# US 12,008,177 B2 · Electronic pen, handwriting input device, and central rod for electronic pen > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,008,177 B2 - Document ID: US12008177B2 - Status: Granted - Kind: B2 - Application number: 18/310,418 - Filed: 2023-05-01 - Published: 2023-08-31 - Granted: 2024-06-11 - Earliest claimed: 2020-12-10 - Assignees: Wacom Co., Ltd. - Applicants: Wacom Co., Ltd. - Inventors: Yoshiharu Matsumoto - Web page: https://patentgrep.com/patent/US12008177B2 ## CPC - G06F 3/03545: {Pens or stylus} - G06F 3/0383: {Signal control means within the pointing device} - G06F 3/04162: {for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware} - G06F 3/046: by electromagnetic means - G06F 3/03: Arrangements for converting the position or the displacement of a member into a coded form - G06F 3/0354: with detection of two-dimensional [2D] relative movements between the device, or an operating part thereof, and a plane or surface, e.g. 2D mice, trackballs, pens or pucks - G06F 3/041: Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract An electronic pen is configured to transmit and receive a signal to and from a position detection sensor by electromagnetic induction. The electronic pen includes a coil and a magnetic core around which the coil is wound. The magnetic core has a through-hole in an axial center direction. The electronic pen includes a capacitor that forms a resonant circuit with the coil. The electronic pen includes a central rod that is inserted in the through-hole of the magnetic core. The central rod has a magnet part and a yoke part that holds the magnet part at a pen tip part of the central rod. ## Claims ### Claim 1 An electronic pen, configured to transmit and receive a signal to and from a position detection sensor by electromagnetic induction, the electronic pen comprising: a coil; a magnetic core around which the coil is wound, the magnetic core having a through-hole in an axial center direction; a capacitor that forms a resonant circuit with the coil; and a central rod that is inserted in the through-hole of the magnetic core, wherein, the central rod includes a magnet part and a yoke part that holds the magnet part at a pen tip part of the central rod, and the electronic pen further comprises a magnet disposed at a rear end of the electronic pen, the magnet having a magnetic pole opposite to a magnetic pole of the magnet part disposed at the pen tip part of the central rod. ### Claim 2 (depends on 1) The electronic pen according to claim 1, wherein the electronic pen is configured for use in a state in which at least the pen tip part of the central rod at which the magnet part and the yoke part are disposed protrudes from an electronic pen casing. ### Claim 3 (depends on 1) The electronic pen according to claim 1, wherein the electronic pen is configured for use in a state in which a tip of the magnetic core and the pen tip part of the central rod at which the magnet part and the yoke part are disposed protrude from an electronic pen casing. ### Claim 4 (depends on 1) The electronic pen according to claim 1, wherein the central rod is configured with the magnet part and the yoke part disposed at a tip of a shaft. ### Claim 5 (depends on 1) The electronic pen according to claim 1, wherein, the central rod includes a shaft, the magnet part and the yoke part are disposed at a tip part of the shaft; and a middle part of the shaft excluding the tip part at which the magnet part and the yoke part are disposed and a rear end part of the shaft is housed in a reinforcing pipe. ### Claim 6 (depends on 1) The electronic pen according to claim 1, wherein, the central rod includes a pen-tip-side shaft and a rear-end-side shaft, the magnet part and the yoke part are disposed at a tip part of the pen-tip-side shaft, a proximal part of the pen-tip-side shaft excluding the tip part at which the magnet part and the yoke part are disposed is housed in a reinforcing pipe; and a distal part of the rear-end-side shaft excluding a rear end part of the rear-end-side shaft is housed in the reinforcing pipe. ### Claim 7 (depends on 1) The electronic pen according to claim 1, wherein, the magnet part is a columnar component in which an N-pole and an S-pole are aligned along the axial center direction; and the yoke part is a cup-shaped component having an opening at a tip, through which a tip part of the magnet part protrudes when the magnet part is held by the cup-shaped component. ### Claim 8 (depends on 1) The electronic pen according to claim 1, further comprising: a second resonant circuit disposed at the rear end of the electronic pen, the second resonant circuit having a resonant frequency different from that of the resonant circuit of the electronic pen. ### Claim 9 A handwriting input device, comprising: a position detecting device including: a magnetic sheet on which a color of a position changes when a magnetic pole nears or contacts the position, and a position detection sensor of an electromagnetic induction type disposed under the magnetic sheet in an overlapping manner; and an electronic pen including: a coil, a magnetic core around which the coil is wound, the magnetic core having a through-hole in an axial center direction, a capacitor that forms a resonant circuit with the coil, a central rod inserted in the through-hole of the magnetic core, the central rod having a magnet part and a yoke part that holds the magnet part at a pen tip part of the central rod, and a magnet disposed at a rear end of the electronic pen, the magnet having a magnetic pole opposite to a magnetic pole of the magnet part disposed at the pen tip part of the central rod; wherein, the position detection sensor of the position detecting device exchanges a signal, which has a frequency corresponding to a resonant frequency of the resonant circuit, with the resonant circuit of the electronic pen, via electromagnetic induction coupling. ### Claim 10 (depends on 9) The handwriting input device according to claim 9, wherein the magnetic sheet includes a layer of microcapsules containing powder formed of magnetic material; and on the magnetic sheet, at a position which a magnetic pole at the pen tip part of the central rod of the electronic pen nears or contacts, the powder formed of magnetic material in the layer of the magnetic sheet is magnetically attracted to the magnetic pole to cause a color change at the position on a front surface of the magnetic sheet. ### Claim 11 (depends on 10) The handwriting input device according to claim 10, further comprising: an eraser configured to undue the color change at the position on the magnetic sheet, by returning the powder in the microcapsules in a vicinity of the position to its original location. ### Claim 12 A central rod for an electronic pen, the central rod comprising: a pen tip part; and a shaft, wherein, the pen tip part has a magnet part and a yoke part that holds the magnet part, and a magnet is disposed at a rear end of the electronic pen, the magnet having a magnetic pole opposite to a magnetic pole of the magnet part disposed at the pen tip part of the central rod. ### Claim 13 (depends on 12) The central rod for an electronic pen according to claim 12, wherein, the magnet part is a columnar component in which an N-pole and an S-pole are aligned along an axial center direction; and the yoke part is a cup-shaped component having an opening at a tip, through which a tip part of the magnet part protrudes when the magnet part is held by the cup-shaped component. ### Claim 14 (depends on 12) The central rod for an electronic pen according to claim 12, wherein the shaft is composed of a non-magnetic material.