Detachable Personal Care Head Detection by Motor Phase Shift

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Solution Overview

Problem

Existing personal care devices require continuous monitoring of motor signals to determine the attachment state of detachable head sections, even when the device is switched off, which is inefficient and may lead to unnecessary power consumption.

Innovation Solution

A personal care device that determines the attachment state of a detachable head section by analyzing phase shift values between a periodic driving signal and a motor response signal, allowing for efficient detection without continuous motor signal monitoring, even when the device is off.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If motor signals are continuously monitored to determine attachment state, then attachment state detection accuracy is improved, but energy consumption increases and device complexity increases

Engineering Contradiction:
Improveattachment state detection accuracyVSAvoidenergy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic motor operation with alternating active and inactive periods. During active periods, the motor runs and attachment state is determined by analyzing motor signals. During inactive periods, the motor stops and no monitoring occurs. This periodic approach maintains detection capability while significantly reducing energy consumption compared to continuous monitoring.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent determines attachment state during motor active periods before the motor enters inactive period. By performing the detection action in advance while the motor is still running, the system prepares the attachment state information for use during subsequent inactive periods without requiring continuous monitoring, thus reducing overall energy consumption.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If motor signals are continuously monitored to determine attachment state, then attachment state detection accuracy is improved, but device complexity increases

Engineering Contradiction:
Improveattachment state detection accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system uses periodic motor operation where attachment state is determined only during active periods when the motor is running. This eliminates the need for continuous monitoring circuits and processing, simplifying the device architecture while maintaining adequate detection accuracy through periodic sampling.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent extracts and utilizes existing motor signals that are already generated during motor operation for attachment state detection. By repurposing signals that naturally occur during motor active periods, the system avoids adding separate sensing components or continuous monitoring infrastructure, thereby reducing device complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If motor is kept running to enable attachment state detection, then attachment state determination is improved, but energy consumption increases

Engineering Contradiction:
Improveattachment state determinationVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The motor operates periodically with defined active and inactive periods. During active periods, the motor runs and attachment state is reliably determined through signal analysis. During inactive periods, the motor stops to conserve energy. This periodic operation maintains reliability during active periods while significantly reducing overall energy consumption compared to continuous operation.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system determines attachment state during motor active periods in advance, before the motor enters inactive period. This preliminary determination ensures reliable attachment state information is available for subsequent operations without requiring the motor to remain continuously running, thus balancing reliability with energy conservation.

Inventive Principle:
Principle #10Preliminary 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 accurate detection of attachment state, type, and wear of the head section, reducing power consumption and preventing potential user injury by adjusting energy levels based on the attachment state.

Implementation Method 1

The controller is structured and/or arranged for determining at least one phase shift value between the periodic driving function and the periodic motor response signal

Methodology Applied
Scientific EffectPhase shift analysis:

Data Source

PatentEP4520294B1Personal care device
Publication Date: 2026.04.22 BRAUN GMBH
  • EP4520294B1 patent drawingFigure 1
  • EP4520294B1 patent drawingFigure 2~3B
  • EP4520294B1 patent drawingFigure 4~5

AI summary

In accordance with the present disclosure, a personal care device has a handle section allowing a user to grasp the personal care device with a hand, a head section for providing a personal care treatment to a personal care area, the head section being detachably attached to the handle section, a drive unit having a motor for driving at least a portion of the head section into motion, a controller arranged and/or structured for (a) providing a periodic driving signal at the motor, the periodic driving function essentially being adaptable by a controllable weighting factor, (b) determining at least one phase-shift value between the periodic drive signal and a periodic motor response signal, and (c) determining, based on the determined phase-shift value, (c1) whether the head section is attached to the handle section, and/or (c2) a type of the head section being attached to the handle section, and/or (c3) a state of wear of the head section being attached to the handle section.