US 11,731,446 B2
Method for multi-color direct thermal printing and printer for multi-color direct thermal printing
Uwe Jannasch, Dortmund (DE)
Assigned to BIZERBA SE & CO. KG, Balingen (DE)
Filed by Bizerba SE & Co. KG, Balingen (DE)
Filed on Dec. 13, 2021, as Appl. No. 17/548,619.
Claims priority of application No. 20218028 (EP), filed on Dec. 31, 2020.
Prior Publication US 2022/0203742 A1, Jun. 30, 2022
Int. Cl. B41J 2/335 (2006.01); B41M 5/34 (2006.01)
CPC B41M 5/34 (2013.01) [B41J 2/335 (2013.01); B41M 2205/04 (2013.01); B41M 2205/42 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A method for operating a direct thermal printer for printing on direct thermal printing paper, the direct thermal printing paper comprising at least one thermo-reactive layer, at least two colors being capable of being formed in the at least one thermo-reactive layer, the thermo-reactive layer being configured to form a first color upon a first temperature being supplied, and configured to form a second color upon a second temperature being supplied, the second temperature being higher than the first temperature, the direct thermal printing paper being movable by the direct thermal printer along a paper path from a paper receptacle to a paper outlet, and the direct thermal printer comprising a printhead, which comprises heat sources that are arranged next to one another transversely to the paper path and are electrically controllable and which selectively apply heat to the direct thermal printing paper, the direct thermal printer further comprising a control device configured to heat a selected plurality of the heat sources of the printhead to a printing temperature, the printing temperature being equal to or higher than the second temperature, the method comprising:
line by line moving, with a transport roller, the direct thermal printing paper past the printhead in a printing direction; and
in each line of the direct thermal printing paper, electrically heating selected heat sources of the heat sources of the printhead,
wherein at points at which the second color is to be formed on the direct thermal printing paper, a plurality of adjacent heat sources of the selected heat sources is heated to the printing temperature, and
wherein at points at which the first color is to be formed on the direct thermal printing paper, a portion of a plurality of the adjacent heat sources is heated to the printing temperature, and the other portion of the adjacent heat sources is not heated.