A multi-pass inkjet printing framework

Abstract

The present invention relates to the field of inkjet printing technology, and provides a multi-pass inkjet printing frame, which is arranged above a printing platform, and includes two sub-frames distributed along the X direction, connected to a cantilever beam below the sub-frame, wherein the sub-frame and the cantilever beam form a buffer space, a printing and spraying space, and an operation space, and the cantilever beam includes one, the cantilever beam supports an inkjet carriage sliding thereon, the inkjet carriage includes multiple groups of nozzles to achieve different color spraying, and specifically includes five steps. It is used to solve the problems of long printing time, insufficient efficiency, high printing cost, insufficient resolution of printed images and texts, large wear of the inkjet carriage during repeated scanning and movement, the stability of the support structure needs to be improved, and the problem that the support structure is not easy to install, thereby improving the printing resolution, accurately controlling the inkjet range of the inkjet carriage, and increasing the supporting force of the frame and the bending strength of the rectangular sub-beam.

Description

Technical Field

[0001] The present invention relates to the technical field of inkjet printing, and more particularly to a multi-pass inkjet printing frame. Background Art

[0002] Traditional digital inkjet printing, or digital inkjet printing, can be divided into two categories based on its operating mode: scanning (multi-pass) and single-pass (single-pass / one-pass). In scanning printing, the substrate is stationary, and image output is achieved by moving the print head; in single-pass printing, the print head is stationary, and image output is achieved by moving the substrate. In the printing industry, the PASS value represents the number of prints required to form an image, or the number of times a unit area is covered. The higher the PASS number, the slower the printing speed and the better the print quality. The PASS number is related to printing accuracy. The advantage of multi-pass scanning printing is that errors that may occur during a single scan of the print head will be covered by the next scan. The more scans, the more likely it is to cover errors caused by a single print.

[0003] The existing technologies for improving printing accuracy mostly increase the number of PASS or increase the number of nozzles. The disadvantage of increasing the number of PASS is that the printing speed is significantly reduced, which is not conducive to improving production efficiency. The problem caused by increasing the number of nozzles is that the cost of the printer is significantly increased, which is not conducive to controlling production costs. How to solve the problems of long printing time, insufficient efficiency, high printing cost, insufficient resolution of printed images and texts in multi-PASS inkjet printing, large wear of the inkjet carriage during repeated scanning and movement, and the need to improve the stability of the supporting structure are technical problems that need to be solved in this field. At the same time, in large-format inkjet printers, being able to provide a frame with sufficient space, sufficient support force, simple manufacture, and convenient installation for the inkjet carriage that produces the above printing effects is also a technical problem that needs to be solved in this field. Summary of the Invention

[0004] The present invention aims to overcome at least one defect (shortcoming) of the above-mentioned prior art and provide a multi-PASS inkjet printing frame to solve the problems of long printing time, insufficient efficiency, high printing cost, insufficient resolution of printed images and texts, large wear of the inkjet carriage during repeated scanning and movement, the stability of the support structure needs to be improved, and the problem of the support structure being not easy to install.

[0005] The technical solution adopted by the present invention is a multi-pass inkjet printing frame, which is arranged on a printing platform, wherein the frame includes two sub-frames distributed along the X direction, connected to the suspension beam below the sub-frame, the sub-frame and the suspension beam forming a buffer space, a printing space and an operation space, the suspension beam includes one, the suspension beam supports the inkjet carriage to slide on it, the inkjet carriage includes multiple groups of nozzles to achieve different color printing, each group of nozzles includes multiple nozzles of the same color arranged in the Y direction, the nozzles are arranged in multiple rows in the X direction, nozzles A and B are any two rows, the distance between nozzles A and B in the Y direction is L, each nozzle includes multiple nozzles, the distance between the nozzles in the Y direction is Δ, and a position on the printing platform is taken as the initial position, specifically including the following steps:

[0006] Step 1: The inkjet vehicle starts from the initial position;

[0007] Step 2: The inkjet carriage completes the first scanning inkjet along the X-axis direction;

[0008] Step 3: The inkjet carriage interchanges the positions of nozzles A and B by a displacement distance P along the Y-axis direction. The displacement distance P = L ± Δ / n or P = (L ± Δ) / n, where n is the number of passes.

[0009] Step 4: The inkjet carriage completes the next scanning inkjet along the X-axis opposite direction of the previous scanning inkjet;

[0010] Step 5: If the number of scanning inkjet times is less than n, the inkjet carriage repeats steps 3 and 4; if the number of scanning inkjet times is equal to n, printing is completed.

[0011] It is beneficial to improve the printing effect of the pattern through the multi-PASS inkjet printing method, eliminate the color difference of the pattern, and increase the resolution; it is beneficial to provide a more stable supporting force for the suspension beam through the sub-frame, and it is beneficial to limit the sliding track of the inkjet vehicle through the suspension beam.

[0012] Furthermore, nozzle A and nozzle B are arranged adjacent to each other.

[0013] It is beneficial to eliminate the color difference of different nozzles on the printing medium by shifting the nozzles, thereby improving the printing accuracy and effect.

[0014] Furthermore, the C nozzles are in a row different from the A nozzles or the B nozzles, and in step 3, the inkjet carriage can interchange the positions of any two rows of the A nozzles, the B nozzles, and the C nozzles by a displacement distance P along the Y-axis direction.

[0015] It is beneficial to reduce the color difference of printed images caused by changes in nozzle height, nozzle voltage and inkjet temperature during the printing process by alternating multiple groups of nozzles, thereby further improving the resolution of inkjet printing.

[0016] Furthermore, the inkjet width I of the inkjet carriage on the Y axis is at least one L greater than the width H of the printing medium.

[0017] This helps the nozzle cover the corners of the printing medium during the printing process, increasing the inkjet coverage of the scanning printer.

[0018] Furthermore, the cantilever beam is a rectangular beam structure, which is composed of at least two rectangular sub-beams with the same length dimension. The rectangular sub-beam is a hollow beam with transverse and longitudinal supports inside. The width dimension of the rectangular sub-beam is not greater than the height dimension.

[0019] It is beneficial to strengthen the strength of the rectangular beam by splicing two rectangular sub-beams, which is beneficial to simplifying the installation of the rectangular beam structure; it is beneficial to manufacture the rectangular beam through the existing hollow beam, thereby reducing the manufacturing cost of the cantilever beam; it is beneficial to evenly guide and distribute the force on the rectangular sub-beam to the entire rectangular beam structure through the transverse support and longitudinal support running through the entire hollow beam, thereby avoiding excessive stress concentration and affecting the service life of the rectangular beam.

[0020] Furthermore, the width dimension of the rectangular beam is not less than that of the height dimension, and the rectangular beam is formed by splicing two rectangular sub-beams with the same cross-section.

[0021] It is beneficial to lower the center of gravity of the suspension beam through a wide and flat rectangular beam, and at the same time it is beneficial to guide the stress on the suspension beam to disperse in the vertical direction; it is beneficial to evenly disperse the force on the suspension beam through rectangular sub-beams with the same cross-sectional area, and at the same time reduce the manufacturing process and cost of the rectangular beam.

[0022] Furthermore, the rectangular sub-beam is a hollow beam with side walls of uniform thickness. The spliced ​​side is composed of the side walls of one side of the two rectangular sub-beams. An intermediate support plate with a thickness twice that of other parts is formed on the rectangular beam. The rounded chamfers on the spliced ​​side form a groove distributed along the length direction in the middle of the upper and lower sides of the rectangular beam. End plates are provided at both ends of the rectangular beam, and the end plates at least cover the side walls of the two rectangular sub-beams, the intermediate support plate and the end faces of the groove.

[0023] It is beneficial to strengthen the structural strength of the rectangular sub-beam through the intermediate support plate, and to form an I-shaped cross-section at both ends of the suspension beam by splicing the rectangular sub-beams, thereby strengthening the bending strength of the suspension beam; it is beneficial to further strengthen the bending strength of the suspension beam by making the thickness of the intermediate support plate twice that of other parts; it is beneficial to connect the end face of the groove, the intermediate support plate and the side wall of the rectangular sub-beam on the same plane through the end plate, thereby playing the role of a reinforcing rib.

[0024] Furthermore, it also includes a horizontal driving device located on the suspension beam, and the horizontal driving device is a synchronous belt or a linear motor, which drives the inkjet vehicle to scan and spray ink along the X-axis direction and to shift and print along the Y-axis direction.

[0025] It is beneficial to realize the movement of the inkjet carriage in the X-axis direction and the Y-axis direction through the horizontal driving device, so that the inkjet carriage can not only scan back and forth in the printing and painting space, but also adjust the displacement of the inkjet carriage in the Y-axis direction, thereby realizing the printing of different nozzles with jack shifting.

[0026] Furthermore, it also includes a vertical driving device located on the suspension beam, and the vertical driving device is a screw that drives the inkjet vehicle to adjust the inkjet height along the Z-axis direction.

[0027] It is beneficial to realize the movement of the inkjet carriage in the Z-axis direction through the vertical driving device, thereby adjusting the inkjet height of the inkjet carriage and improving the positioning accuracy of the inkjet carriage; it is beneficial to simplify the control components of the inkjet carriage through the screw, thereby simplifying the maintenance process of the suspension beam and reducing the maintenance cost of the suspension beam.

[0028] Furthermore, the inkjet vehicle moves at a uniform speed v along the X direction in the printing and spraying space, and moves at a uniform acceleration 0-v in the buffer space and / or the operation space.

[0029] It is beneficial for the inkjet carriage to adjust the acceleration or deceleration before moving to the printing medium to maintain a constant speed on the printing medium, thereby making the ink uniform during the inkjet process and ensuring the printing quality.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: the cantilever beam on the frame provides support for the inkjet carriage that scans and sprays ink back and forth; the spliced ​​rectangular sub-beams increase the bending strength of the cantilever beam; the horizontal driving device on the cantilever beam drives the inkjet carriage to move multiple passes and shift the sockets above the printing and spraying space, thereby realizing the form of alternating operation of multiple groups of nozzles and printing of multiple nozzle sockets, thereby reducing the color difference caused by different nozzles during the printing process, and improving the printing resolution by multiple covering inkjet; the vertical driving device on the cantilever beam drives the inkjet carriage to achieve highly precise control above the printing and spraying space, thereby ensuring the size of the inkjet range; the sub-frame shares the force on the cantilever beam, thereby enhancing the stability of the frame; the distribution of the sub-frame provides a wider space for the scanning and inkjet of the inkjet carriage, and the manufacture and installation of the frame is simpler and more portable. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a front view of the multi-pass inkjet printing frame of the present invention.

[0032] Figure 2It is a three-dimensional schematic diagram of the multi-pass inkjet printing frame of the present invention.

[0033] Figure 3 It is a schematic end view of the cantilever beam structure of the present invention.

[0034] Figure 4 It is a schematic cross-sectional view of the cantilever beam structure of the present invention.

[0035] Figure 5 It is a schematic diagram of the printing effect of the 2PASS jack shift of the present invention.

[0036] Description of the accompanying symbols: buffer space 10, printing and spraying space 20, operation space 30, sub-frame 100, suspension beam 200, rectangular sub-beam 210, lateral support 211, longitudinal support 212, middle support plate 213, inkjet carriage 300, nozzle spacing L, nozzle orifice spacing Δ, PASS number n, displacement distance of inkjet carriage P, printing medium width H, nozzle inkjet width I, nozzle inkjet width I1. DETAILED DESCRIPTION

[0037] The accompanying drawings are for illustrative purposes only and are not to be construed as limiting the present invention. To better illustrate the following embodiments, some components in the accompanying drawings may be omitted, enlarged, or reduced in size, and do not represent actual product dimensions. Those skilled in the art will appreciate that some well-known components and their descriptions may be omitted from the accompanying drawings.

[0038] Example 1

[0039] like Figure 1-4 As shown, this embodiment provides a multi-pass inkjet printing frame, which is arranged above the printing platform, wherein the frame includes two sub-frames 100 distributed along the X direction, and a suspension beam 200 connected to the bottom of the sub-frame 100. The sub-frame 100 and the suspension beam 200 form a buffer space 10, a printing space 20 and an operation space 30. The suspension beam 200 includes one, and the suspension beam 200 supports an inkjet carriage 300 to slide thereon. The inkjet carriage 300 includes multiple groups of nozzles to achieve different color printing. Each group of nozzles includes multiple nozzles of the same color arranged in the Y direction. The nozzles are arranged in multiple rows in the X direction. Nozzle A and nozzle B are any two rows. The distance between nozzle A and nozzle B in the Y direction is L. Each nozzle includes multiple nozzle holes. The distance between the nozzle holes in the Y direction is Δ. A position on the printing platform is taken as the initial position. Specifically, the following steps are included:

[0040] Step 1: The inkjet carriage 300 starts from the initial position;

[0041] Step 2: The inkjet carriage 300 performs the first scanning inkjet along the X-axis direction;

[0042] Step 3: The inkjet carriage 300 interchanges the positions of nozzles A and B by a displacement distance P along the Y-axis direction. The displacement distance P = L ± Δ / n or P = (L ± Δ) / n, where n is the number of passes.

[0043] Step 4: The inkjet carriage 300 completes the next scanning inkjet along the X-axis in the opposite direction of the previous scanning inkjet;

[0044] Step 5: If the number of scanning inkjet times is less than n, the inkjet carriage 300 repeats steps 3 and 4; if the number of scanning inkjet times is equal to n, printing is completed.

[0045] In this embodiment, the sub-frame 100 includes two, which are distributed front and back along the X-axis direction. The suspension beam 200 is simultaneously connected to the bottom of the two sub-frames 100 to form three spaces. The buffer space 10 is used for the pause, speed change and displacement adjustment of the inkjet carriage 300 during the multi-PASS scanning and printing process. The printing and painting space 20 is used for the inkjet carriage 300 to scan and spray ink within this range. The operation space 30 is used for the start, stop and displacement adjustment of the inkjet carriage 300 and the number of scans during the multi-PASS scanning and printing process.

[0046] In this embodiment, before starting the inkjet printing work, the print file is first converted into the format required by the print control software through the artwork raster image processor. After loading, the operator clicks print in the operation space 30, and the printer starts the printing task after reading the loaded print file information. The inkjet carriage 300 slides from the operation space 30 along the track of the suspension beam 200 to the printing and painting space 20; the inkjet carriage 300 moves on the printing and painting space 20 and performs the first scanning and inkjet along the track of the suspension beam 200; after the inkjet is completed, the inkjet carriage 300 continues to move along the track of the suspension beam 200. The track of the suspension beam 200 slides to the buffer space 10, so that the inkjet carriage 300 pauses in the buffer space 10. At the same time, the inkjet carriage 300 begins to adjust the displacement in the Y direction, so that the displacement distance of the inkjet range in the Y direction is P=L±Δ / 2 or P=(L±Δ) / 2; after adjusting the displacement distance, the inkjet carriage 300 slides from the buffer space 30 to the printing and painting space 20; at this time, the inkjet carriage 300 returns along the track of the suspension beam 200 to perform a second scan and inkjet; after completing inkjet, the inkjet carriage 300 stops in the operating space 30.

[0047] Nozzle A and nozzle B are set adjacent to each other.

[0048] In this embodiment, the color difference effect of the nozzles is eliminated by interchangeably shifting nozzle head A and nozzle head B, thereby improving the printing resolution.

[0049] The C nozzles are in a row different from the A nozzles or the B nozzles. In step 3, the inkjet carriage 300 can interchange the positions of any two rows of the A nozzles, the B nozzles, and the C nozzles by a displacement distance P along the Y axis.

[0050] In this embodiment, the nozzles in heads A, B, and C have different colors. To compensate for the color differences between the different heads on the print medium, a multiple-scan overlay inkjet method is used to eliminate color differences. After the inkjet carriage 300 moves a displacement distance P, the positions of heads A and C on the print medium are swapped.

[0051] The inkjet width I of the inkjet carriage on the Y axis is at least one L greater than the width H of the printing medium.

[0052] In this embodiment, the inkjet width I of the inkjet carriage on the Y axis is larger than the width H of the printing medium by one L. The width I can also be larger than the width H by an integer multiple of L.

[0053] The suspension beam 200 is a rectangular beam structure, which is composed of at least two rectangular sub-beams 210 with the same length direction. The rectangular sub-beam 210 is a hollow beam with a transverse support 211 and a longitudinal support 212 provided inside. The width direction of the rectangular sub-beam 210 is not greater than the height direction.

[0054] In this embodiment, the suspension beam 200 is a rectangular beam structure, which is used to offset the bending wear caused by the reciprocating movement of the inkjet vehicle 300 to improve the bending strength of the suspension beam 200; the rectangular beam is welded by two rectangular sub-beams 210 with the same length, width and height. In order to avoid the rectangular sub-beam 210 being too heavy and causing the force strength of the frame to be too large, thereby affecting the service life of the frame, the rectangular sub-beam 210 is a hollow beam; in order to further improve the bending strength of the rectangular sub-beam 210, 9 transverse supports 211 and 9 longitudinal supports 212 are provided in the rectangular sub-beam 210, and the transverse support 211 is simultaneously connected to the two rectangular sub-beams 210.

[0055] The width dimension of the rectangular beam is not less than the height dimension, and the rectangular beam is formed by splicing two rectangular sub-beams with the same cross-section.

[0056] In this embodiment, the rectangular beam is in the shape of a flat square and is formed by two rectangular sub-beams 210 spliced ​​side by side in the Y direction. The dimension of the rectangular beam in the width direction is 60 cm and the dimension in the height direction is 40 cm. The cross-sectional dimension of the rectangular sub-beam 200 is 30 cm x 40 cm. The cross-sectional dimension of the spliced ​​rectangular beam is 60 cm x 40 cm.

[0057] The rectangular sub-beam is a hollow beam with side walls of uniform thickness. The spliced ​​side is composed of the side walls of one side of the two rectangular sub-beams. An intermediate support plate with a thickness twice that of other parts is formed on the rectangular beam. The rounded chamfers on the spliced ​​side form a groove distributed along the length direction in the middle of the upper and lower sides of the rectangular beam. End plates are provided at both ends of the rectangular beam, and the end plates at least cover the side walls of the two rectangular sub-beams, the intermediate support plate and the end faces of the groove.

[0058] In this embodiment, the rectangular sub-beam 210 is a square tube, which is a common tube type in existing specifications. Therefore, the rectangular sub-beam 210 can be made from local materials and welded, and its production cost is low and its structural stability is high. During the welding process, the side walls of the two rectangular sub-beams 210 are connected to form an intermediate support plate 213. Since the thickness of the rectangular sub-beams 210 is uniform, the thickness of the intermediate support plate 213 is twice that of other parts of the rectangular sub-beam 210. The intermediate support plate 213 and the rectangular sub-beam 210 form an I-shape at the end face, which helps to strengthen the bending strength of the rectangular beam. After the two rectangular sub-beams 210 are welded, since the four corners of the rectangular sub-beam 210 are chamfered, the two spliced ​​rectangular sub-beams 210 form a groove distributed along the length direction in the middle of the upper and lower sides of the rectangular beam. The groove, the intermediate support plate 213 and the side walls of the rectangular sub-beam 210 are welded and sealed by the end plate at the end face of the rectangular beam.

[0059] It also includes a horizontal driving device located on the suspension beam 200. The horizontal driving device is a synchronous belt or a linear motor, which drives the inkjet vehicle 300 to scan and spray ink along the X-axis direction and to shift and print along the Y-axis direction.

[0060] In this embodiment, the horizontal driving device on the suspension beam 200 drives the inkjet carriage 300 to move in the X direction and the Y direction, controls the start, stop, speed change and travel direction of the inkjet carriage 300 in the X direction, and controls the displacement distance of the inkjet carriage 300 in the Y direction.

[0061] It also includes a vertical driving device located on the suspension beam 200. The vertical driving device is a lead screw that drives the inkjet carriage 300 to adjust the inkjet height along the Z-axis direction.

[0062] In this embodiment, the vertical driving device on the suspension beam 200 drives the inkjet vehicle 300 to move in the Z direction, controls the height of the inkjet vehicle 300 from the printing platform, and thus accurately controls the inkjet range and printing effect.

[0063] The inkjet vehicle 300 moves at a uniform speed v along the X direction in the printing and spraying space 20 , and moves at a uniform acceleration 0−v in the buffer space 10 and / or the operating space 30 .

[0064] In this embodiment, when the inkjet printing work starts, the inkjet carriage 300 accelerates from the vehicle speed 0 in the stopped state to the vehicle speed v in the started state, and the inkjet carriage 300 slides from the operating space 30 along the track of the suspension beam 200 to the printing and spraying space 20; the inkjet carriage moves on the printing and spraying space 20 at a uniform speed v, and performs the first scanning and inkjet along the track of the suspension beam 200; after the inkjet is completed, the inkjet carriage continues to slide along the track of the suspension beam 200 to the operating space 30, and its vehicle speed is The speed v is reduced to 0 and the inkjet carriage is suspended in the operating space 30. At the same time, the inkjet carriage begins to adjust the displacement in the Y direction. After adjusting the displacement distance, the inkjet carriage accelerates from the speed 0 to the speed v of the restart state, and the inkjet carriage slides from the buffer space 30 to the printing and painting space 20. At this time, the inkjet carriage returns along the track of the suspension beam 200 at a uniform speed v to perform a second scanning and inkjet. After completing inkjet, the inkjet carriage reduces the speed v to 0 and stops in the operating space 30.

[0065] Example 2

[0066] like Figure 5 As shown, the inkjet carriage 300 in this embodiment is a schematic diagram of a 2PASS jack shift printing effect. The inkjet carriage 300 is provided with two groups of nozzles A and B. The two groups of nozzles A and B are arranged in a front-to-back manner. The long circular dotted line is the inkjet range of the nozzle hole, as shown in FIG. Figure 5 As shown, the nozzle on the right side of the printing medium is the position where the inkjet carriage 300 stops when it starts the first PASS, and the nozzle on the left side of the printing medium is the position where the inkjet carriage 300 stops when it starts the second PASS and produces a displacement distance P in the Y-axis direction. The installation spacing between the two groups of nozzles is L. In this embodiment, L = 120mm. The nozzles of group A are provided with 3 nozzles, namely A1, A2, and A3. The nozzles of group B are also provided with 3 nozzles, namely B1, B2, and B3. The nozzle spacing on the two groups of nozzles is Δ. In this embodiment, Δ = 40mm. The socket spacing during the 2PASS socket printing process is 1 / 2 of the nozzle spacing. In this embodiment, the socket spacing is Δ / 2 = 20mm. The starting position A1 is used as the baseline of the inkjet carriage. The displacement distance P of the inkjet carriage for each PASS is the displacement distance of A1. As shown Figure 5 As shown, the dotted area is a schematic diagram of the printing effect of the nozzle holes of the two groups of nozzles A and B, the inkjet width of the nozzle holes is I1, the inkjet width of the nozzle is I, and the width of the printing medium is H.

[0067] When the inkjet carriage 300 is at the starting position, it stays on the right side of the printing medium, and the nozzles above the printing medium are A1, A2, and A3; when the inkjet carriage 300 starts the first PASS in 2PASS, the inkjet carriage 300 moves at a constant speed from the right side of the printing platform to the left side of the printing platform along the X-axis direction, and the nozzles A1, A2, and A3 in the nozzle head A above the printing medium spray ink synchronously, and the nozzles in the nozzle head B do not spray ink. After the inkjet carriage 300 moves to the left side of the printing medium, the printing medium is covered with the first layer of ink droplets; when the inkjet carriage 300 starts the second PASS in 2PASS, the inkjet carriage 300 stays on the left side of the printing platform. At this time, the inkjet carriage 300 first moves from bottom to top along the Y-axis direction. The inkjet carriage 300 moves upward at a uniform speed to the position where the nozzle A originally stopped, and then moves upward by one socket spacing, that is, the displacement distance P of the inkjet carriage 300 in the Y-axis direction is P=L+Δ / 2=120mm+20mm=140mm. The inkjet carriage 300 then moves at a uniform speed from the left side of the printing platform to the right side of the printing platform along the X-axis direction. The nozzles B2 and B3 in the nozzle B above the printing medium spray ink synchronously, and the nozzles in the nozzle A do not spray ink. After the inkjet carriage 300 moves to the right side of the printing medium, the printing medium is covered with a second layer of ink droplets. After the two layers of ink droplets are superimposed, the inkjet carriage 300 returns to the starting position in the Y-axis direction. At this point, a complete 2PASS printing process is completed.

[0068] Because 2-pass printing utilizes two adjacent nozzles, A and B, for printing, the image resolution is doubled compared to single-pass printing. The double layer of ink droplet coverage minimizes color difference between the nozzles in groups A and B. To avoid the noticeable color streaks that can occur when fixed nozzles are used in both nozzle groups, the nozzles in the 2-pass printing process are randomly switched on and off. In this embodiment, the nozzles A1, A2, and A3 used in each pass do not refer to the three fixed nozzles in nozzle A, but rather to any three nozzles in nozzle A. The same applies to nozzle B. The selection of any nozzle is controlled by a random number, which controls the switching ratio of the nozzles in groups A and B. There are multiple ways to set the random number. The implementer can choose between true or false random numbers based on site needs. Alternatively, they can select any color block from an existing image, amplify it, and compare the color of the amplified block with a standard color chart to generate a random number.

[0069] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the technical solutions of the present invention, and are not intended to limit the specific implementation methods of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A multi-pass inkjet printing frame, arranged above the printing platform, characterized in that: The invention comprises two sub-frames distributed along the X-axis direction, and a suspension beam connected to the bottom of the sub-frame. The sub-frame and the suspension beam form a buffer space, a printing and spraying space, and an operation space. The suspension beam includes one, and the suspension beam supports the inkjet carriage to slide on it. The inkjet carriage includes multiple groups of nozzles to achieve different color spraying. Each group of nozzles includes multiple nozzles of the same color arranged in the Y-axis direction. The nozzles are arranged in multiple rows in the X-axis direction. Nozzle A and nozzle B are any two rows. The distance between nozzle A and nozzle B in the Y-axis direction is L. Each nozzle includes multiple nozzle holes. The distance between the nozzle holes in the Y-axis direction is Δ. A position on the printing platform is used as the initial position. Specifically, the following steps are included: Step 1: The inkjet vehicle starts from the initial position; Step 2: The inkjet carriage completes the first scanning inkjet along the X-axis direction; Step 3: The inkjet carriage interchanges the positions of nozzles A and B by a displacement distance P along the Y-axis direction. The displacement distance P = L ± Δ / n or P = (L ± Δ) / n, where n is the number of passes. Step 4: The inkjet carriage completes the next scanning inkjet along the X-axis opposite direction of the previous scanning inkjet; Step 5: If the number of scanning inkjet times is less than n, the inkjet carriage repeats steps 3 and 4; if the number of scanning inkjet times is equal to n, printing is completed.

2. A multi-pass inkjet printing frame according to claim 1, characterized in that: Nozzle A and nozzle B are set adjacent to each other.

3. A multi-pass inkjet printing frame according to claim 1, characterized in that: The C nozzles are in a row different from the A nozzles or the B nozzles. The inkjet carriage can interchange the positions of any two rows of the A nozzles, the B nozzles and the C nozzles by a displacement distance P along the Y axis.

4. A multi-pass inkjet printing frame according to claim 1, characterized in that: The inkjet width I of the inkjet carriage on the Y axis is at least one L greater than the width H of the printing medium.

5. The multi-pass inkjet printing frame according to claim 1, characterized in that: The cantilever beam is a rectangular beam structure, which is composed of at least two rectangular sub-beams with the same length direction. The rectangular sub-beam is a hollow beam with transverse and longitudinal supports provided inside. The width direction of the rectangular sub-beam is not greater than the height direction.

6. A multi-pass inkjet printing frame according to claim 5, characterized in that: The width dimension of the rectangular beam is not less than the height dimension, and the rectangular beam is formed by splicing two rectangular sub-beams with the same cross-section.

7. The multi-pass inkjet printing frame according to claim 5, characterized in that: The rectangular sub-beam is a hollow beam with side walls of uniform thickness. The spliced ​​side is composed of the side walls of one side of the two rectangular sub-beams. An intermediate support plate with a thickness twice that of other parts is formed on the rectangular beam. The rounded chamfers on the spliced ​​side form a groove distributed along the length direction in the middle of the upper and lower sides of the rectangular beam. End plates are provided at both ends of the rectangular beam, and the end plates at least cover the side walls of the two rectangular sub-beams, the intermediate support plate and the end faces of the groove.

8. A multi-pass inkjet printing frame according to any one of claims 1 to 7, characterized in that: It also includes a horizontal driving device located on the suspension beam, which is a synchronous belt or a linear motor, driving the inkjet vehicle to scan and spray ink along the X-axis direction and to insert and shift print along the Y-axis direction.

9. A multi-pass inkjet printing frame according to any one of claims 1 to 7, characterized in that: It also includes a vertical driving device located on the suspension beam, and the vertical driving device is a lead screw that drives the inkjet vehicle to adjust the inkjet height along the Z-axis direction.

10. A multi-pass inkjet printing frame according to any one of claims 1 to 7, characterized in that: The inkjet vehicle moves at a uniform speed v along the X-axis direction in the printing and spraying space, and moves at a uniform acceleration in the buffer space and / or the operation space, accelerating from 0 to v.

Images