Adaptive Resonant Toothbrush Amplitude Control to Reduce Splatter
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Solution Overview
Problem
Resonant, high-frequency electronic toothbrushes often generate a mess when pulled out of the mouth, leading to splatter of saliva and toothpaste, which can deter consumers from using them as part of their regular oral healthcare routine, especially for those transitioning from manual toothbrushes.
Innovation Solution
A personal care appliance with self-adaptive amplitude regulation using an actuator with non-linear response characteristics, which automatically reduces power when outside the mouth and increases power when in use, utilizing capacitive sensors to detect load states and adjust drive signals accordingly, thereby minimizing splatter and enhancing cleaning efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the toothbrush operates at full power to achieve desired cleaning efficacy, then cleaning performance is improved, but splatter and mess increase when operated outside the mouth
Solution Approach 1:
The toothbrush dynamically adjusts its operating amplitude based on detected load conditions. The controller monitors current draw and other parameters to determine whether the brush head is in-mouth or out-of-mouth, then automatically adjusts the drive signal amplitude accordingly. This dynamic adaptation allows full power operation during cleaning while preventing splatter during storage or transport.
Solution Approach 2:
The system employs feedback mechanisms by continuously monitoring operational parameters such as current consumption, vibration characteristics, and acoustic signals to detect the operational state (in-mouth vs. out-of-mouth). Based on this feedback, the controller adjusts the drive signal to maintain optimal cleaning performance while preventing harmful splatter effects.
2Ease of operation
If capacitive sensors are used for automatic actuation without a power button, then ease of operation is improved, but the ability to deliver different amplitudes in-mouth versus outside the mouth is lost
Solution Approach 1:
The control system is segmented into multiple functional layers: capacitive sensors handle automatic power activation (ON/OFF), while separate sensors and control logic monitor operational state (in-mouth vs. out-of-mouth) and adjust amplitude accordingly. This segmentation allows each component to specialize in one function while the system as a whole achieves both automatic operation and adaptive amplitude control.
Solution Approach 2:
The sensor system performs multiple functions: capacitive sensors both detect the presence of the user for automatic activation and continue to monitor operational state for amplitude adjustment. The controller universally handles both power management and amplitude regulation based on sensor inputs, eliminating the need for manual buttons while maintaining adaptability.
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
The solution effectively reduces splatter when the toothbrush is outside the mouth, providing a better user experience and encouraging regular use by maintaining full cleaning efficacy when in use, thus improving initial impressions and long-term adoption.
Implementation Method 1
The actuator is further operable according to a non-linear response characteristic of movement amplitude versus frequency
Implementation Method 2
a resonant system that has significant non-linear behavior in its unloaded amplitude/frequency response
Implementation Method 3
uses capacitive sensors in an arrangement to allow for an automatic activation of the device when inserted into the mouth
Data Source
AI summary
A personal care appliance 10 comprises an actuator 14, a current sensor 28 for monitoring a driving current, and a controller 24. The actuator 14, operable according to a non-linear response characteristic 58 of amplitude versus frequency, includes a movable shaft 18 configured for resonant movement 38 in response to a drive signal 25, further for being coupled with a workpiece 20. The controller 24 (i) detects at least one of a plurality of different characteristic load states (100,102,104,106,108,110) in response to a perturbation in the monitored driving current 29 and (ii) actively delivers the drive signal 25 to the actuator 14 selected from at least two different drive signals (66,70) as a function of a detected characteristic load state. In this manner, the controller 24 implements self-adaptive amplitude regulation of the movable shaft's resonant movement 38 among the plurality of difference characteristic load states that include additional loads of force, spring, mass, and/or damping to a given load state of a resonant spring mass system of actuator 14 coupled with workpiece 20.