Electric Toothbrush Eccentric Shaft with Movable Gravity Center
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Solution Overview
Problem
Conventional electric toothbrushes cannot change the resonant frequency and vibration amplitude of their eccentric shafts, limiting the variability of brushing feel and effectiveness for different teeth areas.
Innovation Solution
The electric toothbrush design includes an eccentric shaft with a movable gravity center position, allowing changes in vibration amplitude and resonant frequency through the use of weights positioned to shift from the shaft center, which can rotate or move axially, and mechanisms like ratchets and coil springs to adjust these parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the gravity center position of the eccentric shaft is fixed, then the structure is simple and reliable, but the resonant frequency and vibration amplitude cannot be adjusted for different brushing needs
Solution Approach 1:
The patent applies the dynamics principle by making the gravity center position of the eccentric shaft movable rather than fixed. The weight can move along the eccentric shaft in the axial direction, allowing the gravity center to change position dynamically. This enables adjustment of resonant frequency and vibration amplitude to suit different brushing needs, while the movement is constrained within a guide structure to maintain reliability.
Solution Approach 2:
The patent applies parameter changes by allowing the mass distribution parameters of the eccentric shaft to be variable. By moving the weight along the shaft, the moment of inertia and gravity center position change, thereby changing the resonant frequency and vibration characteristics. This enables the same physical structure to provide different vibration amplitudes and frequencies for various brushing requirements.
2Ease of operation
If the gravity center position is made movable to change vibration amplitude, then the brushing feel can be customized, but the device complexity increases
Solution Approach 1:
The patent applies self-service by designing a mechanism where the weight can move along the eccentric shaft guided by guide holes and guide pins. The user can adjust the gravity center position by simply moving the weight along the guide structure without requiring complex actuators or control systems. This maintains ease of operation while limiting the complexity increase to only the necessary guide mechanism.
3Adaptability or versatility
If the weight is made rotatable to change the distance to shaft center, then vibration amplitude can be adjusted, but the risk of loosening and vibration increases
Solution Approach 1:
The patent applies dynamics by allowing the weight to rotate relative to the eccentric shaft main body while maintaining controlled stability. The weight can rotate to change its angular position and thus adjust the distance to the shaft center, but the rotation is constrained by the guide structure and engagement features that prevent excessive movement or loosening, maintaining reliability during operation.
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
This design enables adjustable vibration amplitude and resonant frequency, enhancing the brushing experience by allowing customizable feel and improving resonance generation, catering to individual preferences and tooth areas.
Implementation Method 1
the weight is moved by gravitational force in accordance with a posture of the electric toothbrush
Implementation Method 2
a coil spring with one end fixed to the eccentric shaft main body and the other end fixed to the weight
Data Source
AI summary
The invention provides an electric toothbrush capable of changing a resonant frequency and vibration amplitude of an eccentric shaft. An electric toothbrush of the present invention includes a motor, an eccentric shaft with one end fixed to a rotation shaft of the motor, and a stemserving as a vibration transmitting component having a bearing for supporting the other end of the eccentric shaft for transmitting vibration generated in accordance with rotation of the eccentric shaft to a brush portion. In the electric toothbrush, the eccentric shaft is formed so that a gravity center position is movable at least in one direction among a direction in which a distance to a shaft center is changed and an axial direction.