# US 12,178,675 B2 · Dual-stiffness bracket for electric toothbrush with brushing force sensor assembly > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,178,675 B2 - Document ID: US12178675B2 - Status: Granted - Kind: B2 - Application number: 18/226,317 - Filed: 2023-07-26 - Published: 2023-11-16 - Granted: 2024-12-31 - Earliest claimed: 2018-05-15 - Assignees: Koninklijke Philips N.V. - Applicants: Koninklijke Philips N.V. - Inventors: Franciscus Jozef Bosman - Web page: https://patentgrep.com/patent/US12178675B2 ## CPC - A61C 17/221: {Control arrangements therefor} - A46B 5/0037: {Flexible resilience by plastic deformation of the material} - A46B 13/02: power-driven {carriers} - A46B 15/0012: {with a pressure controlling device} - A61C 17/222: {Brush body details, e.g. the shape thereof or connection to handle} - A61C 17/34: driven by electric motor - G01L 1/122: {by using permanent magnets} - A46B 2200/1066: Toothbrush for cleaning the teeth or dentures (A61C17/16 takes precedence; bristles arrangements for toothbrushes A46B9/04) - A61C: DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE (non-driven toothbrushes A46B; {tongue scrapers A61B17/24;} preparations for dentistry A61K6/00; preparations for cleaning the teeth or mouth A61K8/00, A61Q11/00) - A46B: BRUSHES (handles not integral with brushware B25G) - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) ## Abstract An electric toothbrush (10) and method of operating an electric toothbrush. The electric toothbrush includes a handle portion (14) having a shaft (38) configured to receive a brushing load from a bristled end (18) of a brush head (12). A sensor assembly (30) is configured to determine a deflection proportional to the brushing load with respect to a first direction (24) associated with the brushing load. The sensor assembly includes an air gap (32) and is configured to determine the deflection based on changes in the air gap. A mounting bracket (50) is connected between opposite sides of the air gap, the mounting bracket having a first bending stiffness with respect to the first direction, and a second bending stiffness with respect to a second direction (28) generally opposite to the first direction. The first bending stiffness is greater than the second bending stiffness. ## Claims ### Claim 1 An electric toothbrush comprising: a handle portion having a shaft configured to receive a brushing load from a bristled end of a brush head; a sensor assembly configured to determine a deflection proportional to the brushing load with respect to a first direction associated with the brushing load, the sensor assembly including an air gap and configured to determine the deflection based on changes in the air gap; and a mounting bracket connecting between opposite sides of the air gap, the mounting bracket configured with a first bending stiffness with respect to the first direction, and a second bending stiffness with respect to a second direction substantially opposite to the first direction, wherein the first bending stiffness is greater than the second bending stiffness. ### Claim 2 (depends on 1) The electric toothbrush of claim 1, wherein the sensor assembly includes a magnet and magnetic laminations on opposite sides of the air gap configured to create a magnetic field, wherein the brushing load is determinable based on changes in the magnetic field. ### Claim 3 (depends on 2) The electric toothbrush of claim 2, further comprising a back-iron component adjacent to the magnet configured to conduct the magnetic field. ### Claim 4 (depends on 3) The electric toothbrush of claim 3, wherein the back-iron component is arranged as a flat plate or as an L-shaped component with a weakened bend. ### Claim 5 (depends on 1) The electric toothbrush of claim 1, further comprising a compliant element configured to control an amount of the deflection in response to the brushing load. ### Claim 6 (depends on 5) The electric toothbrush of claim 5, wherein the mounting bracket includes a first leg coupled to the shaft and a second leg coupled to the compliant element. ### Claim 7 (depends on 6) The electric toothbrush of claim 6, wherein the mounting bracket includes one or more arms extending transversely between the first and second legs and a stop configured to prevent relative movement of the first and second legs in the first direction. ### Claim 8 (depends on 7) The electric toothbrush of claim 7, wherein the stop includes a hook formed on the one or more arms that is engageable with a boss extending from the mounting bracket. ### Claim 9 (depends on 6) The electric toothbrush of claim 6, wherein the mounting bracket includes one or more arms extending transversely between the first and second legs, wherein the one or more arms are configured to buckle in response to force applied to the first leg in the second direction. ### Claim 10 (depends on 9) The electric toothbrush of claim 9, wherein the one or more arms are bowed outwardly to promote buckling. ### Claim 11 (depends on 1) The electric toothbrush of claim 1, wherein the compliant element includes a V-spring. ### Claim 12 (depends on 1) The electric toothbrush of claim 1, wherein the mounting bracket is configured to attenuate forces applied to the mounting bracket in the second direction to protect a connection of the mounting bracket to the compliant element. ### Claim 13 A method of operating an electric toothbrush comprising: receiving a brushing force at a bristled end of a brush head of the toothbrush, the brushing force causing a deflection in the electric toothbrush with respect to a first direction; measuring the deflection as a change in an air gap by a sensor assembly; and transferring applied forces between opposite sides of the air gap with a mounting bracket connected between the opposite sides of the air gap, wherein the mounting bracket is configured with a first bending stiffness with respect to the first direction, and a second bending stiffness with respect to a second direction generally opposite to the first direction, wherein the first bending stiffness is greater than the second bending stiffness. ### Claim 14 (depends on 13) The method of claim 13, further comprising controlling an amount of the deflection with a compliant element proportionally in response to the brushing force. ### Claim 15 (depends on 14) The method of claim 14, wherein the transferring includes attenuating forces applied to the mounting bracket in the second direction to protect a connection of the mounting bracket to the compliant element.