Gyro Sensor Brushing Site Detection for Electric Toothbrush

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Solution Overview

Problem

Conventional electric toothbrushes face accuracy issues in detecting the translational position of brushing sites due to noise from vibration components in acceleration sensor outputs, affecting the precision of brushing site detection.

Innovation Solution

An electric toothbrush equipped with a gyro sensor and a brushing site detection unit that sets an approximate curve corresponding to the dentition, using positive coefficients or a parabola, to accurately determine the translational position based on angular velocity data, reducing noise interference and improving accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If acceleration sensor output is used to detect brushing site position through second-order integration, then translational position can be obtained, but noise from vibration components significantly degrades measurement precision

Engineering Contradiction:

Improvebrushing site position detection accuracyVSAvoidnoise from vibration components

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes the harmful vibration noise from the acceleration sensor output through signal processing techniques. Specifically, it separates the useful gravitational acceleration component from the harmful vibration noise, allowing accurate brush angle detection without interference from brush head vibrations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical integration process (second-order integration of acceleration) with a more robust detection method using gyro sensor data and gravitational acceleration analysis. This substitution avoids the noise amplification inherent in repeated integration operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of information

If second-order integration is performed on dynamic acceleration components to obtain translational position, then position information is derived, but noise is greatly amplified in the calculation process

Engineering Contradiction:

Improvetranslational position informationVSAvoidposition accuracy

Core Design Contradiction:

Loss of informationVSMeasurement precision

Solution Approach 1:

The patent substitutes the problematic second-order integration process with an alternative approach using gyro sensor angular velocity data and gravitational acceleration components. This replacement method derives brush angle and position information without the noise amplification that occurs during repeated integration of acceleration data.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If gyro sensor is used to detect angular velocity for brush angle calculation, then noise from vibration is reduced, but additional device complexity is introduced

Engineering Contradiction:

Improvebrush angle detection accuracyVSAvoidsensor system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The gyro sensor serves multiple functions within the system: it detects brush angle through angular velocity measurement, provides data for brushing site position detection, and contributes to overall brushing motion analysis. This multi-functionality justifies the added device complexity by delivering comprehensive measurement capabilities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 enhances the accuracy of brushing site detection by minimizing noise impact and allowing for variable coefficient settings to adapt to different dental arch shapes, resulting in precise identification of brushing sites.

Implementation Method 1

a gyro sensor mounted inside the main body and configured to detect an angular velocity of the main body

Methodology Applied

Scientific EffectGyroscopic effect: Gyroscope

Data Source

PatentUS11484113B2Electric toothbrush, system, brushing site detection method, and computer-readable recording medium

Publication Date: 2022.11.01 OMRON HEALTHCARE CO LTD

AI summary

An electric toothbrush includes a gyro sensor inside a main body. The gyro sensor detects an angular velocity of the main body and the main body includes a head portion, a neck portion, and a grip portion in a longitudinal axis direction. An angle formed by a longitudinal axis of the main body in a state that brush bristles of the head portion contact with a brushing site in a dentition with respect to the longitudinal axis of the main body in a state that the brush bristles of the head portion contact with a reference position in the dentition is obtained, based on an output from the gyro sensor. A corresponding point corresponding to the brushing site on an approximate curve that curves corresponding to the dentition is obtained based on the angle, and coordinates of the corresponding point are used as a translational position of the brushing site.