Patent Publication Number: US-2020290286-A1

Title: Printing method and printingdevice

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2018/086089, filed on May 9, 2018, which claims priority to Chinese Patent Application No. 201711312849.2, filed on Dec. 8, 2017, titled “3D Printing Method and Printing System Thereof”, and Chinese Patent Application No. 201810093197.6, filed on Jan. 31, 2018, titled “Printing Method and Printing Device”. All of the aforementioned patent applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The disclosure relates to the field of 3D inkjet printing, and in particular, to a printing method and a printing device. 
     BACKGROUND 
     3D Printing (3DP) technology, also known as Additive Manufacturing (AM) technology or Rapid Prototyping (RP) technology, is a three-dimensional construction technology based on the discrete-stacking principle, which slices a model into layers, prints layer by layer on a support platform and then stacks multiple layers to finally make a 3D object. 
     Usually, a process of making a 3D object mainly includes the steps of converting a model to be printed of a target 3D object into data in an STL data format or data in other data format that can be recognized by slicing software, slicing the model to be printed into layers and performing data processing by using the slicing software, and printing, by a print, layer by layer according to the obtained printing data. In the prior art, when slicing a model into layers by using the slicing software, firstly a minimum cuboid that can accommodate the model to be printed is determined, and then the minimum cuboid is sliced to form multiple slice layers, that is, the length, width and height of the minimum cuboid that accommodates the model to be printed are taken as boundary dimensions for slicing, and when slicing layers, the area of each slice layer is equal, that is, the length and width of each slice layer are equal to the length and width of the minimum cuboid that accommodates the model to be printed, and the thickness of the slice layer is not limited as long as the thickness of all slice layers is equal to the height of the minimum cuboid that accommodates the model. In this way, during actual printing, the printer moves according to the size of each slice layer, that is, when the printer prints layer by layer according to the obtained printing data, the movement trajectory of the printer is completely the same. 
     In the prior art, during the inkjet printing of a 3D inkjet printer with a printhead arranged in a multi-nozzle array, the movement mode of the printhead is that the printing platform moves along the X and Y axes relative to the printhead, and after one layer is completed, the printing platform moves to the origin and descends the height of one layer relative to the printhead, and then starts the printing of a new layer, repeating in this way to form a 3D printed object. 
     The problem caused by this is that in actual inkjet printing, the model to be printed is usually not a regular cuboid shape, which instead can be any other shapes. So, the printhead is located in a no-printing area on most of the slice layers during printing, resulting in low printing efficiency. 
     SUMMARY 
     The present disclosure provides a printing method and a printing device for 3D inkjet printing, which have high printing efficiency. 
     In a first aspect, the present disclosure provides a printing method, including: 
     determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, where the trip starting point and/or the trip ending point of at least one trip matches a contour of the object to be printed in the trip; 
     performing layer printing for the preset layer according to the trips. 
     In a second aspect, the disclosure provides a printing device, including a printhead, a support platform and a control unit, where the control unit is electrically connected to the printhead, and the control unit is configured to perform the forgoing printing method, to cause the printhead to print an object to be printed on the support platform. 
     The printing method and the printing device of the present disclosure, the printing method specifically includes the following steps: firstly, determining a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer according to layer printing data of an object to be printed, where the trip starting point and/or the trip ending point of at least one trip matches a contour of the object to be printed in the trip; then performing layer printing for the preset layer according to the trips. In this way, when a single slice layer is printed, at least one of the trip starting point or the trip ending point of a printing trip matches the contour of the object to be printed in the trip, which can effectively reduce an overall length of the trip, and improve printing speed and printing efficiency. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       In order to explain the technical solutions in the embodiments of the present disclosure or in the prior art more clearly, the drawings used in the description of the embodiments or the prior art will be briefly introduced in the following. Obviously, the drawings described in the following are some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative efforts. 
         FIG. 1  is a schematic flowchart of a printing method provided by a first embodiment of the present disclosure; 
         FIG. 2  is a schematic diagram of an object to be printed on a preset layer; 
         FIG. 3  is a schematic flowchart of another printing method provided by the first embodiment of the present disclosure; 
         FIG. 4  is a schematic diagram of printing status when a printing method is performed, provided by a second embodiment of the present disclosure; 
         FIG. 5 a    is a schematic diagram of a first trip when one-way printing is performed, provided by the second embodiment of the present disclosure; 
         FIG. 5 b    is a schematic diagram of a second trip when one-way printing is performed, provided by the second embodiment of the present disclosure; 
         FIG. 5 c    is a schematic diagram of a third trip when one-way printing is performed, provided by the second embodiment of the present disclosure; 
         FIG. 6  is a schematic diagram of printing status when another printing method is performed, provided by a third embodiment of the present disclosure; 
         FIG. 7 a    is a schematic diagram of a first trip provided by the third embodiment of the present disclosure; 
         FIG. 7 b    is a schematic decomposition diagram of movement of a second trip provided by the third embodiment of the present disclosure; 
         FIG. 7 c    is a schematic decomposition diagram of movement of a third trip provided by the third embodiment of the present disclosure; 
         FIG. 7 d    is a schematic diagram of the second trip provided by the third embodiment three of the present disclosure; 
         FIG. 7 e    is a schematic diagram of the third trip provided by the third embodiment of the present disclosure; 
         FIG. 8  is a schematic flowchart of performing a fourth printing method provided by a fourth embodiment of the present disclosure; 
         FIG. 9  is a schematic diagram of trip division when the fourth printing method is performed provided by the fourth embodiment of the present disclosure; 
         FIG. 10  is a schematic diagram of trip division of the trips in  FIG. 9  after deletion; 
         FIG. 11  is another schematic flowchart of the fourth printing method provided by the fourth embodiment of the present disclosure; 
         FIG. 12  is a schematic flowchart of the fourth printing method provided by the fourth embodiment of the present disclosure; 
         FIG. 13  is a schematic diagram of trip division of performing a fifth printing method provided by a fifth embodiment of the present disclosure; 
         FIG. 14  is a schematic diagram of trip division of the trips in  FIG. 13  after movement; 
         FIG. 15  is a schematic diagram of trip division of the trips before movement provided by the fifth embodiment of the present disclosure; 
         FIG. 16  is a schematic diagram of trip division of the trips in  FIG. 15  after movement; 
         FIG. 17 a    is a schematic decomposition diagram of a third trip provided by the fifth embodiment of the present disclosure; 
         FIG. 17 b    is a schematic diagram of the third trip provided by the fifth embodiment of the present disclosure; 
         FIG. 17 c    is a schematic decomposition diagram of a fourth trip provided by the fifth embodiment of the present disclosure; 
         FIG. 17 d    is a schematic diagram of the fourth trip provided by the fifth embodiment of the present disclosure; 
         FIG. 18  is a schematic diagram of printing status provided by the fifth embodiment of the present disclosure; 
         FIG. 19  is a schematic flowchart of printing status of a sixth printing method provided by a sixth embodiment of the present disclosure; 
         FIG. 20  is a schematic diagram of trip division of the sixth printing method provided by the sixth embodiment of the present disclosure; 
         FIG. 21 a    is a schematic diagram of a first trip provided by the sixth embodiment of the present disclosure; 
         FIG. 21 b    is a schematic diagram of a second trip provided by the sixth embodiment of the present disclosure; 
         FIG. 21 c    is a schematic diagram of a third trip provided by the sixth embodiment of the present disclosure; 
         FIG. 22  is a schematic flowchart of printing status of a seventh printing method provided by a seventh embodiment of the present disclosure; 
         FIG. 23 a    is a schematic diagram of a second trip provided by the seventh embodiment of the present disclosure; 
         FIG. 23 b    is a schematic diagram of a third trip provided by the seventh embodiment of the present disclosure; 
         FIG. 24  is a schematic diagram of a range of printing points in the seventh embodiment of the present disclosure; 
         FIG. 25  is a schematic diagram of printing status of a printing method in an optional embodiment of the present disclosure; 
         FIG. 26  is a schematic structural diagram of a printing system provided by an eighth embodiment of the present disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     To make the objectives, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be described clearly and completely in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, but not all the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by a person of ordinary skill in the art without creative efforts fall within the protection scope of the present disclosure. 
       FIG. 1  is a schematic flowchart of a printing method provided by a first embodiment of the present disclosure.  FIG. 2  is a schematic diagram of an object to be printed on a preset layer. As shown in  FIG. 1  and  FIG. 2 , the printing method in this embodiment may specifically include the following steps: 
     S 101 , determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, where the trip starting point and/or the trip ending point of at least one trip matches a contour of the object to be printed in the trip. 
     Specifically, when printing an object to be printed, firstly, the model of the object to be printed needs to be sliced into layers, and each slice layer includes a part of the object to be printed corresponding to the sliced layer, so that layer printing data of each slice layer can be obtained by performing data processing for each slice layer of the model, and printing can be performed according to the layer printing data. 
     After the layer printing data of the object to be printed corresponding to each slice layer is obtained, a trip of the printing head when printing the layer, that is, the preset layer, can be determined according to the layer printing data of each slice layer. Because a print length of the printhead itself is limited, the printhead needs to go through multiple scans to complete the printing process of this layer. Specifically, taking three-dimensional coordinate axes as an example, the X axis is a scanning direction, the Y axis is a stepping direction, and the Z axis is a layer stacking direction. The printing method is to move once along the X axis and print out a printing material in a place with a valid printing data point during the moving; after the printing of one line is completed, step in the Y-axis direction, and then move along the X-axis again to perform the printing process of another line, and repeat in this way to complete the printing of the slice layer. Then the printing platform descends a preset distance relative to the printhead, and the printing work of another slice layer is restarted, and finally a three-dimensional object to be printed is formed. Each moving process of the printhead along the X axis is a trip, and the starting point of the printhead during the moving is the trip starting point of the trip, and the ending point of the printhead during the moving is the trip ending point. Each trip of the printhead along the X axis needs to go through start, acceleration, constant speed, deceleration, and stop phases, and the print head operates at the constant speed phase. Therefore, for ease of understanding, the start, acceleration, deceleration and stop phases of the printhead are ignored in each trip described in the present disclosure, that is, the trip described in the present disclosure is regarded as a path traveled by the printhead in an operation along the scanning direction. 
     Therefore, after obtaining the layer printing data of the object to be printed, the multiple trips required for the printhead when printing the slice layer can be determined, where at least one of the trip starting points or the trip ending points of part or all of the trips is not the same as the starting points and ending points of the other trips, but is located at a position that matches or fits the contour of the object to be printed in the trip. 
     The trip starting point and/or the trip ending point of the trip matches the contour of the object to be printed in the trip; when the printhead is close to the printing plane, a distance between the two can be neglected, and it can be that the trip starting point and/or trip ending point coincide with the contour of the object to be printed in the trip; when the printhead is far away from the printing plane, due to the inertia of a material flying, the trip starting point and/or the trip ending point of the trip may be located near the contour of the object to be printed. 
     At this time, since at least one of the trip starting point and trip ending point of the trip matches the contour of the object to be printed in the trip, therefore, compared with the trip starting point and trip ending point of the trip and a cuboid containing the object to be printed in the conventional printing process, part of the path corresponding to an empty printing area is removed from the trip, and thus an overall length of the trip is reduced, which effectively improves printing speed and printing efficiency of the printhead when printing the slice layer. 
     S 102 , performing layer printing for the preset layer according to the trips. 
     After obtaining the multiple trips corresponding to the slice layer according to the layer printing data of the preset layer, the printhead can be driven to perform layer printing for the preset layer according to the obtained multiple trips. 
     In this way, printing a single slice layer can be completed by the above steps, and multiple printing layers formed by the slice layers can be stacked to form a three-dimensional object to be printed. 
     Therefore, when a single slice layer is printed, at least one of the trip starting point or the trip ending point of a printing trip in the scanning direction matches the contour of the object to be printed in the trip, which can effectively reduce an overall length of the trip, and improve printing speed and printing efficiency. 
     When the printhead is printing, positions of the trip starting point and the trip ending point of the trip in the scanning direction may be limited by many factors. For example, when the printhead is in a one-way printing mode, each trip is kept relatively independent of the previous trip, and the trip starting point and trip ending point of the trip are not affected by adjacent trips. At this time, in order to reduce the overall length of the trip, in an optional implementation, the trip starting point and the trip ending point can be matched with the contour of the object to be printed in the trip. In this way, the trip can use the positions matching the contour of the object to be printed in the trip as the trip starting point and the trip ending point, so that the trip can skip a blank printing area before and after the contour of the object to be printed in the scanning direction, thereby improving printing efficiency. 
     In another alternative implementation, due to the limitation of the printing mode of the printhead, the trip of the printhead cannot directly start from a position that matches the contour of the object to be printed. For example, when the printhead is in a two-way printing mode, each trip proceeds by moving directly in a stepping direction to start the printing process of this trip after the printing of the previous trip is completed and the printhead moves to the trip ending point of the previous trip. At this time, both the trip starting point and the trip ending point of the trip need to be determined by referring to the trip ending point of the previous trip of the trip or the trip starting point of the next trip of the trip, and cannot be determined only by the contour of the object to be printed. Therefore, optionally, for the trip starting point and trip ending point of the trip, the trip starting point of the trip is determined by a leading one of the contour of the object to be printed in the trip and the trip ending point of a previous trip of the trip in the scanning direction; and/or, the trip ending point of the trip is determined by a lagging one of the contour of the object to be printed in the trip and the trip starting point of a next trip of the trip in the scanning direction. At this time, for the trip starting point and the trip ending point of the trip, reference needs to be made to the positions of the trip starting point and the trip ending point of two adjacent trips, and the contour of the object to be printed in the trip is compared with the trip starting point or the trip ending point of the adjacent trips of the trip, to choose the ones that make the trip have a larger range in the scanning direction. In this way, the trip starting point and the trip ending point of the trip can be determined to avoid the occurrence of the phenomenon that the next trip cannot cover the contour of the object caused by the range formed by the trip starting point and the trip ending point of the trip being smaller than the range of the contour of the object in the next trip. 
       FIG. 3  is a schematic flowchart of another printing method provided by the first embodiment of the present disclosure. As shown in  FIG. 3 , before determining trip starting points and/or trip ending points of the trips, a number of the trips of the printhead in the stepping direction and information such as a position and range of a single trip in the stepping direction may be determined according to the layer printing data of the object to be printed. Specifically, before the preceding step S 101 , that is, the determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, the following steps may be further included: 
     S 201 , determining a number of the multiple trips required for the printhead to print the preset layer. 
     In this way, after obtaining the layer printing data of the object to be printed, the number of trips required for printing the preset layer can be determined for the preset layer according to a parameter of the printhead and a size of the preset layer. In this way, the layer can be divided according to the number of trips to obtain a trip range corresponding to each trip in the preset layer, and determine at least one of the trip starting point or the trip ending point according to the range of each trip. 
     When determining the number of trips, the number of trips can be obtained through different parameters according to different printing modes. For example, in a normal printing mode without performing supplementary printing, the step of determining the number of the multiple trips according to the layer printing data of the object to be printed specifically includes: determining the number of the multiple trips according to a length of the printhead in a stepping direction and a length of the preset layer in the stepping direction. 
     For example, when supplementary printing is not performed, on the basis of the length d of the printhead in the stepping direction, that is, along the Y axis, and the length D of the preset layer in the stepping direction, the number of trips can be determined as N=D/d, so that the number of trips can be obtained. When D/d is not an integer, N is an integer round-up of D/d; e.g., if D/d=1.2, then N=2. 
     In this way, after the number of trips is obtained, the trips can be divided according to the number of trips, so as to obtain the trip starting point and the trip ending point of each trip in the next step. 
     Further, in order to obtain at least one of the trip starting point and the trip ending point of the trip, various methods may be adopted for determination. In an optional implementation, step S 101  specifically includes: determining the trip starting point and/or the trip ending point of the trip according to a range of an area having the contour of the object, that is, an area with a valid printing data point, in the scanning direction in each trip. 
     Since the object to be printed necessarily includes valid printing data points, it is possible to determine which area in the trip corresponds to the object to be printed by detecting the valid printing data points. And an area having the valid printing data point in the trip is a contour area corresponding to the object to be printed, and at least one of the trip starting point or the trip ending point of the trip can be determined according to the range of that area in the scanning direction. 
     After the trips for printing is obtain, the preset layer can be printed according to the trips. The printing process may be performed after trip data is generated, or may be performed during the generation of the trip data. 
     Printing the trip data after generating the trip data may specifically be, after generating the trip data of a trip, sending the trip data to the printhead to perform a printing step, and at the same time, performing the process of generating the next trip data. When performing a printing in the process of generating the trip data, the trip data is synchronously sent to the printhead to perform the printing step while the trip data of a trip is generated. 
     It should be noted that the trips in all the above steps may be different or the same. For example, when the slice layer is a cuboid, each trip on the slice layer is the same as each other, and when the slice layer is circular, irregular, etc., each trip on the slice layer is different from each other. 
     In this embodiment, the printing method may specifically include the following steps: firstly, determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, where the trip starting point and/or the trip ending point of at least one trip matches a contour of the object to be printed in the trip; then performing layer printing for the preset layer according to the trips. In this way, when a single slice layer is printed, at least one of the trip starting point or the trip ending point of a printing trip matches the contour of the object to be printed in the trip, which can effectively reduce an overall length of the trip, and improve printing speed and printing efficiency. 
       FIG. 4  is a schematic diagram of printing status when a printing method is performed, provided by a second embodiment of the present disclosure. As shown in  FIG. 4 , in this embodiment, the printhead performs a one-way printing function. At this time, after performing the printing process of each trip, the printhead will return to the side of the trip starting point, and the printing process will be performed again from this side for the next trip. 
     Specifically, when the printhead performs one-way printing, the printing of each trip will be performed a long the X-axis direction, that is, the scanning direction, and after the printing of each trip is completed, the printhead moves along the Y-axis direction, that is, the stepping direction, to the next trip to print. In this way, the printhead alternately reciprocates on the X axis and the Y axis, thereby completing the printing of the preset layer. Unless otherwise specified, the scanning direction of the printhead is the X-axis direction, that is, the horizontal direction along the paper surface, and the stepping direction is the Y-axis direction, that is, the vertical direction along the paper surface. 
       FIG. 5 a    is a schematic diagram of a first trip when one-way printing is performed, provided by the second embodiment of the present disclosure.  FIG. 5 b    is a schematic diagram of a second trip when one-way printing is performed, provided by the second embodiment of the present disclosure.  FIG. 5 c    is a schematic diagram of a third trip when one-way printing is performed, provided by the second embodiment of the present disclosure. As shown in  FIG. 5 a   ,  FIG. 5 b   , and  FIG. 5 c   , the printhead performs one-way movement and printing along the first trip  111 , the second trip  121 , and the third trip  131 , respectively. At this time, in order to distinguish the printhead in different trips, it may be defined that the printhead  11  is on the first trip  111 , and the printhead  12  and the printhead  13  are on the second trip  121  and the third trip  131 , respectively. The printhead  11 , the printhead  12 , and the printhead  13  may represent the same printhead located on different trips. 
     Since the printhead performs the one-way printing function in this embodiment, the printing ending point of a trip will not be affected by a previous trip. At this time, the trip starting point and the trip ending point of the trip both match the boundary of the object to be printed in the trip; and as can be seen from  FIG. 4 ,  FIG. 5 a   ,  FIG. 5 b    and  FIG. 5 c   , the trip starting points and trip ending points of the first trip  111 , second trip  121  and third trip  131  are located near the boundary of the object to be printed, or at a position coincident with the boundary, and in this way, there is less blank printing area in the trips, which can improve printing speed and printing efficiency. 
     In this embodiment, when performing one-way printing, the printing method may specifically include the following steps: firstly, determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, where a trip starting point and/or the trip ending point of at least one trip matches a boundary of the object to be printed in the trip; then performing layer printing for the preset layer according to the trips. In this way, when a single preset slice layer is printed, at least one of the trip starting point or the trip ending point of a printing trip matches the boundary of the object to be printed in the trip, which can effectively reduce an overall length of the trip, and improve printing speed and printing efficiency. 
       FIG. 6  is a schematic diagram of printing status when another printing method is performed, provided by a third embodiment of the present disclosure. As shown in  FIG. 6 , in this embodiment, the printhead performs a two-way printing function, that is, after printing a trip, the printhead does not return to the side of the original trip starting point, but takes the side of the trip ending point as a trip starting point to start printing the next trip in a reverse direction. Therefore, during the two-way printing, the trip in printing is limited by the position of the trip ending point of the previous s trip, and the position of the trip starting point of the next trip needs also be considered. 
       FIG. 7 a    is a schematic diagram of a first trip provided by a third embodiment of the present disclosure.  FIG. 7 b    is a schematic decomposition diagram of movement of a second trip provided by the third embodiment of the present disclosure.  FIG. 7 c    is a schematic decomposition diagram of movement of a third trip provided by the third embodiment of the present disclosure.  FIG. 7 d    is a schematic diagram of the second trip provided by the third embodiment of the present disclosure.  FIG. 7 e    is a schematic diagram of the third trip provided by the third embodiment of the present disclosure. As shown in  FIG. 7 a   ,  FIG. 7 b   , and  FIG. 7 c   , the printhead performs two-way movement and printing along the first trip  211 , the second trip  221  and the third trip  231 , respectively. At this time, similar to the foregoing second embodiment, in order to distinguish the printhead in different trips, it may be defined that the printhead  21  is on the first trip  211 , and the printhead  22  and the printhead  23  are on the second trip  221  and the third trip  231 , respectively. The printhead  21 , the printhead  22  and the printhead  23  may represent the same printhead located on different trips. 
     Since the trip is limited by the position of the trip starting point or the trip ending point of two adjacent trips, its own trip starting point and trip ending point are also affected by the two upper and lower trips. Specifically, in two-way printing, the trip starting point of a trip is determined by a leading one of the contour of the object to be printed in the trip and the trip ending point of a previous trip of the trip, in the scanning direction; and the trip ending point of a trip could be determined by a lagging one of the contour of the object to be printed in the trip and the trip starting point of a next trip of the trip, in the scanning direction. For example, when determining the trip starting point of a trip, a position of the contour of the object to be printed in the trip needs to be compared with a position in the trip corresponding to the trip ending point of the previous trip of the trip to determine which one is more advanced in the scanning direction of the trip, that is, this position is used as the trip starting point when printing and then a more lagged position can be covered. Similarly, when determining the trip ending point of a trip, the position of the contour of the object to be printed in the trip needs to be compared with a position in the trip corresponding to the trip starting point of the next trip of the trip to determine which one is more lagging in the scanning direction of the trip, and that position is used as the trip ending point when printing and then a more advanced position can be covered. 
     For example, after completing the first trip  211 , the printhead  21  steps from the trip ending point of the first trip  211  to the printhead  22  shown in the figure. Since the trip ending point of the first trip  211  lags behind the contour of the object to be printed in the second trip  222  in the scanning direction, it is necessary to print using the point corresponding to the trip ending point of the first trip  211  as the trip starting point. In this way, a deceleration path of the printhead  21  after the first trip and an acceleration path of the printhead  22  before the second trip are offset by each other, and the second trip actually passed by the printhead  22  includes a portion  221  and a portion  221 ′ shown in  FIG. 7 b   , which is the second trip  222  in  FIG. 7   d.    
     Similarly, the third trip actually passed by the printhead  23  includes a portion  231  and a portion  231 ′, which is the third trip  232  in  FIG. 7   e.    
     After the range of each trip is determined in this way, the printhead can perform the printing process according to the trip data of the trips to complete printing of the preset layer. 
     In this embodiment, when performing two-way printing, the printing method may specifically include the following steps: firstly, determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, where the trip starting point and/or the trip ending point of at least one trip matches a contour of the object to be printed in the trip; then performing layer printing for the preset layer according to the trips. In this way, when a single slice layer is printed, at least one of the trip starting point or the trip ending point of a printing trip matches the contour of the object to be printed in the trip, which can effectively reduce an overall length of the trip, and improve printing speed and printing efficiency. 
       FIG. 8  is a schematic flowchart of performing a fourth printing method provided by a fourth embodiment of the present disclosure.  FIG. 9  is a schematic diagram of trip division when the fourth printing method is performed, provided by the fourth embodiment of the present disclosure. Since portions of the object to be printed on the preset layer may be discontinuous, but divided into multiple different areas, it is possible that among the multiple trips, there will one or more trips without the object to be printed, that is, the printhead does not perform printing in the one or more trips. At this time, in order to avoid a waste of time caused by the movement of the printhead in these trips in which no printing is performed, these trips that do not contain the object to be printed can be deleted to save printing time. Specifically, if a trip does not have any portion of the object to be printed, that is, the printhead does not actually print in the trip, and then the trip is actually meaningless for the printing operation. Therefore, as shown in  FIG. 8 , before the determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for the printhead to print a preset layer, the printing method further includes the following step: 
     S 301 , deleting a trip that does not contain the object to be printed. 
     As shown in  FIG. 9 ,  FIG. 9  includes seven trips, among which the fourth trip does not contain the object to be printed, so the fourth trip shown in  FIG. 9  is a meaningless trip. Therefore, after determining the number of the multiple trips, the fourth trip that does not contain the object to be printed needs to be deleted, so that the total number of trips in the preset layer is changed from seven to six. The other trips have a portion of the object to be printed, so they need to be retained.  FIG. 10  is a schematic diagram of trip division of the trips in  FIG. 9  after deletion. As shown in  FIG. 10 , the fourth trip is deleted, so the original seven trips change to six trips. 
     It should be noted that the step of deleting a trip that does not contain the object to be printed is generally performed after the number of trips in the preset layer is determined, so that after the number of trips is determined, the step S 301  is performed for reduction.  FIG. 11  is another schematic flowchart of the fourth printing method provided by the fourth embodiment of the present disclosure. As shown in  FIG. 11 , after step S 201  is performed firstly, the step of trip deletion may be completed. 
     In addition, in the printing process of the same preset layer, the step of deleting the trip that does not contain the object to be printed can generally be performed one or more times. Since the printing method may have other steps of adjusting parameters, such as the number and the positions of trips, and after the steps of adjusting, there may be a blank trip that does not contain the object to be printed again, therefore, after the other steps of adjusting are completed, the step S 301  can be performed again to delete all blank trips. 
     In this embodiment, the printing method may specifically include the following steps: firstly, determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, where a trip starting point and/or the trip ending point of at least one trip matches a contour of the object to be printed in the trip; then performing layer printing for the preset layer according to the trips; where before the determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, a step of deleting a trip that does not contain the object to be printed is further included. In this way, when a single slice layer is printed, at least one of the trip starting point or the trip ending point of a printing trip matches the contour of the object to be printed in the trip, which can effectively reduce an overall length of the trip, and the trip that does not contain the object to be printed can be deleted, thereby improving printing speed and printing efficiency. 
       FIG. 12  is a schematic flowchart of a fifth printing method provided by a fifth embodiment of the present disclosure.  FIG. 13  is a schematic diagram of trip division of performing a fifth printing method provided by the fifth embodiment of the present disclosure.  FIG. 14  is a schematic diagram of trip division of the trips in  FIG. 13  after movement. In this embodiment, when the object to be printed is in a discontinuous state on the preset layer, but deletion of a trip that does not contain the object to be printed cannot be performed directly, and it is also possible to move a trip along a lagging direction. Specifically, as shown in  FIG. 12 , before the step S 101 , that is, the determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, the printing method further includes the following steps: 
     S 401 , obtaining, for every two adjacent trips, a minimum distance in a stepping direction between the contour of the object to be printed in a trip at a lagging position and a trip at a leading position. 
     S 402 , when the minimum distance is greater than zero, moving the trip at the lagging position and all trips after the trip at the lagging position along the lagging direction by the minimum distance. 
     In this way, since the multiple trips in the preset layer are arranged in order according to the step direction, it is possible to make a comparison between every two adjacent trips and obtain the boundary contour of the object to be printed in a trip at a lagging position in the step direction in the two adjacent trips, so as to obtain the minimum distance between the contour of the object to be printed and the boundary of the trip which is at a leading position in the step direction in the two adjacent trips. Still taking the trip division in  FIG. 13  and  FIG. 14  as an example for illustration. In  FIG. 13 , it can be determined according to the layer printing data of the preset layer that the number of trips in the layer is six. In these six trips, both the first trip and the second trip contain the object to be printed, and the object to be printed crosses over the entire width of the first trip and the second trip in the stepping direction, therefore, the minimum distance between the boundary of the object to be printed in the second trip and the boundary of the first trip is 0. Similarly, the minimum distance between the boundary of the object to be printed in the third trip and the boundary of the second trip is also 0. Therefore, the first trip, the second trip and the third trip do not need to be moved. 
     However, since the boundary of the object to be printed in the fourth trip is not continuous with the boundary of the object to be printed in the third trip. Therefore, the minimum distance between the boundary of the object to be printed in the fourth trip and the boundary of the third trip is the distance S between the boundary of the object to be printed in the fourth trip and the boundary between the third and fourth trips. At this time, it is necessary to move all the trips lagging behind the third trip, that is, the fourth, fifth, and sixth trips, along the lagging direction, and the distance moved is equal to the distance S, as shown in  FIG. 14 . 
     The fourth, fifth, and sixth trips in the lagging direction are compared in pairs. Since the object to be printed in each trip is connected to a trip in the leading direction, the minimum distance is always 0, that is, the fourth, fifth, and sixth trips no longer continue to move along the lagging direction. 
     In this way, through the above steps S 401  and S 402  the trip can be moved and deleted, so as to reset the number of trips and the trip starting points or trip ending points of the trips, thereby reducing waste of time during printing. 
       FIG. 15  is a schematic diagram of trip division of the trips before movement, provided by the fifth embodiment of the present disclosure.  FIG. 16  is a schematic diagram of trip division of the trips in  FIG. 15  after movement. As shown in  FIG. 15  and  FIG. 16 , when the printhead  23  performs the third trip  232  completely and then performs the next trip, that is, the trip of the printhead  24 , the trip can be moved in the lagging direction by a distance S, and the trip  241  is performed. 
     After the moving of the trips, the trip starting point and trip ending point of a single trip can still be obtained according to a method similar to the foregoing embodiments.  FIG. 17 a    is a schematic decomposition diagram of a third trip provided by the fifth embodiment of the present disclosure.  FIG. 17 b    is a schematic diagram of the third trip provided by the fifth embodiment of the present disclosure.  FIG. 17 c    is a schematic decomposition diagram of a fourth trip provided by the fifth embodiment of the present disclosure.  FIG. 17 d    is a schematic diagram of the fourth trip provided by the fifth embodiment of the present disclosure. As shown in  FIG. 17 a    to  FIG. 17 d   , the third trip of the printhead  23  may include a portion  232  and a portion  232 ′, that is,  233  in  FIG. 17 b   . When the printhead performs the fourth trip, it becomes the printhead  24 , and the fourth trip may include two portions of  241  and  241 ′, namely  242  in  FIG. 17 d   . Finally, the printhead  25  performs the fifth trip  251  to complete the printing process of the layer. The printhead  23 , the printhead  24 , and the printhead  25  represent a same printhead in different trips.  FIG. 18  is a schematic diagram of printing status provided by the fourth embodiment of the present disclosure. As shown in  FIG. 18 , the first trip  211 , the second trip  222 , and the third trip  233  are all similar to the previous embodiments, while the fourth trip  242 , the fifth trip  252  and the sixth trip  261  are located at trips after moved along the lagging direction. The printheads  21 ,  22 ,  23 ,  24 ,  25  and  26  all represent a same printhead in different trips. 
     In addition, the step of deleting a trip that does not contain the object to be printed in the foregoing fourth embodiment may also be performed according to the steps S 401  and S 402 . Specifically, as shown in  FIG. 14 , the object to be printed is not included in the fourth trip, therefore, the minimum distance between the boundary of the object to be printed in the fourth trip and the boundary of the third trip is the entire width of the fourth trip in the stepping direction. At this time, it is necessary to move all the trips lagging behind the third trip, that is, the fourth, fifth and sixth trips, along the lagging direction, and the distance moved is equal to the minimum distance, that is, the width of the fourth trip in the stepping direction, that is, the width in the lagging direction. In this way, it is possible to avoid the trip without the object to be printed, shorten an overall printing time of the preset layer, and improve printing efficiency. 
     In this embodiment, the printing method may specifically include the following steps: firstly, obtaining, for every two adjacent trips, a minimum distance in a stepping direction between a contour of an object to be printed in a trip at a lagging position and a trip at a leading position; then, when the minimum distance is greater than zero, moving the trip at the lagging position and all trips after the trip at the lagging position along a lagging direction by the minimum distance; further, determining, according to layer printing data of the object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, where the trip starting point and/or the trip ending point of at least one trip matches the contour of the object to be printed in the trip; then performing layer printing for the preset layer according to the trips. In this way, when a single slice layer is printed, at least one of the trip starting point or the trip ending point of a printing trip matches the contour of the object to be printed in the trip, which can effectively reduce an overall length of the trip, and the printing trip may not be set in the area that does not contain the object to be printed, thereby improving printing speed and printing efficiency. 
       FIG. 19  is a schematic diagram of printing status of a sixth printing method provided by a sixth embodiment of the present disclosure.  FIG. 20  is a schematic diagram of trip division of the sixth printing method provided by the sixth embodiment of the present disclosure. As shown in  FIG. 19  and  FIG. 20 , when performing printing, if printing resolution of the printhead itself cannot meet the resolution required for printing, a supplementary printing is required, and the method of the supplementary printing is: adding printing points between adjacent printing points on the same trip, which can be implemented in the X axis direction, that is, the scanning direction by controlling a movement speed of the printhead relative to the printing platform, and the printing resolution on the X axis is higher when the moving speed is slower, and vice versa; and in the Y-axis direction, that is, the stepping direction, it can be implemented by controlling a stepping distance of the printhead relative to the printing platform, so that the printing points of different trips are staggered. In this embodiment, in order to meet the resolution requirement of the object to be printed, a supplementary printing step may be implemented. At this time, the step of determining the number of multiple trips according to the layer printing data of the object to be printed may specifically include determining the number of the multiple trips according to the length of the printhead in the stepping direction, the length of the preset layer in the stepping direction, the resolution of the printhead and the resolution of the object to be printed. 
     Specifically, when determining the number of the multiple trips, the number of trips N can be obtained on the basis of the length of the printhead in the stepping direction, that is, the Y axis, the length D of the preset layer in the stepping direction, the resolution p of the printhead, and the resolution P of the object to be printed according to a first formula: N=(D/d)*(P/p), where D/d is rounded up to a next integer when D/d is not an integer; i.e., if D/d=1.2, then N=2*(P/p); or, the number of trips N′ is obtained according to a second formula: N′=[(D/d)*(P/p)]+(P/p)−1, where [(D/d)*(P/p)] represents rounding up (D/d)*(P/p) to a next integer; i.e., if (D/d)*(P/p)=4.8, then [(D/d)*(P/p)]=5. 
       FIG. 21 a    is a schematic diagram of a first trip provided by the sixth embodiment of the present disclosure.  FIG. 21 b    is a schematic diagram of a second trip provided by the sixth embodiment of the present disclosure.  FIG. 21 c    is a schematic diagram of a third trip provided by the sixth embodiment of the present disclosure. As shown in  FIG. 20 ,  FIG. 21 a   ,  FIG. 21 b    and  FIG. 21 c   , the printhead  31  prints the trip  311 , the printhead  32  prints the trip  321 , the printhead  33  prints the trip  331 , and the printhead  31 , the printhead  32  and the printhead  33  can be regarded as a same printhead on different trips. 
     Since this embodiment is a supplementary printing step, the number of trips required for the object to be printed on the preset layer is obtained according to the above parameters, and then the trip starting point and trip ending point of each trip are selected, respectively, to determine trip ranges of different trips.  FIG. 21 a   ,  FIG. 21 b    and  FIG. 21 c    respectively show the trip ranges of the printhead  31 , the printhead  32  and the printhead  33  in the trip  311 , trip  321  and trip  331 , respectively. 
     After determining the trip range of each trip, the trip data of the layer can be formed, and then the printing operation can be performed by the printhead according to the trip data. 
     In this embodiment, when performing one-way printing and supplementary printing, the printing method may specifically include the following steps: firstly, determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, where a trip starting point and/or the trip ending point of at least one trip matches a contour of the object to be printed in the trip; then performing layer printing for the preset layer according to the trips. In this way, when a single slice layer is printed, at least one of the trip starting point or the trip ending point of a printing trip matches the contour of the object to be printed in the trip, which can effectively reduce an overall length of the trip, and improve printing speed and printing efficiency. 
       FIG. 22  is a schematic diagram of printing status of a seventh printing method provided by a seventh embodiment of the present disclosure. As shown in  FIG. 22 , when performing two-way printing, the printing resolution can also be improved by supplementary printing. Specifically, since it is a two-way printing mode, the trip starting point and trip ending point of the trip will be affected by both the contour of the object to be printed and the ranges of adjacent trips; and the step of determining the number of multiple trips according to the layer printing data of the object to be printed may specifically include determining the number of the multiple trips according to the length of the printhead in the stepping direction, the length of the preset layer in the stepping direction, the resolution of the printhead and the resolution of the object to be printed. 
     Specifically, when determining the number of the multiple trips, the number of the trips N can be obtained on the basis of the length d of the printhead in the stepping direction, that is, the Y axis, the length D of the preset layer in the stepping direction, the resolution p of the printhead, and the resolution P of the object to-be-printed according to the formula N=(D/d)*(P/p). 
       FIG. 23 a    is a schematic diagram of a second trip provided by the seventh embodiment of the present disclosure.  FIG. 23 b    is a schematic diagram of a third trip provided by the seventh embodiment of the present disclosure. As shown in  FIG. 22 ,  FIG. 23 a   , and  FIG. 23 b   , the printhead  41  prints the first trip  411 , the printhead  42  prints the second trip  422 , the printhead  43  prints the third trip  432 , and the printhead  41 , the printhead  42 , and the printhead  43  can be regarded as a same printhead on different trips. 
     Since this embodiment is a supplementary printing step, the number of trips required for the object to be printed on the preset layer is obtained according to the above parameters, and then the trip starting point and trip ending point of each trip are selected to determine trip ranges of different trips. Here, the trip starting point of the trip is determined by the leading one of the contour of the object to be printed in the trip and the trip ending point of a previous trip of the trip in the scanning direction of the trip; and/or, the trip ending point of the trip is determined by the lagging one of the contour of the object to be printed in the trip and the trip starting point of a next trip of the trip in the scanning direction of the trip.  FIG. 23 a    and  FIG. 23 b    show the trip ranges of the printhead  41 , the printhead  42  and the printhead  43  in the trips  411 ,  422  and  432 , respectively. 
     The printing method in this embodiment may also be used as an example to further explain the concept and definition of the trip starting point and trip ending point of a trip.  FIG. 24  is a schematic diagram of a range of printing points in the seventh embodiment of the present disclosure. As shown in  FIG. 24 , since the valid printing points in a single slice layer are shown as small points in  FIG. 24  (invalid printing points are not shown in the figure), therefore, in each determined trip, it is possible to select the first printing point in the trip direction in each trip as the trip starting point, and the last printing point in the trip direction in each trip as the trip ending point. Referring to  FIG. 24 , the trip starting point of the printhead  42  in the trip  422  is the printing point  42   a  and the trip ending point of the printhead  42  in the trip  422  is the printing point  42   b ; the trip starting point of the print head  43  in the trip  432  is the printing point  43   a , and the trip ending point of the print head  43  in the trip  432  is the printing point  43   b . The above-mentioned valid printing point means that the printhead responds and performs printing operation at a corresponding position, and the invalid printing point means that the printhead does not perform printing operation at the corresponding position. 
     After determining the trip range of each trip, the trip data of the layer can be formed, and then the printing operation can be performed by the printhead according to the trip data. 
     In this embodiment, when performing two-way printing and supplementary printing, the printing method may specifically include the following steps: firstly, determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, where the trip starting point and/or the trip ending point of at least one trip matches a contour of the object to be printed in the trip; then performing layer printing for the preset layer according to the trips. In this way, when a single slice layer is printed, at least one of the trip starting point or the trip ending point of the printing trip matches the contour of the object to be printed in the trip, which can effectively reduce an overall length of the trip, and improve printing speed and printing efficiency. 
     As an optional embodiment, the number of trips N is obtained according to the first formula N=(D/d)*(P/p). The printing status is different from the sixth embodiment in that, in this optional embodiment, the length d of the printhead in the stepping direction completely enters the range of the length D of the preset layer in the first trip in the scanning direction, and the printhead moves a distance of d*(p/P) in the stepping direction in each subsequent trip. As shown in  FIG. 25 , taking p/P=1/4 as an example,  511  represents the position status of the printhead in the stepping direction in the first trip, and  512  represents the position status of the same printhead in the stepping direction in the second trip,  513  represents the position status of the printhead in the stepping direction in the third trip, and  514  represents the position status of the printhead in the stepping direction in the fourth trip. The method for determining the trip starting point and the trip ending point in each trip is the same as that in the sixth embodiment or the seventh embodiment, and will not be described again. 
     On the basis of the foregoing sixth embodiment or seventh embodiment, in the printing method of the present disclosure, the determination of the number of multiple trips required for the printhead to print the preset layer may further include: comparing the number of trips N and N′; when N&gt;N′, determining the number of trips of the current layer as N′, where the printing status of the printing method at this time is as shown in the schematic diagram of  FIG. 19 ; when N&lt;N′, determining the number of trips of the current layer as N, where the printing status of the printing method at this time is as shown in the schematic diagram of  FIG. 25 . When N=N′, the printing status of the printing method at this time may be as shown in the schematic diagram of  FIG. 19  or may be as shown in the schematic diagram of  FIG. 25 . 
     In addition, the present disclosure also provides a printing system capable of performing the printing methods in the foregoing first to seventh embodiments to perform the printing steps of a 3D object.  FIG. 26  is a schematic structural diagram of a printing system provided by an eighth embodiment of the present disclosure. As shown in  FIG. 26 , the printing system  10  provided by this embodiment includes a printhead  1 , a support platform  2  and a control unit  3 . The control unit  3  is electrically connected to the printhead Land the control unit  3  is configured to perform the printing method according to the foregoing first embodiment to seventh embodiments, to cause the printhead  1  to print an object to be printed on the support platform  2 . 
     Specifically, the control unit  3  may include components such as a processing terminal and a drive controller. The processing terminal can be used to process the object to be printed to form printing data for printing, and the drive controller controls the printhead  1  to print on the support platform  2  by an instruction issued by the processing terminal. The instruction issued by the processing terminal includes printing the object to be printed according to the method flow in the first to seventh embodiments. 
     Specifically, the layer printing data includes, and is not limited to, layer structure data and layer non-structure data, and the layer structure data includes, and is not limited to, information such as column structure data, grid structure data, and spiral structure data. 
     Further, the functions of the processing terminal and the drive controller may be implemented by hardware, software executed by a processor, or a combination of the two. Specifically, if implemented by a software module, a program can be pre-burned into the processor, or the software can be installed into a preset system; if implemented by hardware, the corresponding function can be fixed and implemented by using field programmable gate array (FPGA). 
     Further, the software module may be stored in a RAM memory, a flash memory, a ROM memory, an EPROM memory, a hard disk, or any other form of storage medium known in the art. By coupling the storage medium to a processor, the processor can read information from the storage medium and can write information to the storage medium. As a variation, the storage medium may be a component of the processor, or both the processor and the storage medium are located on an application specific integrated circuit (ASIC). 
     Further, the hardware may be a general-purpose processor capable of implementing specific functions, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, or a combination of these hardware. As a variation, it can also be implemented by a combination of computing devices, for example, a combination of a DSP and a microprocessor, a combination of multiple microprocessors, a combination of one or more microprocessors communicatively coupled with a DSP, and so on. 
     The printing system provided in this embodiment includes a printhead, a support platform, and a control unit. The control unit is electrically connected to the printhead, and the control unit is configured to perform the printing method to cause the printhead to print an object to be printed on the support platform, and the printing method may specifically include the following steps: firstly, determining, according to layer printing data of an object to be printed, a trip starting point and/or a trip ending point in a scanning direction for each trip of multiple trips required for a printhead to print a preset layer, where the trip starting point and/or the trip ending point of at least one trip matches a contour of the object to be printed in the trip; then performing layer printing for the preset layer according to the trips. In this way, when a single slice layer is printed, at least one of the trip starting point or the trip ending point of a printing trip matches the boundary of the object to be printed in the trip, which can effectively reduce an overall length of the trip, and improve printing speed and printing efficiency. 
     Those of skilled in the art could understand that all or part of the steps of the foregoing method embodiments may be completed by a program instructing relevant hardware. The aforementioned program may be stored in a computer-readable storage medium. When the program is executed, steps including the foregoing method embodiments are executed; and the foregoing storage medium includes various media that can store program code, such as a ROM, a RAM, a magnetic disk, or an optical disk. 
     Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than limiting it; although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand: they can still modify the technical solutions described in the foregoing embodiments, or equivalently replace some or all of the technical features; however, these modifications or substitutions do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the disclosure.