# US 2018/0024468 A1 · Developing apparatus, process cartridge, and image forming apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0024468 A1 - Document ID: US20180024468A1 - Status: Published application - Kind: A1 - Application number: 15/652,534 - Filed: 2017-07-18 - Published: 2018-01-25 - Earliest claimed: 2016-07-22 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Hiroki Tanaka; Motonari Ito; Satoshi Sunahara; Akihisa Matsukawa; Toshiki Okamura - Web page: https://patentgrep.com/patent/US20180024468A1 ## CPC - G03G 15/0889: {for agitation or stirring} - G03G 15/0921: {Details concerning the magnetic brush roller structure, e.g. magnet configuration} - G03G 21/1814: {Details of parts of process cartridge, e.g. for charging, transfer, cleaning, developing (G03G21/1835 takes precedence)} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract In an axial direction of a developing sleeve that bears magnetic developer on an outer circumferential surface thereof, ends of a sheet-shaped stirring member that stirs the magnetic developer in a container frame to move the magnetic developer toward the developing sleeve are disposed on an outer side of a region in a magnetic field region generated by a magnet roller disposed on an inner side of the developing sleeve, the region having a magnetic field strength equal to or larger than a predetermined magnetic flux density at which the magnetic developer can be borne on the surface of the developing sleeve. ## Claims ### Claim 1 A developing apparatus comprising: a developing sleeve that bears magnetic developer on an outer circumferential surface thereof; a magnet roller disposed on an inner side of the developing sleeve; a container frame in which the magnetic developer is stored; and a stirring unit provided in the container frame and including a rotation shaft disposed in a direction along an axial direction of the developing sleeve, and a sheet-shaped stirring member attached to the rotation shaft to move with the rotation of the rotation shaft, the stirring unit stirring the magnetic developer in the container frame by the movement of the stirring member to move the magnetic developer toward the developing sleeve, wherein, in the axial direction of the developing sleeve, ends of the stirring member are disposed on an outer side of a region in a magnetic field region generated by the magnet roller, the region having a magnetic field strength equal to or larger than a predetermined magnetic flux density at which the magnetic developer can be borne on the surface of the developing sleeve. ### Claim 2 (depends on 1) The developing apparatus according to claim 1, wherein the predetermined magnetic flux density is a magnetic flux density which is 70% of an average magnetic flux density of a magnetic field in a portion corresponding to a region, on an image bearing member, in which an electrostatic latent image can be formed during image formation. ### Claim 3 (depends on 1) The developing apparatus according to claim 1, wherein the magnetic developer is magnetic mono-component developer. ### Claim 4 (depends on 1) The developing apparatus according to claim 1, wherein the developing sleeve develops an electrostatic latent image on an image bearing member in a state of being in contact with the image bearing member during image formation. ### Claim 5 (depends on 1) The developing apparatus according to claim 1, wherein the stirring member has a first end serving as a fixed end fixed to the rotation shaft, and a second end serving as a free end. ### Claim 6 (depends on 5) The developing apparatus according to claim 5, wherein the second end of the stirring member can make contact with the outer circumferential surface of the developing sleeve. ### Claim 7 (depends on 6) The developing apparatus according to claim 6, wherein a region of the developing sleeve that can make contact with the stirring member in an attitude during use is positioned below the position of the rotation shaft of the developing sleeve. ### Claim 8 (depends on 1) The developing apparatus according to claim 1, wherein the stirring member is a single member. ### Claim 9 (depends on 1) The developing apparatus according to claim 1, wherein the container frame includes: a developing chamber in which the developing sleeve is disposed; a storage chamber in which the stirring member is disposed and toner is stored; and a partition portion having an opening through which the developing chamber and the storage chamber communicate with each other. ### Claim 10 (depends on 9) The developing apparatus according to claim 9, wherein the storage chamber is disposed below the developing chamber in an attitude during use. ### Claim 11 (depends on 1) The developing apparatus according to claim 1, wherein a rotation direction of the stirring unit is opposite to a rotation direction of the developing sleeve. ### Claim 12 (depends on 1) The developing apparatus according to claim 1, wherein the rotation shaft is disposed below the developing sleeve in an attitude during use. ### Claim 13 (depends on 1) The developing apparatus according to claim 1, wherein the stirring member has such a shape that a width thereof in an axial direction of the rotation shaft changes in a direction orthogonal to the axial direction of the rotation shaft, and at least ends of the stirring member at a portion having a largest width in the axial direction of the rotation shaft is positioned on an outer side of a region having the magnetic field strength equal to or larger than the predetermined magnetic flux density. ### Claim 14 (depends on 1) The developing apparatus according to claim 1, wherein the magnetic developer remaining on an image bearing member after a developer image formed on the image bearing member by a developing operation is transferred is collected from the image bearing member by the developing sleeve. ### Claim 15 (depends on 1) The developing apparatus according to claim 1, end surfaces of the stirring member are disposed on an outer side of end surfaces of the magnet roller in the axial direction of the developing sleeve. ### Claim 16 (depends on 1) The developing apparatus according to claim 1, wherein a developing bias applied to the developing sleeve is a DC bias. ### Claim 17 (depends on 1) The developing apparatus according to claim 1, the developing apparatus is detachably attached to an image forming apparatus that forms an image. ### Claim 18 (depends on 1) A process cartridge comprising: an image bearing member on which an electrostatic latent image is formed; and the developing apparatus according to claim 1, wherein the process cartridge is detachably attached to an image forming apparatus that forms an image. ### Claim 19 (depends on 1) An image forming apparatus comprising: an image bearing member on which an electrostatic latent image is formed; and the developing apparatus according to claim 1. ### Claim 20 (depends on 18) An image forming apparatus comprising: the process cartridge according to claim 18; and a replenishment cartridge that replenishes the container frame with magnetic developer. ### Claim 21 A developing apparatus comprising: a developing sleeve that bears magnetic developer on an outer circumferential surface thereof; a magnet roller disposed on an inner side of the developing sleeve; a container frame in which the magnetic developer is stored; and a stirring unit provided in the container frame and including a rotation shaft disposed in a direction along an axial direction of the developing sleeve, and a sheet-shaped stirring member attached to the rotation shaft to move with the rotation of the rotation shaft, the stirring unit stirring the magnetic developer in the container frame by the movement of the stirring member to move the magnetic developer toward the developing sleeve, wherein ends of the stirring member are disposed on an outer side of ends of the magnet roller in the axial direction of the developing sleeve. ### Claim 22 A developing apparatus comprising: a developing sleeve that bears magnetic developer on an outer circumferential surface thereof; a magnet roller disposed on an inner side of the developing sleeve; a container frame in which the magnetic developer is stored; and a stirring unit provided in the container frame and including a rotation shaft disposed in a direction along an axial direction of the developing sleeve, and a sheet-shaped stirring member attached to the rotation shaft to move with the rotation of the rotation shaft, the stirring unit stirring the magnetic developer in the container frame by the movement of the stirring member to move the magnetic developer toward the developing sleeve, wherein a length of the stirring member in the axial direction of the developing sleeve is greater than a length of the magnet roller, and when seen from a direction orthogonal to the axial direction of the developing sleeve, a region corresponding to the magnet roller is present on an inner side of a region corresponding to the stirring member.