US 11,703,788 B2
Image forming apparatus with detection of state of exposure unit
Atsushi Sano, Tokyo (JP)
Assigned to Canon Kabushiki Kaisha, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Sep. 2, 2021, as Appl. No. 17/465,317.
Claims priority of application No. 2020-153953 (JP), filed on Sep. 14, 2020.
Prior Publication US 2022/0082972 A1, Mar. 17, 2022
Int. Cl. G03G 15/00 (2006.01)
CPC G03G 15/5016 (2013.01) [G03G 15/55 (2013.01)] 9 Claims
OG exemplary drawing
 
1. An image forming apparatus for forming a toner image on a recording material, said image forming apparatus comprising:
a photosensitive member;
an exposure unit, provided with a light source and a rotatable polygon mirror including a plurality of reflecting surfaces for scanning a light beam emitted from said light source, and configured to expose said photosensitive member with the light beam according to image information;
a developing roller configured to supply toner to said photosensitive member and develop an electrostatic latent image formed on said photosensitive member by said exposure unit and to form the toner image;
an image bearing belt;
a transfer roller configured to transfer the toner image formed on said photosensitive member to said image bearing belt;
at least two density sensors configured to sense density of the toner image formed on said image bearing belt; and
a controller configured to determine an end of lifetime of said exposure unit based on a detecting result of density of the toner image detected by said two density sensors at a first timing, and a detecting result of density of the toner image detected by said two density sensors at a second timing after the first timing.