US 12,265,338 B2
Image forming apparatus having controller to control voltage to first and second corona chargers
Tadashi Fukuda, Tokyo (JP); and Hiroshi Kusukawa, Chiba (JP)
Assigned to Canon Kabushiki Kaisha, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Oct. 27, 2023, as Appl. No. 18/496,249.
Claims priority of application No. 2022-173089 (JP), filed on Oct. 28, 2022.
Prior Publication US 2024/0142889 A1, May 2, 2024
Int. Cl. G03G 15/02 (2006.01); G03G 15/00 (2006.01)
CPC G03G 15/0266 (2013.01) [G03G 15/0216 (2013.01); G03G 15/0291 (2013.01); G03G 15/5004 (2013.01); G03G 2215/026 (2013.01)] 7 Claims
OG exemplary drawing
 
1. An image forming apparatus comprising:
an image bearing member that is rotatable;
a charging device that charges the image bearing member by a plurality of corona chargers including a first corona charger and a second corona charger that is disposed downstream of the first corona charger with respect to a rotational direction of the image bearing member, the first corona charger including a first discharge electrode and a first grid electrode, the second corona charger including a second discharge electrode and a second grid electrode;
a first voltage applying portion that applies a voltage to the first grid electrode;
a second voltage applying portion that applies a voltage to the second grid electrode; and
a controller that controls the first voltage applying portion and the second voltage applying portion,
wherein the controller performs a first adjusting operation and thereafter the controller performs a second adjusting operation,
wherein in the first adjusting operation, a voltage applied to the first grid electrode by the first voltage applying portion is set so that a surface potential of the image bearing member charged by the first corona charger becomes a first target value, the voltage applied to the first grid electrode by the first voltage applying portion being set in a state that a voltage is applied to the second discharge electrode and a voltage whose absolute value is less than the first target value is applied to the second grid electrode by the second voltage applying portion, and
wherein in the second adjusting operation, a voltage applied to the second grid electrode by the second voltage applying portion is set so that a surface potential of the image bearing member charged by the first corona charger and the second corona charger becomes a second target value whose absolute value is greater than the first target value, the voltage applied to the second grid electrode by the second voltage applying portion being set in a state that a voltage is applied to the first discharge electrode and the voltage set by the first adjusting operation is applied to the first grid electrode by the first voltage applying portion.