PRINTING SYSTEM FOR PRINTING ON A SUBSTANTIALLY PLANAR SURFACE OF A 3D-OBJECT AND A METHOD FOR PRINTING THEREOF

Abstract

A printing system for printing on a substantially planar surface of a 3D-object includes a printer for printing on the planar surface of the 3D-object and a controller configured to control printing of the printer. The printing system further includes a mask generation module configured to generate a mask having the shape of the planar surface from a 3D-model of the 3D-object and to provide the controller with the mask to prevent printing outside the planar surface according to the mask.

Claims

1. A printing system for printing on a substantially planar surface of a 3D-object, the printing system comprising: a printer configured to print on the planar surface of the 3D-object; a controller configured to control printing of the printer; and a mask generation module configured to generate a mask having the shape of the planar surface from a 3D-model of the 3D-object and to provide the controller with the mask to prevent printing outside said planar surface according to the mask.

2. The printing system according to claim 1, wherein the mask generation module is configured to generate the shape of the mask from a mesh model defined by a plurality of 2D-faces by selection of 2D-faces of the plurality having a corresponding normal with respect to a reference normal of a reference 2D-face arranged in an area of the mesh model corresponding to the planar surface of the 3D-object.

3. A method for generating a mask of a substantially planar surface of a 3D-object, said method comprising the step of generating the mask from a 3D-model of the 3D-object such that said mask has the shape of the planar surface.

4. The method according to claim 3, wherein the 3D-model of the 3D-object object is a mesh model defined by a plurality of 2D-faces, and the step of generating the mask comprises the sub-steps of: generating a reference normal vector of a reference 2D-face arranged in an area of the mesh model corresponding to the planar surface of the 3D-object; generating a normal vector of a 2D-face of the plurality of 2D-faces of said mesh model to yield a normal vector; and selecting the 2D-face by comparison of the normal vector with the reference normal vector.

5. The method according to claim 4, wherein the selecting sub-step is done when both the normal vector and the reference normal vector are substantially equal.

6. A method for printing on a planar surface of a 3D-object, the method comprising the step of using a mask to limit printing, wherein the mask is generated according to a method corresponding to claim 3.

7. A method for printing on a planar surface of a 3D-object, the method comprising the step of using a mask to limit printing, wherein the mask is generated according to a method corresponding to claim 4.

8. A method for printing on a planar surface of a 3D-object, the method comprising the step of using a mask to limit printing, wherein the mask is generated according to a method corresponding to claim 5.

9. A computer program product comprising a non-transitory computer readable storage medium, wherein the non-transitory computer readable storage medium comprises a program, and the program enables a computer and/or a mask generation module of a printing system to execute the method of generating a mask according to claim 3 when the program is run in the computer and/or the mask generation module.

10. A computer program product comprising a non-transitory computer readable storage medium, wherein the non-transitory computer readable storage medium comprises a program, and the program enables a computer and/or a mask generation module of a printing system to execute the method of generating a mask according to claim 4 when the program is run in the computer and/or the mask generation module.

11. A computer program product comprising a non-transitory computer readable storage medium, wherein the non-transitory computer readable storage medium comprises a program, and the program enables a computer and/or a mask generation module of a printing system to execute the method of generating a mask according to claim 5 when the program is run in the computer and/or the mask generation module.

12. A computer program product comprising a non-transitory computer readable storage medium, wherein the non-transitory computer readable storage medium comprises a program, and the program enables a computer and/or a mask generation module of a printing system to execute the method of generating a mask according to claim 6 when the program is run in the computer and/or the mask generation module.

13. A computer program product comprising a non-transitory computer readable storage medium, wherein the non-transitory computer readable storage medium comprises a program, and the program enables a computer and/or a mask generation module of a printing system to execute the method of generating a mask according to claim 7 when the program is run in the computer and/or the mask generation module.

14. A computer program product comprising a computer readable storage medium, wherein the non-transitory computer readable storage medium comprises a program, and the program enables a computer and/or a mask generation module of a printing system to execute the method of generating a mask according to claim 8 when the program is run in the computer and/or the mask generation module.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] For the purpose of illustrating the invention, the drawings show aspects of one or more embodiments of said invention. However, it should be understood that the present invention is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:

[0032] FIG. 1 is a view of a printer according to the invention;

[0033] FIG. 2A is a view of a 3D-object to be printed on;

[0034] FIG. 2B is a view of a mask to be used for printing a surface of the 3D-object depicted in FIG. 2A;

[0035] FIG. 3A is a view of a 3D-model of the 3D-object of FIG. 2A;

[0036] FIG. 3B is a surface of the 3D-model of FIG. 3A; and

[0037] FIG. 4 is a schematic view of a printing method using the printer of FIG. 1

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] It should be noted that items which have the same reference numbers in different figures, have the same structural features and the same functions. Where the function and/or structure of such item has been explained, there is no necessity for repeated explanation thereof in the detailed description.

[0039] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments.

[0040] FIG. 1 depicts a printing system 100 according to an example of the invention. The printing system 100 comprises a flatbed printer 101 as known in the art. The flatbed printer 101 comprises a carriage comprising printing means 110. Control means are arranged in a detached workstation (not shown). The printing means 110 comprises a print head 111 arranged on a gantry 112. In this way the printing head may move in a X, Y and Z direction thanks to the cooperation with the gantry 112. The control means comprises a user interface for controlling printing performed by the flatbed printer 101.

[0041] The flatbed printer 101 is configured to print on 3D-objects, as for example a 3D-object 200 depicted in FIG. 2, in the present example by having a gantry adjustable in height. The printing means 110 may thus apply ink to a planar surface 210 of the 3D-object 200 via the printing head 111 according to the instructions provided by the control means.

[0042] A challenge that the printing means 110 faces when printing on the planar surface 210 of the 3D-object 200 depicted in FIG. 2A is that the perimeter of said planar surface 210 is rounded and further comprises an opening 220. This might make it difficult to control printing and increases the possibility of applying ink in the opening 220 or the lateral surfaces 230 and 230′ of the 3D-object 200, which can be easily noticed in the printing outcome.

[0043] In order to improve control of the printing means 110, the printing system 100 further comprises a mask generation module. In the present example, the mask generation module is a software program arranged in the user interface and configured to provide a mask 250 (see FIG. 2B) from a 3D-model 300 (see FIG. 3) of the 3D-object 200. Further, the mask generation module is further configured to provide the control means with the mask to limit printing provided by the printing means 110 to said planar surface 210 according to the mask 250. However, it is important to note that in a more specific example, a flatbed printer may be configured to perform printing according to a mask and that said mask is obtained offline, that is that said mask is generated separately from the flatbed printer to be input to the control means together with an image to be printed on the substantially planar surface to perform printing.

[0044] The mask 250 comprises a rectangular bitmap 251 having an area 252 and 252′ filled with white pixels and an area 253 filled with black pixels. The areas 252 and 252′ represent the area of the mask where there will be no printing and the area 253 represent the area where there is printing, as known in 2.5D printing. It is important to note that other descriptions of the mask known in the art may be used.

[0045] The mask 250 generated by the mask generation module is obtained from a 3D-model 300 of the 3D-object 200, as depicted in FIG. 3A. In the present example, the 3D-model 300 is mesh model 300. The mesh model 300 may have been obtained by any method known in the art for such a purpose to be input to the mask generation module of the printing system 100.

[0046] The mesh model 300 defines the 3D-object 200 as a plurality of 2D-faces 301 arranged in space. In the present example, each 2D-face 301 of the plurality has four edges, corresponding to a quad 301.

[0047] In the present example, the mask generation module is capable of generating the mask 250 from a surface 310 (see FIG. 3B) of the mesh model 300 by application of the method 400 as depicted in FIG. 4. The surface 310 is an area of the mesh model 300 corresponding to the planar surface 210 of the 3D-object 200.

[0048] The method 400 starts with a step S1, in which a quad 301′ of the area 310 of the mesh model 300 (see FIG. 3A). For the sake of clarity, this quad 301′ will be referred below as reference quad 301′. In the present example, the selection of the reference quad 301′ is done via the user interface.

[0049] The mask generation module of the present example is configured to generate a normal vector 302 corresponding to each of the quads 301 of the mesh model 300. In the present example, the normal vector is arranged outwardly with respect to the 3D-model. Since each of said quads 301 has only two dimensions, there is only a single corresponding normal vector 302 arranged also outwardly for each of said quads 301. Thus, the following step S2 of the method 400 corresponds to the generation of the normal vector 302′ of the reference quad 301′ that has been selected in the step S1. This normal vector 302′ will be referred as reference normal vector 302′. Then, the mask generation module of the present example generates the normal vector corresponding to each of the quads 301 of the plurality according to step S3. For the sake of clarity, FIG. 3A shows the normal vectors 302″ and 302′″ corresponding to quads 301″ and 301′″ arranged across the mesh model 300. It is important to note that the mask generation module may also generate normal vectors selectively, that is for squads adjacent to the reference quad, or by choice of the user.

[0050] In a following step S4, the mask generation module compares each normal vector 302 with the reference normal vector 302′. In this way, the quads 301 of the plurality defining an area of the mesh model 300 corresponding to the planar surface 210 of the 3D-object 200 and comprising the reference quad 301′ can be detected in an easy way. The detection is possible since the normal vectors 302 corresponding to said quads 301 are substantially similar or within a range arranged with respect to the reference normal vector 302′ such that all those quads are arranged in a substantially planar area. Thus, selection of said detected quads 301 by comparison yields the surface 310 having the shape of the planar surface 210.

[0051] It has to be noted, that the comparison in S4 may be done within a range of values, which is known as tolerance height variation. In the present example, the mask generation unit is configured to set the range as desired, which may have an impact in the selection of the quads 301 depending of the 3D-object.

[0052] In a final step S5, the mask 250 is generated. This is achieved since the mask generation module computes the resulting surface 310 to create the rectangular bitmap 251. Then, the resulting surface 310 is used to compute the area 252 and 252′ filled with white pixels and the area 253 filled with black pixels. Thus, as both the mask 250 and the area of the mesh model 300 corresponding to the planar surface 210 have the same shape, the mask 250 matches said planar surface 210 of the 3D-object 200. Computation of the area 253 may be done by mapping the selected 2D-faces to the mask 250, for example by orthogonal projection. Note that to properly mask out all areas of the image to be printed that will fall outside the substantially planar surface, the size of the mask should at least be the size of the image to be printed, or alternatively the area outside the mask is implicitly to be treated as an area to be masked out, or in other words an area where printing is to be prevented. In a preferred embodiment the dimensions of the mask are determined by the minimum bounding box of the selected 2D-faces or alternatively the axis-aligned minimum bounding box of the selected 2D-faces.

[0053] In one particular embodiment, the image to be printed is mapped to the 3D-model through conventional UV mapping techniques, wherein a mapping maps between the u- and v-coordinates of the image to be printed and the x-, y-, and z-coordinates of the 3D-model. In such embodiment, the mask 250 may be positioned in the same UV-space as the image to be printed and the UV mapping may be used to map the selected 2D-faces to the mask 250. Alternatively, a mapping between the image to be printed and the mask 250 is determined after the mask 250 with the area 253 has been determined, for example by visually relatively positioning and scaling the mask 250 and the image to be printed.