# US 5,707,326 A · Charging roller with blended ceramic layer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,707,326 A - Document ID: US5707326A - Status: Granted - Kind: A - Application number: 08/699,086 - Filed: 1996-08-16 - Granted: 1998-01-13 - Earliest claimed: 1992-11-09 - Assignees: American Roller Company - Inventors: Bruce E. Hyllberg - Web page: https://patentgrep.com/patent/US5707326A ## CPC - H05B 3/0095: {Heating devices in the form of rollers (heated by induction H05B6/145)} - G03G 15/0233: {Structure, details of the charging member, e.g. chemical composition, surface properties} - H05B 3/141: {Conductive ceramics, e.g. metal oxides, metal carbides, barium titanate, ferrites, zirconia, vitrous compounds} - H05B 3/46: heating conductor mounted on insulating base - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract A charging roller for use in a xerographic copying machine includes a cylindrical roller core, and a ceramic layer formed by plasma spraying a blend of an insulating ceramic material and a semiconductive ceramic material in a ratio which is selected to control an RC circuit time constant of the ceramic layer in response to an applied voltage differential. The ceramic layer is sealed with a solid, low viscosity sealer, such as Carnauba wax, to protect the ceramic layer from moisture penetration. ## Claims ### Claim 1 A charging roller for assisting in charging toner in a machine, the charging roller comprising: a cylindrical roller core; a ceramic layer disposed around the cylindrical roller core; wherein the ceramic layer is a plasma-sprayed blend of an insulating ceramic material and a semiconductive ceramic material; and wherein the insulating ceramic material and the semiconductive ceramic material are blended in a ratio to control an RC circuit time constant relating to the ceramic layer. ### Claim 2 (depends on 1) The roller of claim 1, wherein the ceramic layer includes a plurality of sublayers. ### Claim 3 (depends on 2) The roller of claim 2, wherein the ceramic layer has a thickness in a range from 0.006 to 0.010 inches inclusive. ### Claim 4 (depends on 3) The roller of claim 3, further comprising a sealant penetrating and protecting the ceramic layer from moisture contamination, said sealant also being selected to control an RC circuit time constant relating to electrical response of the sealed ceramic layer to the applied voltage differential. ### Claim 5 (depends on 4) The roller of claim 4, wherein the insulating ceramic material is alumina or zirconia; and wherein the semiconductive ceramic material is titanium dioxide or chromium oxide. ### Claim 6 (depends on 4) The roller of claim 4, wherein the sealant is a solid material. ### Claim 7 (depends on 5) The roller of claim 5, wherein the sealant is a Carnauba wax. ### Claim 8 (depends on 1) The roller of claim 1, wherein the ceramic layer has a thickness in a range from 0.006 to 0.010 inches inclusive. ### Claim 9 (depends on 8) The roller of claim 8, wherein the ceramic layer is formed in a plurality of sublayers which form the ceramic layer. ### Claim 10 (depends on 9) The roller of claim 9, further comprising a sealant penetrating and protecting the ceramic layer from moisture contamination, said sealant also being selected to control an RC circuit time constant relating to electrical response of the sealed ceramic layer to the applied voltage differential. ### Claim 11 (depends on 10) The roller of claim 10, wherein the insulating ceramic material is alumina or zirconia; and wherein the semiconductive ceramic material is titanium dioxide or chromium oxide. ### Claim 12 (depends on 10) The roller of claim 10, wherein the sealant is a solid material. ### Claim 13 (depends on 10) The roller of claim 10, wherein the sealant is a Carnauba wax. ### Claim 14 (depends on 1) The roller of claim 1, further comprising a sealant penetrating and protecting the ceramic layer from moisture contamination, said sealant also being selected to control an RC circuit time constant relating to electrical response of the sealed ceramic layer to the applied voltage differential. ### Claim 15 (depends on 14) The roller of claim 14, wherein the ceramic layer includes a plurality of sublayers which form the ceramic layer. ### Claim 16 (depends on 14) The roller of claim 14, wherein the ceramic layer has a thickness in a range from 0.006 to 0.010 inches inclusive. ### Claim 17 (depends on 14) The roller of claim 14, wherein the insulating ceramic material is alumina or zirconia; and wherein the semiconductive ceramic material is titanium dioxide or chromium oxide. ### Claim 18 (depends on 14) The roller of claim 14, wherein the sealant is a solid material. ### Claim 19 (depends on 18) The roller of claim 18, wherein the sealant is a Carnauba wax. ### Claim 20 A charging roller for assisting in charging toner in a machine, the charging roller comprising: a cylindrical roller core; a ceramic layer disposed around the cylindrical roller core; wherein the ceramic layer includes an insulating ceramic material and a semiconductive ceramic material; and wherein the ceramic layer is formed by plasma spraying a blend of the insulating ceramic material and the semiconductive ceramic material to form the ceramic layer around the roller core, while controlling a selected RC circuit time constant for the ceramic layer. ### Claim 21 (depends on 20) The roller of claim 20, wherein the plasma spraying is performed in a number of repetitions to apply successive sublayers which form the ceramic layer. ### Claim 22 (depends on 20) The roller of claim 20, wherein the plasma-sprayed ceramic layer is sealed with a sealant being selected to control a selected RC circuit time constant for the sealed ceramic layer. ### Claim 23 (depends on 22) The roller of claim 22, wherein the sealant is a solid material. ### Claim 24 (depends on 23) The roller of claim 23, wherein the sealant is a Carnauba wax. ### Claim 25 (depends on 20) The roller of claim 20, wherein the plasma-sprayed ceramic layer is sealed with a sealant being selected to control a selected RC circuit time constant for the sealed ceramic layer. ### Claim 26 (depends on 25) The roller of claim 25, wherein the plasma spraying step is performed in a number of repetitions to apply successive sublayers which form the ceramic layer. ### Claim 27 (depends on 26) The roller of claim 26, wherein the sealant is a solid material. ### Claim 28 (depends on 27) The roller of claim 27, wherein the sealant is a Carnauba wax. ### Claim 29 (depends on 20) The roller of claim 20, wherein the insulating ceramic material is alumina or zirconia; and wherein the semiconductive material is titanium dioxide or chromium oxide. ### Claim 30 (depends on 29) The roller of claim 29, wherein the plasma-sprayed ceramic layer is sealed with a sealant being selected to control a selected RC circuit time constant for the sealed ceramic layer. ### Claim 31 (depends on 29) The roller of claim 29, wherein the plasma spraying is performed in a number of repetitions to apply successive sublayers which form the ceramic layer. ### Claim 32 (depends on 29) The roller of claim 29, wherein the sealant is a solid material. ### Claim 33 (depends on 32) The roller of claim 32, wherein the sealant is a Carnauba wax. ### Claim 34 (depends on 29) The roller of claim 29, wherein the ceramic layer has a thickness in a range from 0.006 to 0.010 inches inclusive. ### Claim 35 (depends on 34) The roller of claim 34, wherein the plasma spraying is performed in a number of repetitions to apply successive sublayers which form the ceramic layer. ### Claim 36 (depends on 35) The roller of claim 35, wherein the plasma-sprayed ceramic layer is sealed with a sealant being selected to control a selected RC circuit time constant for the sealed ceramic layer. ### Claim 37 (depends on 36) The roller of claim 36, wherein the sealant is a solid material. ### Claim 38 (depends on 37) The roller of claim 37, wherein the sealant is a Carnauba wax. ### Claim 39 (depends on 1) The roller of claim 1, wherein: the ceramic layer is a plasma-sprayed blend of a first material and a second material, said first material comprising the insulating ceramic material and the semiconductive ceramic material in a first ratio and said second material comprising the insulating ceramic material and the semiconductive ceramic material in a second ratio. ### Claim 40 (depends on 39) The roller of claim 39, wherein the insulating ceramic material is alumina and the semiconductive ceramic material is titanium dioxide. ### Claim 41 (depends on 40) The roller of claim 40, wherein the ceramic layer includes a plurality of sublayers. ### Claim 42 (depends on 40) The roller of claim 40, wherein the ceramic layer has a thickness in a range from 0.006 to 0.010 inches inclusive. ### Claim 43 (depends on 20) The roller of claim 20, wherein: the ceramic layer is formed by plasma spraying a blend of a first material and a second material, said first material being a mixture of the insulating ceramic material and the semiconductive material in a first ratio and said second material being a mixture of the insulating ceramic material and the semiconductive ceramic material in a second ratio. ### Claim 44 (depends on 43) The roller of claim 43, wherein the insulating ceramic material is alumina and the semiconductive ceramic material is titanium dioxide. ### Claim 45 (depends on 44) The roller of claim 44, wherein the plasma spraying step is performed in a number of repetitions to apply successive sublayers which form the ceramic layer. ### Claim 46 (depends on 44) The roller of claim 44, wherein the ceramic layer has a thickness in a range from 0.006 to 0.010 inches inclusive.