US 12,143,553 B2
Method and machine for digital printing with neutral colours
Jesus Francisco Barberan Latorre, Castelldefels (ES)
Appl. No. 17/614,250
Filed by Jesus Francisco Barberan Latorre, Castelldefels (ES)
PCT Filed Jun. 2, 2020, PCT No. PCT/ES2020/070363
§ 371(c)(1), (2) Date Nov. 24, 2021,
PCT Pub. No. WO2020/245481, PCT Pub. Date Dec. 10, 2020.
Claims priority of application No. 201930518 (ES), filed on Jun. 7, 2019; and application No. 193826039 (ES), filed on Jul. 16, 2019.
Prior Publication US 2022/0224803 A1, Jul. 14, 2022
Int. Cl. H04N 1/62 (2006.01); B41M 5/00 (2006.01); B41M 7/00 (2006.01); H04N 1/40 (2006.01)
CPC H04N 1/40012 (2013.01) [B41M 5/0023 (2013.01); B41M 7/0081 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A method for digital printing neutral colors in an image, which comprises:
using a single pass type digital printing machine comprising a print head;
providing a substrate for receiving digital printing;
providing a printing ink set comprising a cyan (C) printing ink, a magenta (M) printing ink, a yellow (Y) printing ink and a black (K) printing ink, and at least one light black (LR) printing ink having a first concentration of black pigment that is lower than a second concentration of the black (K) printing ink;
arranging the print head with the printing ink set such that the print head is adapted to eject the printing inks on the substrate;
adjusting a first printing design that includes a first amount of cyan (C) printing ink, a second amount of magenta (M) printing ink, and a third amount of yellow (Y) ink by substituting a fourth amount of black (K) printing ink for a selected one of the printing inks of the first design, thereby generating an adjusted printing design that includes the fourth amount of black (K) printing ink and corresponding amounts of two non-selected printing inks of the first printing design;
determining a first number of pixels of black (K) printing ink to be ejected in the adjusted printing design;
determining a second number of pixels of light black (LK) printing ink to be ejected based on the first number of pixels, wherein the second number of pixels is greater than the first number of pixels;
performing a digital printing in the image, on the substrate, based on the adjusted printing design and the second number of pixels, by means of ejecting the corresponding amounts of the two non-selected printing inks and the second number of pixels of light black (LK) printing ink, in areas of the substrate where visible defects due to print head misalignments would be noticed in the form of a change in tonality when the digital printing were to be performed ejecting only the cyan (c), magenta (M) or yellow (Y) printing inks.