Electric Toothbrush Pressure Feedback via Hall Sensor

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Solution Overview

Problem

Existing pressure-sensing systems in toothbrushes are often costly, inaccurate, and lack continuous monitoring, only providing feedback when excessive pressure is applied, rather than offering real-time feedback tailored to the user.

Innovation Solution

A compact, inexpensive pressure feedback system that continuously monitors pressure by measuring the change in rotational speed of the drive shaft using a magnet and Hall effect sensor, activating a feedback device such as an LED, audible, or haptic device when a predetermined threshold is exceeded.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

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

Engineering Contradiction:

Improvepressure detection capabilityVSAvoidsystem structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical pressure-sensing system (spring, moment arm, switch) with an electromagnetic sensing system using a Hall effect sensor and magnet. The Hall effect sensor detects changes in magnetic field caused by drive shaft oscillation, eliminating the need for complex mechanical components while maintaining pressure detection capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnet as an intermediary element that couples the drive shaft's mechanical motion to the Hall effect sensor. The magnet's movement in response to drive shaft oscillation creates a varying magnetic field that the sensor detects, serving as a mediator between mechanical motion and electrical signal generation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of information

If a traditional pressure-sensing system is used, then pressure threshold indication is provided, but continuous monitoring capability is lacking

Engineering Contradiction:

Improvepressure information continuityVSAvoidfeedback quality

Core Design Contradiction:

Loss of informationVSProductivity

Solution Approach 1:

The patent implements continuous pressure monitoring by using the Hall effect sensor to continuously track the drive shaft's oscillation characteristics throughout the brushing cycle. Unlike threshold-based switches that only trigger at specific pressure levels, the Hall sensor provides ongoing data about pressure changes, enabling real-time feedback and more informative user guidance.

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If a traditional pressure-sensing system is used, then pressure threshold detection is achieved, but measurement accuracy is reduced

Engineering Contradiction:

Improvepressure detection accuracyVSAvoidpressure measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical pressure measurement with electromagnetic field sensing. The Hall effect sensor measures changes in magnetic field strength caused by drive shaft oscillation, providing more precise and consistent measurements compared to mechanical switches that suffer from contact wear and positioning tolerances.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If a traditional pressure-sensing system is used, then pressure feedback is provided, but cost is significantly increased

Engineering Contradiction:

Improvepressure feedback capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs inexpensive Hall effect sensors and simple magnets that are readily available and easy to manufacture. These components are significantly cheaper than precision mechanical assemblies requiring spring calibration, moment arm fabrication, and switch positioning, thereby reducing overall manufacturing costs while maintaining functional reliability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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

Provides continuous, real-time pressure feedback to the user, ensuring optimal brushing pressure is maintained, reducing the risk of over-exertion and enhancing user experience with improved accuracy and cost-effectiveness.

Implementation Method 1

The sensor may be a Hall effect sensor, or another sensor that is responsive to a magnetic field.

Methodology Applied

Scientific EffectHall effect: Hall Effect

Data Source

PatentUS11324307B2Pressure sensing system and method for an electric toothbrush

Publication Date: 2022.05.10 RANIR LLC

AI summary

A pressure feedback system continuously monitors the level of pressure or force on a brush head and is programmed to provide a feedback signal to a user based on the amount of pressure. The pressure level is monitored as a function of the change in the speed of the drive shaft. The system includes a housing, a motor, a drive shaft for attachment to a brush head, a feedback device, a sensor capable of detecting a change in the rotational speed of the drive shaft, and a microprocessor. The microprocessor is programmed activate the feedback device as a function of the measured change in rotational speed. The sensor may be a Hall effect sensor, or another sensor that is responsive to a magnetic field. A magnet may be positioned on the drive shaft, or another portion of the system that moves as a function of the drive shaft.