to the drive motor in the printer for detecting the surface temperature of the drive motor; A control module is respectively connected to the data processing module, the printing module and the detection module, and is used to determine the ink injection pressure of the first nozzle according to the deviation between the target position and the actual position of the first nozzle, or to determine the exposure time of the overprint image according to the overprint failure rate of the code pattern, and to determine the printing speed of the printer according to the rate of increase of the surface temperature of the drive motor.

2. The precise overprinting and anti-diffusion compensation system for digital printing according to claim 1, characterized in that: The control module is used to determine whether the overprinting accuracy of the printer meets the requirements based on the deviation between the target position and the actual position of the first nozzle. If the deviation between the target position and the actual position of the first nozzle is greater than the preset first deviation, it is determined that the overprinting accuracy of the printer does not meet the requirements.

3. The precise overprinting and anti-diffusion compensation system for digital printing according to claim 2, characterized in that: The control module is used to preliminarily determine that the operating stability of the overprinting algorithm does not meet the requirements when the deviation between the target position and the actual position of the first nozzle is greater than the preset first deviation and less than or equal to the preset second deviation, and to determine whether the operating stability of the overprinting algorithm meets the requirements based on the overprinting failure rate of the code graphic.

4. The precise overprinting and anti-diffusion compensation system for digital printing according to claim 3, characterized in that: The control module is used for increasing the ink ejection pressure of the first nozzle when the deviation between the target position and the actual position of the first nozzle is greater than the preset second deviation; The increase range of the ink ejection pressure of the first nozzle is determined by the difference between the deviation between the target position and the actual position of the first nozzle and a preset second deviation.

5. The precise overprinting and anti-diffusion compensation system for digital printing according to claim 4, characterized in that: The control module is used to determine whether the operation stability of the overprint algorithm meets the requirements according to the overprint failure rate of the code pattern. If the overprint failure rate of the code pattern is greater than the preset first failure rate, it is determined that the operation stability of the overprint algorithm does not meet the requirements.

6. The precise overprinting and anti-diffusion compensation system for digital printing according to claim 5, characterized in that: The control module is used to preliminarily determine that the environmental stability of the printer's overprinting does not meet the requirements when the overprint failure rate of the code pattern is greater than a preset second failure rate, and determine whether the environmental stability of the printer's overprinting meets the requirements based on the rate of increase of the surface temperature of the drive motor.

7. The precise overprinting and anti-diffusion compensation system for digital printing according to claim 6, characterized in that: The control module is used to increase the exposure time of the overprint image when the overprint failure rate of the code pattern is greater than the preset first failure rate and less than or equal to the preset second failure rate.

8. The precise overprinting and anti-diffusion compensation system for digital printing according to claim 7, characterized in that: The increase range of the exposure time of the overprint image is determined by the difference between the overprint failure rate of the code pattern and a preset first failure rate.

9. The precise overprinting and anti-diffusion compensation system for digital printing according to claim 8, characterized in that: The control module is used to determine whether the environmental stability of the printer overprinting meets the requirements based on the rate of increase of the surface temperature of the drive motor. If the rate of increase of the surface temperature of the drive motor is greater than the preset rate of increase, it is determined that the environmental stability of the printer overprinting does not meet the requirements, and the printing speed of the printer is reduced.

10. The precise overprinting and anti-diffusion compensation system for digital printing according to claim 9, characterized in that: The reduction range of the printing speed of the printer is determined by the difference between the increase rate of the surface temperature of the driving motor and the preset increase rate.

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