Resonant Actuator with Programmable Axial and Tangential Motion
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Solution Overview
Problem
Existing power toothbrushes and personal care appliances are limited to a single mode of motion, such as rotation, which is inadequate for effectively cleaning different regions of the mouth, as they cannot perform complex patterns or switch between tangential and axial movements.
Innovation Solution
A drive system incorporating a combination of tangential and axial motion capabilities, utilizing stationary permanent magnet assemblies and armature assemblies with programmable control to selectively energize windings, allowing for varied and complex movements of the workpiece, including a housing with orthogonal magnet arrangements and elastic bearing elements to reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single mode of motion (e.g., rotational mode with DC motor) is used, then the device structure is simple, but the cleaning functionality is limited and cannot effectively clean different regions of the mouth
Solution Approach 1:
The patent implements multi-functionality by integrating two independent armature assemblies (first armature for rotational motion, second armature for linear motion) that can be selectively activated. This allows a single device to perform multiple cleaning functions including circular brushing, linear scrubbing, and combined figure-eight motions, thereby resolving the contradiction between versatility and device complexity.
Solution Approach 2:
The patent applies dynamics by enabling the workpiece to transition between different motion modes (rotational, linear, combined) through selective energization of armature assemblies. The control system dynamically switches between first and second armature assemblies to produce varied motion patterns, allowing the device to adapt to different cleaning requirements while maintaining a relatively simple overall structure.
2Adaptability or versatility
If a single mode of motion is used, then the device structure is simple, but the motion pattern is simple and cannot perform complex patterns like figure eight motion
Solution Approach 1:
The patent merges two distinct motion capabilities (rotational motion from first armature assembly and linear motion from second armature assembly) into a single integrated system. By combining these orthogonal motions through the common shaft member, the device can generate complex figure-eight motion patterns without requiring a completely complex actuator configuration, thus resolving the contradiction between motion pattern capability and actuator complexity.
Solution Approach 2:
The patent transitions from single-dimensional rotational motion to two-dimensional combined motion by adding the second armature assembly that produces linear motion perpendicular to the rotational axis. This dimensional expansion enables complex motion patterns like figure-eight while keeping each individual armature assembly relatively simple, addressing the contradiction between motion pattern capability and actuator complexity.
3Use of energy by moving object
If traditional motor actuation is used, then the structure is simple, but energy consumption is high due to friction in bearing surfaces
Solution Approach 1:
The patent replaces traditional continuous-rotation motor actuation with a magnetic field-based armature assembly system that converts electrical energy directly into controlled linear and rotational motions. This substitution reduces reliance on continuous mechanical bearing contact, thereby reducing friction losses and energy consumption while maintaining actuation capability.
Solution Approach 2:
The patent employs periodic activation of the armature assemblies rather than continuous operation. The control system selectively energizes the first and second armature assemblies in periodic cycles to produce the desired motion patterns, reducing overall energy consumption compared to continuous motor rotation while maintaining effective cleaning action during active periods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables multiple modes of movement, including complex patterns like a figure eight motion, enhancing cleaning efficacy across different mouth regions while minimizing energy consumption through reduced friction in the bearing surfaces.
Implementation Method 1
a first armature assembly attached to or forming a part of the shaft member for moving the shaft member rotationally in cooperation with the first pair of stationary permanent magnets when energized; a second armature assembly attached to or forming a part of the shaft member for moving the shaft member longitudinally in cooperation with the second pair of stationary permanent magnets when energized
Data Source
AI summary
The drive system for a personal care appliance, such as a toothbrush, includes a first opposing pair of permanent magnet assemblies positioned longitudinally along the length of the internal surface of a cylindrical appliance housing, each first permanent magnet assembly having one portion with a north polarity and the other portion a south polarity, and a second pair of permanent magnet assemblies which are orthogonal to the first pair of permanent magnet assemblies, one second permanent magnet assembly having a plurality of abutting first parts along the length thereof, the parts alternating between a north polarity and a south polarity, the other second permanent magnet assembly having similar parts with reversed polarity. First and second armatures are mounted on, or a portion thereof forms, a spindle element which extends along the length of and outward from the cylindrical housing. A plurality of drive windings are positioned around the armatures in such a manner that application of current to the windings, under programmable control, produces axial and/or tangential movement of the spindle and the workpiece.