CN110625935A

CN110625935A - 3D printing method and 3D printing equipment

Info

Publication number: CN110625935A
Application number: CN201910889337.5A
Authority: CN
Inventors: 李佳
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-09-19
Filing date: 2019-09-19
Publication date: 2019-12-31

Abstract

The invention relates to the technical field of 3D printing, in particular to a 3D printing method and 3D printing equipment, which comprise the following steps: step S1, at least partial projection overlap is carried out between two digital micro-mirror assemblies which are installed adjacently to form a plurality of printing areas; step S2, generating each layer of graph to be printed based on the printing area formed among the digital micro-mirror assemblies, wherein the projection area in the graph to be printed of different layers is variable; and step S3, moving the light source and the plurality of digital micromirror devices synchronously along a direction to realize the layer-by-layer projection of the image. By using the 3D printing method provided by the invention, the projection overlapping areas among a plurality of digital micromirror components can be dispersed, so that stress concentration is avoided, and the mechanical property of a final product is improved.

Description

3D printing method and 3D printing equipment

[ technical field ] A method for producing a semiconductor device

The invention relates to the technical field of 3D printing, in particular to a 3D printing method and 3D printing equipment.

[ background of the invention ]

The biggest shortcoming of the current 3D printing is that the production speed is slow, so that expensive 3D printing equipment is bought back, and 3D printing products are expensive due to low yield and low cost. The present invention seeks to address this problem. The current popular 3D printing methods include the following: FDM (Fused Deposition Modeling), SLA (Stereo Light curing), SLS (printing selective Laser sintering), SLM (selective Laser Melting), liquid crystal projection, DLP (Digital Light Processing), each of which has great limitations.

In SLS, for example, a plastic powder or a metal powder coated with a binder (the binder is usually another metal with a low melting point) is irradiated by a laser spot light, and the surfaces of the powder are melted at a high temperature and are bonded to each other to form a dot-shaped solid. The motion of the laser point generates a linear solid, then a planar solid is generated by the linear solid, and finally a three-dimensional object is generated by a plurality of layers of planes, so that the 3D printing process is completed. If the printing material is metal powder, after printing is finished, the printing material needs to enter a sintering furnace for sintering, and then a product with satisfactory mechanical properties can be generated. In the sintering process, the size of the product shrinks, so that the size of the final product is not the designed size, and the final product is a point light source, so that the forming speed is slow, the processing time is long, and the preheating time is 2 hours before processing; after the part is constructed, it takes 5 to 10 hours to cool down before it can be removed from the powder jar, and in addition, there is an off-flavor during the sintering process. In the SLS process, a powder layer needs laser to be heated to a molten state, and peculiar smell gas can be volatilized from high polymer materials or powder particles during laser sintering.

Compared with SLS, DLP adopts a surface light source, so that the forming speed is high, the size of a final product appearing in SLS is not the original design size, the DLP is similar to liquid crystal projection, but the light generation is realized by the reflected light of a digital micro-mirror assembly. The light power can be made very large, the printing of photosensitive resin, plastic powder and metal powder can be realized, the printing speed is high, and the printing of one surface can be finished at one time. The disadvantages are as follows: the digital micromirror device is expensive, and the high power and high resolution digital micromirror device is very expensive. If a large product is to be printed, its resolution is still insufficient. The current solution to this problem in the industry is to splice a plurality of lower resolution digital micromirror devices into a long strip, and then to perform large-format printing by means of horizontal movement. However, this solution has a problem that at the joint of the digital micromirror assembly, due to the fact that the splicing cannot be aligned accurately, or due to different illuminance or other reasons, the mechanical properties of the 3D printed product at the joint are poor, and thus, it is difficult to implement large-format 3D printing in the prior art.

[ summary of the invention ]

In order to overcome the technical problem that the mechanical property of the current 3D printing product at the joint corresponding to the digital micromirror component is poor, the invention provides a novel 3D printing method and system thereof, and 3D printing equipment.

In order to solve the technical problems, the invention provides the following technical scheme: a 3D printing method comprising the steps of:

step S1, at least partial projection overlap is carried out between two digital micro-mirror assemblies which are installed adjacently to form a plurality of printing areas;

step S2, generating each layer of graph to be printed based on the printing area formed among the digital micro-mirror assemblies, wherein the projection area in the graph to be printed of different layers is variable; and

in step S3, the light source and the plurality of digital micromirror devices are moved synchronously along a direction to realize the layer-by-layer projection of the image.

Preferably, after step S1 and before step S2, performing calibration of the digital micromirror device further comprises:

step S40, after the digital micro-mirror assemblies are installed, one of the digital micro-mirror assemblies is selected to form a projection area by projection between two adjacent digital micro-mirror assemblies;

step S41, judging whether the position coordinates of the corresponding points in the selected printing area and the projection area are the same, if so, executing step S44, otherwise, executing step S42;

step S42, calculating the offset through the corresponding proportion or the functional relation;

step S43, after all the points in the printing area are subjected to offset processing based on the offset, the printing area corresponding to the two digital micromirror components and the overlapping area of the two printing areas are output; and

step S44, outputting a print area corresponding to the two digital micromirror devices and an overlapping area of the two print areas;

preferably, the step S42 may further include:

step S421, judging whether any pixel point M of the graph to be printed is in the overlapping area D, if so, executing step S422, and if not, executing step S423;

step S422, the pixel point M is randomly or according to a preset rule distributed to a projection area C1 or a projection area C2, and step S423 is executed;

step S423, determining whether the pixel point M is in the projection area C1, if so, performing step S424, and if not, performing step S426;

step S424, calculating the corresponding proportion by acquiring the positions of the corresponding points in the printing area and the projection area, and further acquiring the position of a new pixel point m; and performs step S425;

step S425, outputting a new pixel point M, and calculating to obtain the required offset based on the pixel point M and the new pixel point M; and

in step S426, a calibration operation is performed on the projection area C2 according to the relative position between the projection area C1 and the projection area C2, and an offset corresponding to the calibration operation is obtained.

In the above steps S425 and S426, the offset amount may include, but is not limited to, an offset distance, an offset angle, and the like.

Preferably, in the step S426, the calibration operation includes a calibration function established based on an offset angle and an offset distance between an edge of the projection area C1 and an edge of the projection area C2, and the calibration function is combined to obtain a new offset required by the pixel point m.

Preferably, in step S426, the calibration operation includes using any one or a combination of a perspective deformation calibration method, a pincushion distortion calibration method, a scale adjustment calibration method, a barrel distortion calibration method, a parallelogram distortion calibration method, or a translation and rotation calibration method.

Preferably, in step S2, the display of the corresponding overlapping area at the projection overlap between two adjacent digital micromirror devices is changed in any one of continuous variation, interval variation or random dispersion variation.

Preferably, in the step S3, the method further includes the steps of:

step S31, a dividing line is set in the overlapping area to divide the overlapping area into a plurality of sub-printing areas, and each of the plurality of digital micromirror assemblies is responsible for printing and imaging one sub-printing area; and

step S32, the digital micromirror devices perform layer-by-layer printing along a direction, and the separation position of the separation line changes during the layer-by-layer printing process, so that the size of the sub-printing areas changes layer-by-layer.

Preferably, the 3D printing apparatus includes one or more controllers and a storage device, wherein the storage device stores one or more programs, which when executed by the one or more controllers, cause the one or more controllers to implement the 3D printing method according to any one of the preceding claims.

Preferably, the 3D printing apparatus further includes a light source, a workbench and at least two digital micromirror components, wherein the workbench is used for forming and bearing an object to be printed, the digital micromirror components include the light source, and the digital micromirror components project light of the light source onto the workbench.

Preferably, the 3D printing apparatus further comprises a moving member connected to the digital micromirror assembly, and the moving member is connected to the digital micromirror assembly and drives the digital micromirror assembly to move or rotate.

Compared with the prior art, the 3D printing method and the 3D printing equipment provided by the invention have the following beneficial effects:

the invention provides a 3D printing method which comprises at least partial projection overlapping between two digital micro-mirror assemblies which are installed adjacently. To form a plurality of overlapping regions; generating each layer of to-be-printed graph based on an overlapping area formed among the digital micromirror components, wherein the projection area in the to-be-printed graph of different layers is variable; and synchronously moving the light source and the digital micro-mirror assemblies along a direction to realize the layer-by-layer image projection. The 3D printing method provided by the invention can disperse the projection overlapping area among a plurality of digital micromirror components, and the projection area in the to-be-printed graph of different layers is variable, so that stress concentration is avoided, the mechanical property of a final product is improved, the splicing of the overlapping area is realized, and further large-breadth printing is realized.

Further, after step S1 and before step S2, the present invention may further include calibrating a printing range between the two digital micromirror devices, and generating a new printing pixel position by determining any dot position of the pattern to be printed, distributing randomly or according to a preset rule, moving an offset, and calculating a function, so as to solve the problem of incomplete printing area caused by the inclination of the digital micromirror devices and obtain an effective printing area.

Furthermore, because each layer of to-be-printed graph in 3D printing is not limited to the same position, if damaged points exist on the digital micromirror component, the corresponding damaged points can be selectively avoided when each layer of to-be-printed graph is specifically generated, so that the irradiation times of the damaged points are reduced, the irradiation can be completed on a normal mirror surface as much as possible, and the product quality defect caused by the damage of individual pixels of the digital micromirror component can be avoided.

Further, in the invention, the adjacent digital micromirror components are arranged at intervals, and only partial projection overlapping of the digital micromirror components is required, so that the digital micromirror component can be applied to different use scenes.

Further, in the invention, due to the abnormal reason of the installation position or the optical path, the pattern projected by the digital micromirror component is distorted, and the position point parameters of all the pixel points are correctly output through the calibration operation, wherein the calibration operation comprises the step of adopting any one or the combination of a perspective deformation calibration method, a pincushion distortion calibration method, a proportion adjustment calibration method, a barrel distortion calibration method, a parallelogram distortion calibration method or a translation rotation calibration method, and the correct position parameters of all the pixel points in the pattern to be printed are calibrated through various calibration operations, so that the distortion of the pattern projected by the digital micromirror component due to the abnormal reason of the installation position or the optical path is avoided, and the integrity and the correctness of the printed pattern are further improved.

In the present invention, in step S2, the display of the corresponding overlapping area at the projection overlap between two adjacent mounted digital micromirror devices is changed in any one of continuous variation, interval variation or random dispersion variation. Based on the change mode, the dispersion degree of the projection overlapping area among the digital micromirror components is better, so that stress concentration is avoided, and the mechanical property of a final product is improved.

In the present invention, in step S3, a plurality of printing regions may be partitioned by providing a partition line, and in the layer-by-layer printing process, the size of the plurality of printing regions may be changed layer by changing the position of the partition line. Based on the arrangement of the separation lines, corresponding adjustment can be obtained for corresponding overlapping areas of a plurality of digital micromirror assemblies, so that the 3D printing accuracy is improved.

The invention also provides 3D printing equipment which has the same beneficial effect as the 3D printing method, and by adopting the 3D printing equipment, the projection overlapping areas among a plurality of digital micromirror components can be dispersed, so that stress concentration is avoided, and the mechanical property of a final product is improved. Furthermore, the light of the light source is projected to the workbench through the digital micromirror components, large-format printing and rapid forming printing of the surface light source are achieved, the size of a product cannot shrink or deform, and peculiar smell cannot be generated in the printing process. Furthermore, because each layer of to-be-printed graph is not limited to the same position in the 3D printing process, if damaged points exist on the digital micromirror component, the corresponding damaged points can be selectively avoided when each layer of to-be-printed graph is specifically generated, so that the irradiation times of the damaged points are reduced, the irradiation can be completed on a normal mirror surface as much as possible, and the product quality defect caused by the damage of individual pixels in the digital micromirror component can be avoided.

Further, the 3D printing equipment further comprises a moving part connected with the digital micromirror component, the moving part is connected with the digital micromirror component and drives the digital micromirror component to move or rotate, so that the digital micromirror component can be adjusted based on different objects to be printed, and the optimal 3D printing effect can be obtained.

[ description of the drawings ]

FIG. 1 is a schematic flow chart of a 3D printing method according to a first embodiment of the invention;

FIG. 2 is a schematic plan view of the overlapping of the partial projections of two adjacent digital micromirror assemblies according to the present invention;

FIG. 3 is a schematic diagram of the overlapping area A divided into multiple rows of display areas for one embodiment of two of the DMDs shown in FIG. 2 mounted adjacent to each other;

FIG. 4 is a schematic view of the division lines in the overlapping region formed by two adjacent digital micromirror assemblies shown in FIG. 3;

fig. 5 is a detailed flowchart illustrating step S3 in the 3D printing method shown in fig. 1;

FIG. 6 is a schematic plan view of the two adjacently mounted digital micromirror assemblies shown in FIG. 4 tilted when mounted therebetween;

FIG. 7 is a schematic plan view of the tilt between two adjacently mounted digital micromirror assemblies according to the present invention;

FIG. 8 is a flow chart illustrating a calibration process between two adjacently mounted digital micromirror devices according to the present invention;

fig. 9 is a detailed flowchart of step S42 in the calibration process shown in fig. 8;

FIG. 10 is a schematic plan view of the tilt between two adjacently mounted digital micromirror assemblies according to the present invention;

FIG. 11 is a schematic plan view of another digital micromirror device according to the present invention;

FIG. 12 is a schematic view of the digital micromirror device of FIG. 1 aligned in a linear direction to form a printhead moving in a certain direction;

fig. 13 is a detailed flowchart illustrating step S2 in the 3D printing method shown in fig. 1;

fig. 14 is a schematic configuration diagram of a 3D printing apparatus according to a second embodiment of the present invention;

FIG. 15 is a schematic diagram of two adjacent digital micromirror devices forming an overlapping region or a non-overlapping region therebetween;

FIG. 16 is a schematic illustration of the separation of the first print area from the second print area when the separation line shown in FIG. 15 is disposed at the first position of the overlap area;

fig. 17 is a schematic diagram illustrating the separation of the first print area from the second print area when the separation line shown in fig. 15 is disposed at the second position of the overlap area.

The attached drawings indicate the following:

10. a 3D printing device; 11. a light source; 12. a work table; 13. a digital micromirror assembly; 14. a moving member; 19. a separation line; 21. a first printing area; 22. a second printing area; 100. a digital micromirror assembly; 109. printing an object; 111. a separation line; 800. a print head; 900. a working surface.

[ detailed description ] embodiments

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1, a first embodiment of the present invention provides a 3D printing method S10, the 3D printing method S10 is performed based on a 3D printing apparatus, the 3D printing method is projected in the form of a surface light source by a digital micromirror device, and the 3D printing method includes the following steps:

in step S1, light emitted from the light source passes through at least two Digital Micromirror Devices (DMDs) mounted adjacent to each other to form a plurality of printing areas, wherein the plurality of printing areas at least partially overlap to form a plurality of overlapping areas.

Step S2, generating each layer of graphics to be printed based on the printing area formed among the digital micro-mirror assemblies, wherein the overlapping area in the graphics to be printed of different layers is variable; and

Specifically, in step S1, as shown in fig. 2, a plurality of the digital micromirror assemblies 100 partially overlap in projection along the first direction (X direction), wherein a region is an overlapping region a between two adjacent digital micromirror assemblies, and a region B is a non-overlapping region B. Specifically, the adjacent digital micromirror devices 100 are spaced apart from each other, so long as at least a portion of the projection overlap between the digital micromirror devices 100 is satisfied.

The 3D printing method provided in the present embodiment may be applicable to an apparatus that performs 3D printing using laser, electron beam, or the like.

In step S2, the overlapping areas in the to-be-printed patterns of different layers may be adjusted when the printing areas corresponding to different digital micromirror devices are divided, so that the corresponding overlapping areas in the to-be-printed patterns of different layers do not overlap, thereby avoiding the problem of stress concentration of the 3D printed object and improving the stability of the 3D printed object.

In the present invention, the dmd 100 is an optical reflection surface consisting of millions of tiny mirror assemblies, and the tiny mirrors operate continuously at high speed when displaying images.

Referring to fig. 3, in the step S2, assuming that the projection overlapping area between two adjacent digital micromirror devices 100 is denoted as an overlapping area a, for convenience of description, the display area of the overlapping area a may be divided into 100 rows, and when generating the to-be-printed pattern for each layer, that is, performing the slicing process, the specific steps are as follows:

a first layer: component 1 shows line 1 of the overlap region, and component 2 shows lines 2 through 100 of the overlap region;

a second layer: component 1 shows rows 1 to 2 of the overlap region, and component 2 shows rows 3 to 100 of the overlap region;

and a third layer: component 1 shows rows 1 to 3 of the overlap region, and component 2 shows rows 4 to 100 of the overlap region;

and the rest of the sliced layers are subjected to overlapping display processing by analogy.

It will be appreciated that the display of the overlapping area need not necessarily be done in the continuously varying manner described above, but may also be varied at intervals, or randomly, in order to meet the characteristics of different objects to be printed. Through multiple variation mode, can be with the projection overlap region decentralization between the different sliced layer, the setting is in order to avoid overlap region all in same position between the multilayer like this, and leads to stress concentration's problem to can make the mechanical properties of final product improve.

In other embodiments of the present invention, as shown in fig. 3 and 4, the overlapping area includes N rows of pixels, two adjacent digital micromirror devices 100 are divided into two digital micromirror devices 100 according to the front and back directions of the arrangement direction, and the two digital micromirror devices 100 can be distinguished by a separation line 111.

Specifically, in the present invention, the following linear division is taken as an example, and the rule of the position change of the redistribution lines 111 is as follows:

rule 1:

printing a first layer: the separation line is positioned between the nth row and the (N + 1) th row, wherein one digital micro-mirror assembly 100 prints the 1 st row to the nth row, N is an integer which is more than or equal to 1 and less than N, and the other digital micro-mirror assembly 100 prints the rest rows of pixels;

printing the second layer: the separation line increases/decreases one row of pixels at the position when the first layer is printed, wherein one digital micromirror assembly 100 prints the 1 st row to the N +/-1 st row, N is an integer which is more than or equal to 1 and less than N, the other digital micromirror assembly 100 prints the rest rows of pixels, and so on, the number of printing rows of the next layer of each digital micromirror assembly 100 is added or subtracted by 1 row on the basis of the number of printing rows of the previous layer, and the printing of all the layers is completed in the continuous change mode;

rule 2:

printing the second layer: increasing/decreasing a rows of pixels on the position of the separation line when printing the first layer, wherein one digital micromirror assembly 100 prints 1 st row to N +/-a th row, N is an integer which is more than or equal to 1 and less than N, a is an integer which is more than or equal to 2, N +/-a is less than or equal to N, the other digital micromirror assembly 100 prints the rest rows of pixels, and so on, the number of printing rows of the next layer of each digital micromirror assembly 100 is added or subtracted with a rows on the basis of the number of printing rows of the previous layer, and the printing of all the layers is completed in a mode of changing the interval;

rule 3:

printing a first layer: the separation line is positioned between the nth row and the (N + 1) th row, wherein one digital micro-mirror assembly 100 prints the 1 st to nth rows, N is an integer which is more than or equal to 1 and less than or equal to N, and the other digital micro-mirror assembly 100 prints the rest rows of pixels;

printing the second layer: the separation line is located between the x-th row and the x + 1-th row, wherein one digital micromirror device 100 prints the 1 st row to the x-th row, x is any integer greater than or equal to 1 and less than N, x can be equal to N and less than or equal to N, and the other digital micromirror device 100 prints the remaining rows of pixels; and by analogy, the position of the separation line of the pixel of the previous layer of printing line does not influence the position of the separation line of the next layer of printing, and the printing of all layers is completed in the random variation mode.

Specifically, as shown in fig. 5, in order to obtain a better layer-by-layer projection picture, the step S3 can be further subdivided into the following steps:

By providing the separation lines in the above steps S31 and S32, there is no instability of the slicing operation due to the overlapping portion between the digital micromirror devices in the adjacent portions during the printing of each layer, and no adjustment of the digital micromirror devices is required. In addition, with the above method, since the selected separation lines between different layers are different, the influence caused by the damage of the mirror surface can be minimized, for example, a dead pixel occurs in the digital micromirror assembly, if the prior art is adopted, the irradiation needs to be repeated for 100 times, but after the 3D printing method provided by the present invention is adopted, the irradiation of the dead pixel only once can be avoided, and the irradiation of the normal mirror surface can be completed for the remaining 99 times, so that the product quality defect caused by the damage of individual pixels of the digital micromirror assembly can be avoided, optionally, in some specific embodiments, if the overlapping area reaches 50%, the printing quality defect caused by the dead pixel can be almost completely avoided.

In some embodiments of the present invention, since the arrangement between the plurality of digital micromirror assemblies 100 is not absolutely possible vertically and horizontally, nor is edge alignment possible, it is highly likely that either or both of two adjacently mounted digital micromirror assemblies 100 are tilted and not aligned, as shown in fig. 6.

For the digital micromirror components which are adjacently installed, the two digital micromirror components are not in a parallel state due to inevitable problems of processes, installation errors and the like, and can be corrected on a slicing system, so that the final rectangular projection area is longitudinally overlapped. Since in actual operation, if the digital micromirror device 100 is tilted, the effect of the object obtained by the subsequent 3D printing will be affected.

In some embodiments of the present invention, a printing calibration method is provided, which includes a projection area C1 of component 1, a projection area C2 of component 2, a printing area C1 of component 1, a printing area C2 of component 2, and an overlapping area D formed by printing area C1 and printing area C2;

referring to fig. 7 and 8, the dotted line is a print area formed by the print area c1 and the print area c2, the shaded portion is an overlap area D formed by the overlap of the print area c1 and the print area c2, and the black frame portion is an effective print area in the overlap area, and the digital micromirror device calibration comprises the following steps:

step S44, outputting a print area corresponding to the two digital micromirror devices and an overlapping area of the two print areas; here, as shown in fig. 7, two printing areas corresponding to the digital micromirror assembly are denoted as a printing area c1, a printing area c2, and an overlapping area is denoted as an overlapping area D.

Step S42, calculating the offset through the corresponding point or the functional relation;

step S43, after all the points in the printing area are subjected to offset processing based on the offset, the printing area corresponding to the two digital micromirror components and the overlapping area of the two printing areas are output;

optionally, in some specific embodiments, in combination with the illustration in fig. 8, step S41 may specifically include the following:

selecting any corner x1 of a projection area and obtaining a coordinate value thereof, obtaining a coordinate value of a corner x2 of a printing area corresponding to the corner, judging whether the coordinate values of the corner x1 and the corner x2 are the same, if so, performing step S44 without correction, and if not, performing step S42;

referring to fig. 7 and 9, further, in some embodiments, the step S42 may further include:

In some specific embodiments, the step S424 can be replaced by the step S424:

respectively corresponding the position parameters of a new pixel point M and a pixel point M through the position parameters of the corner point x2 and the corner point x1, and further obtaining the position (corresponding to the point proportion) of the pixel point M corresponding to the new pixel point M in the printing area c 1;

referring to fig. 7 and 10, optionally, in some specific embodiments, the calibration operation in the step S426 includes a calibration function established based on an offset angle and an offset distance between an edge e of the projection area C1 and an edge w of the projection area C2, where the edge e is a side of the rectangular area formed by the projection area C1 and close to the projection area C2, and the edge w is a side of the rectangular area formed by the projection area C2 and close to the projection area C1. The calibration function may be denoted as y-k x + b. Specifically, a dotted line Q is drawn in the projection area C2 through the slicing system, so that a left end point of the dotted line Q intersects with a side line e of the projection area C1, the dotted line Q is parallel to a side line w of the projection area C2, a distance between the dotted line Q and the side line w is an offset distance between the projection area C1 and the projection area C2, namely an intercept b, and an inclination angle, namely a slope k, is formed by the dotted line Q and the side line e of the projection area C1, at this time, a calibration function can be generated on the slicing system, and a new offset required by the pixel point m is obtained by combining the calibration function.

Optionally, in some specific embodiments, the dotted line Q may be: by translating the edge w within the projected area C2, the dashed line Q is obtained by intersecting the edge w with the edge e.

Referring to fig. 11, alternatively, in other embodiments, due to an abnormal installation position or light path, a parallelogram distortion may occur on a projection pattern of a digital micromirror assembly (not shown), and thus the calibration operation includes a calibration method of the parallelogram distortion, which may be further described as: the projection region C3 is shifted due to parallelogram distortion to form a projection region C4 of a virtual line portion, taking a pixel point n1 in the projection region C3 and a pixel point n2 in the projection region C4 as examples, the pixel point n1 in the projection region C3 undergoes parallelogram distortion to form a pixel point n2 in the projection region C4, and the pixel point b1 in the projection region C3 undergoes parallelogram distortion to form a pixel point b2 in the projection region C4.

Referring to fig. 11, the offset of the pixel point n2 from the pixel point n1 is greater than the offset of the pixel point b2 from the pixel point b1, the offset can be represented as a relative position change formed when one pixel point moves to another pixel point, an inclined sideline L is formed on the projection area C3, a vertical sideline V is formed on the projection area C4, an inclination angle J is formed between the sideline L and the sideline V, the offset and the position parameter of the pixel point n2 correspond to the inclination angle J in a functional relation, and the offset and the position parameter of the pixel point b2 correspond to the inclination angle J in a functional relation. Specifically, the parallelogram distortion calibration operation is: by forming a calibration function corresponding to the inclination angle J on the slicing system, acquiring a required offset from the pixel point n2 to the pixel point n1 and a required offset from the pixel point b2 to the pixel point b1 by combining the calibration function, and respectively and correspondingly outputting position parameters of the pixel point n1 and the pixel point b1 in the projection area C3 by the slicing system according to the position parameters and the offsets of the pixel point n2 and the pixel point b2 in the projection area C4.

Optionally, in other specific embodiments, the calibration operation may further include using any one or a combination of a perspective deformation calibration method, a pincushion distortion calibration method, a scale adjustment calibration method, a barrel distortion calibration method, or a translational-rotational calibration method.

Based on the offset distance and the tilt angle, according to a calibration function: y ═ k × x + b, the relative positions of the projected area C1 and the projected area C2 can be determined. Obviously, for the projection area C2, the slope k and the intercept b of one of the edges are determined, so that new positions of all the points in the projection area C2 after being shifted by a certain distance and a certain rotation angle can be obtained, and conversely, based on any point in the area to be printed, the positions of the pixel points actually corresponding to the projection area C2 can be reversely deduced;

combining the above steps, combining the projected area C1 and the projected area C2, and modifying to obtain the corresponding printed area C1 and the printed area C2 of the component 2, the obtained printed area C1 and the printed area C2 of the component 2 can spell out a larger printed area compared with the prior art.

Referring to fig. 12, after the calibration of the digital micromirror device is completed, the method for sequentially modifying the digital micromirror device 100 further includes: a plurality of digital micromirror assemblies are arranged in a same linear direction to form a print head.

The arranged print heads reciprocate on the operation surface in a direction perpendicular to the arrangement direction thereof. Referring to fig. 8, a plurality of dmd's 100 may be arranged in Y direction to form a print head 800 arranged in a same linear direction (Y direction shown in fig. 8), and the print head 800 may move back and forth on the working surface 900 of the resin tank in a direction perpendicular to the arrangement direction (X direction shown in fig. 8) from the print start point to the print end point along a same plane to complete the first layer slice printing.

As shown in fig. 12, after printing the first layer slice, the print head 800 may also return along the path of printing the first layer slice and print the second layer slice, ending printing the second layer slice when returning to the printing start point; the print head 800 may also print the second layer slice again along the path of the first layer slice after returning to the print start point along the path of the first layer slice.

In other embodiments of the present invention, in order to solve the problem of defective product quality caused by the damaged mirror surface of the dmd 100, as shown in fig. 13, the step S2 may further include:

step S21, generating each layer of graphics to be printed based on the printing area formed among the digital micro-mirror assemblies; and

step S22, analyzing layer by layer whether the graph to be printed contains a dead pixel area, if so, updating the layer of graph to be printed to remove the dead pixel area; if not, directly outputting the layer of the pattern to be printed.

Based on the above steps, the influence of the damage of the mirror surface of the digital micromirror assembly 100 can be minimized.

It can be seen that, based on the 3D printing method provided in the first embodiment, the projection overlapping regions between the digital micromirror devices can be dispersed, so as to avoid stress concentration and improve the mechanical properties of the final product. Furthermore, because each layer of slices is not limited to the same position in 3D printing, if damaged points exist on the digital micromirror component, corresponding damaged points can be selectively avoided when each layer of patterns to be printed is specifically generated, so that the irradiation times of the damaged points are reduced, the irradiation can be completed on a normal mirror surface as much as possible, and the product quality defect caused by the damage of individual pixels of the digital micromirror component can be avoided.

Referring to fig. 14, a second embodiment of the present invention provides a 3D printing apparatus 10, where the 3D printing apparatus 10 includes one or more controllers 101 and a storage device 102, where the storage device 102 stores one or more programs, and when the one or more programs are executed by the one or more controllers 101, the one or more controllers 101 implement the 3D printing method as described in the first embodiment.

As shown in fig. 14, the 3D printing apparatus 10 further includes a light source 11, a workbench 12, at least two digital micromirror devices 13, and a moving member 14 connected to the digital micromirror devices 13, wherein the workbench 12 is used for forming and supporting an object 109 to be printed, the digital micromirror devices 13 include the light source 11, and the digital micromirror devices 13 project light of the light source 11 onto the workbench 12. The light source 11 includes any one or a combination of ultraviolet laser beam, digital light, light source ultraviolet light or electron beam.

The moving member 14 is connected to the digital micromirror device 13 and drives the digital micromirror device 13 to move or rotate. Each of the digital micromirror devices 13 can be independently connected to the moving member 14, so that the tilt angle and the relative position (e.g. up-down, left-right, etc.) of each of the digital micromirror devices 13 can be precisely adjusted.

Referring to fig. 15, 16 and 17, the printing area between two adjacent digital micromirror devices 13 is represented as an overlapping area a, and the non-overlapping area is represented as an area B. The projection areas of any two adjacent digital micromirror components 13 have an overlapping area A and non-overlapping areas B positioned at two sides of the overlapping area, and the overlapping area A and the non-overlapping areas B form the printing area;

as shown in fig. 16 and 17, a separation line 19 is provided in the overlapping area a to separate the printing area into a first printing area 21 and a second printing area 22, and two adjacent digital micromirror assemblies 13 are respectively responsible for printing and imaging of the first printing area 21 and the second printing area 22; the digital micro-mirror assemblies 13 perform layer-by-layer printing along a direction perpendicular to the arrangement direction, and the separation position of the separation line 19 changes during the layer-by-layer printing process, so that the area size of the first printing area 21 and the second printing area 22 changes layer by layer.

As shown in particular in fig. 16, when the separation line 19 is in the first position, the area of the first printing region 21 is smaller than the area of the second printing region 22; as shown in fig. 13, when the separation line 19 is in the second position, then the area of the first print region 21 is larger than the area of the second print region 22.

Further, in order to solve the problem of product quality defect caused by the damaged mirror surface of the dmd 100, in the embodiment, the dmd further includes a graphics processing unit (not shown), and the graphics processing unit may obtain that after the controller generates each layer of graphics to be printed based on the overlapping area formed between the plurality of dmms, the controller analyzes layer by layer whether the graphics to be printed includes a dead pixel area, and if so, updates the layer of graphics to be printed to remove the dead pixel area; if not, directly outputting the layer of the pattern to be printed.

the invention provides a 3D printing method which comprises at least partial projection overlapping between two digital micro-mirror assemblies which are installed adjacently. To form a plurality of overlapping regions; generating each layer of to-be-printed graph based on an overlapping area formed among the digital micromirror components, wherein the projection area in the to-be-printed graph of different layers is variable; and synchronously moving the light source and the digital micro-mirror assemblies along a direction to realize the layer-by-layer image projection. The 3D printing method provided by the invention can disperse the projection overlapping area among a plurality of digital micromirror components, and the projection area in the to-be-printed graph of different layers is variable, so that stress concentration is avoided, the mechanical property of a final product is improved, the splicing of the overlapping area is realized, and further large-format rapid printing is realized.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit of the present invention are intended to be included within the scope of the present invention.

Claims

1. A3D printing method is characterized in that: the 3D printing method comprises the following steps:

2. The 3D printing method as defined in claim 1 wherein: after step S1 and before step S2, performing calibration of the digital micromirror device, further comprising:

in step S44, a print area corresponding to two digital micromirror devices and an overlap area of the two print areas are output.

3. The 3D printing method as claimed in claim 2, wherein: the step S42 further includes:

4. The 3D printing method as defined in claim 3, wherein: in the step S426, the calibration operation includes a calibration function established based on the offset angle and the offset distance between the edge of the projection area C1 and the edge of the projection area C2, and the calibration function is combined to obtain the offset required by the new pixel point m.

5. The 3D printing method as defined in claim 3, wherein: in step S426, the calibration operation includes using any one or a combination of a perspective deformation calibration method, a pincushion distortion calibration method, a scale adjustment calibration method, a barrel distortion calibration method, a parallelogram distortion calibration method, or a translation and rotation calibration method.

6. The 3D printing method as defined in claim 1 wherein: in the above step S2, the display of the corresponding overlapping area at the projection overlap between two adjacent mounted digital micromirror devices is changed in any one of continuous variation, interval variation or random dispersion variation.

7. The 3D printing method as defined in claim 1 wherein: in the step S3, the method further includes the steps of:

8. The utility model provides a 3D printing apparatus which characterized in that: the 3D printing apparatus includes one or more controllers and a storage device, wherein the storage device stores one or more programs that, when executed by the one or more controllers, cause the one or more controllers to implement the 3D printing method of any one of claims 1 to 7.

9. The 3D printing device as defined in claim 8 wherein: the 3D printing equipment further comprises a light source, a workbench and at least two digital micromirror components, wherein the workbench is used for forming and bearing an object to be printed, the digital micromirror components comprise the light source, and the digital micromirror components project light of the light source onto the workbench.

10. The 3D printing device as defined in claim 9 wherein: the 3D printing equipment further comprises a moving part connected with the digital micromirror component, and the moving part is connected with the digital micromirror component and drives the digital micromirror component to move or rotate.