US 12,491,685 B2
Mold thickness uniformity calibration method and apparatus
Alon Feldman, Kibbutz Kfar-Menachem (IL); Orit Raz, Hod Hasharon (IL); and Itamar Carmel, Tel Aviv (IL)
Assigned to Tritone Technologies Ltd., Rosh HaAyin (IL)
Appl. No. 18/026,353
Filed by Tritone Technologies Ltd., Rosh HaAyin (IL)
PCT Filed Sep. 30, 2021, PCT No. PCT/IL2021/051180
§ 371(c)(1), (2) Date Mar. 15, 2023,
PCT Pub. No. WO2022/070192, PCT Pub. Date Apr. 7, 2022.
Claims priority of provisional application 63/086,065, filed on Oct. 1, 2020.
Prior Publication US 2023/0373165 A1, Nov. 23, 2023
Int. Cl. B29C 64/393 (2017.01); B29C 33/38 (2006.01); B29C 64/112 (2017.01); B29C 64/188 (2017.01); B33Y 10/00 (2015.01); B33Y 50/02 (2015.01)
CPC B29C 64/393 (2017.08) [B29C 33/3842 (2013.01); B29C 64/112 (2017.08); B29C 64/188 (2017.08); B33Y 50/02 (2014.12); B33Y 10/00 (2014.12)] 12 Claims
OG exemplary drawing
 
1. A method of printing layers to form an object, using a plurality of printheads, to maintain a smooth surface over the course of printing by compensating for printing density differences between the printheads, the print heads each having a plurality of nozzles, the method comprising:
obtaining for each of said print heads a print head relative printing strength, the print head relative printing strength being relative to a weakest print head printing strength of all of said print heads, the print head relative printing strength being obtained by measuring thicknesses across a calibration layer that is printed, and being based on step changes at print head boundaries across said calibration layer;
calculating a print head compensation value for each print head, the print head compensation value being set to modify printing at each print head to print at a printing level of said weakest one of said plurality of print heads, said modified printing comprising switching off a number of nozzles in said print head, said number being defined by said respective compensation value, said nozzles to be switched off being selected using a stochastic process; and
carrying out printing of said layers to form an object, wherein each print head is operated according to said respective print head compensation value, thereby to provide smooth printing of further layers.
 
12. A method of pre-printing compensation for printing a plurality of layers to form an object using a plurality of printheads, each print head having a plurality of nozzles, said compensation being to achieve a smooth printed surface over the course of printing, by correcting for printing density differences between the printheads, the method comprising:
printing regions using each of said print heads;
measuring layer thicknesses of each of said regions printed, to find step changes at print head boundaries;
obtaining for each of said print heads a relative printing strength based on said step changes;
calculating a print head compensation value for each print head; and
applying respective print head compensation values for regulating printing by each of said print heads by switching off a number of nozzles in each respective print head, said number being defined by the corresponding compensation value, nozzles to be switched off being selected using a stochastic process, thereby to allow printing of respective layers of said plurality of layers by respectively remaining nozzles, such that said printing density differences between said print heads are compensated for to eliminate said step changes.