Simultaneous multiple layer curing in stereolithography

• US 6,366,825 B1
• Filed: 04/12/1999
• Issued: 04/02/2002
• Est. Priority Date: 10/30/1990
• Status: Expired due to Fees

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Inventors: Earl, Jocelyn M., VanDorin, Stacie L., Vorgitch, Thomas J., Smalley, Dennis R., Hull, Charles W., Manners, Chris R., Bedal, Bryan J. L.
• Primary Examiner(s): Grant, William
• Assistant Examiner(s): CABRERA, ZOILA E
• Application Number:
  US09/289,842
• Time in Patent Office: 1,086 Days
• Field of Search: 700/120, 700/118, 700/119, 264/401
• US Class Current: 700/120
• CPC Class Codes: B29C 64/135 the energy source being concentrated, e.g. scanning lasers or focused light sources
• CPC Class Codes: B29C 64/40 Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof
• CPC Class Codes: B33Y 50/00 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: G05B 2219/49013 Deposit layers, cured by scanning laser, stereo lithography SLA, prototyping
• CPC Class Codes: G06T 17/00 Three dimensional [3D] modelling, e.g. data description of 3D objects
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

A method and apparatus for making high resolution objects by stereolithography utilizing low resolution materials which are limited by their inability to form unsupported structures of desired thinness and/or their inability to form coatings of desired thinness. Data manipulation techniques, based on layer comparisons, are used to control exposure in order to delay solidification of the material on at least portions of at least some cross-sections until higher layers of material are deposited so as to allow down-facing features of the object to be located at a depth in the building material which is equal to or exceeds a minimum cure depth that can effectively be used for solidifying these features. Similar data manipulations are used to ensure minimum reliable coating thicknesses exist, above previously solidified material, before attempting solidification of a next layer. In addition, horizontal comparison techniques are used to provide enhanced cross-sectional data for use in forming the object. Further, several techniques for automatically performing Z-error correction through the manipulation of a three-dimensional object representation are described.

Claims

1. An improved method of stereolithographically forming a three-dimensional object from layers of a material capable of physical transformation upon exposure to synergistic stimulation comprising the steps of receiving data descriptive of cross-sections of the three-dimensional object, each cross-section representing one layer of the object to be formed, forming layers of said material, and selectively exposing said layers to synergistic stimulation according to said data descriptive of said cross-sections to build up the three-dimensional object layer-by-layer, the improvement comprising the steps of:

modifying data descriptive of at least a portion of at least one cross-section by shifting said data from a first cross-section to a second cross-section which is located at least one layer thickness from said first cross-section; and

using said modified data in forming said three-dimensional object.

2. The method of claim 1 further comprising the step of:

further modifying data descriptive of said second cross-section by differencing any other data on the second cross-sections from and on any intermediate cross-sections between the first and second cross-section from the shifted data;

using said further modified data in forming said three-dimensional object.

3. The method of claim 2 wherein said step of modifying comprises shifting data descriptive of at least a portion of a down-facing feature.

4. The method of claim 3 wherein said step of shifting of at least a portion of a down-facing feature comprises exposing said shifted portion with an amount of synergistic stimulation necessary to achieve a cure depth of approximately the amount shifted plus one layer thickness.

5. The method of claim 4 wherein the synergistic stimulation is electromagnetic radiation and the material is a photopolymer which solidifies in response to said radiation.

6. The method of claim 4 wherein the shifting is one layer thickness and the exposure applied to the shifted portion is approximately two layer thicknesses.

7. The method of claim 4 wherein the shifting is at least two layer thicknesses and the exposure applied to the shifted portion is at least approximately three layer thicknesses.

8. The method of claim 2 wherein said step of modifying comprises shifting data descriptive of a non-down-facing feature such that at least a two layer thickness separation occurs between at least a portion of the modified cross-sectional data on said second cross-section and any modified data located directly below it.

9. The method of claim 8 wherein the synergistic stimulation is electromagnetic radiation and the material is a photopolymer which is solidifies in response to said radiation.

10. The method of claim 8 wherein the shifting of data is at least one layer thicknesses.

11. The method of claim 10 wherein the shifting of data is at least two layer thicknesses.

12. An improved method of stereolithographically forming a three-dimensional object from layers of a material capable of physical transformation upon exposure to synergistic stimulation comprising the steps of receiving data descriptive of cross-sections of the three-dimensional object, forming layers of said material, and selectively exposing said layers to synergistic stimulation according to said data to build up the three-dimensional object layer-by-layer, the improvement comprising the steps of:

modifying data descriptive of at least portions of three cross-sections by shifting said data from a first cross-section through at least one intermediate cross-section to a second cross-section which is located at least one layer thickness from said first cross-section and by differencing data on the second cross-section and on said at least one intermediate cross-section between said first and second cross-sections from the shifted data; and

using said modified data in forming said three-dimensional object.

13. An improved method of stereolithographically forming a three-dimensional object from layers of a material capable of physical transformation upon exposure to synergistic stimulation comprising the steps of receiving data descriptive of cross-sections of the three-dimensional object, each cross-section representing one layer of the object to be formed, forming layers of said material, and selectively exposing said layers to synergistic stimulation according to said data descriptive of said cross-sections to build up the three-dimensional object layer-by-layer, the improvement comprising the steps of:

modifying data descriptive of at least a portion of a second cross-section by copying said data from a first cross-section to the second cross-section which is located at least one layer thickness from said first cross-section and determining how much of said copied data should be utilized in exposing the second cross-section by intersecting the copied data with any other data on the second cross-section and keeping only that portion which is common; and

using said modified data in forming said three-dimensional object.

14. The method of claim 13 wherein the first cross-section is located below the second cross-section and the shifted data is down-facing skin data.

15. The method of claim 14 wherein the down-facing skin data on the first cross-section is final down-facing skin data that was shifted from a cross-section below the first cross-section prior to copying the down-facing data from the first cross-section to the second cross-section.

16. The method of claim 13 wherein the first cross-section is located above the second cross-section and the shifted data is up-facing skin data.

17. The method of claim 13 wherein a non-flat priority embodiment is used to determine appropriate regions to misplace in regions where the object thickness is less than the MSD.

18. The method of claim 13 wherein at least some regional boundaries, which are not exterior boundaries of a cross-section, are not used in exposing the cross-section of the object.

19. An improved method of stereolithographically forming a three-dimensional object from layers of a material capable of physical transformation upon exposure to synergistic stimulation comprising the steps of receiving data descriptive of cross-sections of the three-dimensional object, each cross-section representing one layer of the object to be formed, forming layers of said material, and selectively exposing said layers to synergistic stimulation according to said data descriptive of said cross-sections to build up the three-dimensional object layer-by-layer, the improvement comprising the steps of:

modifying data descriptive of at least a portion of at least one cross-section by copying said data from a first cross-section to a second cross-section which is located at least one layer thickness from said first cross-section; and

using said modified data in forming said three-dimensional object.

20. An improved method of forming a three-dimensional object from layers of a material comprising the steps of supplying data descriptive of the object, forming layers of the object, and automatically adhering the layers of the object together upon formation to build up the three-dimensional object layer-by-layer, the improvement comprising the steps of:

modifying data descriptive of at least a portion of at least one layer of the object either by at least partially copying data or at least partially shifting data associated with at least one cross-section to data associated with at least a second cross-section; and

using said modified data in forming said three-dimensional object.

21. The method of claim 20 wherein the copied or shifted data results in a reduction in Z-error when the object is formed.

22. The method of claim 20 wherein the copied or shifted data results in a reduction in slice layer rounding error when the object is formed.

23. The apparatus of claim 20 wherein the copied or shifted data results in a reduction in Z-error when the object is formed.

24. The apparatus of claim 20 wherein the copied or shifted data results in a reduction in slice layer rounding error when the object is formed.

25. An improved apparatus for forming a three-dimensional object from layers of a material comprising means for supplying data descriptive of the object, means for forming layers of the object and automatically adhering the layers of the object together upon formation to build up the three-dimensional object layer-by-layer, the improvement comprising;

means for modifying data descriptive of at least a portion of at least one layer of the object either by at least partially copying data or at least partially shifting data associated with at least one cross-section to data associated with at least a second cross-section; and

means for using said modified data in forming said three-dimensional object.