# US 11,480,892 B2 · Developing device to form electrostatic latent images > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,480,892 B2 - Document ID: US11480892B2 - Status: Granted - Kind: B2 - Application number: 17/282,483 - Filed: 2019-09-24 - Published: 2021-11-18 - Granted: 2022-10-25 - Earliest claimed: 2018-10-12 - Assignees: Hewlett-Packard Development Company, L.P. - Applicants: Hewlett-Packard Development Company, L.P. - Inventors: Naoya Iwata - Web page: https://patentgrep.com/patent/US11480892B2 ## CPC - G03G 15/0891: {for conveying or circulating developer, e.g. augers} - G03G 15/0893: {in a closed loop within the sump of the developing device} - G03G 15/00: Apparatus for electrographic processes using a charge pattern (G03G16/00, G03G17/00 take precedence) - G03G 15/08: using a solid developer, e.g. powder developer - G03G 15/0844: {Arrangements for purging used developer from the developing unit} - G03G 15/0889: {for agitation or stirring} - G03G 15/0942: {with means for preventing toner scattering from the magnetic brush, e.g. magnetic seals} - G03G 2215/0838: Circulation of developer in a closed loop within the sump of the developing device - G03G 2215/085: Stirring member in developer container - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract An example device to develop an electrostatic latent includes first and second passages coupled to each other through first and second openings. A first stir-and-transport member located in the first passage includes a first helical blade to stir and transport a developer along the first passage in a first direction and to supply the developer to a developing roller. A second stir-and-transport member located in the second passage includes a second helical blade to stir and transport the developer along the second passage in a second direction. A developer discharge pipe is coupled to the developer container to communicate with a downstream side of the first passage. The first stir-and-transport member includes a first reverse helical blade having a pitch between approximately 0.5 times and 1.5 times the pitch of the first helical blade and located downstream of the first helical blade and disposed downstream of the second opening. ## Claims ### Claim 1 A device to develop an electrostatic latent image in an imaging apparatus, the device comprising: a developer container including first and second passages coupled to each other through first and second openings to form a circulation passage; a first stir-and-transport member located in the first passage and including a first helical blade to stir and transport a developer from the first opening to the second opening along the first passage in a first direction and to supply the developer to a developing roller; a second stir-and-transport member located in the second passage and including a second helical blade to stir and transport the developer from the second opening to the first opening along the second passage in a second direction; and a developer discharge pipe coupled to the developer container to communicate with a downstream side of the first passage, wherein the first stir-and-transport member includes a first reverse helical blade located downstream of the first helical blade and located downstream of the second opening, the first reverse helical blade comprising two or more reverse helical blades, and wherein the pitch of the first reverse helical blade is between approximately 0.5 times and 1.5 times the pitch of the first helical blade, the pitch being a distance between adjacent spirals of a particular one of the two or more reverse helical blades in a direction of an axis of rotation. ### Claim 2 (depends on 1) The device according to claim 1, wherein the pitch of the first helical blade at an end facing the first reverse helical blade is narrower than the pitch of the remaining portion of the first helical blade, and wherein the pitch of the first reverse helical blade is between approximately 0.5 times and 1.5 times the pitch of the first helical blade at the end facing the first reverse helical blade. ### Claim 3 (depends on 1) The device according to claim 1, wherein the developer discharge pipe has a developer outlet spaced from an end of the developer discharge pipe, and wherein the first stir-and-transport member includes: a third helical blade located adjacent to the first reverse helical blade on the opposite side of the first helical blade and located in the developer discharge pipe to transport the developer that has flown from the first passage into the developer discharge pipe toward the developer outlet, and a second reverse helical blade located adjacent to a downstream side of the third helical blade and located downstream of the developer outlet. ### Claim 4 (depends on 1) The device according to claim 1, wherein the developer container includes a filter as a means for pressurized air to escape from the developer container to the outside. ### Claim 5 (depends on 1) An imaging apparatus comprising the device according to claim 1. ### Claim 6 (depends on 1) The device according to claim 1, comprising a magnet disposed on an inner wall of the first passage facing the first reverse helical blade. ### Claim 7 (depends on 6) The device according to claim 6, wherein the magnet comprises a one-sided multipole magnetized magnet. ### Claim 8 (depends on 6) The device according to claim 6, wherein the magnet includes N and S poles alternately arranged along a longitudinal direction of the first stir-and-transport member. ### Claim 9 (depends on 6) The device according to claim 6, wherein the magnet is disposed on at least 50% of a gravitationally upper side of the inner periphery of the inner wall of the first passage facing the first reverse helical blade and 20% or less of a gravitationally lower side of the inner periphery of the inner wall of the first passage facing the first reverse helical blade. ### Claim 10 A method of manufacturing a developing device, the method comprising: forming a developer container that includes first and second passages coupled to each other through first and second openings to form a circulation passage; disposing in the first passage a first stir-and-transport member that includes a first helical blade to stir and transport a developer from the first opening to the second opening along the first passage in a first direction and to supply the developer to a developing roller; disposing in the second passage a second stir-and-transport member that includes a second helical blade to stir and transport the developer from the second opening to the first opening along the second passage in a second direction; and coupling a developer discharge pipe to the developer container to communicate with a downstream side of the first passage, wherein the first stir-and-transport member includes a first reverse helical blade located downstream of the first helical blade and disposed downstream of the second opening, the first reverse helical blade comprising two or more reverse helical blades, and wherein the pitch of the first reverse helical blade is between approximately 0.5 times and 1.5 times the pitch of the first helical blade, the pitch being a distance between adjacent spirals of a particular one of the two or more reverse helical blades in a direction of an axis of rotation. ### Claim 11 (depends on 10) The method according to claim 10, wherein the pitch of the first helical blade at an end facing the first reverse helical blade is narrower than a pitch of a remaining portion of the first helical blade, and wherein the pitch of the first reverse helical blade is between approximately 0.5 times and 1.5 times the pitch of the first helical blade at the end facing the first reverse helical blade. ### Claim 12 (depends on 10) The method according to claim 10, comprising disposing in the developer container a filter for pressurized air to escape from the developer container to the outside. ### Claim 13 (depends on 10) The method according to claim 10, comprising disposing a magnet on an inner wall of the first passage facing the first reverse helical blade. ### Claim 14 (depends on 13) The method according to claim 13, wherein the magnet comprises a one-sided multipole magnetized magnet. ### Claim 15 (depends on 13) The method according to claim 13, wherein the magnet is disposed on at least 50% of a gravitationally upper side of the inner periphery of the inner wall of the first passage facing the first reverse helical blade and 20% or less of a gravitationally lower side of the inner periphery of the inner wall of the first passage facing the first reverse helical blade.