Edge smoothness with low resolution projected images for use in solid imaging

• US 20060239588A1
• Filed: 04/01/2005
• Published: 10/26/2006
• Est. Priority Date: 04/01/2005
• Status: Active Grant

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Inventors: Manners, Chris R., Dunne, Patrick, Hull, Charles W., Partanen, Jouni P., Sperry, Charles R., Scott, Suzanne M., McNamara, Dennis F.
• Granted Patent: US 7,758,799 B2
• Time in Patent Office: Days
• US Class Current: 382/285
• CPC Class Codes: B29C 64/106 using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 50/00 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes

Abstract

A solid imaging apparatus and method employing sub-pixel shifting in multiple exposures of the digitally light projected image of a cross-section of a three-dimensional object on a solidifiable liquid medium. The multiple exposures provide increased resolution, preserving image features in a three-dimensional object and smoothing out rough or uneven edges that would otherwise be occur using digital light projectors that are limited by the number of pixels in an image projected over the size of the image. Algorithms are used to select pixels to be illuminated within the boundary of each image projected in the cross-section being exposed.

Claims

1. A method for forming a three-dimensional object layer-by-layer comprising the steps of:

a. receiving three-dimensional CAD data of an object to be built;

b. processing the three-dimensional CAD data to receive slice data representative of cross-sectional layers of the object;

c. converting the slice data into bit-map data;

d. delivering a photocurable solidifiable liquid medium to an imaging area via a radiation transparent carrier;

e. projecting an image representative of cross-sectional image data from a radiation source through the radiation transparent carrier to selectively illuminate pixels in an image plane in a first exposure to selectively solidify the liquid medium;

f. displacing the cross-sectional image data by a subpixel amount; and

g. projecting an image representative of the displaced cross-sectional image to selectively illuminate pixels in the image plane in the second exposure to selectively solidify the liquid medium.

2. The method according to claim 1 further comprising repeating steps e-g multiple times until a complete object cross-section is formed.

3. The method according to claim 1 further comprising displacing the cross-sectional image data by rotating a transparent plate positioned between the radiation source and the image plane through an angle in one of an X- or Y-plane to shift the cross-sectional image data equally.

4. The method according to claim 1 further comprising displacing the cross-sectional image data by rotating a transparent plate positioned between the radiation source and the image plane independently through an angle in the X-plane and the Y-plane to shift the cross-sectional image data equally.

5. The method according to claim 1 further comprising displacing the cross-sectional image data by rotating a first transparent plate in the X-plane and a second transparent plate in the Y-plane, the transparent plates being positioned between the radiation source and the image plane.

6. The method according to claim 1 further comprising displacing the cross-sectional image data by moving the radiation source.

7. The method according to claim 1 further comprising displacing the cross-sectional image data by moving the imaging area.

8. The method according to claim 7 further comprising the solidified liquid medium in the imaging plane being supported by a moveable platform on which the three-dimensional object is built.

9. The method according to claim 1 further comprising a radiation source being selected from the group consisting of a UV radiation source and a visible light source.

10. The method according to claim 1 further comprising using an algorithm to select pixels for illumination so that only those pixels are illuminated that have a fill pixel within a boundary of the image in the cross-section being exposed.

11. The method according to claim 1 further comprising using an algorithm to select pixels for illumination so that only those pixels are illuminated that have a desired percentage of the fill pixel within a boundary of the image in the cross-section being exposed.

12. The method according to claim 1 further comprising using an algorithm to select pixels for illumination so that are only those pixels are illuminated that have the boundary of the image pass therethrough at a selected angle in the cross-section being exposed.

13. The method according to claim 11 further comprising the algorithm including a selected angle at which the boundary of the image passes through a pixel in a selection process of pixels to be illuminated in the cross-section being exposed.

14. The method according to claim 2 further comprising using an algorithm to select out pixels for non-illumination so that only those pixels are illuminated in a subsequent illumination in areas that have not previously been illuminated in the cross-section being exposed.

63. The method according to claim 1 further comprising displacing the cross-sectional image by moving mirrors positioned between the radiation source and the transparent transport means.

15. In an apparatus for forming a three-dimensional object layer-by-layer by solid imaging comprising in combination:

a. a frame;

b. transparent transport means moveably mounted to the frame;

c. a radiation source mounted to the frame for projecting a full image one cross-section at a time of a three-dimensional object to be built through the transparent transport means;

d. a source of solidifiable liquid medium in fluid flow communication with the transparent transport means effective to apply the solidifiable liquid medium to the transparent transport means;

e. a support platform moveably mounted to the frame to support the three-dimensional object as it is built layer-by-layer;

f. control means mounted to the frame effective to control movement of the transparent transport means and the support platform and to control illumination of selected pixels by the radiation source in an image exposure of a cross-section of the three-dimensional object on the solidifiable liquid medium;

g. processing means in data flow communication with the control means to receive CAD data and convert the CAD data into sliced data representative of cross-sections of the three-dimensional object; and

h. a supixel image placement device connected to the frame effective to move a projected image of the three-dimensional object in at least one additional exposure of a previously exposed cross-section of the three-dimensional image to obtain a high resolution image and a three-dimensional object that has all features properly positioned and smooth edges.

16. The apparatus according to claim 15 further comprising the radiation source being selected one from the group consisting of a UV radiation source and a visible light source.

17. The apparatus according to claim 16 further comprising the radiation source being a digital light projector.

18. The apparatus according to claim 15 further comprising the transparent transport means being an endless belt.

19. The apparatus according to claim 15 further comprising the transparent transport means further being a flexible film.

20. The apparatus according to claim 15 further comprising the transparent transport means being a plate.

21. The apparatus according to claim 15 further comprising the control means being a microprocessor that selects pixels to be illuminated in the exposure of a cross-section of the three-dimensional object on the solidifiable liquid by use of an algorithm.

22. The apparatus according to claim 21 further comprising the microprocessor using an algorithm to select pixels for illumination so that only those pixels are illuminated that have a full pixel within a boundary of the image in the cross-section being exposed.

23. The apparatus according to claim 22 further comprising the microprocessor using an algorithm to select pixels for illumination so that only those pixels are illuminated that have a desired percentage of the fill pixel within a boundary of the image in the cross-section being exposed.

24. The apparatus according to claim 16 further comprising the sub-pixel image displacement device being a rotatable transparent plate positioned between the light source and the transparent transport means effective to displace the data representative of a cross-section through an angle in one of an X- or Y-plane to shift the cross-sectional image data equally.

25. The apparatus according to claim 16 the sub-pixel image displacement device being a rotatable transparent plate positioned between the light source and the transparent transport means effective to move independently through an angle in the X-plane and the Y-plane to shift cross-sectional image data actually.

26. The apparatus according to claim 16 further comprising the sub-pixel image displacement device being a fist transparent plate rotatable in the X-plane and a second transparent plate rotatable in the Y-plane positioned between the light source and the transparent transport means.

27. The apparatus according to claim 16 further comprising the sub-pixel image displacement device being means to move the light source a fraction of a pixel.

28. The apparatus according to claim 16 further comprising the sub-pixel image displacement device being means to move the support platform on which the thee-dimensional object is being built a fraction of a pixel.

29. The apparatus according to claim 15 further comprising the sub-pixel image displacement device being mirrors positioned between the light source and the transparent transport means to move the image a fraction of a pixel.

30. The apparatus according to claim 21 further comprising the microprocessor using an algorithm to select pixels for illumination so that only those pixels are illuminated that have the boundary of the image pass therethrough at a selected angle in the cross-section being exposed.

31. The apparatus according to claim 23 further comprising the algorithm including a selected angle at which the boundary of the image passes through a pixel in a selection process of pixels to be illuminated in the cross-section being exposed.

32. The apparatus according to claim 21 further comprising the microprocessor using an algorithm to select out pixels for non-illumination so that only those pixels are illuminated in a subsequent illumination in areas that have not previously been illuminated in the cross-section being exposed.

43. The apparatus according to claim 32 further comprising the control means being a microprocessor that selects pixels to be illuminated in the exposure of a cross-section of the three-dimensional object on the solidifiable liquid by use of an algorithm.

44. The apparatus according to claim 43 further comprising the microprocessor using an algorithm to select pixels for illumination so that only those pixels are illuminated that have a fill pixel within a boundary of the image in the cross-section being exposed.

45. The apparatus according to claim 43 further comprising the microprocessor using an algorithm to select pixels for illumination so that only those pixels are illuminated that have a desired percentage of the full pixel within a boundary of the image in the cross-section being exposed.

46. The apparatus according to claim 43 further comprising the microprocessor using an algorithm to select pixels for illumination so tat are only those pixels are illuminated that have the boundary of the image pass therethrough at a selected angle in the cross-section being exposed.

47. The apparatus according to claim 45 further comprising the algorithm including a selected angle at which the boundary of the image passes through a pixel in a selection process of pixels to be illuminated in the cross-section being exposed.

48. The apparatus according to claim 43 further comprising using an algorithm to select out pixels for non-illumination so that only those pixels are illuminated in a subsequent illumination in areas that have not previously been illuminated in the cross-section being exposed.

33. In an apparatus for forming a three-dimensional object layer-by-layer by solid imaging comprising in combination:

a. a frame;

b. a source of solidifiable liquid medium effective to supply the solidifiable liquid medium to form a layer of medium to be solidified with an exposed surface;

c. a radiation source mounted to the frame for projecting onto the surface of the liquid medium a cross-section at a time of a three-dimensional object to be built effective to solidify each cross-section of the three-dimensional object;

d. a support platform moveably mounted to the frame to support the three-dimensional object as it is built layer-by-layer;

e. control means mounted to the frame effective to control recoating of an exposed layer of the liquid medium with a fresh layer of the solidifiable liquid medium, movement of the support platform, and to control illumination of selected pixels by the radiation source in an image exposure of a cross-section of the three-dimensional object on the solidifiable liquid medium;

f. processing means in data flow communication with die control means to receive three-dimensional CAD data and convert the CAD data into sliced data representative of cross-sections of the three-dimensional object; and

g. a sub-pixel image placement device connected to the frame effective to move a projected image of the three-dimensional object in at least one additional exposure of a previously exposed cross-section of the three-dimensional image to obtain a high resolution image and a three-dimensional object that bas all features properly positioned and smooth edges.

34. The apparatus according to claim 33 further comprising the radiation source being selected one from the group consisting of a UV radiation source and a visible light source.

35. The apparatus according to claim 34 further comprising the radiation source being a digital light projector.

36. The apparatus according to claim 33 further comprising a recoater moveable mounted to the frame to recoat an exposed layer of the liquid medium with a fresh layer of the solidifiable liquid medium.

37. The apparatus according to claim 33 further comprising the sub-pixel image displacement device being a rotatable transparent plate positioned between the radiation source and the layer of liquid medium to be solidified effective to displace the data representative of a cross-section through an angle in one of an X- or Y-plane to shift the cross-sectional image data equally.

38. The apparatus according to claim 33 the sub-pixel image displacement device being a rotatable transparent plate positioned been the radiation source and the layer of liquid medium to be solidified effective to move independently through an angle in the X-plane and the Y-plane to shift cross-sectional image data equally.

39. The apparatus according to claim 33 further comprising the sub-pixel image displacement device being a first transparent plate rotatable in the X-plane and a second transparent plate rotatable in the Y-plane positioned between the radiation source and the layer of liquid medium to be solidified.

40. The apparatus according to claim 33 further comprising the sub-pixel image displacement device being means to move the radiation source a fraction of a pixel.

41. The apparatus according to claim 33 further comprising the sub-pixel image displacement device being means to move the support platform on which the three-dimensional object is being built a fraction of a pixel.

42. The apparatus according to claim 33 further comprising the sub-pixel image displacement device being mirrors positioned between the radiation source and the layer of liquid medium to move the image projected onto the liquid medium a fraction of a pixel.

49. A method for forming a three-dimensional object layer-by-layer comprising the steps of:

a. receiving three-dimensional CAD data of an object to be built;

b. processing the three-dimensional CAD data to receive slice data representative of cross-sectional layers of the object;

c. converting the slice data into bit-map data;

d. delivering a photocurable solidifiable liquid medium to an imaging area;

e. projecting an image representative of cross-sectional image data from a radiation source onto the photocurable solidifiable liquid in the imaging area to selectively illuminate pixels in an image plane in a first exposure to selectively solidify the liquid medium;

f. displacing the cross-sectional image data by a sub-pixel amount; and

g. projecting an image representative of the displaced cross-sectional image to selectively illuminate pixels onto the photocurable solidifiable liquid in the image plane in a second exposure to selectively solidify the liquid medium;

50. The method according to claim 49 further comprising repeating steps e-g multiple times until a complete object cross-section is formed.

51. The method according to claim 49 further comprising displacing the cross-sectional image data by rotating a transparent plate positioned between the radiation source and the image plane through an angle in one of an X- or Y-plane to shift the cross-sectional image data equally.

52. The method according to claim 49 further comprising displacing the cross-sectional image data by rotating a transparent plate positioned between the radiation source and the image plane independently through an angle in the X-plane and the Y-plane to shift the cross-sectional image data equally.

53. The method according to claim 49 further comprising displacing the cross-sectional image data by rotating a first transparent plate in the X-plane and a second transparent plate in the Y-plane, the transparent plates being positioned between the radiation source and the image plane.

54. The method according to claim 49 further comprising displacing the cross-sectional image data by moving the radiation source.

55. The method according to claim 49 further comprising displacing the cross-sectional image data by moving the imaging area.

56. The method according to claim 55 further comprising the imaging area being supported by a moveable platform on which the three-dimensional object is built.

57. The method according to claim 49 further comprising a light source being selected from the group consisting of a UV radiation source and a visible light source.

58. The method according to claim 49 further comprising using an algorithm to select pixels for illumination so that only those pixels are illuminated that have a full pixel within a boundary of the image in the cross-section being exposed.

59. The method according to claim 49 further comprising using an algorithm to select pixels for illumination so that only those pixels are illuminated that have a desired percentage of the full pixel within a boundary of the image in the cross-section being exposed.

60. The method according to claim 49 further comprising using an algorithm to select pixels for illumination so that are only those pixels are illuminated that have the boundary of the image pass therethrough at a selected angle in the cross-section being exposed.

61. The method according to claim 59 further comprising the algorithm including a selected angle at which the boundary of the image passes through a pixel in a selection process of pixels to be illuminated in the cross-section being exposed.

62. The method according to claim 49 further comprising using an algorithm to select out pixels for non-illumination so that only those pixels are illuminated in a subsequent illumination in areas that have not previously been illuminated in the cross-section being exposed.

64. The method according to claim 49 further comprising displacing the cross-sectional image by moving mirrors positioned between the radiation source and the image plane.