Adaptive Drive System Using Stator Current for Resonance Control
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Solution Overview
Problem
Mass-produced personal care appliances, such as power toothbrushes, face challenges in efficiently maintaining the desired amplitude of motion due to the high cost and complexity of frequency matching and amplitude measurement, often resulting in resonance being designed away to simplify manufacturing and reduce costs.
Innovation Solution
A system within the appliance uses average electrical current through a stator member to adjust the operating frequency, correlating with stored information to match the resonant frequency, allowing for efficient operation without expensive sensors or separate mounting equipment, utilizing a processor to adjust the frequency based on current values and curves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If resonant drive systems are used to produce reciprocating motion of the workpiece, then operational efficiency is improved, but frequency matching complexity and cost increase
Solution Approach 1:
The system uses the stator's own electrical current as a self-diagnostic signal to determine resonant frequency, eliminating the need for external sensors or separate measurement systems. The stator current naturally varies with frequency and provides built-in feedback about the system's resonant state.
Solution Approach 2:
The patent replaces mechanical vibration sensors with electrical current measurements. Instead of using mechanical means to detect and measure workpiece amplitude, the system uses electrical measurements of stator current to infer mechanical resonance conditions through the established relationship between current and amplitude.
2Measurement precision
If sensors are used to adapt operation to actual use conditions, then operational accuracy is improved, but cost and packaging difficulty increase
Solution Approach 1:
The patent uses stator current as an intermediary parameter that indirectly indicates workpiece amplitude. Instead of directly measuring mechanical amplitude with sensors, the system measures electrical current which correlates with amplitude through the resonant system's characteristics, providing a simpler measurement path.
Solution Approach 2:
The patent replaces mechanical vibration sensors with electrical current measurements. Instead of using mechanical means to detect and measure workpiece amplitude, the system uses electrical measurements of stator current to infer mechanical resonance conditions through the established relationship between current and amplitude.
3Manufacturing precision
If tight manufacturing standards are applied to resonant components, then frequency matching precision is improved, but manufacturing cost increases
Solution Approach 1:
The system performs frequency calibration during the manufacturing process by measuring stator current at different frequencies and storing the optimal frequency-amplitude relationship in memory. This preliminary action ensures accurate frequency matching without requiring tight component tolerances, as the system learns and adapts to its specific resonant characteristics during production.
Solution Approach 2:
The patent changes the operating frequency parameter based on stored calibration data that maps frequency to amplitude performance. Instead of relying on fixed component specifications, the system dynamically adjusts frequency based on pre-determined optimal values established during manufacturing, allowing cost-effective production with standard components.
4Ease of manufacture
If resonance is designed away from the system, then manufacturing simplicity and cost are improved, but operational efficiency decreases
Solution Approach 1:
The patent makes the operating frequency dynamic rather than fixed. The system continuously monitors stator current and adjusts the operating frequency in real-time to maintain resonance conditions, allowing the appliance to adapt to changing load conditions and component variations while maintaining high efficiency without requiring complex resonant component design.
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 approach enables efficient operation by maintaining the desired amplitude of motion at both manufacturing and usage stages, reducing costs and complexity while ensuring high efficiency and adaptability to varying loads and wear over the appliance's lifetime.
Implementation Method 1
a power toothbrush having a workpiece which is driven through an amplitude of motion by a stator-driven resonant frequency drive system
Implementation Method 2
resonant drive systems, such as those used for driving a workpiece portion of an appliance, for example, a power toothbrush, are highly efficient in producing a reciprocating motion of the workpiece
Data Source
AI summary
An adaptive system for a personal care appliance, such as a power toothbrush, having a workpiece which is driven through an amplitude of motion by a drive mechanism which includes a stator member includes a circuit (13) for measuring average electrical current through the stator member and stored information (19) in the personal care appliance which relates the average current values through the stator during operation of the device to corresponding amplitude of motion of the workpiece. A processor (17) utilizing a stored program adjusts the operating frequency to produce a stator current value which correlates to the desired amplitude of motion of the workpiece.