Ink-jet printing device and printing method

Abstract

The ink-jet printing device comprises a printing trolley, a supporting cross beam, a supporting clamp of a rotating mechanism, an automatic angle adjusting device of the rotating mechanism and a control system, in the printing process, a spray head is located above a to-be-printed area, and when the to-be-printed object rotates by one circle, the spray head is located above the to-be-printed area; the nozzle steps by a fixed distance along the bus direction of the to-be-printed object, the fixed distance is N times of the distance between two pixel points in the resolution of the to-be-printed image, N is a positive integer, the nozzle continuously jets ink droplets to form an image-text in the stepping process, and the to-be-printed object rotates at a constant speed around the rotation center axis of the to-be-printed object while ink is jetted. According to the dynamic micro-deviation printing mode, the printing efficiency is improved while the inkjet effect is guaranteed, and the dynamic micro-deviation printing mode can be used for printing various curved-surface objects.

Description

Technical Field

[0001] This invention relates to an inkjet printing device and method for high-quality and rapid printing on curved surfaces in the industrial inkjet printer industry. Background Technology

[0002] Currently, in the industrial inkjet printer industry, printing patterns on the outer surface of three-dimensional curved objects typically involves mounting the curved object on a fixture, with a crossbeam above the fixture and a printhead mounted on the crossbeam. Before printing, the positions of the curved object and the printhead are adjusted so that the outer surface of the curved object is parallel to the bottom surface of the printhead, and the parallel height between them is within the printhead's optimal printing range. During printing, the curved object usually rotates, and the printhead moves along the crossbeam from outside the printing area to one end of the curved object to begin printing. The printhead continues to move and spray ink until it leaves the tail end of the curved object, then stops printing and returns to its initial position before printing. This printing method is suitable for printing large-area or full-page graphics on regular curved objects and has broad applicability.

[0003] However, when the printhead's physical resolution is lower than the target resolution of the image to be printed, the printhead's physical resolution needs to be doubled. This is achieved by using a step-printing method to increase the target resolution of the image to be printed. The specific method is as follows: Figure 1 As shown, Figure 1This diagram illustrates the various positions of a printhead 61 during the printing process on the surface of an object 62 located below it. The physical resolution of the printhead 61 is 150 dpi. The object 62 is a cylinder, and the target resolution of the printed image is 600 dpi. Therefore, the number of steps required by the printhead is 600 dpi ÷ 150 dpi = 4. The length h of the printing area of ​​the object 62 is less than the length L of the printhead 61. S00-S08 in the attached diagram represent the positions of the printhead 61 from when it is about to enter the printing area S00 above the object to when it just leaves the printing area S08 above the object.After clicking the print button, the printhead 61 moves from its initial position toward the object 62 to be printed. When the printhead moves from position S00 above the object 62, it stops at position S01. At this point, the printhead 61 has moved a step distance of l, which is one-quarter of the length of the printhead nozzle. As shown in the figure, the shaded area of ​​the nozzle in the printhead 61, which is one-quarter of the nozzle length, performs inkjet printing on the object below. After the object 62 rotates one full turn and completes printing in this area, the printhead moves a step distance l along the stepping direction to position S02, at which point the printing carriage stops. The shadow area, which is half the area of ​​the nozzle, sprays ink onto the object 62 below. After the object 62 rotates one full turn and completes printing of half the nozzle area, the printhead 61 moves a step distance l along the stepping direction to position S03, and the printing carriage stops moving. At this time, the shadow area of ​​the nozzle in the printhead 61, which is three-quarters of the nozzle area, sprays ink onto the object 62 below. After the object 62 rotates one full turn and completes printing of three-quarters of the nozzle area, the printhead 61 moves a step distance l along the stepping direction to position S04, and the printing carriage stops moving. At this time, the shadow area of ​​the nozzle in the printhead 61... The printhead 61, covering less than three-quarters of the area to be printed, sprays ink onto the object 62 below. After the object 62 rotates one full turn and completes printing in the covered area, the printhead 61 moves a step distance l along the stepping direction to position S05, at which point the printing carriage stops. At this point, the shadow area of ​​the printhead 61, covering less than three-quarters of the area, sprays ink onto the object 62 below. After the object 62 rotates one full turn and completes printing in the shadow area, the printhead 61 moves a step distance l along the stepping direction to position S06, at which point the printing carriage stops. At this point, the shadow area of ​​the printhead 61... The printhead 61 sprays ink onto the object 62 below, covering less than half the area of ​​the nozzle. After the object 62 rotates one full turn and completes printing of the shaded area, the printhead moves a step distance l along the stepping direction to position S07, at which point the printing carriage stops. At this point, the printhead 61 sprays ink onto the object below, covering less than a quarter of the area of ​​the nozzle. After the object 62 rotates one full turn and completes printing of the shaded area, the printhead moves a step distance l along the stepping direction to position S08. At this point, the printhead 61 has passed over the area to be printed and completed the printing of the entire pattern. In this stepping printing method, the printhead 61 needs to move from the initial position to position S00 and then to the end position S08. The distance H required for the printhead to complete the printing operation is three times the printhead length L. This printing method requires a relatively long distance for the printhead to pass through, necessitating sufficient space before and after the printed image, thus increasing the machine's overall size. Furthermore, during the printhead stepping process, the printhead nozzles do not eject ink droplets, requiring a waiting time, which reduces printing efficiency. When the length h of the pattern to be printed is less than or equal to the printhead length L, it is necessary to adopt a new printing method to overcome the above problems.

[0004] Furthermore, if the object to be printed has protruding parts on its outer surface, the above printing method, due to the very close printing distance between the printhead and the object's surface, prevents the printhead from passing over the protruding parts, as it might collide with them. In this case, the area around the protruding parts cannot be printed, thus limiting the printable area. For example, when the object to be printed is a tapered cup with a protruding edge on one side, the above-mentioned step-by-step printing method cannot print the area near the tapered edge because the protruding edge at the end of the cup is higher than the side wall of the bottle. When the printhead passes over the tapered cup, the protruding edge will collide with the printhead, causing damage. However, the demand for customized printing of objects with protruding ends, such as tapered cups, is increasing daily. Therefore, it is necessary to design an inkjet printing device suitable for printing such special objects.

[0005] Furthermore, depending on the customer's printing needs, if multiple color inks are required, or if white background inks, pre-processing inks, or post-processing transparent inks are also needed, in addition to overcoming the drawbacks of the above printing methods, it is also necessary to consider how to quickly and efficiently print multiple different inks onto the surface of curved objects without affecting the machine's external dimensions or printing time, while ensuring the resolution of the printed pattern. Summary of the Invention

[0006] This invention is applicable to the printing of images and text on curved objects in the industrial printer industry. It employs a novel printing method that ensures print quality while also enabling more efficient printing of objects with protruding parts, thereby improving printing efficiency and enhancing customer production efficiency.

[0007] This invention discloses an inkjet printing device, including a printing carriage, a supporting beam, a support fixture for a rotating mechanism, an automatic angle adjustment device for the rotating mechanism, and a control system. The supporting beam is arranged horizontally, and a printing carriage is mounted on the supporting beam. A printhead is mounted below the printing carriage. A support fixture for the rotating mechanism is arranged below the supporting beam, and a curved object to be printed is mounted on the support fixture. An automatic angle adjustment device is provided below the support fixture of the rotating mechanism to adjust the upper surface of the object to be printed to be horizontal. The invention is characterized in that, during the printing process, the printhead is located above the area to be printed. For each rotation of the object to be printed, the printhead steps a fixed distance along the generatrix of the object to be printed. The fixed distance is N times the distance between two pixels in the resolution of the image to be printed, where N is a positive integer. During the stepping process, the printhead continuously ejects ink droplets to form images and text. At the same time as the ink is ejected, the object to be printed rotates uniformly around its own rotation center axis.

[0008] In the inkjet printing device described above, the number of steps is N-1, where N=D / d, and D is the resolution of the image to be printed, and d is the physical resolution of the printhead.

[0009] As described above, in the inkjet printing device, a grating caliper is horizontally mounted on the support beam. The grating caliper is used to provide feedback on the horizontal position of the printing carriage.

[0010] As described above, in an inkjet printing device, at least two printheads are connected in series along the length of the printhead nozzles to form a printhead module. The printing width of the printhead module is equal to the number of printheads multiplied by the printing width of a single printhead. The width of the area to be printed is greater than or equal to the printing width of the printhead module.

[0011] As in the inkjet printing device described above, one side of the support fixture of the rotating mechanism is connected to a detection device of the rotating mechanism, which is used to provide feedback on the rotation information of the object to be printed.

[0012] As described above, in an inkjet printing device, the object to be printed is a curved object with a protruding part at one end. The printing device also includes a clearance mechanism, which allows the printing carriage to avoid the protruding part of the curved object, thereby allowing the printhead to reach above the area to be printed.

[0013] The object to be printed by the inkjet printing device described above is a rolled-edge cup.

[0014] As described above, the control system of the inkjet printing device is mainly divided into a low-level control program, color processing software, and a host computer program, which can perform color processing of graphics, user interaction with the printer, and control the start and stop of the printer.

[0015] The inkjet printing device described above is used for inkjet printing on curved surfaces. The printing process includes a dynamic micro-deviation printing method, and the specific steps are as follows: Step 1: After the printhead reaches the area to be printed, the printhead nozzles spray ink droplets downwards to form images and text, while the object to be printed rotates at a constant speed around its own rotation axis. Step 2: The software determines the relationship between the printhead's physical resolution d and the resolution D of the image to be printed, defining N = D / d. If N = 1, proceed to step 5; if N > 1, proceed to steps 3 and 4. Step 3: The printhead moves a fixed distance along the generatrix of the object to be printed. The fixed distance is N times the distance between two pixels in the resolution of the image to be printed, where N is a positive integer. During the stepping process, the printhead continuously ejects ink droplets to form images and text, while the object to be printed rotates at a constant speed around its own rotation center axis. Step 4: The software determines whether the number of nozzle steps n has reached N-1 times. If n < (N-1), repeat steps 3 and 4. If n = N-1, proceed to step 5. Step 5: The software determines whether the printing of all text and images in the area to be printed has been completed. If not, it continues to the next stage of the process; if so, printing ends.

[0016] As described above, before step one, the printhead first performs a avoidance operation. At this time, the object to be printed is an object with a protruding part at one end. The printing carriage first avoids the protruding part and arrives directly above the area to be printed.

[0017] As described in the above printing method, the next stage of the operation in step five includes a spiral continuous printing method, in which the printhead continuously passes over the area to be printed, and while it is continuously passing over, the printhead nozzles eject ink droplets to form images and text, while the object to be printed rotates at a constant speed around its own rotation center axis.

[0018] As described above, at the junction with the next stage of the work, feathering, blurring, or fading the color gaps at the junction are used to connect the text and images.

[0019] As described in the above printing method, the next stage of the operation in step five includes moving the printhead in large steps along the generatrix of the object to be printed to the area above the next area to be printed, and then proceeding with the process from step one to step five. At this time, there are at least two areas to be printed, and they are spaced apart.

[0020] The printing method of the inkjet printing device described above is used for inkjet printing on curved objects. Its characteristic is that two rows of printheads are installed side-by-side below the printing carriage in a direction perpendicular to the stepping direction, and the printing carriage can move in a direction perpendicular to the stepping direction. The specific steps are as follows: Step 1: After the first row of printheads reaches above the area to be printed, the nozzles of the first row of printheads spray ink droplets downward to form images and text, while the object to be printed rotates at a constant speed around its own rotation center axis. Step 2: The software determines the relationship between the physical resolution d1 of the first row of printheads and the resolution D1 of the image to be printed corresponding to that row of printheads. Define N1 = D1 / d1. If N1 = 1, proceed to step 5. If N1 > 1, proceed to steps 3, 4 and 5. Step 3: The printing carriage moves a fixed distance along the generatrix of the object to be printed. The fixed distance is the distance between two pixels in the resolution of the image to be printed. During the stepping process, the first row of nozzles continuously sprays ink droplets to form images and text. At the same time, the object to be printed rotates at a constant speed around its own rotation center axis. Step 4: The software determines whether the number of steps n of the printing car has reached N1-1 times. If n < (N1-1), repeat steps 3 and 4. If n = N1-1, proceed to step 5. Step 5: The printing carriage moves in a direction perpendicular to the stepping direction so that the second row of nozzles is positioned above the area to be printed. Step 6: After the second row of printheads reaches above the area to be printed, the nozzles of the second row of printheads spray ink droplets downward to form images and text, while the object to be printed rotates at a constant speed around its own rotation center axis. Step 7: The software determines the relationship between the physical resolution d2 of the second row of printheads and the resolution D2 of the image to be printed corresponding to that row of printheads. Define N2 = D2 / d2. If N2 = 1, proceed to step 10. If N2 > 1, proceed to steps 8 and 9. Step 8: The printing carriage moves a fixed distance along the generatrix of the object to be printed. The fixed distance is the distance between two pixels in the resolution of the image to be printed. During the stepping process, the second row of nozzles continuously sprays ink droplets to form images and text. At the same time, the object to be printed rotates at a constant speed around its own rotation center axis. Step 9: The software determines whether the number of nozzle steps n has reached N2-1 times. If n < (N2-1), repeat steps 8 and 9. If n = N2-1, execute step 10. Step 10: The software determines whether the printing of all text and images in the area to be printed has been completed. If not, it continues to the next stage of the process; if so, printing ends.

[0021] The beneficial effects of this invention are as follows: 1. When the size of the area to be printed is less than or equal to the total print length of the printhead, the printing method of this invention can save the number of printing steps while printing patterns of the same resolution. Furthermore, during dynamic micro-deviation printing, ink droplets are ejected simultaneously during the stepping process, saving printing time and improving printing efficiency. 2. In dynamic micro-deviation printing, the printhead's total moving area is reduced by two printhead lengths compared to traditional printing, saving design space for the printing device and reducing costs. 3. When the curved surface to be printed has protruding parts, the printing method of this invention can avoid these protruding parts and print patterns in the area next to them, avoiding the risk of printhead collision. 4. When printing multiple colored inks and other functional inks, such as pre-treatment inks, white background inks, or transparent inks, a single printhead cannot print multiple different inks. Printheads can be added side-by-side, and a U-shaped printing method can be added to improve printing quality and meet various customer needs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a method for printing curved objects using a printhead in the prior art; Figure 2 This is a schematic diagram of the printing device in one embodiment of the present invention; Figure 3 This is a schematic diagram of a dynamic micro-deviation printing method in one embodiment of the present invention; Figure 4 This is a flowchart of a printing method according to one embodiment of the present invention; Figure 5This is a schematic diagram of a method for spraying images and text onto an object to be printed using a dynamic micro-deviation printing method and a spiral continuous printing method, according to another embodiment of the present invention; Figure 6 This is a schematic diagram of the printing method of dynamic micro-deviation printing method with increased step movement and dynamic micro-deviation printing method in another embodiment of the present invention; Figure 7 This is a schematic diagram of a dual-station, multi-ink printing method in another embodiment of the present invention; Figure 8 for Figure 7 A schematic diagram of the model; Figure 9 This is a schematic diagram of a method for increasing the printing width by splicing multiple printheads in another embodiment of the present invention. Detailed Implementation

[0023] The printing device of the present invention is used to print curved objects, as described below. Figure 2 Let's take an example to illustrate. Figure 2 This is a schematic diagram of the printing device in one embodiment of the present invention. The inkjet printing device includes a printing carriage 1, a support beam 2, a rotating mechanism support fixture 4, an automatic angle adjustment device 5, and a control system 6. The support beam 2 is arranged in a horizontal direction. A printing carriage 1 is installed on the support beam 2. A printhead 12 is installed below the printing carriage 1. The length direction of the printhead 12 is arranged in a horizontal direction. The printhead can print multiple colors of ink, such as connecting C (cyan), M (magenta), Y (yellow) and K (black) colored inks, or connecting W (white), V (transparent) and P (primer) inks, thereby improving the effect of inkjet printing. A grating caliper 21 is horizontally installed on the support beam 2. The grating caliper 21 is used to provide feedback on the horizontal position information of the printing carriage 1. A rotating mechanism support fixture 4 is installed below the support beam 2. The object to be printed 3 is installed on the rotating mechanism support fixture 4. In this embodiment, the object to be printed 3 is a conical rolled-edge cup. A detection device 31 is connected to one side of the rotating mechanism support fixture 4. The detection device 31 is used to provide feedback on the rotation information of the object to be printed 3. An automatic angle adjustment device 5 is provided below the rotating mechanism support fixture 4. The automatic angle adjustment device 5 is used to adjust the upper surface of the object to be printed 3 to be parallel to the plane where the nozzle is located. Usually, it is sufficient to adjust it to be horizontal. The control system 6 is used to control the entire printing process. Specifically, after the host computer program of the control system 6 receives the printing command, it automatically adjusts the angle adjustment device 5 to adjust the generatrix of the upper surface of the object to be printed 3 to be horizontal; controls the rotation mechanism to support the fixture 4 to rise to the printing position; controls the printing carriage 1 to move along the support beam 2, i.e., in the horizontal direction, and controls the nozzle to spray ink droplets to form the required image; at the same time, during the ink spraying process, it controls the object to be printed 3 to rotate at a constant speed around its own rotation center axis 32.

[0024] In the printing area next to the protruding part at the end of the object to be printed, the printhead nozzle uses a dynamic micro-deviation printing method to eject ink droplets. The following is based on... Figure 3 This printing method will be described in detail. Figure 3 The rectangle shown below is a schematic diagram of the outer surface of the printing area 52 in the object to be printed 3. The length of the printing area 52 is less than the printing length of one nozzle. In this embodiment, the physical resolution d of the nozzle is 150 dpi, and the image resolution D to be printed on the curved object surface is 600 dpi. Let N = D ÷ d, then the number of steps the nozzle needs to take is N-1. In this embodiment, N = 600 ÷ 150 = 4. Therefore, during the printing process, the nozzle needs to take 3 steps to complete the dynamic micro-deviation printing within one cycle. First, the nozzle avoids the protruding rolled edge of the object to be printed 3, and moves from the outside of the object to be printed 3 along a direction perpendicular to the generatrix of the object to be printed 3 to the area to be printed next to the rolled edge of the object to be printed 3, at which point it is located... Figure 3At position S0, the printhead nozzles above the printing area 52 eject ink droplets to form the image. The trajectory of the ink droplet ejected from the rightmost nozzle is shown as the rightmost inclined linear ink droplet in the rectangle unfolded on the curved surface. Then, the printhead 12 moves a fixed distance s along the stepping direction. This distance s is the distance between two adjacent pixels in the resolution of the image to be printed. At this point, the printhead reaches position S1 in the figure. While the printhead is stepping, the nozzles continue to eject ink droplets. The trajectory of the ink droplet ejected from the rightmost nozzle is shown as the second inclined linear ink droplet from the right in the rectangle unfolded on the curved surface. Then, the printhead 12 continues to move a fixed distance s along the stepping direction, again the distance s being the distance between two adjacent pixels in the resolution of the image to be printed. At this point, the printhead reaches position S2 in the diagram. While the printhead steps forward, the nozzles continuously eject ink droplets. The trajectory of the ink droplets ejected from the first nozzle at the far right of the printhead is the third inclined linear ink droplet from the right in the unfolded rectangle of the curved surface, as shown in the diagram. The printhead 12 then continues to move a fixed distance s along the stepping direction. This distance s is the distance between two adjacent pixels in the resolution of the image to be printed. At this point, the printhead reaches position S3 in the diagram. While the printhead steps forward, the nozzles continuously eject ink droplets. The trajectory of the ink droplets ejected from the first nozzle at the far right of the printhead is the fourth inclined linear ink droplet from the right in the unfolded rectangle of the curved surface, as shown in the diagram. This process completes one cycle of dynamic micro-deviation printing, resulting in a final image resolution four times the physical resolution of the printhead. During the printing process, the object to be printed continuously rotates at a constant speed around its own rotation axis. The ink droplet image printed in this way has a slight deviation, which the software does not correct or adjust, thus improving printing efficiency and saving development costs. Furthermore, this slight deviation is imperceptible to the naked eye, thus ensuring print quality. The dynamic micro-deviation printing method performs inkjet printing while the printhead is stepping, which greatly improves printing efficiency and avoids the time wasted waiting for inkjet printing during stepping. Of course, this invention does not exclude the possibility of not printing ink during stepping.

[0025] It should be noted that each tiny step can be the distance between two pixels in the resolution of the image to be printed, or it can be N times the distance between two pixels in the resolution of the image to be printed, where N is a positive integer. During the stepping process, the printhead nozzle can stop spraying ink or continue spraying ink. During continuous ink spraying, the printed lines exhibit a slightly tilted curve pattern, but it is not visually perceptible. Because the printhead moves a tiny distance each time, the range of printhead movement remains very small even after multiple print passes. This allows it to remain unaffected by protruding parts at the ends of the object to be printed, such as the curled edge protrusion at the end of a curled cup, and can still print text and images in the area near the curled edge.

[0026] The following is based on Figure 4This document describes the workflow for printing multiple objects using a dynamic micro-deviation printing method, where the length of the printing area on each object is less than or equal to the printing length of one printhead. At the start of the process, the objects are mounted on an automatically adjusting angle fixture. Upon receiving the printing command, the software system controls a movable printing carriage to move horizontally along the support beam to the printing position. If the object is a rolled-edge cup, this position is the initial printing position above the starting point of the printing area, avoiding the rolled edge. The automatic angle adjustment device aligns the upper surface of the object with the plane of the printhead nozzle and adjusts the distance between the upper surface and the nozzle to the optimal printing distance. The control system controls the object to rotate continuously and uniformly around its central axis, while the software system controls the printhead to eject ink. After one rotation, the movable carriage moves the printhead forward in a stepping direction. The printhead moves a tiny distance, which is N times the distance between two pixels in the resolution of the image to be printed, where N is a positive integer. The software system controls the printhead to continue inkjet printing. If printing is not complete, the carriage can be moved to move the printhead another tiny distance along the stepping direction. The software system controls the printhead to continue inkjet printing. This process is repeated until the image to be printed on the surface of the object is completed. Then, the software determines whether all objects to be printed have been printed. If not, the next object to be printed is remounted on the fixture, and the dynamic micro-deviation printing method described above is used again to print the image until all objects to be printed are completed. If so, the carriage can be moved quickly out of the printing area to the starting position to prepare for the next printing, and the printing job ends.

[0027] Based on the dynamic micro-deviation printing method disclosed in this invention, the following are some other different application examples.

[0028] like Figure 5 As shown, when the length of the print head on the printing carriage cannot cover the length of the area to be printed, it can be used. Figure 5 The illustrated printing method is a combination of dynamic micro-deviation printing and spiral continuous printing.

[0029] and Figure 3 The difference in the dynamic micro-deviation printing method described is that the inkjet printing operation includes two stages. The first stage: if printing a rolled-edge cup, first avoids the rolled edge of the cup, then the printhead reaches directly above the area to be printed next to the rolled edge, and then proceeds... Figure 3 The dynamic micro-deviation printing method shown applies; if the object to be printed has no protruding parts, the nozzle does not need to avoid the printing area, and the printhead proceeds after the tip enters the printing area. Figure 3The dynamic micro-deviation printing method shown here proceeds to the second stage after the target print resolution is achieved. In the second stage, the printhead continuously ejects ink droplets to form the image as it moves along the support beam. The object to be printed below rotates uniformly around its own axis of rotation. The printhead tip passes over the end of the image to be printed, completing the print. During continuous inkjet printing, the software performs spiral processing based on the image, controlling the nozzles to dispense ink according to the processed information. At the junction of the first stage (dynamic micro-deviation printing) and the second stage (spiral continuous printing), ink jet gaps may occur. These gaps are addressed using feathering to blur and fade the color seams.

[0030] like Figure 6 As shown, when the print head length on the printing carriage cannot cover the entire area to be printed and the pattern to be printed is distributed in a jumpy manner, but the length of each local pattern to be printed can be covered by the print head length, the following can be used: Figure 6 The illustration shows a three-stage printing method: dynamic micro-deviation printing method combined with stepping movement and dynamic micro-deviation printing method. Stage 1: If printing a rolled-edge cup, first avoid the rolled edge of the cup, then the printhead reaches directly above the area to be printed next to the rolled edge, and then proceeds. Figure 3 The dynamic micro-deviation printing method shown applies; if the object to be printed has no protruding parts, the nozzle does not need to avoid the printing area, and the printhead proceeds after the tip enters the printing area. Figure 3 The dynamic micro-deviation printing method shown proceeds to the second stage after the expected target print resolution has been achieved. Second stage: The printhead steps a large distance along the support beam, moving directly above the next pattern to be printed. During this large step, the printhead nozzles do not eject ink. Third stage: After the printhead nozzles enter the area above the next printing zone, ink is ejected... Figure 3 The dynamic micro-deviation printing method is shown. If there are still unprinted local patterns, the second and third stages are repeated, and so on, until all the jumping patterns are printed.

[0031] In addition, to improve printing efficiency, multi-station printing can be added; to improve printing quality, the use of multiple color inks can be increased, such as... Figure 7 and Figure 8In the illustrated embodiment, the printhead base plate uses Ricoh printheads, each printhead including four rows of nozzles, each row capable of printing one color. Each rolled cup is printed using two rows of printheads. The printheads include cyan, magenta, yellow, black, white, clear, and primer inks. When printing two rolled cups at once using a double-row fixture, two sets of printheads are set, two in each set, for a total of four printheads. Simultaneously, two drive mechanisms are installed on the printing carriage: one drive mechanism drives the printheads to move left and right along the length of the printhead, and the other drive mechanism drives the printheads to move back and forth along the width of the printhead. During printing, the first printhead connected to the white ink is moved to directly above the crimped cup. The software system controls the white ink to print on the crimped cup below using the dynamic micro-deviation printing method described above. Then, the drive mechanism drives the printing carriage to move in the front-to-back direction (the width direction of the printhead), so that the second printhead connected to the color ink is moved to directly above the crimped cup. The software system then controls the color ink connected to the second printhead to print on the crimped cup below using the dynamic micro-deviation printing method described above, thereby improving the printing resolution and printing quality.

[0032] To improve printing efficiency, this embodiment is designed with a double fixture that can simultaneously install two rolled-edge cups, and print on both cups at the same time. At this time, the printing carriage is equipped with a total of four print heads, and each pair of print heads prints on one cup. The printing method is the same as described above.

[0033] Furthermore, when the length of the pattern to be printed on the object is greater than the printing length of a single printhead, the printing width of the printhead base plate can be increased by splicing multiple printheads. For example... Figure 9 As shown, the first printhead 41, the second printhead 42, the third printhead 43, and the fourth printhead 44 are sequentially connected end-to-end along the length of the printhead nozzles on the printhead base plate 45 to form a printing module. This module forms the printing width HH shown in the figure, extending from the initial end of the nozzle of the first printhead 41 to the end of the nozzle of the fourth printhead 44, thus creating a distance four times the printing width of a single printhead. When the area to be printed on the object is large, such as... Figure 9 H in the diagram represents the area to be printed. Using the above-described serial splicing method of printheads as a single large-width printhead can improve printing efficiency. The printing principles of other printing methods, including dynamic micro-deviation printing, are the same as described above and will not be repeated here.

[0034] When printing white ink, transparent ink, or pre-treated ink is required in addition to color ink, two sets of spliced ​​printheads can be set up. Specifically, next to the module consisting of a first printhead 41, a second printhead 42, a third printhead 43, and a fourth printhead 44 connected in series along the length of the printhead orifice, another module consisting of four printheads connected in series along the length of the printhead orifice can be set up side-by-side. The printing principle is the same as... Figures 7-8 The methods used to describe them are the same.

[0035] It should be noted that any modifications made according to the embodiments of the present invention do not depart from the scope of protection claimed by the present invention.

Claims

1. An inkjet printing apparatus, comprising a printing carriage, a supporting beam, a support fixture for a rotating mechanism, an automatic angle adjustment device for the rotating mechanism, and a control system, wherein the supporting beam is arranged horizontally, a printing carriage is mounted on the supporting beam, a printhead is mounted below the printing carriage, a support fixture for the rotating mechanism is arranged below the supporting beam, a curved object to be printed is mounted on the support fixture of the rotating mechanism, and an automatic angle adjustment device is provided below the support fixture of the rotating mechanism for adjusting the upper surface of the object to be printed to be horizontal, characterized in that… During the printing process, the printhead is positioned above the area to be printed. For each rotation of the object to be printed, the printhead steps a fixed distance along the generatrix of the object. This fixed distance is N times the distance between two pixels in the resolution of the image to be printed, where N is a positive integer. During this stepping process, the printhead continuously ejects ink droplets to form images and text. Simultaneously with ink ejection, the object to be printed rotates at a constant speed around its own rotational axis. The number of steps is N-1, where N=D / d, and D is the resolution of the image to be printed, and d is the physical resolution of the printhead.

2. The inkjet printing apparatus as described in claim 1, characterized in that, The at least two printheads are connected in series along the length of the printhead nozzles to form a printhead module. The printing width of the printhead module is equal to the number of printheads × the printing width of a single printhead. The width of the area to be printed is less than or equal to the printing width of the printhead module.

3. The inkjet printing apparatus as described in claim 1, characterized in that, The object to be printed is a curved object with a protruding part at one end. The printing device also includes a avoidance mechanism, which allows the printing carriage to avoid the protruding part of the curved object, thereby allowing the nozzle to reach above the area to be printed.

4. An inkjet printing method for inkjet printing curved objects, characterized in that, The printing process includes a dynamic micro-deviation printing method, and the specific steps are as follows: Step 1: After the printhead reaches the area to be printed, the printhead nozzles spray ink droplets downwards to form images and text, while the object to be printed rotates at a constant speed around its own rotation axis. Step 2: The software determines the relationship between the printhead's physical resolution d and the resolution D of the image to be printed, defining N = D / d. If N = 1, proceed to step 5; if N > 1, proceed to steps 3 and 4. Step 3: The printhead moves a fixed distance along the generatrix of the object to be printed. The fixed distance is N times the distance between two pixels in the resolution of the image to be printed, where N is a positive integer. During the stepping process, the printhead continuously ejects ink droplets to form images and text, while the object to be printed rotates at a constant speed around its own rotation center axis. Step 4: The software determines whether the number of nozzle steps n has reached N-1 times. If n < (N-1), repeat steps 3 and 4. If n = N-1, proceed to step 5. Step 5: The software determines whether the printing of all text and images in the area to be printed has been completed. If not, it continues to the next stage of the process; if so, printing ends.

5. The inkjet printing method as described in claim 4, characterized in that, Before step one, the printhead first performs a avoidance operation. At this time, the object to be printed is an object with a protruding part at one end. The printing carriage first avoids the protruding part and arrives directly above the area to be printed.

6. The inkjet printing method as described in claim 4, characterized in that, Step five describes the next stage of the operation, which includes a spiral continuous printing method. In this method, the printhead continuously passes over the area to be printed, and while passing over it, the printhead nozzles eject ink droplets to form images and text. At the same time, the object to be printed rotates at a constant speed around its own rotational axis.

7. The inkjet printing method as described in claim 4, characterized in that, The next stage of the operation described in step five involves the printhead moving in large steps along the generatrix of the object to be printed to the next area to be printed, and then repeating the process from step one to step five. At this time, there are at least two areas to be printed, and they are spaced apart.

8. The inkjet printing method as described in claim 6, characterized in that, At the junction with the next stage of the work, use feathering, blurring or fading the color gaps at the junction to connect the text and images.

9. An inkjet printing method for inkjet printing curved objects, characterized in that, Two rows of printheads are installed side-by-side below the printing carriage in a direction perpendicular to the stepping direction, and the printing carriage can move in this direction. The specific steps are as follows: Step 1: After the first row of printheads reaches above the area to be printed, the nozzles of the first row of printheads spray ink droplets downward to form images and text, while the object to be printed rotates at a constant speed around its own rotation center axis. Step 2: The software determines the relationship between the physical resolution d1 of the first row of printheads and the resolution D1 of the image to be printed corresponding to that row of printheads. Define N1 = D1 / d1. If N1 = 1, proceed to step 5. If N1 > 1, proceed to steps 3, 4 and 5. Step 3: The printing carriage moves a fixed distance along the generatrix of the object to be printed. The fixed distance is the distance between two pixels in the resolution of the image to be printed. During the stepping process, the first row of nozzles continuously sprays ink droplets to form images and text. At the same time, the object to be printed rotates at a constant speed around its own rotation center axis. Step 4: The software determines whether the number of steps n of the printing car has reached N1-1 times. If n < (N1-1), repeat steps 3 and 4. If n = N1-1, proceed to step 5. Step 5: The printing carriage moves in a direction perpendicular to the stepping direction so that the second row of nozzles is positioned above the area to be printed. Step 6: After the second row of printheads reaches above the area to be printed, the nozzles of the second row of printheads spray ink droplets downward to form images and text, while the object to be printed rotates at a constant speed around its own rotation center axis. Step 7: The software determines the relationship between the physical resolution d2 of the second row of printheads and the resolution D2 of the image to be printed corresponding to that row of printheads. Define N2 = D2 / d2. If N2 = 1, proceed to step 10. If N2 > 1, proceed to steps 8 and 9. Step 8: The printing carriage moves a fixed distance along the generatrix of the object to be printed. The fixed distance is the distance between two pixels in the resolution of the image to be printed. During the stepping process, the second row of nozzles continuously sprays ink droplets to form images and text. At the same time, the object to be printed rotates at a constant speed around its own rotation center axis. Step 9: The software determines whether the number of nozzle steps n has reached N2-1 times. If n < (N2-1), repeat steps 8 and 9. If n = N2-1, execute step 10. Step 10: The software determines whether the printing of all text and images in the area to be printed has been completed. If not, it continues to the next stage of the process; if so, printing ends.

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