# US 9,519,234 B2 · Carrier, two-component developer, supplemental developer, image forming method, 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 9,519,234 B2 - Document ID: US9519234B2 - Status: Granted - Kind: B2 - Application number: 14/410,711 - Filed: 2013-06-26 - Published: 2015-06-04 - Granted: 2016-12-13 - Earliest claimed: 2012-06-27 - Assignees: Ricoh Company, Ltd. - Applicants: Hiroyuki Kishida; Shigenori Yaguchi; Hiroshi Tohmatsu; Koichi Sakata; Hitoshi Iwatsuki; Toyoaki Tano - Inventors: Hiroyuki Kishida; Shigenori Yaguchi; Hiroshi Tohmatsu; Koichi Sakata; Hitoshi Iwatsuki; Toyoaki Tano - Web page: https://patentgrep.com/patent/US9519234B2 ## CPC - G03G 9/0839: {Treatment of the magnetic components; Combination of the magnetic components with non-magnetic materials (G03G9/0834 takes precedence)} - G03G 9/1075: {Structural characteristics of the carrier particles, e.g. shape or crystallographic structure} - G03G 9/1139: {Inorganic components of coatings} - G03G 21/18: using a processing cartridge {, whereby the process cartridge comprises at least two image processing means in a single unit} - H01F 1/01: of inorganic materials (H01F1/44 takes precedence) - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES ## Abstract There is provided a carrier including magnetic core particles; and a coating layer on a surface of each of the magnetic core particles, wherein the coating layer contains electroconductive particles; wherein the electroconductive particles are electroconductive particles in which white inorganic pigments are coated with phosphorus-doped tin or tungsten-doped tin; and wherein a dope ratio of phosphorus or tungsten to tin in the phosphorus-doped tin or tungsten-doped tin is 0.010 to 0.100. ## Claims ### Claim 1 A carrier comprising: magnetic core particles; and a coating layer on a surface of each of the magnetic core particles, wherein the coating layer comprises electroconductive particles, wherein the electroconductive particles are electroconductive particles in which a white inorganic pigment is coated with phosphorus-doped tin or tungsten-doped tin, wherein a dope ratio of phosphorus or tungsten to tin in the phosphorus-doped tin or the tungsten-doped tin is 0.010 to 0.100, and wherein a particle diameter of the white inorganic pigment in the electroconductive particles R1 (μm) and a particle diameter of the electroconductive particles R2 (μm) satisfy the following expression: 1.4≦R2/R1≦2.6. ### Claim 2 (depends on 1) The carrier according to claim 1, wherein the white inorganic pigment is aluminum oxide, titanium dioxide, or barium sulfate. ### Claim 3 (depends on 1) The carrier according to claim 1, wherein a powder specific resistivity of the electroconductive particles is 3 Ω·cm to 20 Ω·cm. ### Claim 4 (depends on 1) The carrier according to claim 1, wherein a volume average particle diameter of the electroconductive particles is 0.35 μm to 0.65 μm. ### Claim 5 (depends on 1) The carrier according to claim 1, wherein a volume average particle diameter of the carrier is 32 μm to 40 μm. ### Claim 6 (depends on 1) The carrier according to claim 1, wherein a volume resistivity of the carrier is 8 Log Ω·cm to 14 Log Ω·cm. ### Claim 7 (depends on 1) A two-component developer comprising: the carrier according to claim 1; and a toner. ### Claim 8 (depends on 7) The two-component developer according to claim 7, wherein the toner is a color-toner. ### Claim 9 (depends on 1) A supplemental developer comprising: a carrier; and a toner, wherein 2 parts by mass to 50 parts by mass of the toner is contained relative to 1 part by mass of the carrier, and wherein the carrier is the carrier according to claim 1. ### Claim 10 (depends on 7) A process cartridge comprising: a developer being the two-component developer according to claim 7; an electrostatic latent image bearing member; and a developing unit configured to develop with a developer an electrostatic latent image formed on the electrostatic latent image bearing member to thereby form a visible image. ### Claim 11 (depends on 7) An image forming method comprising: forming an electrostatic latent image on an electrostatic latent image bearing member; developing the electrostatic latent image with a developer to thereby form a visible image; transferring the visible image to a recording medium; and fixing the visible image transferred to the recording medium, wherein the developer is the two-component developer according to claim 7. ### Claim 12 (depends on 9) A process cartridge comprising: a developer being the supplemental developer according to claim 9; an electrostatic latent image bearing member; and a developing unit configured to develop with a developer an electrostatic latent image formed on the electrostatic latent image bearing member to thereby form a visible image. ### Claim 13 (depends on 9) An image forming method comprising: forming an electrostatic latent image on an electrostatic latent image bearing member; developing the electrostatic latent image with a developer to thereby form a visible image; transferring the visible image to a recording medium; and fixing the visible image transferred to the recording medium, wherein the developer is the supplemental developer according to claim 9.