Coloring of three-dimensional printed objects

Patent metadata

Field	Value
Publication number	US-11872828-B2
Application number	US-202117370061-A
Country	US
Kind code	B2
Filing date	Jul 8, 2021
Priority date	Jan 26, 2014
Publication date	Jan 16, 2024
Grant date	Jan 16, 2024

Abstract

A method of printing a three-dimensional (3D) color object, layer-by-layer, comprises: obtaining a 3D CAD specification defining a 3D geometry and a surface color distribution for the color object to be printed, defining regions on a surface of the color object; defining colors for each region based on the CAD specification; determining, using the 3D geometry of the specification, conditions applying at respective regions that are liable to cause color variation, such that using the colors as defined at the respective regions may give rise to a coloration error; selecting color corrections defined for respective determined conditions; correcting the defined colors; and printing the 3D color object with the color corrections.

First claim

What is claimed is:

1. A three-dimensional (3D) color printer for printing 3D color objects layer-by-layer, the printer comprising:
a specification input for inputting a 3D CAD specification defining a 3D geometry and a surface color distribution for said color object;
a region definer for defining regions on a surface of said color object;
a color definer for defining colors for each region based on said surface color distribution;
an error determination unit for determining, using said 3D geometry, conditions applying at respective regions that are liable to cause color variation, such that using said colors as defined at said respective regions may give rise to a coloration error;
a selector, for selecting color corrections defined for respective determined conditions; and
a corrector for correcting said defined colors using said defined corrections, to compensate for respectively corresponding coloration errors;
wherein said printer is configured to print said 3D color object using respective corrected defined colors at each region.

2. A three-dimensional (3D) color printer for printing 3D color objects layer-by-layer, the printer comprising:
a specification input for obtaining a 3D CAD file defining a 3D geometry and a color texture for said color object;
a region definer configured to divide said 3D geometry into a core and a color shell, and further to divide said color shell into volumetric regions;
an assigner configured to assign, based on a look up table (LUT), each of said regions with an arrangement of voxels in a color stack, which arrangement results in an optimal reproduction of the requested color;
an error determination unit, for determining, based on said 3D geometry, conflicting instances in which the color stack of one region interferes with a color stack of another region; and
a corrector associated with said error determination unit configured to apply a color correction in case of conflict between color stacks wherein the 3D color printer is configured to print using said color correction.

3. The 3D color printer of claim 2 , configured to compile said LUT by printing various color stack compositions and measuring the resulting colors.

4. The 3D color printer of claim 2 , wherein said arrangement of voxels comprises up to and not including 10 voxels.

5. The 3D color printer of claim 2 , wherein the thickness of said color shell is calculated relative to the extinction depth of the materials used.

6. The 3D color printer of claim 2 , wherein the conflicting instances are selected from junctions between faces, sharp edges and thin parts.

7. The 3D color printer of claim 6 , wherein the thin part is a thin wall.

8. The 3D color printer of claim 2 , configured to carry out said color correction by selecting the best match of color stacks from a library of color combinations, measuring a distance between the actual colors and the colors provided by the library, and modifying the color stacks provided by the library to better fit the actual colors.

9. The 3D color printer of claim 8 , configured to carry out said modifying of color stacks by applying a model predicting color change as a function of inks or placing lighter colored inks at the inner layers of the stack.

10. The 3D color printer of claim 2 , wherein said color correction involves the use of a dithering process between voxels of interfering color stacks.

11. The 3D color printer of claim 10 , wherein said dithering process comprises selecting different dithering vectors of voxels for each of said requested colors and combining said dithering vectors of voxels to find a combination requiring a minimal amount of voxel overwriting.

12. The 3D color printer of claim 11 , wherein combining said dithering vectors of voxels is performed via a tail matching algorithm that takes into account collisions between neighboring dithering stacks.

13. The 3D color printer of claim 12 , wherein said tail matching algorithm comprises looking for vectors which have the same tail of common colors in the inner part of the color stack.

14. The 3D color printer of claim 13 , wherein said tail matching algorithm comprises selecting the combination of vectors having the longest length common tail.

15. The 3D color printer of claim 14 , wherein said LUT is compiled according to a specific printing condition.

16. The 3D color printer of claim 15 , wherein said printing condition comprises one or more predetermined levels of UV exposure.

17. A three-dimensional (3D) color printer for printing 3D color objects layer-by-layer, comprising:
a table constructor, configured to construct a lookup table (LUT) of color values against actual printed color composition under different printing conditions by:
printing color calibration targets using actual printed color compositions while

exposing to different printing conditions;
measuring the resulting color value for each of said targets using a colorimetry device; and
tabulating the measured color values against the actual printed color composition and the respective printing conditions;

a specification input for obtaining a 3D CAD file defining a 3D geometry and a color texture for said color object;
a region definer configured to divide said 3D geometry into a core and a color shell, and to divide said color shell into volumetric regions; and
a color correction unit configured to calculate expected printing conditions for each of the volumetric regions, and to populate each of the volumetric regions with color voxels to provide an intended color according to said LUT of color values against actual printed color composition under different printing conditions; and wherein said 3D colored printer is configured to print using said color voxels.

18. The 3D color printer of claim 17 , wherein said printing conditions are selected from UV exposure level, sample orientation on tray, gloss/matte print mode, and any combination thereof.

19. The 3D color printer of claim 17 , wherein said actual printed color compositions are based on C, M, Y, white and black color materials.

20. The 3D color printer of claim 17 , wherein said color values are represented by one of RGB color coordinates, CIE Lab coordinates, HSL, LCH and Grey Values.

Assignees

• Stratasys Ltd

Inventors

• Dikovsky Daniel
• Shtilerman Stanislav
• Bressler Yoav

Classifications

• B41M5/0082 Primary

  Digital printing on bodies of particular shapes (sublimation or volatilisation of pre-printed design B41M5/035) · CPC title

• B29C64/112

  using individual droplets, e.g. from jetting heads · CPC title

• B29C64/386

  Data acquisition or data processing for additive manufacturing · CPC title

• B33Y10/00 Primary

  Processes of additive manufacturing · CPC title

• B33Y30/00

  Apparatus for additive manufacturing; Details thereof or accessories therefor · CPC title