US 12,346,037 B2
Image forming apparatus
Hiroki Tanaka, Kanagawa (JP); Naoya Sawamura, Kanagawa (JP); and Akihisa Matsukawa, Tokyo (JP)
Assigned to Canon Kabushiki Kaisha, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Mar. 21, 2024, as Appl. No. 18/612,419.
Application 18/612,419 is a continuation of application No. PCT/JP2022/036697, filed on Sep. 30, 2022.
Claims priority of application No. 2021-165724 (JP), filed on Oct. 7, 2021; and application No. 2022-127522 (JP), filed on Aug. 10, 2022.
Prior Publication US 2024/0241464 A1, Jul. 18, 2024
Int. Cl. G03G 15/02 (2006.01); G03G 5/087 (2006.01); G03G 15/00 (2006.01); G03G 21/00 (2006.01)
CPC G03G 15/0266 (2013.01) [G03G 15/0216 (2013.01); G03G 15/0233 (2013.01); G03G 15/025 (2013.01); G03G 15/751 (2013.01); G03G 21/0011 (2013.01); G03G 21/0064 (2013.01); G03G 5/087 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An image forming apparatus comprising:
a photosensitive drum that is rotatable and includes a support and a surface layer constituting a surface of the photosensitive drum;
a first charging member configured to form a first charging portion by coming into contact with the surface of the photosensitive drum and to charge the surface of the photosensitive drum in the first charging portion;
a development member configured to supply a developer to the surface of the photosensitive drum in a facing portion where the development member faces the surface of the photosensitive drum;
a second charging member configured to charge the surface of the photosensitive drum, which has been charged by the first charging member, in a second charging portion where the second charging member faces the surface of the photosensitive drum, wherein the second charging portion is located downstream of the first charging portion and upstream of the facing portion in a rotation direction of the photosensitive drum;
a first charging voltage applying unit configured to apply a first charging voltage to the first charging member;
a second charging voltage applying unit configured to apply a second charging voltage to the second charging member; and
a control unit configured to control the first charging voltage applying unit and the second charging voltage applying unit,
wherein the surface layer of the photosensitive drum has a volume resistivity of 1.0×109 ohm centimeters (Ω·cm) or more and 1.0×1014 Ω·cm or less, and, in the second charging voltage applying unit applying the second charging voltage, the control unit controls the second charging voltage applying unit such that a second potential difference formed between the second charging member and the surface of the photosensitive drum charged by the first charging member is equal to or higher than a discharge starting voltage.