# US 12,529,977 B2 · Image forming apparatus and process cartridge > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,529,977 B2 - Document ID: US12529977B2 - Status: Granted - Kind: B2 - Application number: 18/735,919 - Filed: 2024-06-06 - Published: 2024-12-26 - Granted: 2026-01-20 - Earliest claimed: 2023-06-20 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Hirokazu Fujino; Motonari Ito; Naoki Fukushima; Masahiro Kurachi - Web page: https://patentgrep.com/patent/US12529977B2 ## CPC - G03G 15/0225: {provided with means for cleaning the charging member} - G03G 15/0233: {Structure, details of the charging member, e.g. chemical composition, surface properties} - G03G 15/0875: {cartridges having a box like shape} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract An image forming apparatus includes an image bearing member, a charging roller, a cleaning roller and a developing member. The charging roller is provided with a surface contacting a surface of the image bearing member and charges the surface of the image bearing member. The cleaning roller is provided with an elastic foam layer contacting the surface of the charging roller cleans the surface of the charging roller. A storage elastic modulus of the surface of the charging roller measured in a measuring environment of 23° C., 50% RH and a measuring frequency of 10 Hz is defined as E′C and a storage elastic modulus of the elastic foam layer of the cleaning roller is defined as E′CC. The storage elastic modulus E′C of the surface of the charging roller and the storage elastic modulus E′CC of the elastic foam layer of the cleaning roller satisfy E′C>E′CC. ## Claims ### Claim 1 An image forming apparatus, comprising: a rotatable image bearing member; a charging roller having a surface that contacts a surface of the image bearing member, and that is configured to be rotated in contact with the rotating image bearing member and to charge the surface of the image bearing member; a cleaning roller having an elastic foam layer that contacts the surface of the charging roller and that is configured to be rotated in contact with the rotating charging roller and to clean the surface of the charging roller; and a developing member that is configured to supply a developer to the surface of the image bearing member and to form a developer image thereon, wherein E′C>E′CC when E′C is a storage elastic modulus measured within a depth of 10 μm from the surface of the charging roller in a measuring environment of 23° C., 50% RH and a measuring frequency of 10 Hz and E′CC is a storage elastic modulus of the elastic foam layer of the cleaning roller measured in the measuring environment at the measuring frequency, and a Martens hardness of the surface of the charging roller is 15 to 40 N/mm2 when it reaches a pushing depth of 0.1 μm. ### Claim 2 (depends on 1) The image forming apparatus according to claim 1, wherein the charging roller includes an elastic layer forming the surface of the charging roller. ### Claim 3 (depends on 2) The image forming apparatus according to claim 2, wherein the elastic layer of the charging roller includes a matrix containing a first rubber and a plurality of domains dispersed in the matrix, the domains containing a second rubber and an electroconductive agent. ### Claim 4 (depends on 3) The image forming apparatus according to claim 3, wherein the matrix has a volume resistivity of more than 1.0×108 to equal or less than 1.0×1017 Ω·cm. ### Claim 5 (depends on 3) The image forming apparatus according to claim 3, wherein the domains have a volume resistivity of 1.0×101 to 1.0×104 Ω·cm. ### Claim 6 (depends on 1) The image forming apparatus according to claim 1, wherein the charging roller includes an elastic layer and a surface layer forming the surface of the charging roller. ### Claim 7 (depends on 1) The image forming apparatus according to claim 1, wherein the cleaning roller is rotated with rotation of the charging roller. ### Claim 8 (depends on 1) The image forming apparatus according to claim 1, wherein the storage elastic modulus is a value indicating a capability to hold a stress stored inside a rubber or a resin. ### Claim 9 (depends on 1) The image forming apparatus according to claim 1, wherein an adhesive force of an external additive externally added to the developer to the cleaning roller is larger than an adhesive force of the external additive to the charging roller. ### Claim 10 A process cartridge mountable to and demountable from a main assembly of an image forming apparatus that is configured to form a developer image by supplying a developer to a surface of a rotatable image bearing member and form an image on a recording material by transferring the developer image onto the recording material, the process cartridge comprising: the rotatable image bearing member; a charging roller having a surface that contacts a surface of the image bearing member, and that is configured to be rotated in contact with the rotating image bearing member and to charge the surface of the image bearing member; a cleaning roller having an elastic foam layer that contacts the surface of the charging roller and that is configured to be rotated in contact with the rotating charging roller and to clean the surface of the charging roller; and a developing member that is configured to supply a developer to the surface of the image bearing member and to form a developer image thereon, wherein E′C>E′CC when E′C is a storage elastic modulus measured within a depth of 10 μm from the surface of the charging roller in a measuring environment of 23° C., 50% RH and a measuring frequency of 10 Hz and E′CC is a storage elastic modulus of the elastic foam layer of the cleaning roller measured in the measuring environment at the measuring frequency, and a Martens hardness of the surface of the charging roller is 15 to 40 N/mm2 when it reaches a pushing depth of 0.1 μm. ### Claim 11 (depends on 10) The process cartridge according to claim 10, wherein the charging roller includes an elastic layer forming the surface of the charging roller. ### Claim 12 (depends on 11) The process cartridge according to claim 11, wherein the elastic layer includes a matrix containing a first rubber and a plurality of domains dispersed in the matrix, the domains containing a second rubber and an electroconductive agent. ### Claim 13 (depends on 12) The image forming apparatus according to claim 12, wherein the matrix has a volume resistivity of more than 1.0×108 to equal or less than 1.0×1017 Ω·cm. ### Claim 14 (depends on 12) The image forming apparatus according to claim 12, wherein the domains have a volume resistivity of 1.0×101 to 1.0×104 Ω·cm. ### Claim 15 (depends on 10) The process cartridge according to claim 10, wherein the charging roller includes an elastic layer and a surface layer forming the surface of the charging roller. ### Claim 16 (depends on 10) The process cartridge according to claim 10, wherein the cleaning roller is rotated with rotation of the charging roller. ### Claim 17 (depends on 10) The process cartridge according to claim 10, wherein the storage elastic modulus is a value indicating a capability to hold a stress stored inside a rubber or a resin. ### Claim 18 (depends on 10) The process cartridge according to claim 10, wherein an adhesive force of an external additive externally added to the developer to the cleaning roller is larger than an adhesive force of the external additive to the charging roller.