Adjustment of a halftoning threshold

• US 10,488,846 B2
• Filed: 01/30/2015
• Issued: 11/26/2019
• Est. Priority Date: 01/30/2015
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Donovan, David H., Wright, Jacob T., Fung, Erica M.
• Primary Examiner(s): Bahta, Kidest
• Application Number:
  US15/539,973
• Publication Number:
  US 20180011475A1
• Time in Patent Office: 1,761 Days
• CPC Class Codes: B22F 10/14 by jetting of binder onto a bed of metal powder
• CPC Class Codes: B22F 10/85 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B22F 12/53 Nozzles
• CPC Class Codes: B22F 12/80 Plants, production lines or modules
• CPC Class Codes: B22F 12/90 Means for process control, e.g. cameras or sensors
• CPC Class Codes: B29C 64/112 using individual droplets, e.g. from jetting heads
• CPC Class Codes: B29C 64/386 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: B29C 64/393 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• 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
• CPC Class Codes: G05B 19/4099 Surface or curve machining, making 3D objects, e.g. desktop manufacturing
• CPC Class Codes: G05B 2219/49023 3-D printing, layer of powder, add drops of binder in layer, new powder
• CPC Class Codes: H04N 1/405 Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

Adjustment of a halftoning threshold can, in an example implementation, include assigning a relative energy value, relative to a reference energy value, to a location of a build area and adjusting a halftoning threshold based on the relative energy value.

Claims

1. A system of adjustment of a halftoning threshold, comprising:

a determine engine to determine an actual energy value of a first location of a plurality of locations of a build area;

an assign engine to assign a reference energy value to the first location;

a relative engine to assign a relative energy value to a second location of the plurality of locations based on the reference energy value; and

an adjust engine to adjust a halftoning threshold for the second location based on the relative energy value.

2. The system of claim 1, comprising a comparison engine to compare an incoming three-dimensional (3-D) object model pixel value corresponding to the second location to the adjusted halftone threshold to determine element placement.

3. The system of claim 1, wherein the first location is a center of the build area.

4. The system of claim 1, wherein the first location is a hottest location of the build area.

5. The system of claim 1, wherein the first location is a portion of the build area monitored by a temperature control system.

6. The system of claim 1, wherein the first location is a portion of the build area where a nozzle of a plurality of nozzles with a comparatively highest drop weight deposits an absorber material.

16. The system of claim 1, wherein the adjust engine adjusts the halftoning threshold to make uniform a delivery of energy to the first and second locations based on a quantity of energy absorbing material delivered.

17. The system of claim 1, wherein the relative engine assigns the relative energy value based on an actual energy value of the second location relative to the actual energy value of the first location.

18. The system of claim 1, wherein the assign engine assigns the reference energy value to the first location based on the actual energy value of the first location.

7. A non-transitory computer readable medium storing instructions executable by a processing resource to cause a computer to:

generate a spatial energy map of a portion of a build area;

generate a nozzle drop weight map of the portion of the build area;

generate a two-dimensional (2-D) matrix of a relative energy value received at each of a plurality of addressable locations of the portion of the build area based on the spatial energy map and the nozzle drop weight map; and

adjust a halftoning threshold for an addressable location of the plurality of addressable locations based on the 2-D matrix.

8. The non-transitory computer readable medium of claim 7, wherein the addressable location is a location of the build area corresponding to a voxel in a layer of a 3-D object model.

9. The non-transitory computer readable medium of claim 7, wherein the addressable location is a location of the build area corresponding to a region of voxels in a layer of a 3-D object model.

10. The non-transitory computer readable medium of claim 7, wherein the spatial energy map is generated based on a measurement captured from the portion of the build area.

11. The non-transitory computer readable medium of claim 7, wherein the spatial energy map is generated based on a measurement of a test part created in the portion of the build area.

12. The non-transitory computer readable medium of claim 7, the instructions executable by the processing resource to cause the computer to adjust the halftoning threshold include instructions to apply an offset to each incoming pixel of a 3-D object model during error diffusion.

19. The non-transitory computer readable medium of claim 7, wherein the halftoning threshold is adjusted to make uniform a delivery of energy to the plurality of addressable locations based on a quantity of energy absorbing material delivered.

13. A method of adjustment of a halftoning threshold for three-dimensional (3-D) printing, comprising:

determining an amount of energy received at each of a plurality of addressable locations of a portion of a build area of a 3-D printer;

generating a relative energy value for each of the plurality of addressable locations, relative to a reference energy value, based on the determined amount of energy received; and

adjusting a halftone matrix threshold of the plurality of addressable locations based on the relative energy value for each of the plurality of addressable locations.

14. The method of claim 13, wherein adjusting the halftone matrix includes multiplying each element of the halftone matrix by the generated relative energy value of a corresponding addressable location of the plurality of addressable locations, and wherein the matrix corresponds to the entire build area.

15. The method of claim 13, wherein adjusting the halftone matrix includes selecting a pre-computed adjusted halftone matrix value for a measured addressable location, and wherein the matrix corresponds to the size of the measured addressable location.

20. The method of claim 13, wherein the halftoning threshold matrix is adjusted to make uniform a delivery of energy to the plurality of addressable locations based on a quantity of energy absorbing material delivered.