Battery Voltage and Motor Current Control for Toothbrush Performance
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Solution Overview
Problem
Electric toothbrushes powered by replaceable or rechargeable batteries experience performance degradation due to declining battery voltage before the batteries are completely depleted, leading to suboptimal operation during a significant period.
Innovation Solution
A system that measures battery voltage and motor current to adjust the motor drive signal's duty cycle, pulse width, or frequency, maintaining performance by increasing the toothbrush's amplitude of movement and terminating operation when thresholds are reached to ensure consistent functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the toothbrush operates continuously with a battery, then the battery provides power for extended use, but the battery voltage declines with discharge causing performance degradation
Solution Approach 1:
The patent applies dynamics by making the drive signal parameters adjustable and variable during operation. The system dynamically changes the duty cycle or pulse width of the drive signal based on real-time battery voltage measurements, allowing the motor to maintain consistent performance despite declining battery voltage. This transforms a static system into a dynamic one that adapts to changing conditions.
Solution Approach 2:
The patent implements parameter changes by modifying the drive signal characteristics (duty cycle, pulse width, or frequency) in response to measured battery voltage levels. When voltage drops below a threshold, the system adjusts these parameters to compensate for power loss, thereby maintaining motor performance and brushhead movement amplitude throughout the battery's discharge cycle.
2Reliability
If the duty cycle or pulse width of the drive signal is increased to maintain performance, then the amplitude of movement is maintained, but energy consumption increases
Solution Approach 1:
The patent employs feedback by continuously measuring battery voltage during operation and using this information to adjust the drive signal parameters. The microprocessor monitors voltage levels and automatically modifies the duty cycle or pulse width accordingly, creating a closed-loop control system that optimizes energy usage while maintaining performance. This feedback mechanism ensures energy is used efficiently only when necessary to maintain performance thresholds.
3Reliability
If the drive signal frequency is changed to increase workpiece amplitude, then the amplitude of movement increases, but the system complexity increases
Solution Approach 1:
The patent achieves universality by using a single microprocessor-based control system that performs multiple functions: measuring battery voltage, determining motor current, calculating workpiece amplitude, and adjusting drive signal parameters. This multi-functional approach consolidates what could be separate complex subsystems into one integrated control unit, maintaining amplitude maintenance capability while minimizing overall system complexity.
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
Extends the number of brushings with desired performance by improving efficiency, reducing battery costs, and ensuring effective operation until battery replacement is necessary.
Implementation Method 1
a motor (14) that receives a drive signal from the control unit (10) and has a stator portion (16) through which a current flows when the drive signal is supplied to the motor (14)
Data Source
AI summary
The system periodically measures the battery voltage of the toothbrush and the current in a stator portion of the motor for the appliance. The amplitude of movement of the toothbrush workpiece is determined from the measured stator current. A circuit/control program changes the duty cycle or pulse width of the drive signal from the motor if the battery voltage drops below a first threshold value and a circuit or control program changes the drive frequency of the appliance if the amplitude of the workpiece movement falls below a first threshold value. A circuit/control program terminates the operation of the toothbrush if the voltage drops below a second threshold value or if the amplitude drops below a second threshold value, both of which are less than the respective first thresholds.