Multi-sensor based cross-carton continuous inkjet printing control method and apparatus

Abstract

The application discloses a kind of based on multi-sensor's cross carton continuous ink-jet printing control method and device, method includes: according to the edge pixel feature of PRT image, image edge is obtained, calculates the starting printing coordinate of carton, end printing coordinate, skip white interval in printing coordinate system;According to the paper box electric eye information reported by paper feeding control unit, the interval of two cartons is calculated, and the printing image between adjacent cartons is spliced into a new printing image according to the interval, to realize continuous cross carton printing;Paper feeding control unit uses PID+feedforward control algorithm based on control front paper feeding power wheel and synchronous belt power main roller follow-up operation, to ensure that the front and rear two cartons follow synchronous movement according to fixed interval, so as to improve printing accuracy, printing efficiency;Carton stacking control unit controls industrial camera to collect printing image on carton, and judges printing image quality using template matching method, controls stacking manipulator to grab qualified carton, and rejects unqualified carton.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carton inkjet printing control, and particularly relates to a cross-carton continuous inkjet printing control method and device based on multiple sensors. BACKGROUND

[0002] At present, with the continuous expansion of network consumption, a large number of new types of goods are born, which brings new challenges to packaging work. With the dramatic increase in the number of goods and the diversification of types, the requirements for packaging work are becoming more and more stringent. Compared with other printing methods, digital inkjet technology can maximize the production efficiency of packaging printing and can quickly and efficiently meet the customization needs of personalized patterns. At the same time, since inkjet printing belongs to non-contact flexographic printing, it can greatly reduce the mechanical impact force on the paperboard caused by printing pressure, thereby improving the overall printing quality and minimizing maintenance and management costs.

[0003] In the prior art, when the trolley width is much larger than the height of a carton, the digital carton printer can only print one carton at a time and cannot perform cross-carton continuous printing. When the trolley width is smaller than the height of a carton, due to the low control precision of the front edge paper feeding shaft and the stepping shaft, cross-carton continuous printing cannot be achieved. When there is a blank in front, behind or in the middle of the image, the printer cannot automatically adapt to quickly position the starting printing position coordinates between the cartons and skip the blank, thereby affecting the printing efficiency. SUMMARY

[0004] Therefore, the present application provides a cross-carton continuous inkjet printing control method and device based on multiple sensors to solve the problem of cross-carton continuous printing in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] In a first aspect, a cross-carton continuous inkjet printing control method based on multiple sensors comprises:

[0007] Receiving a carton electric eye signal reported by a paper feeding control unit and starting a printing process according to the electric eye signal; the paper feeding control unit uses a PID+feedforward control algorithm to control the front edge paper feeding power wheel and the synchronous belt power main roller to keep follow-up movement;

[0008] Loading a pre-reading PRT image and obtaining an image edge according to the edge pixel characteristics of the PRT image;

[0009] Calculating the starting printing position coordinates and the ending printing position coordinates of the image in the pixel coordinate system according to the image edge;

[0010] Converting the start printing position coordinate and the end printing position coordinate of the image in the pixel coordinate system to the start printing position coordinate, the end printing position coordinate and the white space interval of the carton in the printing coordinate system;

[0011] According to the start printing position coordinate of the carton, issuing a step command to the step control unit; after receiving the step command, the step control unit synchronizes the belt to send the carton to the start printing position coordinate for printing;

[0012] Issuing the printing image data information to the printing control unit for printing;

[0013] During the printing process, detecting whether the next carton electric eye signal reported by the paper feeding control unit is received;

[0014] If the next carton electric eye signal is not received, the remaining printing is continued to be completed, and the printing process is ended;

[0015] If the next carton electric eye signal is received, the real time interval of the two cartons is calculated;

[0016] According to the real time interval, the printing image and the white space interval of the adjacent two cartons are spliced into new image data information;

[0017] The new image data information is issued to the printing control unit for cross-carton continuous printing.

[0018] As a preferred embodiment, the edge of the image is obtained by using the 8-neighborhood pixel statistics method.

[0019] As a preferred embodiment, when the printing image data information is issued to the printing control unit for printing, if the start position of the printing image is a blank pattern, a white space operation process is started, and the step is continued until the printing pattern position coordinate.

[0020] As a preferred embodiment, when the printing image and the white space interval of the adjacent two cartons are spliced into new image data information according to the real time interval, the number of back-filled blank lines between the nth picture and the n+1th picture is linenum=(s(n+1)-s(n)) / dpixel-H;

[0021] Wherein, the picture two-row spacing dpixel = (d(n)-d(0)) / (Y(n)-Y(0)), Y(n) is the scanning line number of the nth time, d(n) is the relative coordinate of the scanning position coordinate of the nth time, s(n) is the relative coordinate of the electric eye triggering position coordinate of the nth time, and H is the pixel height of the picture.

[0022] As preferred, the carton stacking control unit further comprises: a camera, a camera control unit, a camera image acquisition module, a camera image edge calculation module, a pixel coordinate calculation module, a print coordinate calculation module, a sending module, a detection module, a paper box real time interval calculation module, and an image splicing module.

[0023] In a second aspect, a multi-sensor-based cross-carton continuous inkjet printing control device comprises:

[0024] A receiving module is configured to receive a carton electric eye signal reported by a paper feeding control unit and start a printing process according to the electric eye signal; the paper feeding control unit uses a PID+feedforward control algorithm to control the front paper feeding power wheel and the synchronous belt power main roller to keep follow-up movement.

[0025] An image edge calculation module is configured to load a pre-reading PRT image and obtain an image edge according to edge pixel features of the PRT image.

[0026] A pixel coordinate calculation module is configured to calculate starting and ending printing position coordinates of an image in a pixel coordinate system according to the image edge.

[0027] A print coordinate calculation module is configured to convert the starting and ending printing position coordinates of the image in the pixel coordinate system into starting and ending printing position coordinates of a carton in a printing coordinate system and a white space interval.

[0028] A sending module is configured to send a stepping command to the stepping control unit according to the starting printing position coordinates of the carton; after receiving the stepping command, the stepping control unit synchronously feeds the carton to the starting printing position for printing.

[0029] The sending module is further configured to send printing image data information to a printing control unit for printing.

[0030] A detection module is configured to detect whether a next carton electric eye signal reported by the paper feeding control unit is received during the printing process.

[0031] A paper box real time interval calculation module is configured to calculate a real time interval between two cartons after receiving the next carton electric eye signal.

[0032] An image splicing module is configured to splice the printing image and the white space interval of adjacent two cartons into new image data information according to the real time interval.

[0033] In a third aspect, a computer device comprises a memory and a processor, the memory storing a computer program, and the processor implements the steps of the multi-sensor-based continuous ink-jet printing control method across cartons when executing the computer program.

[0034] In a fourth aspect, a computer-readable storage medium stores a computer program, and the computer program implements the steps of the multi-sensor-based continuous ink-jet printing control method across cartons when executed by a processor.

[0035] Compared with the prior art, the present application has at least the following beneficial effects:

[0036] The present application provides a multi-sensor-based continuous ink-jet printing control method and device across cartons, which comprises: loading a pre-reading PRT image, obtaining an image edge according to the edge pixel characteristics of the PRT image, and calculating the starting printing position coordinates, the ending printing position coordinates, and the white skipping interval of the image in the printing coordinate system; calculating the distance between two cartons in real time according to the carton electric eye signal reported by the paper feeding control unit, and splicing the printing image information and the white skipping interval between adjacent cartons into new printing image information according to the distance information, to realize continuous printing across cartons; and the paper feeding control unit uses a PID+feedforward control algorithm to control the front paper feeding power wheel and the synchronous belt power main roller to follow, to ensure that the front and rear two cartons follow the synchronous movement at a fixed distance, thereby improving the printing precision and efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more intuitively illustrate the prior art and the present application, several exemplary drawings are given below. It should be understood that the specific shapes, structures shown in the drawings should not be considered as limiting conditions in the implementation of the present application; for example, based on the technical concepts disclosed in the present application and the exemplary drawings, those skilled in the art can easily make routine adjustments or further optimizations to some units (components) such as increase / decrease / attribute division, specific shape, positional relationship, connection mode, size ratio relationship, etc.

[0038] Figure 1 A multi-sensor-based continuous ink-jet printing control method across cartons provided for Embodiment One of the present application is shown in the execution sequence flowchart;

[0039] Figure 2 A multi-sensor-based continuous ink-jet printing control method across cartons provided for Embodiment One of the present application is shown in the judgment flowchart;

[0040] Figure 3 A continuous ink-jet printing control system structure schematic diagram across cartons provided for Embodiment One of the present application is shown in the judgment flowchart;

[0041] Figure 4 A carton printing step control schematic diagram provided for Embodiment One of the present application is shown in the judgment flowchart;

[0042] Figure 5 The paper feeding control unit follow-up control flow chart provided for the embodiment one of the application;

[0043] Figure 6 The carton printing flow control schematic diagram provided for the embodiment one of the application.

[0044] Explanation of reference signs:

[0045] 1, front baffle; 2, electric eye inductor; 3, next printed carton; 4, upper pressure wheel; 5, photoelectric inductor; 6, printing trolley; 7, rear pressure wheel; 8, printed carton; 9, industrial camera; 10, detected carton; 11, power wheel; 12, driven wheel; 13, synchronous belt driving main roll; 14, synchronous belt driven roll; 15, paper feeding power wheel; 16, paper feeding driven main wheel; 17, carton waiting to be printed. DETAILED DESCRIPTION

[0046] The application will be further described in detail below with specific embodiments in combination with the accompanying drawings.

[0047] In the description of the application: unless otherwise specified, the meaning of "multiple" is two or more. The terms "first", "second", "third" and the like in the application are intended to distinguish the objects referred to, and do not have a special meaning in the technical connotation aspect (for example, it should not be understood as emphasizing importance or order, etc.). The expressions such as "include", "contain", "have" and the like also mean "not limited to" (some units, components, materials, steps, etc.).

[0048] The terms such as "upper", "lower", "left", "right", "intermediate" and the like referred to in the application are generally for the purpose of intuitive understanding by referring to the drawings, and are not an absolute limitation on the positional relationship in the actual product. Without departing from the technical concept disclosed in the application, the change of these relative positional relationships is also considered as the scope of the description of the application.

[0049] Embodiment one

[0050] Please refer to Figure 1 and Figure 2 The embodiment provides a multi-sensor-based cross-carton continuous inkjet printing control method, which comprises the following steps:

[0051] S1: receiving the carton electric eye signal reported by the paper feeding control unit, and starting the printing process according to the electric eye signal; the paper feeding control unit adopts a PID+feedforward control algorithm to control the front paper feeding power wheel and the synchronous belt driving main roll to keep follow-up movement;

[0052] After the paper feeding control unit reports the carton electric eye signal, the printing management software (PM) starts the printing process.

[0053] In detail, please refer to Figure 3 , the electric eye signal is generated by the photoelectric sensor 5 in the I area (i.e. the print control area). When the paper feed control unit feeds the paper box 8 from the II area (i.e. the front edge paper feed servo control area) to the position of the photoelectric sensor 5 in the I area, the electric eye signal is generated. Then, the step control unit starts to control the paper box to step with the synchronous belt driving force main roller 13 and the synchronous belt driven roller 14.

[0054] S2: load the pre-reading PRT image, and obtain the image edge according to the edge pixel characteristics of the PRT image;

[0055] Specifically, the print management software (PM) loads the pre-reading PRT image, and obtains the image edge according to the characteristics of the edge pixel points of the PRT image by using the 8-neighborhood pixel statistics method.

[0056] S3: calculate the starting print position coordinates and the ending print position coordinates of the image in the pixel coordinate system according to the image edge;

[0057] S4: convert the starting print position coordinates and the ending print position coordinates of the image in the pixel coordinate system into the starting print position coordinates, the ending print position coordinates and the white skipping interval of the paper box in the print coordinate system;

[0058] Specifically, through the transformation of the pixel coordinate system and the printer coordinate system, the starting print position coordinates, the ending print position coordinates and the white skipping interval of the paper box in the printer coordinate system are obtained, i.e. the position coordinates PJS10 and the ending print position coordinates PJE10 of the print pattern in the formula (1). Figure 4

[0059] S5: according to the starting print position coordinates of the paper box, send a step command to the step control unit; after receiving the step command, the step control unit synchronously feeds the paper box to the starting print position coordinates to prepare for the first BAND printing;

[0060] Specifically, if the starting position of the image is a white pattern, the white skipping operation process is started, and the step is continuously performed until the print pattern position coordinates.

[0061] S6: send the print image data information to the print control unit for printing;

[0062] Specifically, during the printing operation, the print control unit controls the X-axis motor to perform the scanning movement, and the nozzle scans once, and the synchronous belt steps once. Each scanning can correspond to the number of rows of the image.

[0063] S7: during the printing process, detect whether the next paper box electric eye signal reported by the paper feed control unit is received;

[0064] ​Specifically, according to the number of passes P of the current job, the print management software (PM) searches whether the next paper box electric eye signal is reported by the paper feeding control unit at the last P-1 pass scanning.

[0065] S8: If the next paper box electric eye signal is not received, the remaining printing is continued to be completed, and the printing process is ended;

[0066] Specifically, if the next paper box electric eye signal is not received, the remaining printing is continued to be completed until the last 1 PASS, and the paper box is fed to the pattern end printing position coordinate by the stepping control unit. If the pattern end printing position coordinate is the image end, the printing job is completed; if the pattern end printing position coordinate is the image edge, the white skipping job process is started, and the continuous stepping is performed until the image end.

[0067] S9: If the next paper box electric eye signal is received, the real time interval of the two paper boxes is calculated;

[0068] Specifically, if the next paper box electric eye signal is received, the cross-paper box printing process is started.

[0069] S10: According to the real time interval, the printed images of the adjacent two paper boxes and the white skipping interval are spliced into new image data information;

[0070] S11: The new image data information is sent to the print control unit for cross-paper box continuous printing.

[0071] Specifically, the cross-paper box printing process is that the print management software (PM) receives the reported paper box interval information, calculates the real time interval of the two paper boxes, and splices the images printed by the adjacent paper boxes into new image information according to the distance information, that is Figure 4 The image splicing in IV. The necessary condition for realizing continuous splicing is that the detection electric eye signal of the n+1 paper box can be triggered when the n paper box is printed, so that real-time variable splicing can be realized during the printing process; the number of scanning lines of the n time is Y(n), the relative coordinate of the scanning position coordinate of the n time is d(n), the relative coordinate of the electric eye triggering position coordinate of the n time is s(n), the pixel height of the image is H, the distance between two rows of the image can be calculated as dpixel = (d(n)-d(0)) / (Y(n)-Y(0)), the number of white skipping rows between the n image and the n+1 image is linenum=(s(n+1)-s(n)) / dpixel-H, the calculated dpixel is a real-time calculation result, and the main purpose is to remove the cumulative error.

[0072] In the embodiment, the print control unit receives the print image data information sent by the print management software (PM), and transmits the print image data to the inside of the printhead;Figure 3 The printing carriage 6 in the middle moves along the X-axis for scanning; an ignition signal is generated according to the grating coordinates to control the printhead to spray ink.

[0073] The stepper control unit includes Figure 3 The system includes cardboard box photoelectric sensor 2 for signal detection, synchronous belt-driven main roller 13 for servo stepping control, cardboard box spacing calculation, upper pressure roller 4 for control, and rear pressure roller 7 for control. When the stepping control unit detects the rising edge of the signal from photoelectric sensor 2, it indicates that the cardboard box has entered the printing area I. The control board DO1 outputs a high level, the cylinder actuates, and the upper pressure roller 4 presses down. The cardboard box 8 to be printed enters the printhead working area synchronously with the synchronous belt-driven main roller 13 and synchronous belt driven roller 14 under the combined action of friction and suction. When a printing job is completed, the control board DO1 outputs a low level, the cylinder actuates, the upper pressure roller 4 moves upward, and the paper feeding structure feeds the next cardboard box 3 from the waiting cardboard box 17.

[0074] The paper feeding control unit uses a PID+feedforward control algorithm to control the paper feeding power wheel 15 to follow the synchronous belt power main roller 13, ensuring that the distance between the front and rear cartons remains unchanged, thereby improving the system control accuracy and printing efficiency. Figure 5 The following is a block diagram of the follow-up control, and the specific process is as follows:

[0075] S101: Start the paper feeding function. The front edge baffle 1 rises, the paper feeding power wheel 15 starts, and the paper feeding driven main wheel 16 moves synchronously with the paper feeding power wheel 15.

[0076] S102: When the paper box 17 waiting to be printed is sent to the photoelectric sensor 5, the photoelectric sensor 5 detects the paper box and generates a rising edge. The paper feeding control unit detects the signal and the paper feeding power wheel 15 begins to enter the follow-up control stage. At this time, the paper feeding power wheel 15, the synchronous belt power main roller 13, and the synchronous belt driven roller 14 maintain linear speed synchronous movement.

[0077] S103: During follow-up motion, the differential calculates the theoretical speed ω1 of the paper feeding drive roller 15 based on the speed ω0 of the synchronous drive main roller 13 given by the stepper control unit; the PID controller combines the theoretical speed ω1 of the paper feeding drive roller 15 with the current speed ω0 of the synchronous drive main roller 13. m Paper feeding drive wheel 15 speed ω s Bad u e As input, calculate the current velocity given u. p And add feedforward u f The actual speed u of the current paper feeding drive wheel 15 is obtained, that is:

[0078]

[0079] S104: When the paper box 17 to be printed is sent to the lower side of the upper pressing wheel 4, the photoelectric sensor 5 detects the paper box 17 to be printed and generates an electric eye signal, the paper feeding driving wheel 15 and the paper feeding driven master wheel 16 are pushed out to follow the control, and the paper box 17 to be printed is controlled by the synchronous belt driving master roller 13 and the synchronous belt driven roller 14 to make a synchronous stepping motion.

[0080] Please refer to Figure 6 , a paper box is sent into the printing control area (i.e. I area) from the front edge paper feeding follow-up control area (i.e. II area), and after the printing is completed, it is sent to the stacking control area (i.e. III area) by the synchronous belt driving master roller 13, the synchronous belt driven roller 14, the driving wheel 11 and the driven wheel 12.

[0081] The paper box stacking control unit controls the field of view and the depth of field of the paper box industrial camera 9 according to the coordinates PM13 of the detected paper box 10 and the image position coordinates PJS13, PJS14, PJE13 and PJE14, and collects the paper box image Job1. The image processing software uses the template matching method to determine whether the printed image quality is qualified. If the printed image quality is qualified, the paper box stacking control unit sends the paper box coordinates PM13 and the center coordinates to the stacking PLC controller to start the stacking machine manipulator to grab the paper box and complete the printing flow operation; if the printed image quality is not qualified, an alarm is given and the defective product is rejected.

[0082] Embodiment two

[0083] The embodiment provides a multi-sensor-based cross-paper-box continuous ink-jet printing control device, which comprises:

[0084] A receiving module is configured to receive a paper box electric eye signal reported by a paper feeding control unit and start a printing process according to the electric eye signal; the paper feeding control unit controls the front edge paper feeding driving wheel and the synchronous belt driving master roller to keep follow-up motion based on a PID+feedforward control algorithm.

[0085] An image edge calculation module is configured to load a pre-reading PRT image and obtain an image edge according to edge pixel features of the PRT image.

[0086] A pixel coordinate calculation module is configured to calculate starting printing position coordinates and ending printing position coordinates of an image in a pixel coordinate system according to the image edge.

[0087] A printing coordinate calculation module is configured to convert the starting printing position coordinates and the ending printing position coordinates of the image in the pixel coordinate system into starting printing position coordinates, ending printing position coordinates and white space intervals of a paper box in a printing coordinate system.

[0088] The sending module is configured to send a stepping command to the stepping control unit according to the starting printing position coordinate of the carton; and the stepping control unit sends the carton to the starting printing position coordinate to prepare for printing after receiving the stepping command.

[0089] The sending module is configured to send a stepping command to the stepping control unit according to the starting printing position coordinate of the carton; and the stepping control unit sends the carton to the starting printing position coordinate to prepare for printing after receiving the stepping command.

[0090] The detection module is configured to detect whether the next carton electric eye signal reported by the paper feeding control unit is received during the printing process.

[0091] The carton real time interval calculation module is configured to calculate the real time interval of two cartons after receiving the next carton electric eye signal.

[0092] The image splicing module is configured to splice the printing images and the white space interval of adjacent two cartons into new image data information according to the real time interval.

[0093] For specific limitations of the multi-sensor-based cross-carton continuous inkjet printing control device, refer to the limitations of the multi-sensor-based cross-carton continuous inkjet printing control method, which will not be repeated here.

[0094] Embodiment three

[0095] The embodiment provides a computer device, including a memory and a processor, the memory stores a computer program, and the processor realizes the steps of the multi-sensor-based cross-carton continuous inkjet printing control method when executing the computer program.

[0096] Embodiment four

[0097] The embodiment provides a computer readable storage medium, which stores a computer program, and the computer program realizes the steps of the multi-sensor-based cross-carton continuous inkjet printing control method when executed by a processor.

[0098] The technical features of the above embodiments can be combined in any manner (as long as the combination of the technical features does not exist contradictions), in order to make the description simple, not all possible combinations of the technical features in the above embodiments are described; these embodiments which are not explicitly written should also be considered as the scope of the present application.

[0099] The above application is described in detail through general description and specific embodiments. It should be understood that, based on the technical concept of the application, some conventional adjustments or further innovations can be made to these specific embodiments; however, as long as these conventional adjustments or further innovations do not deviate from the technical concept of the application, the technical solutions obtained by these conventional adjustments or further innovations also fall within the protection scope of the claims of the application.

Claims

1. A multi-sensor based continuous inkjet printing control method across cartons, characterized by, The method comprises the following steps: receiving a carton electric eye signal reported by a paper feeding control unit, and starting a printing process according to the electric eye signal; the paper feeding control unit controls the front paper feeding power wheel and the synchronous belt power main roll to keep follow-up movement based on a PID+feedforward control algorithm; loading a pre-reading PRT image, and obtaining an image edge according to edge pixel characteristics of the PRT image; calculating starting printing position coordinates and ending printing position coordinates of the image in a pixel coordinate system according to the image edge; converting the starting printing position coordinates and the ending printing position coordinates of the image in the pixel coordinate system into starting printing position coordinates, ending printing position coordinates and white space intervals of a carton in a printing coordinate system; issuing a stepping command to a stepping control unit according to the starting printing position coordinates of the carton; after the stepping control unit receives the stepping command, the synchronous belt feeds the carton to the starting printing position coordinates to prepare for printing; issuing printing image data information to a printing control unit for printing; during the printing process, detecting whether a next carton electric eye signal reported by the paper feeding control unit is received; if the next carton electric eye signal is not received, the remaining printing is continued, and the printing process is ended; if the next carton electric eye signal is received, the real time interval of two cartons is calculated; according to the real time interval, the printing image and the white space intervals of the adjacent two cartons are spliced into new image data information; the new image data information is issued to the printing control unit for cross-carton continuous printing.

2. The multi-sensor based cross carton continuous inkjet printing control method according to claim 1, wherein, The image edge is obtained by using an 8-neighborhood pixel statistics method.

3. The multi-sensor based cross carton continuous inkjet printing control method of claim 1, wherein, When the printing image data information is issued to the printing control unit for printing, if the starting position of the printing image is a blank pattern, a white space skipping operation process is started, and continuous stepping is performed until the printing pattern position coordinates.

4. The multi-sensor based cross carton continuous inkjet printing control method of claim 1, wherein, When the printing image and the white space intervals of the adjacent two cartons are spliced into new image data information according to the real time interval, the number of rear blank lines linenum between the nth picture and the n+1th picture is linenum=(s(n+1)-s(n)) / dpixel-H; wherein, the picture two-row spacing dpixel=(d(n)-d(0)) / (Y(n)-Y(0)), Y(n) is the scanning row number of the nth time, d(n) is the relative coordinates of the scanning position coordinates of the nth time, s(n) is the relative coordinates of the electric eye triggering position coordinates of the nth time, and H is the pixel height of the picture.

5. The multi-sensor based cross carton continuous inkjet printing control method of claim 1, wherein, The method further comprises the following steps:

6. A multi-sensor based cross carton continuous inkjet printing control apparatus, characterized by, receiving a carton electric eye signal reported by a paper feeding control unit, and starting a printing process according to the electric eye signal; the paper feeding control unit controls the front paper feeding power wheel and the synchronous belt power main roll to keep follow-up movement based on a PID+feedforward control algorithm; ​ An image edge computing module is configured to load a pre-reading (PRT) image, and obtain an image edge according to edge pixel point features of the PRT image. A pixel coordinate computing module is configured to compute starting and ending printing position coordinates of the image in a pixel coordinate system according to the image edge. A printing coordinate computing module is configured to convert the starting and ending printing position coordinates of the image in the pixel coordinate system into starting and ending printing position coordinates of a carton in a printing coordinate system and a white space interval. A sending module is configured to send a stepping command to a stepping control unit according to the starting printing position coordinates of the carton. After receiving the stepping command, the stepping control unit synchronizes a belt to send the carton to the starting printing position coordinates for printing. The printing control unit receives the printing image data information and prints the image. A detection module is configured to detect whether a next carton electric eye signal reported by the paper feeding control unit is received during the printing process. A carton real time interval computing module is configured to compute a real time interval between two cartons after receiving the next carton electric eye signal. An image splicing module is configured to splice the printing image and the white space interval of the adjacent two cartons into new image data information according to the real time interval. 7.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is configured to perform the method according to any one of claims 1-6 when the computer program is executed by the processor. The computer program is executed by the processor to implement the steps of the method of any one of claims 1 to 5.

8. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the steps of the method of any one of claims 1 to 5.

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