Apparatus and methods for servicing 3D printers

• US 20060061613A1
• Filed: 11/30/2004
• Published: 03/23/2006
• Est. Priority Date: 09/21/2004
• Status: Active Grant

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: Z CORPORATION (A Holdings Corp.)
• Inventors: Kinsley, Joshua P., Fienup, William James, Hernandez, Andres Tomas, Zengerle, Walter H. III, Berlin, Andrew A.
• Granted Patent: US 7,824,001 B2
• Time in Patent Office: Days
• US Class Current: 347/19
• CPC Class Codes: B29C 64/112 using individual droplets, e.g. from jetting heads
• CPC Class Codes: B33Y 40/00 Auxiliary operations or equipment, e.g. for material handling
• CPC Class Codes: B41J 2/16532 by applying vacuum only
• CPC Class Codes: B41J 2/16538 with brushes or wiper blades perpendicular to the nozzle plate
• CPC Class Codes: B41J 2/16552 using cleaning fluids
• CPC Class Codes: B41J 2/16585 for paper-width or non-reciprocating print heads
• CPC Class Codes: B41J 2/1752 Mounting within the printer
• CPC Class Codes: B41J 29/393 Devices for controlling or analysing the entire machine ; Controlling or analysing mechanical parameters involving printing of test patterns
• CPC Class Codes: B41J 3/4073 Printing on three-dimensional objects not being in sheet or web form, e.g. spherical or cubic objects B41J3/283, B41J3/286 take precedence; building up a 3D object using individual droplets from jetting heads B29C64/112
• CPC Class Codes: H04N 1/6033 using test pattern analysis H04N1/6055 takes precedence

Abstract

The invention relates to apparatus and methods for producing three-dimensional objects and auxiliary systems used in conjunction with the aforementioned apparatus and methods. The apparatus and methods involve 3D printing and servicing of the equipment used in the associated 3D printer.

Claims

1. A method of creating a test pattern with a plurality of printheads of a three-dimensional printer, the method comprising:

defining an area on a build surface for receiving the test pattern;

selecting a reference printhead capable of printing with a high contrast;

printing a reference line with the reference printhead; and

printing a test line proximate to the reference line with at least one of the remaining printheads.

2. The method of claim 1, wherein the step of defining an area includes producing a contrast-enhancing sublayer on the build surface.

3. The method of claim 2, wherein producing the contrast-enhancing sublayer comprises:

printing the area in a solid, high contrast color using at least one printhead; and

overlaying the printed area with at least one unprinted layer of build material.

4. The method of claim 2, wherein the step of selecting a printhead comprises the steps of:

printing a target above the contrast-enhancing sublayer with each of the printheads;

comparing the targets to identify which target has a highest contrast relative to an unprinted area; and

selecting a printhead associated with the highest contrast target.

5. The method of claim 1, wherein each of the printheads prints with a liquid binder having a color selected from the group consisting of magenta, yellow, cyan, clear, and black.

6. The method of claim 1, wherein the steps of printing a reference line and printing a test line include printing a plurality of reference lines and printing a corresponding plurality of test lines.

7. The method of claim 1, wherein the steps of printing a reference line and printing a test line comprise:

printing a plurality of nominally identical line pairs parallel to a fast-axis travel of the printheads, each line pair comprising one reference line and one test line; and

printing a plurality of nominally identical line pairs perpendicular to the fast-axis travel of the printheads, each line pair comprising one reference line and one test line.

8. The method of claim 7, wherein each plurality of line pairs is arranged as an equally spaced linear array.

9. The method of claim 8, wherein each test line comprises a series of test bars, where each of the remaining printheads prints a central test bar that is nominally located at a distance from a corresponding reference line equal to ½

of a nominal array spacing of the reference lines.

10. The method of claim 9, wherein each remaining printhead prints a plurality of additional test bars that are incrementally displaced about the central test bar.

11. A test pattern for aligning a plurality of printheads in a three-dimensional printer, the test pattern comprising:

a plurality of substantially evenly spaced solid reference lines; and

a plurality of test lines disposed in an alternating pattern with the plurality of reference lines, wherein each of the test lines comprises at least one bar of a non-reference color.

12. The test pattern of claim 11, wherein the plurality of lines is oriented substantially parallel to a fast-axis printhead travel and a second plurality of lines is oriented substantially perpendicular to the fast-axis printhead travel.

13. A method of determining correction factors for aligning a plurality of printheads, the method comprising:

printing a test pattern on a build surface;

generating a set of electrical signals representative of the test pattern;

analyzing the electrical signals to determine a harmonic content thereof at at least one frequency; and

determining correction factors based on the harmonic content of the electrical signals.

14. The method of claim 13, wherein the step of generating an electrical signal comprises:

illuminating the test pattern; and

measuring reflectance of the test pattern at predetermined locations.

15. The method of claim 14, wherein the step of analyzing the electrical signals comprises determining the harmonic content of the signals at a predetermined frequency by application of at least one of an analog filter and a digital filter.

16. The method of claim 15, wherein the correction factor is near a nominal test bar displacement for which a lowest value of the selected harmonic is determined.

17. The method of claim 16, wherein the correction factor is determined by locating a minimum value of an analytical curve that has been fitted to (representative of) the set of harmonic values.

18. The method of claim 16, wherein the correction factors are determined from a set of third harmonic values.

19. The method of claim 16, wherein the correction factors are determined from a set of first harmonic values.