# US 12,761,576 B2 · Charging members > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,761,576 B2 - Document ID: US12761576B2 - Status: Granted - Kind: B2 - Application number: 18/996,447 - Filed: 2022-07-29 - Published: 2026-01-15 - Granted: 2026-10-13 - Earliest claimed: 2022-07-29 - Assignees: Hewlett-Packard Development Company, L.P. - Applicants: Hewlett-Packard Development Company, L.P. - Inventors: Taehyun Kim; Ara Kim; Yunhyung Bae; Se Young Yoon; Youngphil Ji; Yong-Sang Ryu - Web page: https://patentgrep.com/patent/US12761576B2 ## CPC - G03G 15/0233: {Structure, details of the charging member, e.g. chemical composition, surface properties} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract An example charging member has a conductive support; a conductive elastic body layer on the conductive support; and a surface layer on the conductive elastic body layer, wherein the surface layer includes a binder resin and particles, wherein the surface layer includes a first portion of the binder resin having the particles and a second portion of the binder resin having an absence of the particles, and wherein the second portion has a peak height (Spk)/core roughness depth (Sk) of less than 0.2. ## Claims ### Claim 1 A charging member, comprising: a conductive support; a conductive elastic body layer on the conductive support; and a surface layer on the conductive elastic body layer, wherein the surface layer consists of a binder resin, particles having an average particle size of from 21 microns to about 35 microns, and optionally a conducting agent, and wherein the surface layer includes a first portion of the binder resin having the particles and a second portion of the binder resin having an absence of the particles, and wherein the second portion has a peak height (Spk)/core roughness depth (Sk) of less than 0.2. ### Claim 2 (depends on 1) The charging member of claim 1, wherein the average particle size of the particles ranges from 22 μm to about 35 μm. ### Claim 3 (depends on 1) The charging member of claim 1, wherein the particles are present in an amount of from about 1 part by weight to about 50 parts by weight, based on 100 parts by weight of the binder resin. ### Claim 4 (depends on 1) The charging member of claim 1, wherein the binder resin is a urethane resin. ### Claim 5 (depends on 1) The charging member of claim 1, wherein a Spk/Sk of the first portion/the Spk/Sk of the second portion is >10. ### Claim 6 (depends on 1) The charging member of claim 1, wherein the average particle size of the particles ranges from 22 microns to about 27 microns. ### Claim 7 (depends on 1) The charging member of claim 1, wherein the particles comprise acrylic resin particles, and wherein the acrylic resin particles are polymethyl methacrylate (PMMA) particles or polymethyl acrylate (PMAA) particles. ### Claim 8 (depends on 1) The charging member of claim 1, wherein the charging member is a charging roller. ### Claim 9 A cartridge for an electrophotographic imaging apparatus, the cartridge comprising: a conductive support; a conductive elastic body layer on the conductive support; and a surface layer on the conductive elastic body layer, wherein the surface layer consists of a binder resin, particles having an average particle size of from 21 microns to about 35 microns, and optionally a conducting agent, wherein the surface layer includes a first portion of the binder resin having the particles disposed in the binder resin and a second portion of the binder resin having an absence of the particles disposed in the binder resin, and wherein a peak height (Spk)/core roughness depth (Sk) of the first portion/a Spk/Sk of the second portion is>10. ### Claim 10 (depends on 9) The cartridge of claim 9, wherein the Spk/Sk of the second portion is less than 0.2. ### Claim 11 (depends on 9) The cartridge of claim 9, wherein a sum of the Spk of the first portion and the Sk of the first portion is greater than 8. ### Claim 12 (depends on 9) The cartridge of claim 9, wherein: the binder resin is selected from the group consisting of a fluorine resin, a polyamide resin, an acrylic resin, a nylon resin, a urethane resin, a silicone resin, a butyral resin, styrene-ethylene/butylene-olefin copolymer (SEBC), olefin-ethylene/butylene-olefin copolymer (CEBC), and a combination thereof; and the particles are present in an amount of from about 5 parts by weight to about 20 parts by weight, based on 100 parts by weight of the binder resin. ### Claim 13 An electrophotographic imaging apparatus, comprising: an electrophotographic photoconductor; and a charging member to contact the electrophotographic photoconductor to charge the electrophotographic photoconductor, the charging member comprising: a conductive support; a conductive elastic body layer on the conductive support; and a surface layer on the conductive elastic body layer, the surface layer consisting of a binder resin, particles having an average particle size of from 21 microns to about 35 microns, and optionally a conducting agent, wherein the surface layer has a first portion including the particles and a second portion with an absence of the particles, and wherein: a reduced peak height (Spk)/core roughness depth (Sk) of the first portion/a Spk/Sk of the second portion is >10; and the second portion has a Spk/Sk of less than 0.2. ### Claim 14 (depends on 13) The electrophotographic imaging apparatus of claim 13, further comprising: an exposure unit to form an electrostatic latent image on the surface layer; a developing unit to develop the electrostatic latent image to a visible image; and a transfer unit to transfer the visible image onto an image receiving member.