Hall Sensor Pressure Feedback for Resonant Toothbrush
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Solution Overview
Problem
Existing pressure-sensing systems in toothbrushes are often costly, inaccurate, and provide only intermittent feedback on pressure, lacking continuous pressure information and being difficult to implement in resonantly driven systems.
Innovation Solution
A power toothbrush with a V-spring assembly, a Hall effect sensor, and a processor that uses temperature compensation and magnetic shielding to provide continuous pressure feedback, utilizing a Hall effect sensor within a changing magnetic field to detect pressure and adjust for temperature variations, while offering feedback on minimum and maximum pressure thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional pressure-sensing system with spring, moment arm and switch is used, then pressure threshold detection is achieved, but the system becomes complex and costly
Solution Approach 1:
The patent replaces the traditional mechanical pressure-sensing system (spring, moment arm, switch) with a magnetic field-based Hall effect sensor system. The Hall sensor detects changes in magnetic field caused by magnet displacement, converting mechanical pressure into electrical signals without requiring complex mechanical components. This substitution dramatically simplifies the device structure while maintaining or improving measurement precision.
Solution Approach 2:
The patent introduces a magnet as an intermediary element between the brushhead assembly and the Hall effect sensor. The magnet couples the mechanical motion of the brushhead to the magnetic field detected by the Hall sensor, enabling indirect measurement of brushhead position and applied pressure through magnetic field changes rather than direct mechanical contact.
2Loss of information
If a traditional pressure-sensing system is used, then pressure threshold indication is provided, but continuous pressure feedback is not achieved
Solution Approach 1:
The Hall effect sensor provides continuous analog output signals that reflect real-time changes in magnetic field position, enabling continuous monitoring of brushhead position and applied pressure throughout the brushing cycle. This continuous feedback replaces the intermittent threshold-based switching signals of traditional systems, allowing the processor to track pressure dynamics continuously without additional complexity.
Solution Approach 2:
The patent implements a feedback system where the Hall sensor output is fed to a processor that analyzes the continuous pressure information and provides real-time feedback to the user through visual or haptic signals. This closed-loop feedback enables users to adjust their brushing pressure dynamically based on continuous information about the force applied to the brushhead.
3Measurement precision
If temperature compensation is added to the Hall effect sensor system, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The system uses the existing processor and existing temperature sensor (already present in the toothbrush for battery management) to perform temperature compensation of the Hall effect sensor output. The processor automatically adjusts the pressure measurements based on detected temperature variations, eliminating the need for separate compensation hardware and using existing system resources to maintain measurement accuracy.
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 provides accurate, continuous pressure feedback to the user, ensuring proper brushing pressure is maintained, enhancing dental care through reliable and cost-effective means.
Implementation Method 1
a Hall effect sensor mounted within the changing magnetic field produced by the magnet as the rear end of the V-spring moves, wherein the output of the Hall effect sensor changes from a no-load condition corresponding to the displacement of the rear end of the V-spring due to pressure on the brush member
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The power toothbrush includes a brushhead arm (36) and a brush element (38) at a distal end thereof. A V-spring assembly (14) converts the movement of a power drive assembly in a back-and-forth movement. A mounting member (55) at the rear end of the V-spring assembly provides a base for a magnet (56). The back end of the V- spring assembly is displaced in accordance with pressure applied to the brush member. A Hall effect sensor (58) is mounted within the changing magnetic field produced by the magnet as the rear end of the V-spring assembly is displaced due to pressure on the brushhead. A processor (65) is responsive to the output from the Hall sensor and provides an indication when the pressure exceeds a threshold value.