阅读说明：本技术 喷墨宽度调整方法以及立体打印设备 (Ink jet width adjusting method and three-dimensional printing equipment ) 是由 施可葳 谢欣达 黄郁庭 袁国砚 于 2018-07-09 设计创作，主要内容包括：本发明提出一种喷墨宽度调整方法以及立体打印设备。所述喷墨宽度调整方法包括：获取立体数字模型,对立体数字模型进行切层处理而产生切层物件,其中切层物件具有截面轮廓；自立体数字模型获取截面轮廓所对应的表面倾斜程度,并依据截面轮廓所对应的表面倾斜程度计算切层物件的理想喷墨宽度；以及在控制打印模块打印该切层物件之后,依据理想喷墨宽度而控制喷墨模块朝该切层物件且沿截面轮廓进行喷墨。(The invention provides an ink jet width adjusting method and a three-dimensional printing device. The ink jet width adjusting method includes: obtaining a three-dimensional digital model, and performing layer cutting processing on the three-dimensional digital model to generate a layer cutting object, wherein the layer cutting object has a cross-sectional profile; obtaining the surface inclination degree corresponding to the cross section outline by a digital model of the independent body, and calculating the ideal ink jet width of the layer cutting object according to the surface inclination degree corresponding to the cross section outline; and after controlling the printing module to print the layer cutting object, controlling the ink jet module to jet ink towards the layer cutting object and along the cross section contour according to the ideal ink jet width.)

1. An ink-jet width adjusting method is suitable for printing a color three-dimensional object, and is characterized by comprising the following steps:

the method comprises the steps of obtaining a three-dimensional digital model, and carrying out layer cutting processing on the three-dimensional digital model to generate a layer cutting object, wherein the layer cutting object has a cross-sectional profile;

acquiring the surface inclination degree corresponding to the cross section outline from the three-dimensional digital model, and calculating the ideal ink jet width of the layer cutting object according to the surface inclination degree corresponding to the cross section outline; and

and after the printing module is controlled to print the layer cutting object, controlling an ink jetting module to jet ink towards the layer cutting object and along the section outline according to the ideal ink jetting width.

2. The inkjet width adjustment method according to claim 1, wherein the step of obtaining the surface inclination degree corresponding to the cross-sectional profile from the three-dimensional digital model and calculating the ideal inkjet width of the sliced layer object according to the surface inclination degree corresponding to the cross-sectional profile comprises:

obtaining at least one polygonal mesh unit corresponding to the section outline from the three-dimensional digital model;

calculating at least one included angle between the at least one polygonal grid unit and the horizontal plane to represent the surface inclination degree; and

and calculating the ideal ink jet width of the layer cutting object according to the at least one included angle, the layer cutting thickness and a preset ink jet width.

3. The method for adjusting inkjet width according to claim 2, wherein the step of calculating the ideal inkjet width of the slice object according to the at least one included angle, the slice thickness and the preset inkjet width comprises:

calculating the product of the cotangent value of the at least one included angle and the thickness of the cutting layer; and

taking the maximum value between the product and the preset ink jet width as the ideal ink jet width of the layer cutting object.

4. The inkjet width adjustment method of claim 2, wherein the at least one polygonal mesh unit comprises a first polygonal mesh unit and a second polygonal mesh unit, and the step of calculating the at least one angle between the at least one polygonal mesh unit and the horizontal plane comprises:

and calculating a first included angle between the first polygonal grid unit and the horizontal plane, and calculating a second included angle between the second polygonal grid unit and the horizontal plane.

5. The method of claim 4, wherein the step of calculating the ideal ink-jet width according to the at least one angle, the slice thickness and the preset ink-jet width comprises:

calculating a first ideal ink jet width in the ideal ink jet widths according to the first included angle, the thickness of the cutting layer and the preset ink jet width; and

and calculating a second ideal ink jet width in the ideal ink jet widths according to the second included angle, the thickness of the cutting layer and the preset ink jet width.

6. The inkjet width adjustment method of claim 1, the method further comprising:

and generating an ink jet image according to the ideal ink jet width and the section outline, wherein the ink jet image comprises an ink jet range formed based on the ideal ink jet width.

7. A stereoscopic printing apparatus adapted to print a stereoscopic object in color, comprising:

a printing module comprising a printhead;

an inkjet module including an inkjet head;

the storage device is recorded with a plurality of modules; and

a processing device coupled to the storage device and configured to execute the plurality of modules to:

the method comprises the steps of obtaining a three-dimensional digital model, and carrying out layer cutting processing on the three-dimensional digital model to generate a layer cutting object, wherein the layer cutting object has a cross-sectional profile; and

acquiring the surface inclination degree corresponding to the cross section outline from the three-dimensional digital model, and calculating the ideal ink jet width of the layer cutting object according to the surface inclination degree corresponding to the cross section outline; and

after controlling the printing module to print the layer cutting object, controlling the ink jetting module to jet ink towards the layer cutting object and along the cross section outline according to the ideal ink jetting width.

8. The stereoscopic printing apparatus of claim 7, wherein the processing device is configured to: obtaining at least one polygonal mesh unit corresponding to the section outline from the three-dimensional digital model; calculating at least one included angle between the at least one polygonal grid unit and the horizontal plane to represent the surface inclination degree; and calculating the ideal ink jet width of the layer cutting object according to the at least one included angle, the layer cutting thickness and a preset ink jet width.

9. The stereoscopic printing apparatus of claim 8, wherein the processing device is configured to: calculating the product of the cotangent value of the at least one included angle and the thickness of the cutting layer; and taking the maximum value between the product and the preset ink jet width as the ideal ink jet width of the layer cutting object.

10. The stereoscopic printing apparatus of claim 8, wherein the at least one polygon mesh cell comprises a first polygon mesh cell and a second polygon mesh cell, and the processing device is configured to: and calculating a first included angle between the first polygonal grid unit and the horizontal plane, and calculating a second included angle between the second polygonal grid unit and the horizontal plane.

11. The stereoscopic printing apparatus of claim 10, wherein the processing device is configured to: calculating a first ideal ink jet width in the ideal ink jet widths according to the first included angle, the thickness of the cutting layer and the preset ink jet width; and calculating a second ideal ink jet width in the ideal ink jet widths according to the second included angle, the cutting layer thickness and the preset ink jet width.

12. The stereoscopic printing apparatus of claim 7, wherein the processing device is configured to: and generating an ink jet image according to the ideal ink jet width and the section outline, wherein the ink jet image comprises an ink jet range formed based on the ideal ink jet width.

Technical Field

The present invention relates to an inkjet technique for three-dimensional printing, and more particularly, to an inkjet width adjustment method and a three-dimensional printing apparatus.

Background

With the advancement of Computer-Aided Manufacturing (CAM), the Manufacturing industry has developed stereoscopic printing technology to quickly make the original design. The three-dimensional printing technology is a general name of a series of Rapid Prototyping (RP) technologies, and the basic principle thereof is to manufacture a plurality of layers of cut-layer objects in a stacked manner on a printing platform by a Rapid Prototyping machine, wherein the cut-layer objects are sequentially printed on the printing platform in a scanning manner in a horizontal plane, so that the cut-layer objects can be stacked to form a three-dimensional printed object. Taking Fused Deposition Modeling (FDM) technology as an example, a molding material is made into a wire, and the molding material is heated and fused and then stacked layer by layer on a molding platform according to a required shape/contour to form a three-dimensional object.

In response to the requirement of color three-dimensional printing, the current three-dimensional printing technology further includes performing an inkjet operation on the three-dimensional printed object under printing. That is, when the stereoscopic printing apparatus prints the cut-layer objects, the stereoscopic printing apparatus may simultaneously perform ink-jetting for each layer of the cut-layer object, thereby manufacturing a colored stereoscopic object. In a color three-dimensional printing technology, a three-dimensional printing device performs ink-jet operation on the outline edge part of each layer-cutting object according to the same preset ink-jet width, so that the surface of the three-dimensional object stacked by the layer-cutting objects presents color. However, the size of the ink-jetting range on the cut-layer object will affect the adhesion between the cut-layer objects and the color development effect.

For example, when the distance between the cross-sectional edges of two vertically adjacent layered objects is greater than the preset ink-jet width, the surface of the three-dimensional object will present uncolored blocks, thereby affecting the printing quality of the color three-dimensional printing. Fig. 1 shows an example of ink-jetting an object to be cut according to a predetermined ink-jetting width. As shown in fig. 1, when the distance D1 between the cross-sectional edge of the upper layered object L1 and the cross-sectional edge of the lower layered object L2 is greater than the preset ink jetting width Wd1, the portion of the layered object L2 exposed on the surface of the three-dimensional object will have uncolored blocks B1. In particular, when the inclination of the surface of the three-dimensional object is relatively flat, the phenomenon shown in fig. 1 is more remarkable. Therefore, how to design a better color three-dimensional printing method becomes one of the issues that the related technical personnel need to think about.

Disclosure of Invention

The invention provides an ink jet width adjusting method and a three-dimensional printing device, which can determine an ideal ink jet width according to the surface inclination degree corresponding to a layer cutting object, so that the three-dimensional printing device can accurately color and jet ink on the three-dimensional printing object.

The embodiment of the invention provides an ink jet width adjusting method which is suitable for manufacturing a color three-dimensional object. The ink jet width adjusting method includes: obtaining a three-dimensional digital model, and performing layer cutting processing on the three-dimensional digital model to generate a layer cutting object, wherein the layer cutting object has a cross-sectional profile; obtaining the surface inclination degree corresponding to the cross section outline by a digital model of the independent body, and calculating the ideal ink jet width of the layer cutting object according to the surface inclination degree corresponding to the cross section outline; and after controlling the printing module to print the layer cutting object, controlling the ink jet module to jet ink towards the layer cutting object and along the cross section contour according to the ideal ink jet width.

In an embodiment of the present invention, the step of obtaining the degree of surface inclination corresponding to the cross-sectional profile from the stereo digital model, and calculating the ideal ink ejection width according to the degree of surface inclination corresponding to the cross-sectional profile includes: obtaining at least one polygonal mesh unit corresponding to the cross section outline by a digital model of the independent body; calculating at least one included angle between at least one polygonal grid unit and the horizontal plane to represent the surface inclination degree; and calculating the ideal ink jet width of the layer cutting object according to the at least one included angle, the layer cutting thickness and the preset ink jet width.

In an embodiment of the present invention, the step of calculating the ideal ink ejection width according to at least one of the included angle, the thickness of the slice layer, and the preset ink ejection width includes: calculating the product of the cotangent value of at least one included angle and the thickness of the cutting layer; and taking the maximum value between the product and the preset ink jet width as the ideal ink jet width of the layer cutting object.

In an embodiment of the present invention, the at least one polygon mesh unit includes a first polygon mesh unit and a second polygon mesh unit, and the step of calculating at least one included angle between the at least one polygon mesh unit and the horizontal plane includes: and calculating a first included angle between the first polygonal grid unit and the horizontal plane, and calculating a second included angle between the second polygonal grid unit and the horizontal plane.

In an embodiment of the present invention, the step of calculating the ideal ink ejection width according to at least one of the included angle, the thickness of the slice layer, and the preset ink ejection width includes: calculating a first ideal ink jet width in the ideal ink jet widths according to the first included angle, the thickness of the cutting layer and the preset ink jet width; and calculating a second ideal ink jet width in the ideal ink jet width according to the second included angle, the thickness of the cutting layer and the preset ink jet width.

In an embodiment of the present invention, the method further includes: and generating an ink jet image according to the ideal ink jet width and the cross section outline, wherein the ink jet image comprises an ink jet range formed based on the ideal ink jet width.

From another perspective, an embodiment of the present invention provides a stereoscopic printing apparatus suitable for manufacturing a stereoscopic color object, which includes a printing module, an inkjet module, a storage device, and a processing device. The print module includes a printhead and the inkjet module includes an inkjet head. The storage device records a plurality of modules, and the processing device is coupled to the storage device and configured to execute the modules to: obtaining a three-dimensional digital model, and performing layer cutting processing on the three-dimensional digital model to generate a layer cutting object, wherein the layer cutting object has a cross-sectional profile; obtaining the surface inclination degree corresponding to the cross section outline by a digital model of the independent body, and calculating the ideal ink jet width of the layer cutting object according to the surface inclination degree corresponding to the cross section outline; and after controlling the printing module to print the layer cutting object, controlling the ink jet module to jet ink towards the layer cutting object and along the cross section contour according to the ideal ink jet width.

Based on the above, the inkjet width adjusting method and the three-dimensional printing apparatus of the embodiments of the invention can adaptively adjust the ideal inkjet width according to the surface inclination degree corresponding to the upper layer cutting object of the three-dimensional object. Therefore, after the printing head prints the layer cutting object, the three-dimensional printing equipment can control the ink jet module to jet ink towards the layer cutting object and along the cross section contour according to the ideal ink jet width. Therefore, even if the surface inclination degree of the three-dimensional object is quite gentle or the interval between the edges of the upper and lower adjacent layer cutting objects is overlarge, the part exposed on the surface of the three-dimensional object can be accurately colored, and the printing quality of color three-dimensional printing is greatly improved.

In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

Fig. 1 shows an example of ink-jetting an object to be cut according to a predetermined ink-jetting width.

Fig. 2 is a block diagram of a stereoscopic printing apparatus according to an embodiment of the present invention.

Fig. 3 is a schematic view of a stereoscopic printing apparatus according to the embodiment of fig. 2.

FIG. 4 is a flowchart illustrating an ink jet width adjusting method according to an embodiment of the invention.

FIG. 5 is a schematic diagram of determining an ideal ink ejection width according to an embodiment of the invention.

FIG. 6 is a schematic view of an inkjet image according to an embodiment of the present invention.

Fig. 7A is a schematic view of a three-dimensional digital model and a layer-cutting object according to an embodiment of the invention.

Fig. 7B is a schematic diagram of calculating an angle between a polygon mesh unit and a horizontal plane according to an embodiment of the present invention.

Fig. 8 shows an example of the ink jetting range of the layer cutting object 72(3) of the embodiment shown in fig. 7A.

FIG. 9 is a flowchart illustrating an inkjet width adjustment method according to an embodiment of the invention.

FIG. 10 is a schematic diagram of an exemplary method for obtaining a desired ink ejection width according to an embodiment of the invention.

[ notation ] to show

L1, L2, 80a, 80c, 52(1), 52(2), 52(k), 52(n-1), 52(n), 72(1), 72(2), 72(3), 72(4), 72(5), 72 (6): layer cutting article

B1: uncolored block

20: three-dimensional printing equipment

210: printing module

220: ink jet module

230: storage device

240: processing apparatus

210 a: printing head

220 a: ink jet head

220 b: ink cartridge

S1: bearing surface

80: three-dimensional object

F1: molding material

I1: ink for ink jet recording

S401 to S403, S901 to S907: step (ii) of

51. 71, 1001: stereo digital model

T1, T2, T3, T4, T5, T6: degree of surface inclination

C1, C2, C3: cross-sectional profile

Img1, Img 2: ink jet image

M1, M2, M3, M4, M5: triangular mesh unit

V1, V2, V3, V4, V5: endpoint

V7, V8: intersection point

V9: drop foot point

LA, LB: vertical line

HP: horizontal plane

81. 1002, 1003: ink jet range

Detailed Description

In order that the present disclosure may be more readily understood, the following specific examples are given as illustrative of the invention which may be practiced in various ways. Further, wherever possible, the same reference numbers will be used throughout the drawings and the description to refer to the same or like parts.

Fig. 2 shows a schematic diagram of a stereoscopic printing apparatus according to an embodiment of the present invention. Referring to fig. 2, the stereoscopic printing apparatus 20 includes a printing module 210, an inkjet module 220, a storage device 230, and a processing device 240. The processing device 240 is coupled to the printing module 210, the inkjet module 220, and the storage device 230. In the present embodiment, the processing device 240 is used for controlling the printing module 210 and the inkjet module 220 to perform a stereoscopic printing operation.

In the present embodiment, the storage device 230 may be used for storing data, and may be a buffer memory, an internal storage medium, an external storage medium, other types of storage devices, or a combination thereof. For example, the buffer memory may include random access memory, read only memory, or other similar devices. For example, the internal storage medium may include a hard Disk (HDD), a Solid State Disk (Solid State Disk), a flash (flash) storage device, or the like. For example, the external storage medium may include an external hard disk, a USB drive (USB drive), a cloud hard disk, or other similar devices. In an embodiment, the storage device 230 may further be configured to store a plurality of modules, which may be software programs, so that the processing device 240 can read or execute the modules to implement the inkjet width adjusting method according to the embodiments of the present invention.

In the embodiment, the Processing Device 240 may include a Processing chip, an image Processing chip, or a Central Processing Unit (CPU), or other Programmable general purpose or special purpose microprocessor (microprocessor), a Digital Signal Processor (DSP), a Programmable controller, an Application Specific Integrated Circuit (ASIC), a Programmable Logic Device (PLD), other similar Processing Circuits, or a combination thereof.

In the present embodiment, the processing device 240 may control the printing module 210 and the inkjet module 220 to perform the stereoscopic printing operation and the inkjet operation based on the stereoscopic digital model. For example, the three-dimensional printing operation includes feeding out the molding material on the molding platform, and the inkjet module 220 may perform the inkjet operation on the cured or curing molding material on the molding platform. In addition, those skilled in the art should understand that the stereo printing apparatus 20 may further include other components (e.g., a platform, a feeding line, an ink jetting line, a print head linkage mechanism, a driving motor, etc.) for performing the stereo printing operation and the ink jetting operation together with the printing module 210 and the ink jetting module 220.

It should be noted that, in an embodiment, the stereoscopic printing apparatus 20 may include a computer host and a stereoscopic printer having the printing module 210 and the inkjet module 220, and the processing device 240 may include a processor of the computer host and a processor and/or a controller of the stereoscopic printer. For example, the stereo printing apparatus 20 may be composed of a notebook computer or a desktop computer and a stereo printer, and the invention is not limited thereto. In another embodiment, the stereo printing apparatus 20 may also be a stereo printer with the capability of processing stereo digital models, and the invention is not limited thereto.

Fig. 3 is a schematic view of a stereoscopic printing apparatus according to the embodiment of fig. 2. Referring to fig. 3, the printing module 210 may include a printing head 210a, and the inkjet module 220 may include an inkjet head 220a, and a rectangular coordinate system is provided to describe the related components and the motion states thereof. The forming platform 250 includes a carrying surface S1 for carrying the color three-dimensional object 80 during printing. The forming platform 250 is disposed below the print head 210a and the inkjet head 220 a.

In detail, in the present embodiment, the processing device 240 may obtain a three-dimensional digital model, wherein the three-dimensional digital model conforms to a three-dimensional File Format of a Polygon File (PLY), an STL File, an OBJ File, or the like. The three-dimensional model in the three-dimensional file format is composed of a plurality of polygonal Mesh units (Mesh), and each polygonal Mesh unit has a plurality of end points, wherein the end points have different coordinates respectively. In this embodiment, the processing device 240 may be configured to perform layer cutting processing on the three-dimensional digital model to obtain a plurality of layer cutting objects, so as to obtain layer cutting information of each layer cutting object. The layer cutting information includes the cross-sectional profile and ink jetting range of the layer cutting object. The processing device 240 may control the stereoscopic printing apparatus 20 according to the above-mentioned layer cutting information, so that the stereoscopic printing apparatus 20 generates a plurality of layer cutting objects layer by layer and colors the layer cutting objects layer by layer.

In the present embodiment, the stereoscopic printing apparatus 20 prints the stereoscopic object 80 in a Fused Deposition Modeling (FDM) technique. That is, the print head 210a is configured to move along the XY plane and along the normal direction (Z axis) of the XY plane, the molding material F1 enters the print head 210a through the supply line to be melted by heating, and is extruded by the print head 210a to be molded layer by layer on the carrying surface S1 of the molding platform 250 to form a plurality of layer-cutting objects (fig. 3 illustrates the layer-cutting objects 80a and 80 c). Thus, the layer-by-layer formed layer-by- layer cut pieces 80a and 80c are stacked on the carrying surface S1 to form the three-dimensional piece 80. Specifically, the molding material F1 may be a hot melt material suitable for use in a manufacturing method such as a Fused Fiber Fabric (FFF) method or a melt and pressure molding (Melted and extruded molding), but the present invention is not limited thereto.

In the present embodiment, the inkjet head 220a sprays the ink I1 on the layer-cutting objects 80a and 80c layer by layer, so that the ink I1 overlaps the upper surfaces of the layer-cutting objects 80a and 80 c. Therefore, the inkjet head 220a may include an ink cartridge 220b, wherein the ink cartridge 220b is used to contain the ink I1, and the inkjet head 220a sprays the ink I1 in the ink cartridge 220b onto the layer-cutting objects 80a, 80c according to the control of the processing device 240 to color the layer-cutting objects 80a, 80 c. Although FIG. 3 shows only one ink cartridge 220b, the number of ink cartridges and the number of colors of ink are not limited in the present invention. For example, the inkjet module 220 may include 4 ink cartridges respectively holding different colors (e.g., yellow (Y), magenta (M), cyan (C), and black (K)), and 4 corresponding inkjet heads.

With this arrangement, after the printing head 210a prints the layer-cutting object 80a on the forming platform 250, the ink can be sprayed on the upper surface of the layer-cutting object 80a by the ink-jet head 220a to color the layer-cutting object 80 a. After the print head 210a prints another layer of the layered object 80c on the forming platform 250, the ink can be sprayed on the upper surface of the layered object 80c by the ink jet head 220a to color the layered object 80 c. It can be known that by repeatedly and alternately performing the three-dimensional printing operation and the ink-jet operation, a plurality of colored cut-layer objects are sequentially stacked to form a color three-dimensional object.

It should be noted that, in the embodiment of the present invention, the stereoscopic printing apparatus 20 performs the inkjet operation on the contour edge of each layer-cutting object according to the inkjet width, so that the surface of the stereoscopic object is colored. In detail, when the inkjet module 220 colors the layered object, the inkjet module 220 moves along the XY plane according to the cross-sectional profile of the layered object to apply the ink I1 to the outer edge of the cross-section of the upper surface of the layered object. The outer edge of the section of each cut layer object is colored, so that the outer surface of the finally formed colored three-dimensional object can present diversified colors. That is, the ink ejection range for each layer-cutting object is determined based on the cross-sectional profile of the layer-cutting object and the ink ejection width, which can be regarded as a profile linear region according to the cross-sectional profile, and the ink ejection width is the line width of the linear region. More specifically, the processing device 240 may generate inkjet images corresponding to the respective layer-cutting objects in advance according to the cross-sectional profiles and the inkjet widths of the layer-cutting objects, so as to control the inkjet module 220 to perform inkjet operations on the XY plane according to the inkjet images. In particular, in the embodiment of the invention, the ink jetting width corresponding to each layer cutting object can be adaptively changed according to the surface inclination degree of the three-dimensional object.

Fig. 4 is a flowchart of a method for stereoscopic color printing according to an embodiment of the invention. The method of the present embodiment is applied to the three-dimensional printing apparatus 20 of fig. 2 and 3, and the detailed steps of the inkjet width adjustment method of the present embodiment will be described below with reference to the components of the three-dimensional printing apparatus 20.

In step S401, the processing device 240 obtains the stereoscopic digital model, and performs a layer cutting process on the stereoscopic digital model to generate a layer-cut object, wherein the layer-cut object has a cross-sectional profile. Specifically, the stereoscopic digital model (e.g., STL file) will be further compiled and computed to be converted into relevant information for performing the color stereoscopic printing function. First, the processing device 240 performs a layer-cutting process on the three-dimensional digital model to generate a plurality of layer-cut objects. Generally, the stereoscopic digital model is cut with a plurality of cut-layer planes at regular intervals to extract the cross-sectional profiles of the cut-layer objects. Herein, the cutting interval for cutting the stereoscopic digital model may be regarded as a slice thickness of the slice object.

Next, in step S402, the processing device 240 obtains the surface inclination degree corresponding to the cross-sectional profile from the stereo digital model, and calculates the ideal ink-jet width of the layer-cutting object according to the surface inclination degree corresponding to the cross-sectional profile. Specifically, after the layer cutting process is performed to obtain a plurality of layer cutting objects, the processing device 240 may further determine the ink jetting range of each layer cutting object. In the embodiment of the present invention, the processing device 240 can obtain the surface inclination degree corresponding to the layer cutting object according to the three-dimensional digital model, and then determine the ideal ink jet width (unit: cm) of the layer cutting object according to the surface inclination degree corresponding to the layer cutting object.

For example, referring to fig. 5, fig. 5 is a schematic diagram illustrating determination of an ideal ink jet width according to an embodiment of the present invention. Assume that the processing device 240 obtains the stereoscopic digital model 51, and the stereoscopic digital model 51 is a hemisphere. The processing device 240 may perform slicing on the three-dimensional digital model 51 according to the same slicing thickness to obtain a plurality of slicing objects 52(1), (52), (2), (…), (52 (k), (…), (52 (n-1), and (52 (n), where n is an integer greater than 0 and k is between 1 and n. Thus, the processing device 240 can obtain the cross-sectional profiles of the sliced objects 52(1) to 52(n) by the slicing process. In this example, since the three-dimensional digital model 51 is a hemisphere, the cross-sectional profiles of the layered objects 52(1) to 52(n) are circular profiles with different radii, and the surface slopes corresponding to the cross-sectional profiles of the same layered object are uniform.

Take the layer-cutting object 52(k) and the layer-cutting object 52(n-1) as an example. The processing device 240 may obtain the surface inclination degree T1 corresponding to the cross-sectional profile of the sliced layer object 52(n-1) from the stereo digital model. Thereafter, the processing device 240 may calculate the ideal ink-jet width Wd2 according to the surface inclination degree T1 corresponding to the cross-sectional profile of the layer-cutting object 52 (n-1). Similarly, the processing device 240 may obtain the surface inclination T2 corresponding to the cross-sectional profile of the sliced object 52(k) from the stereo digital model. Then, the processing device 240 calculates the ideal ink-jet width Wd3 of the layer-cutting object 52(k) according to the surface inclination degree T2 corresponding to the cross-sectional profile of the layer-cutting object 52 (k). Since the surface inclination degree T1 corresponding to the cross-sectional profile of the cut-layer piece 52(k) and the surface inclination degree T2 corresponding to the cross-sectional profile of the cut-layer piece 52(n-1) are different from each other, the ideal ink ejection width Wd2 is different from the ideal ink ejection width Wd 3. Here, since the surface inclination degree T2 corresponding to the cross-sectional profile of the layer-cut piece 52(k) is steeper than the surface inclination degree T1 corresponding to the cross-sectional profile of the layer-cut piece 52(n-1), the ideal ink ejection width Wd2 is greater than the ideal ink ejection width Wd 3. That is, in one embodiment, the desired ink ejection width may be determined for each layer of the sliced object. Thus, the situation that ink is jetted to the cut layer object 52(n-1) with an excessively narrow ink jetting width, and uncolored blocks are obviously shown on the surface of the manufactured color three-dimensional object can be avoided.

Then, in step S403, after controlling the printing module 210 to print the layer-cutting object, the processing device 240 controls the ink-jetting module 220 to jet ink toward the layer-cutting object and along the cross-sectional profile according to the ideal ink-jetting width. Specifically, after the processing device 240 determines the ideal ink-jet width, the processing device 240 may generate a corresponding ink-jet image according to the ideal ink-jet width, so that the ink-jet module 220 may jet ink to the cross-sectional edge portion of the laminated object according to the ink-jet image. For example, the description is continued by taking the example of fig. 5 as an example. Referring to fig. 6, fig. 6 is a schematic view of an inkjet image according to an embodiment of the invention. After the processing device 240 calculates the ideal ink jetting width Wd2, the processing device 240 may generate the ink-jet image Img1 according to the cross-sectional profile C1 of the layer cutting object 52(n-1) and the ideal ink jetting width Wd 2. After the processing device 240 calculates the ideal ink jetting width Wd3, the processing device 240 may generate the ink jetting image Img2 according to the cross-sectional profile C2 of the layer cutting object 52(k) and the ideal ink jetting width Wd 3. Thus, the inkjet module 220 can spray the ink I1 on the edge of the layer-cutting object 52(k) according to the pixel position and the color feature value recorded by the inkjet image Img 2. Moreover, the inkjet module 220 may spray the ink I1 on the edge of the layer-cutting object 52(n-1) according to the pixel position and the color feature value recorded by the inkjet image Img 1.

The following examples will be presented to illustrate how the degree of surface inclination of the cross-sectional profile is achieved. In one embodiment, the stereoscopic digital model is composed of a plurality of polygonal Mesh units (Mesh), and each polygonal Mesh unit has a plurality of endpoints, wherein the endpoints have different coordinates respectively. For example, the polygonal mesh cells are typically triangular mesh cells, which may be considered as triangular faces formed by three endpoints. When the layer cutting processing is executed, a certain layer cutting plane for performing the layer cutting processing passes through a part of polygonal mesh units of the three-dimensional digital model, so that the section outline of the layer cutting object is extracted. Thus, in one embodiment, the processing device 240 may obtain at least one polygonal mesh unit corresponding to the cross-sectional profile from the stereo digital model. Then, the processing device 240 may calculate at least one included angle between the at least one polygon mesh unit and the horizontal plane to represent the degree of surface inclination corresponding to the cross-sectional profile. Specifically, according to the coordinates of the end points of the polygon mesh units, the processing device 240 can calculate the included angle between the polygon mesh units and the horizontal plane.

Referring to fig. 7A, fig. 7A is a schematic view of a three-dimensional digital model and a layer-cutting object according to an embodiment of the invention. In the present exemplary embodiment, it is assumed that the processing device 240 performs layer-cutting processing on the stereoscopic digital model 71, and the stereoscopic digital model 71 is composed of 12 triangular mesh cells, such as triangular mesh cells M1, M2, M3, and so on. Here, the triangular mesh cell M1 has 3 terminals V1, V2, and V3. The triangular mesh cell M2 has 3 endpoints V1, V3, V4. The triangular mesh cell M3 has 3 endpoints V4, V3, V5. It is assumed that 6 slice objects 72(1) - (72 (6)) are generated after the processing device 240 performs slice processing on the stereoscopic digital model 71 according to the slice thickness. The cross-sectional profiles of the cut-layer pieces 72(1) to 72(6) are rectangular shapes having different dimensions, respectively. Taking the layer cutting object 72(3) as an example, based on the cross-sectional profile C3 of the layer cutting object 72(3), the processing device 240 may obtain a plurality of triangular mesh units (e.g., the triangular mesh units M1, M2, M3, M4, etc. in this example) corresponding to the layer cutting object 72 (3).

Next, referring to fig. 7B, fig. 7B is a schematic diagram illustrating an angle between a polygon mesh unit and a horizontal plane according to an embodiment of the invention. Taking the triangular mesh cell M1 as an example, the processing device 240 may calculate an angle θ 1 between the triangular mesh cell M1 and the horizontal plane HP to obtain the angle θ 1 representing the surface inclination degree of the cross-sectional profile C3. For example, when the slicing process is performed using the horizontal plane HP, the horizontal plane HP intersects the triangular mesh unit M1 at the intersection point V7 and the intersection point V8, and the straight line Ln1 between the intersection point V7 and the intersection point V8 may constitute a part of the cross-sectional profile C3. The included angle θ 1 between the triangular mesh unit M1 and the horizontal plane HP is the included angle between the triangular plane formed by the endpoint V1 and the two intersection points V7 and V8 and the horizontal plane HP. The angle θ 1 between the triangular mesh cell M1 and the horizontal plane HP can be obtained as follows. The endpoint V1 is a perpendicular LA perpendicular to the line Ln1 (the line between the intersection V7 and the intersection V8), and the perpendicular LA intersects the line Ln1 at the foothold point V9. Then, another perpendicular line LB perpendicular to the straight line Ln1 and located on the horizontal plane HP is obtained from the foot passing point V9, and the included angle θ 1 can be obtained from the included angle between the perpendicular line LA and the perpendicular line LB. It is noted that the processing means 240 will also calculate the angle between the further triangular mesh unit M2 and the horizontal plane HP to obtain a further angle representing the degree of surface tilt corresponding to the cross-sectional profile C3. In this case, since the angle between the triangular plane formed by the end points V3 to the two intersection points (i.e., the two intersection points of the horizontal plane HP and the triangular mesh unit M2) and the horizontal plane HP is calculated, the angle between the triangular mesh unit M2, which presents an inverted triangle, and the horizontal plane HP may be greater than 90 degrees. Similarly, the processing means 240 will also calculate the angle between the other triangular mesh cell M3 and the horizontal plane HP to obtain a further angle representing the degree of surface tilt corresponding to the cross-sectional profile C3. That is, for the same layer-cutting object, the layer-cutting object can correspond to a plurality of different included angles. In other words, for the same sliced layer object, since the shape of the stereoscopic digital model is irregular, the cross-sectional profile of the sliced layer object will likely correspond to a plurality of different degrees of surface inclination.

As described above, when the slicing process is performed using the horizontal plane HP, the horizontal plane HP intersects the triangular mesh unit M1 at the intersection point V7 and the intersection point V8, and the straight line Ln1 between the intersection point V7 and the intersection point V8 is a partial section of the cross-sectional profile C3. Accordingly, the processing device 240 may calculate an ideal ink ejection width for the partial section corresponding to the cross-sectional profile C3 of the triangular mesh unit M1, and may obtain an ink ejection range having a width equal to the ideal ink ejection width and a length equal to the length of the straight line Ln 1. Similarly, when the slicing process is performed using the horizontal plane HP, the horizontal plane HP intersects the triangular mesh unit M2 at an intersection point V8 and another intersection point (not shown), and another straight line between the intersection point V8 and the other intersection point will constitute another partial section of the cross-sectional profile C3. Therefore, the processing device 240 can calculate not only an ideal ink ejection width for the straight line Ln1 corresponding to the triangular mesh cell M1, but also another ideal ink ejection width for another straight line (between the intersection point V8 and another intersection point) corresponding to the triangular mesh cell M2. The length of the straight line Ln1 corresponding to the triangular mesh cell M1 may be the same as or different from the length of another straight line corresponding to the triangular mesh cell M2. Then, since the processing device 240 may calculate another ideal ink ejection width for the partial section corresponding to the cross-sectional profile C3 of the triangular mesh unit M2, the processing device 240 may acquire an ink ejection range having a width equal to the another ideal ink ejection width and a length equal to the length of another straight line.

That is, since the same slice plane can pass through different triangular mesh cells, the processing device 240 can calculate a plurality of ideal ink jetting widths corresponding to different profile sections of the cross-sectional profile for the same slice object. In addition, the profile lengths of the different profile sections of the cross-sectional profile of the single cut layer article may be the same or different, and thus the lengths of the ink ejection ranges corresponding to the different profile sections may also be different or the same.

However, fig. 7A and 7B are only exemplary and not intended to limit the present invention. After referring to fig. 7A and 7B, those skilled in the art will be able to obtain sufficient teaching and suggestions to deduce how to calculate the surface inclination degree of the sliced object for the stereoscopic digital model with other shapes.

In one embodiment, after obtaining at least one angle representing the degree of surface inclination, the processing device 240 may calculate the ideal ink-jet width of the layer-cutting object according to at least one angle between the polygonal mesh unit and the horizontal plane, the layer-cutting thickness, and the preset ink-jet width. In one embodiment, the processing device 240 can calculate the ideal ink-jet width of the layer-cutting object according to the following formula (1).

Wd_idealMax (h × cot θ |, Wdp) formula (1)

Wherein, Wd_idealRepresents an ideal ink ejection width, h represents a skive layer thickness, θ represents an angle between the polygonal mesh unit and a horizontal plane (e.g., an angle θ 1 shown in fig. 7B), and Wdp represents a preset ink ejection width. As can be appreciated, θ is between 0 and 180 degrees. Referring to the formula (1), the processing device 240 calculates the product of the cotangent value of at least one angle and the thickness of the cut layer, and takes the maximum value between the product and the preset ink jet width as the ideal ink jet width. The preset ink-jet width is a preset minimum ink-jet width, which can be designed according to actual requirements. It should be noted that when the angle between the polygonal mesh unit and the horizontal plane is greater than 90 degrees, cot θ is negative. Based on this, equation (1) also takes the absolute value for cot θ.

Continuing with the example of the layer-cutting device 72(3) in fig. 7A, please refer to fig. 8, in which fig. 8 is an example of the ink-jetting range of the layer-cutting device 72(3) in the embodiment shown in fig. 7A. Assuming that the triangular mesh cells M3, M4 are perpendicular to the horizontal plane, based on the formula (1), the ideal ink ejection width of the section C3_2 of the cross-sectional profile C3 will be equal to the preset ink ejection width Wdp. Assuming that the triangular mesh cells M1, M2, M5 are coplanar, based on equation (1), the ideal ink ejection width of the section C3_1 of the cross-sectional profile C3 would be equal to Wd5 ═ h × cot θ, where θ is equal to θ 1 shown in fig. 7B.

Based on the foregoing, for an irregularly shaped three-dimensional digital model, the same sliced object may correspond to different degrees of surface inclination. Therefore, the polygon cells corresponding to the slice objects 72(3) may include the triangle cell M1 (i.e., the first polygon cell) and the triangle cell M3 (i.e., the second polygon cell). In one embodiment, the processing device 240 calculates a first angle between the triangular mesh cell M1 and the horizontal plane, and calculates a second angle between the triangular mesh cell M3 and the horizontal plane. Then, the processing device 240 calculates a first ideal ink ejection width (for example, Wd5 shown in the ink ejection range 81 of fig. 8) of the ideal ink ejection widths according to the first angle, the slice thickness, and the preset ink ejection width, and calculates a second ideal ink ejection width (for example, Wdp shown in the ink ejection range 81 of fig. 8) of the ideal ink ejection widths according to the second angle, the slice thickness, and the preset ink ejection width. That is, it is possible to have a variety of different ideal ink ejection widths for the same sliced piece. Generally, two solid digital models of similar volume sizes, where a more complex or irregular model has more polygonal grid cells of smaller area than the other model, may correspond to more different ideal ink ejection widths.

Note that the calculation method of the formula (1) is only one embodiment of the present invention. In other embodiments, the processing device 240 may perform a table look-up operation by using a preset look-up table based on the included angle representing the degree of surface inclination, so as to obtain the corresponding ideal ink-jet width. In the embodiment of the present invention, the ideal ink-jet width increases with the decrease of the included angle, and the ideal ink-jet width decreases with the increase of the included angle. For example, if the included angle representing the degree of surface inclination is within a first predetermined range, the processing device may directly obtain the ideal ink ejection width corresponding to the first predetermined range according to the lookup table. If the included angle representing the surface inclination degree is within a second preset range, the processing device can directly acquire the ideal ink jet width corresponding to the second preset range according to the lookup table. Herein, the first predetermined range is different from the second predetermined range.

Fig. 9 is a flowchart illustrating an inkjet width adjustment method according to an embodiment of the invention, and details of the implementation of the inkjet width adjustment method can be found in the description of the embodiment of fig. 2 to 8. Referring to fig. 9, in step S901, a stereo digital model is obtained, and a layer cutting process is performed on the stereo digital model to generate a layer-cut object. In step S902, at least one polygonal mesh unit corresponding to the cross-sectional profile is obtained from the stereo digital model. In step S903, at least one angle between at least one polygon mesh unit and the horizontal plane is calculated to represent the degree of surface inclination. In step S904, the product of the cotangent value of at least one of the included angles and the thickness of the slice is calculated. In step S905, the maximum value between the product and the predetermined ink-jet width is taken as the ideal ink-jet width of the layer-cutting object. In step S906, an inkjet image is generated according to the ideal inkjet width and the cross-sectional profile, wherein the inkjet image includes an inkjet range formed based on the ideal inkjet width. In step S907, after the printing module is controlled to print the layer-cutting object, the ink-jet module is controlled to jet ink toward the layer-cutting object and along the cross-sectional profile according to the ideal ink-jet width.

FIG. 10 is a schematic diagram of an exemplary method for obtaining a desired ink ejection width according to an embodiment of the invention. Referring to fig. 10, it is assumed that the stereoscopic digital model 1001 is set as a stereoscopic egg-shaped model laid out in a landscape orientation. The cross-sectional profile of the sliced layer of the layer X1 will correspond to different degrees of surface slope (e.g., surface slope T3 and surface slope T4). Accordingly, by calculating the ideal ink jetting width of the layer cutting object at the X1 th layer according to the surface inclination degree, the ink jetting range 1003 of the layer cutting object at the X1 th layer can be as shown in fig. 10 based on the cross-sectional profile and the corresponding surface inclination degree of the layer cutting object at the X1 th layer. From the ink ejection range 1003, since the surface inclination degree T4 is steeper than the surface inclination degree T3 (i.e., the surface inclination degree T3 is gentler than the surface inclination degree T4), the ideal ink ejection width Wd6 corresponding to the surface inclination degree T3 is larger than the ideal ink ejection width Wd7 corresponding to the surface inclination degree T4. On the other hand, the cross-sectional profile of the layer-cut pieces of the layer X2 will also correspond to different degrees of surface inclination (e.g., the degree of surface inclination T5 and the degree of surface inclination T6). Based on the degree of inclination of the cross-sectional profile of the layer-cut article at the X2 th layer to the corresponding surface, the ink-jetting range 1002 of the layer-cut article at the X2 th layer can be as shown in fig. 10. From the ink ejection range 1002, since the surface inclination degree T5 is gentler than the surface inclination degree T6, the ideal ink ejection width Wd8 corresponding to the surface inclination degree T5 is greater than the ideal ink ejection width Wd9 corresponding to the surface inclination degree T6. Thus, the inkjet module of the three-dimensional printing apparatus performs inkjet operation on the cross-sectional edges of the layer X1 and the layer X2 cut objects according to the inkjet range 1002 and the inkjet range 1003, so as to color the outer surfaces of the layer X1 and the layer X2 cut objects.

In summary, the inkjet width adjusting method and the three-dimensional printing apparatus according to the embodiments of the invention can adaptively adjust the ideal inkjet width according to the surface inclination degree corresponding to the top-cut layer object of the three-dimensional object. Therefore, after the printing head prints the layer cutting object, the three-dimensional printing equipment can control the ink jet module to jet ink towards the layer cutting object and along the cross section contour according to the ideal ink jet width. Therefore, even if the surface inclination degree of the three-dimensional object is quite gentle or the interval between the edges of the upper and lower adjacent layer cutting objects is overlarge, the part exposed on the surface of the three-dimensional object can be accurately colored, and the printing quality of color three-dimensional printing is greatly improved. Therefore, the three-dimensional printing equipment can perform ink-jet operation on the three-dimensional printing object according to the ink-jet range with higher precision, so that the situation that the surface of the manufactured three-dimensional object presents uncolored blocks is avoided.

Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.