# US 2014/0150265 A1 · Electromagnetic actuator having improved force density and use therof for an electric razor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0150265 A1 - Document ID: US20140150265A1 - Status: Published application - Kind: A1 - Application number: 14/000,069 - Filed: 2012-02-22 - Published: 2014-06-05 - Earliest claimed: 2011-02-23 - Assignees: Moving Magnet Technologies - Inventors: Richard Arlot; Guillaume Loussert - Web page: https://patentgrep.com/patent/US20140150265A1 ## CPC - H02K 33/18: with coil systems moving upon intermittent or reversed energisation thereof by interaction with a fixed field system, e.g. permanent magnets - B26B 19/3873: {Electric features; Charging; Computing devices} - H02K 7/065: Electromechanical oscillators; Vibrating magnetic drives - H02K 33/16: with polarised armatures moving in alternate directions by reversal or energisation of a single coil system - H02K 35/02: with moving magnets and stationary coil systems - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) - B26B: HAND-HELD CUTTING TOOLS NOT OTHERWISE PROVIDED FOR (for harvesting A01D; for horticulture, for forestry A01G; for butchering or meat treatment A22; for manufactering or repairing footwear A43D; nail clippers or cutters A45D29/02; kitchen equipment A47J; {vegetable slicers, julienne cutters and similar devices and holders therefor, B26D3/28}; for surgical purposes A61B; for metal B23D; cutting by abrasive fluid jets B24C5/02; plier-like tools with cutting edges B25B7/22; pincers B25C11/02; handles for hand implements, in general B25G; guillotine-type cutters B26D; {perforating by non-mechanical means, e.g. by fluid jet, B26F1/26}; for erasing B43L19/00; for textile materials D06H) ## Abstract An electromagnetic actuator includes a stator unit having N poles having the width LP, and at least one coil surrounding one of the poles, wherein N≦3, and a magnetic portion, which is movable, relative to the stator unit, in a direction of relative movement and over a course of travel C, and including N+1 magnetized areas, the magnetizations of which are perpendicular to the relative movement direction and in alternate directions. The magnetic portion includes a yoke for closing off the magnetic fluxes passing through the magnetized areas, the course of travel C of the magnetic portion being less than or equal to the width LP of each pole, and the thickness of the magnetized areas perpendicular to the direction of movement being less than the course of travel C of the magnetic portion. ## Claims ### Claim 1 An electromagnetic actuator comprising at least a stator unit and a magnetic portion, with the stator unit having N poles having the width LP, and at least one coil surrounding one of the poles, wherein N≧3, and the magnetic portion being movable, relative to the stator unit, in a direction of relative movement and over a course of travel C, and including N+1 magnetized areas, the magnetizations of which are perpendicular to the direction of relative movement and in alternate directions, the magnetic portion further comprises a yoke contiguous to the magnetized areas and closing off the magnetic fluxes passing through the magnetized areas, the course of travel C of the magnetic portion being less than or equal to the width LP of each pole of the stator unit, and the thickness of the magnetized areas perpendicular to the direction of movement being less than the course of travel C of the magnetic portion. ### Claim 2 (depends on 1) An actuator according to claim 1, wherein N is equal to 3. ### Claim 3 (depends on 1) An actuator according to claim 1, wherein magnetized areas comprise at least two inner magnetized areas having, along the direction of movement, a length LA2 equal to the distance between the respective median planes of two consecutive stator poles. ### Claim 4 (depends on 3) An actuator according to claim 3, wherein the magnetized areas comprise at least two end magnetized areas having, along the direction of movement, a length LA1 between LP and 1.2×LP. ### Claim 5 (depends on 1) An actuator according to claim 1, wherein the magnetized areas are independent and contiguous magnets, fixed on the yoke. ### Claim 6 (depends on 1) An actuator according to claim 1, wherein the magnetized areas are formed by only one magnet, having areas magnetized alternately in opposite directions and transitions having a length less than 0.2×LP. ### Claim 7 (depends on 1) An actuator according to claim 1, further comprising another moveable magnetic portion, the two movable magnetic portions moving in opposite directions. ### Claim 8 (depends on 1) An actuator according to claim 1, further comprising two additional moveable magnetic portions, the three movable magnetic portions moving in alternate directions. ### Claim 9 (depends on 1) An actuator according to claim 1, wherein the at least one coil is a single coil surrounding the central pole of the stator unit. ### Claim 10 (depends on 1) An actuator according to claim 1, wherein the stator unit is connected to each magnetic portion by suspension blades. ### Claim 11 (depends on 1) An actuator according to claim 1, wherein the stator unit is connected to each magnetic portion by resilient return elements so designed as to return such magnetic portion to the middle of the course of travel C thereof. ### Claim 12 (depends on 1) An actuator according to claim 1, wherein the coil is so designed as to be powered by an alternate current and to produce a vibratory movement of the magnetic portion relative to the stator unit. ### Claim 13 (depends on 1) An actuator according to claim 1, wherein surfaces of the stator poles are inscribed within a cylindrical enclosure and in that the magnetic portion(s) has/have a semi-tubular shape cooperating with a cylindrical enclosure. ### Claim 14 (depends on 1) An actuator according to claim 1, wherein the yoke has chamfers at the ends thereof, along the direction of movement. ### Claim 15 (depends on 1) An actuator according to claim 1, wherein each pole of the stator unit has a head with a width LP and a body with a width less than LP. ### Claim 16 (depends on 1) An actuator according to claim 1, further comprising a magnetic sensor and an electronic control circuit, with the magnetic sensor being positioned opposite the magnetic portion and so designed as to provide an output signal representative of the absolute position of such magnetic portion, and the electronic control circuit receiving the output signal from the magnetic sensor and being so designed as to control the position of the magnetic portion in a position determined by a set value powered to such electronic control circuit. ### Claim 17 (depends on 1) An actuator according to claim 1, further comprising an electric razor head provided with vibrating knives, each one of the knives being kinematically linked with the magnetic portion of the actuator.