Electric Toothbrush Motor Control for Smooth Oscillation Adjustment

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Solution Overview

Problem

Existing electric toothbrushes lack the ability to smoothly and continuously adjust oscillation intensity without steps or jumps, limiting the effectiveness of teeth cleaning.

Innovation Solution

A control circuit that varies the frequency and duty cycle of a voltage signal to the electric motor, allowing for a substantially linear change in oscillation amplitude in response to user input, enabling smooth intensity adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional electric toothbrushes are used with fixed oscillation settings, then the device structure remains simple, but the cleaning effectiveness is limited due to inability to smoothly adjust oscillation intensity

Engineering Contradiction:
Improvecleaning effectivenessVSAvoidcontrol circuit complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent implements dynamic oscillation control by enabling continuous adjustment of oscillation intensity through varying the duty cycle and frequency of the voltage signal in real-time, allowing the toothbrush to transition smoothly between different cleaning intensities based on user needs and gum sensitivity

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control circuit varies the duty cycle and frequency parameters of the voltage signal supplied to the motor to achieve continuous oscillation amplitude adjustment. By changing these electrical parameters, the system enables smooth transitions between oscillation intensities without mechanical complexity

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If oscillation intensity is adjusted in steps or jumps, then the control mechanism remains simple, but the transitions are not smooth causing discomfort during use

Engineering Contradiction:
Improvesmoothness of oscillation transitionsVSAvoidcontrol mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent ensures continuous oscillation adjustment by varying the duty cycle and frequency of the voltage signal continuously rather than in discrete steps. This allows the oscillation amplitude to change smoothly over time, providing a comfortable user experience during intensity transitions

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The control circuit uses periodic voltage signals with variable duty cycles to drive the motor. By modulating the duty cycle of these periodic signals, the system achieves smooth oscillation amplitude control while maintaining the periodic nature of the motor operation

Inventive Principle:
Principle #19Periodic action

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

Enables continuous and seamless transitions in oscillation intensity, enhancing the cleaning performance of the toothbrush by ensuring a smooth and efficient cleaning process.

Implementation Method 1

an electric motor configured to, in response to a voltage signal, oscillate a drive shaft in an oscillatory motion

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a pulse width modulation signal generator... the voltage signal having a frequency and a duty cycle, the control circuit configured to vary the frequency and the duty cycle of the voltage signal

Methodology Applied
Scientific EffectPulse width modulation:

Data Source

PatentEP4684755A2Personal care system and method
Publication Date: 2026.01.28 COLGATE PALMOLIVE CO
  • EP4684755A2 patent drawingFigure 1
  • EP4684755A2 patent drawingFigure 2
  • EP4684755A2 patent drawingFigure 3A~4

AI summary

In one embodiment, a personal care appliance includes an electric motor having a drive shaft. In response to a voltage signal, the drive shaft is oscillated in an oscillatory motion having an oscillation amplitude. A control circuit includes, in operable cooperation, a user interface, a processor, a pulse width modulation signal generator, and a power source. The control circuit supplies the voltage signal to the electric motor, the voltage signal having a frequency and a duty cycle. The control circuit varies the frequency and the duty cycle of the voltage signal in response to an oscillation adjustment input received from the user interface so that the oscillation amplitude of the drive shaft is varied along a substantially linear rate of change profile relative to the frequency.