Stereo lithographic 3D printing assembly and stereo lithographic 3D printing method

Abstract

The invention provides a stereo lithographic 3D printing assembly comprising a digital projection system for projecting a first pattern having a first resolution at a projection location, and a photo mask system for projecting a second pattern having a second resolution at said projection location. This provides a fast 3D printing assembly allowing high resolution details.

Claims

1. A stereo lithographic 3D printing assembly comprising a digital projection system configured to project a digitally defined first pattern having a first resolution at a projection location, and a photo mask system configured to project a second pattern having a second resolution and said second pattern and said first pattern aligned with one another at said projection location, said photo mask system providing at least one photo mask between said digital projection system and said projection location.

2. The stereo lithographic 3D printing assembly of claim 1, wherein said second resolution is at least ten times higher than said first resolution at said projection location.

3. The stereo lithographic 3D printing assembly of claim 1, wherein said first resolution is lower than 200 dots per inch and said second resolution is higher than 200 dots per inch, or wherein said first resolution is lower than 250 dots per inch and said second resolution is higher than 250 dots per inch, or wherein said first resolution is lower than 100 dots per inch and said second resolution is higher than 300 dots per inch.

4. The stereo lithographic 3D printing assembly of claim 1, wherein said photo mask system comprises a substrate comprising at least part of said second pattern permanently defined on said substrate.

5. The stereo lithographic 3D printing assembly of claim 4, wherein said photo mask system comprises a series of substrates each comprising at least part of said second pattern permanently defined on said respective substrate.

6. The stereo lithographic 3D printing assembly of claim 1, comprising an alignment system having said second pattern and said first pattern aligned.

7. The stereo lithographic 3D printing assembly of claim 6, wherein said alignment system comprises an alignment provision on said digital projection system and on said photo mask system, a detector for detecting said alignment provision, and an alignment actuator for aligning said digital projection system and said photo mask system with respect to one another.

8. The stereo lithographic 3D printing assembly of claim 1, wherein said digital projection system comprises a source of electromagnetic radiation for producing a beam of electromagnetic radiation, collimating optics downstream of said source of electromagnetic radiation for collimating said beam of electromagnetic radiation, a digital mirror device downstream of said collimating optics, and an at least one axis translation device for translating said projection location, wherein said photo mask system is provided for positioning at least one photomask in a collimated beam of said collimating optics.

9. The stereo lithographic 3D printing assembly of claim 1, wherein said digital projection system comprises a light source, collimating optics downstream of said light source, a digital mirror device downstream of said collimating optics, and an at least one axis translation device for translating said projection location.

10. The stereo lithographic 3D printing assembly of claim 1, wherein said digital projection system comprises a patterned light source, collimating optics downstream of said patterned light source, and an at least one axis translation device for translating said projection location.

11. The stereo lithographic 3D printing assembly of claim 1, further comprising a container for holding a photo-curable resin and a target surface for defining said projection location for receiving a solidified layer that is polymerized with radiation from said digital projection system.

12. The stereo lithographic 3D printing assembly of claim 1, wherein said photo mask system comprises a series of photo masks and a selection system for selecting at least one of said photo masks for generating said second pattern.

13. The stereo lithographic 3D printing assembly of claim 1, wherein said photo mask system comprises an actuator for displacing said at least one photo mask during projecting of said first pattern for generating said second pattern, optionally said actuator comprises at least one selected from a translation stage and a rotation stage.

14. The stereo lithographic 3D printing assembly of claim 1, wherein said photo mask system is provided as an add-on system to a stereo lithographic 3D printing assembly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

(2) FIG. 1 schematically depicts a side view of an embodiment of the assembly;

(3) FIG. 2 a perspective view of FIG. 1;

(4) FIG. 3 a cross sectional view of FIG. 1;

(5) FIG. 4 an expanded view of FIG. 1;

(6) FIG. 5 an alternative setup showing an object being printed;

(7) FIG. 6 a photograph showing an object with a micro pattern;

(8) FIG. 7 a detail photograph of the object of FIG. 6.

(9) FIG. 8 a further detail of FIG. 6.

(10) The drawings are not necessarily on scale

DESCRIPTION OF PREFERRED EMBODIMENTS

(11) FIGS. 1-4 schematically depicts an embodiment of a stereo lithographic printing assembly 1. The assembly 1 comprises a digital projection system 2. This digital projection system as such is well known in the arts. The light source for the digital projection system can comprise a UV or visible-light LED system or mercury-arc lamp. The projected image can be defined by a digital mirror device (DMD), laser-rastering or laser screening, liquid crystal display (LCD) or a liquid crystal on silicon-based illumination system.

(12) The stereo lithographic printing system 1 comprises a surface 4 defining a projection location. Often, such a surface will be a flat surface. The surface is attached to a displacement system 5. Often, such a displacement system 5 will comprise a so called Z-axis displacement table. This can move the surface 4 up and down, i.e., as indicated in FIG. 1.

(13) The stereo lithographic printing system 1 further comprises a container 6 for holding a polymerizable resin 7.

(14) The stereo lithographic printing system 1 further comprises a photo mask system 3. The photo mask system 3 comprises a frame holding a first mask 8 and in this embodiment also a second mask 8′. The photo mask system 3 further comprises an actuator 9 for translating the masks 8, 8′ in the X-Y plane (indicated). In an embodiment, the actuator has a micro translation setting for moving or translating a mask 8, 8′ just a minor amount, usually in the order of microns, and a macro translation setting, for instance for replacing mask 8 with mask 8′ and vice versa.

(15) ##########Mask 8, 8′ is a pattern permanently defined on a substrate. Possible substrate examples include soda lime, quartz, or Teflon. Alignment can be added, e.g., with a photomask translation table, a calibration spot on a photomask, a detector, and/or software matching spots.

(16) In FIG. 5, a further schematic embodiment of a stereo lithographic printing system 1 is depicted, showing details of an embodiment of the digital projection system 2. In this embodiment, a light source and collimating optics system 10 are provided to produce a collimated optical beam 14. The system 10 projects a beam 14 on a mirror 11 set here at 45 degrees with respect to the surface 4. In this embodiment, the mirror 11 is provided with a first pattern 12. Such a pattern 12 can be static. In an embodiment, the pattern 12 is dynamic, for instance comprising an LCD or DMD element allowing the pattern 12 to be changed.

(17) In FIG. 5, formation of an object 13 is indicated in an embodiment of the current system. In this embodiment, a next layer of the object is formed at projection surface 4′. This projection surface 4′ is in fact one end of the object 13 that is being formed. The displacement system 5 translates the object in the Z-direction, pulling it in fact out of the resin 7. When pulling the object in the Z-direction, new resin flows between the just-formed new layer of the object 13 and the (optically transparent) bottom 15 of resin container 6.

(18) In FIG. 6, a picture of an object is shown that was 3D printed. The object has a first pattern showing relatively broad walls. In the relatively broad walls, a second pattern of a lower resolution is printed. In FIGS. 7 and 8, pictures are shown of these second patterns.

(19) It will also be clear that the above description and drawings are included to illustrate some embodiments of the invention, and not to limit the scope of protection. Starting from this disclosure, many more embodiments will be evident to a skilled person. These embodiments are within the scope of protection and the essence of this invention and are obvious combinations of prior art techniques and the disclosure of this patent.

REFERENCE NUMBERS

(20) 1 stereolithographic printing assembly; 2 digital projection system; 3 photo mask system 4 printing surface; 5 displacement system (of an object that is printed) 6 container 7 polymerizable resin 8, 8′ mask 9 actuator 10 collimating optics system 11 mirror 12 first pattern 13 object being printed 14 projection beam. 15 optically transparent bottom of the resin container