Electric Toothbrush Vibration Frequency Pressure Detection
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Solution Overview
Problem
Existing electric toothbrushes face challenges in accurately detecting brush pressure due to motor heat causing current fluctuations and strain gauge inaccuracies, especially with angle changes and risk of wire damage from vibrations.
Innovation Solution
An electric toothbrush employing an accelerometer to detect vibration frequency, which serves as a reference for estimating member pressure, along with a consumed current detection unit and power compensation to adjust motor output, ensuring accurate pressure measurement and reduced risk of wire damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If current consumption by motor is used to detect brush pressure, then brush pressure can be detected without additional sensors, but detection accuracy deteriorates due to motor heat causing current fluctuations
Solution Approach 1:
The patent introduces vibration frequency as an intermediary parameter to detect brush pressure. Instead of directly measuring current consumption which is affected by motor heat, the system measures vibration frequency which correlates with brush pressure but is not affected by temperature changes. This intermediary measurement approach resolves the contradiction by providing accurate pressure detection without the interference of motor heat.
Solution Approach 2:
The patent replaces the electrical measurement approach (current consumption) with a mechanical measurement approach (vibration frequency detection using accelerometer). This substitution eliminates the problem of current fluctuations caused by motor heat, as mechanical vibration frequency is not affected by electrical thermal effects.
2Measurement precision
If strain gauge is used to detect brush pressure, then direct pressure measurement is achieved, but measurement accuracy deteriorates when brush angle changes and wire connections are at risk from vibration
Solution Approach 1:
The patent replaces the strain gauge mechanical system with an accelerometer-based vibration frequency detection system. This substitution eliminates the wire connection problems and angle sensitivity issues of strain gauges, as the accelerometer measures vibration frequency which is not affected by brush orientation or wire integrity.
Solution Approach 2:
The patent uses vibration frequency as a proxy measurement for brush pressure. Instead of directly measuring strain on the brush (which requires physical contact and vulnerable connections), the system copies the pressure information through its effect on vibration frequency, providing an indirect but more reliable measurement method.
3Measurement precision
If accelerometer is used to detect vibration frequency for pressure estimation, then detection accuracy is improved and wire damage risk is reduced, but device complexity increases due to additional detection units
Solution Approach 1:
The patent makes the accelerometer serve multiple functions: it detects both the vibration frequency for pressure estimation and provides data for motor control optimization. This multi-functionality justifies the addition of the accelerometer by extracting maximum value from a single component, reducing the net increase in device complexity.
Solution Approach 2:
The system uses the vibration frequency information detected by the accelerometer to automatically adjust motor output and optimize performance. The detected vibration characteristics serve the dual purpose of pressure measurement and motor control feedback, making the system self-regulating without requiring additional complex control mechanisms.
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 a simple configuration for estimating member pressure with high accuracy, reducing motor heat issues and wire damage risks, while maintaining effective plaque removal and user comfort.
Implementation Method 1
a vibration frequency detection unit that detects the vibration frequency based on the waveform of a signal outputted by the accelerometer
Data Source
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AI summary
An oral care apparatus (1) is an apparatus for performing care on an oral cavity using a care member, and includes an accelerometer (15), a driving unit (10) for vibrating the care member, and a vibration frequency detection unit for detecting a vibration frequency of the care member. The vibration frequency detection unit detects the vibration frequency based on the waveform of a signal outputted by the accelerometer.