# US 12,603,213 B2 · Inductor core, electronic pen core body portion, electronic pen, and input device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,603,213 B2 - Document ID: US12603213B2 - Status: Granted - Kind: B2 - Application number: 17/764,860 - Filed: 2020-09-28 - Published: 2022-10-27 - Granted: 2026-04-14 - Earliest claimed: 2019-09-30 - Assignees: KYOCERA Corporation - Applicants: KYOCERA Corporation - Inventors: Hitomi Ochiai - Web page: https://patentgrep.com/patent/US12603213B2 ## CPC - H01F 17/045: {with core of cylindric geometry and coil wound along its longitudinal axis, i.e. rod or drum core} - G06F 3/03545: {Pens or stylus} - G06F 3/046: by electromagnetic means - H01F 1/344: {Ferrites, e.g. having a cubic spinel structure (X2+O)(Y23+O3), e.g. magnetite Fe3O4} - H01F 27/255: made from particles (H01F27/26 takes precedence) - H01F 1/34: non-metallic substances, e.g. ferrites - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract An inductor core includes a tubular shaped or pillar shaped magnetic main body comprising a magnetic material. The magnetic main body includes: an inclined portion including an inclined surface with an outer circumferential surface of a truncated cone having an outer diameter increasing from one end of the magnetic main body toward the other end; and a straight body portion that is coaxial with the inclined portion and extends from the other end toward the one end, the straight body portion being connected to the inclined portion and including an outer peripheral surface with an outer circumferential surface of a circle tubular body or a cylindrical column body. A skewness Rsk of an outer peripheral surface of the straight body portion located near the inclined portion is smaller than a skewness Rsk of an outer peripheral surface of the straight body portion located near the other end. ## Claims ### Claim 1 An inductor core comprising a magnetic main body having a tubular shape or a pillar shape and comprised of a magnetic material, wherein the magnetic main body includes: an inclined portion including an inclined surface that constitutes an outer circumferential surface of a truncated cone having an outer diameter increasing from one end of the magnetic main body toward the other end; and a straight body portion that is coaxial with the inclined portion and extends from the other end toward the one end, the straight body portion being connected to the inclined portion and including an outer peripheral surface that constitutes an outer circumferential surface of a circular tubular body or a cylindrical column body, and a skewness Rsk of an outer peripheral surface of the straight body portion located at or around the inclined portion is smaller than a skewness Rsk of an outer peripheral surface of the straight body portion located at or around the other end. ### Claim 2 (depends on 1) The inductor core according to claim 1, wherein the skewness Rsk of the outer peripheral surface of the straight body portion located at or around the other end is not more than 4. ### Claim 3 (depends on 1) The inductor core according to claim 1, wherein a root mean square roughness Rq of the outer peripheral surface of the straight body portion located at or around the other end is smaller than a root mean square roughness Rq of the outer peripheral surface of the straight body portion located at or around the inclined portion. ### Claim 4 (depends on 3) The inductor core according to claim 3, wherein the root mean square roughness Rq of the outer peripheral surface of the straight body portion located at or around the inclined portion is not more than 10 μm. ### Claim 5 (depends on 1) The inductor core according to claim 1, wherein the magnetic main body is made of a ceramic containing, as a main constituent, ferrite comprised of an oxide of Fe, Zn, Ni, and Cu, and a coefficient of variation CV of an average crystal grain size of the ceramic expressed as Equation 1 below is not less than 0.08 and not more than 0.3, CV=σ/x (1), where x is an average value of the average crystal grain size of the ceramic, and σ is a standard deviation of the average crystal grain size of the ceramic. ### Claim 6 (depends on 5) The inductor core according to claim 5, wherein a kurtosis Ku of the average crystal grain size is equal to or more than 0. ### Claim 7 (depends on 5) The inductor core according to claim 5, wherein a composition in 100 mol % obtained by adding up the main constituents includes Fe of not less than 49 mol % and not more than 50 mol % on a Fe2O3 basis, Zn of not less than 29 mol % and not more than 34 mol % on a ZnO basis, Ni of not less than 10 mol % and not more than 12.5 mol % on a NiO basis, and Cu of not less than 4 mol % and not more than 9 mol % on a CuO basis. ### Claim 8 (depends on 7) The inductor core according to claim 7, comprising at least any of an oxide of Mo and an oxide of Bi, wherein a content of the oxide of Mo with respect to 100 parts by mass of the main constituent is not less than 0.01 parts by mass and not more than 0.2 parts by mass on a MoO3 basis, or a content of the oxide of Bi with respect to 100 parts by mass of the main constituent is not less than 0.01 parts by mass and not more than 0.2 parts by mass on a Bi2O3 basis. ### Claim 9 (depends on 8) The inductor core according to claim 8, comprising at least any of an oxide of Mn and an oxide of Ti, wherein a content of the oxide of Mn with respect to 100 parts by mass of the main constituent is not less than 0.01 parts by mass and not more than 0.3 parts by mass on a MnO2 basis, or a content of the oxide of Ti with respect to 100 parts by mass of the main constituent is not less than 0.01 parts by mass and not more than 0.2 parts by mass on a TiO2 basis. ### Claim 10 (depends on 7) The inductor core according to claim 7, comprising an oxide of Zr, wherein a content of the oxide of Zr with respect to 100 parts by mass of the main constituent is not less than 0.01 parts by mass and not more than 0.2 parts by mass on a ZrO2 basis. ### Claim 11 (depends on 7) The inductor core according to claim 7, comprising an oxide of Cr, wherein a content of the oxide of Cr with respect to 100 parts by mass of the main constituent is not less than 0.02 parts by mass and not more than 0.3 parts by mass on a Cr2O3 basis. ### Claim 12 (depends on 7) The inductor core according to claim 7, wherein at least the inclined portion contains Mo, and a grain boundary layer interposed between the ferrite crystals adjacent to each other contains more Mo than that contained in grains of a ferrite crystal. ### Claim 13 (depends on 7) The inductor core according to claim 7, wherein in at least a portion of a ferrite crystal, a content of Fe at a center portion of the ferrite crystal is greater than a content of Fe at an outer edge portion of the ferrite crystal. ### Claim 14 (depends on 13) The inductor core according to claim 13, wherein a difference between the content of Fe at the center portion and the content of Fe at the outer edge portion is not less than 1.3 mass % and not more than 4.0 mass %. ### Claim 15 (depends on 7) The inductor core according to claim 7, wherein I2/I1 is not less than 0.29 and not more than 0.38, where I1 is an X-ray diffraction peak intensity at a diffraction angle (2θ) falling within a range of not less than 35° and not more than 36° and obtained through X-ray diffraction using a Cu-Kα line, and I2 is an X-ray diffraction peak intensity at a diffraction angle (2θ) falling within a range of not less than 29.5° and not more than 30.5°. ### Claim 16 (depends on 7) The inductor core according to claim 7, wherein a half width of the X-ray diffraction peak intensity I1 is not less than 0.05 and not more than 0.35. ### Claim 17 (depends on 15) The inductor core according to claim 15, wherein I3/I1 is equal to or less than 0.14, where I3 is an X-ray diffraction peak intensity at a diffraction angle (2θ) falling within a range of not less than 42° and not more than 43°. ### Claim 18 (depends on 1) An electronic pen comprising: a housing including an opening; and the electronic pen core body portion comprising the inductor core according to claim 1, and a core body configured to be inserted into the inductor core and disposed in a manner such that a tip portion protrudes from one end of the inductor core; wherein the electronic pen core body portion is accommodated in the housing, and the tip portion of the electronic pen core body portion protrudes from the opening of the housing or is disposed to be able to protrude from the opening of the housing. ### Claim 19 (depends on 1) An electronic pen comprising: a housing including an opening; a writing unit that can be used to write to a target writing surface; and the inductor core according to claim 1, wherein the writing unit is disposed along a central axis of the housing, and the inductor core is disposed alongside the writing unit within the housing. ### Claim 20 (depends on 18) An input device comprising: the electronic pen according to claim 18; and a position detection device including a sensor configured to detect a position at which the electronic pen approaches.