US 12,145,359 B2
Liquid ejection apparatus and control method
Yoshihiro Hamada, Kanagawa (JP); Tomoki Ishiwata, Kanagawa (JP); So Aizawa, Kanagawa (JP); and Keiji Tomizawa, Kanagawa (JP)
Assigned to Canon Kabushiki Kaisha, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Jul. 6, 2022, as Appl. No. 17/858,162.
Claims priority of application No. 2021-113311 (JP), filed on Jul. 8, 2021.
Prior Publication US 2023/0007995 A1, Jan. 12, 2023
Int. Cl. B41J 2/045 (2006.01); B41J 2/14 (2006.01)
CPC B41J 2/04508 (2013.01) [B41J 2/0458 (2013.01); B41J 2/14072 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A liquid ejection apparatus comprising:
a liquid ejection head including a plurality of element boards each comprising (1) a conversion element that generates energy required to eject liquid, (2) a first protection layer that blocks contact between the conversion element and the liquid, (3) a second protection layer that partially covers the first protection layer and functions as a first electrode, (4) a second electrode that is electrically connected to the first electrode through the liquid, and (5) an ejection port that ejects the liquid; and
a control unit configured to control a potential difference between the first electrode and the second electrode in printing to a predetermined value by changing at least one of potentials of the first electrode and the second electrode, wherein the control unit sets the potential difference based on at least one of a condition and a configuration of the liquid ejection head, wherein the control unit is capable of setting the potential difference for each of the element boards;
a count unit configured to count the number of ejected droplets of the liquid for each of the element boards;
a deriving unit configured to derive a difference in the number of ejected droplets between the element board with the largest number of ejected droplets and each of the element boards other than the element board with the largest number of ejected droplets; and
a determination unit configured to determine whether or not the difference in the number of ejected droplets is equal to or larger than a predetermined threshold for all of the element boards other than the element board with the largest number of ejected droplets,
wherein the control unit sets the potential of the second electrode to a value obtained by performing subtraction on a current value, for the element board for which a determination result provided by the determination unit is true.