Adaptive External Cutter Speed Control in Electric Shavers

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Solution Overview

Problem

Existing electric shavers face issues with suboptimal hair-catching efficiency and user discomfort due to varying rotational speeds of external cutting members, which are not adaptable to individual user-specific factors such as skin sensitivity, hair properties, and shaving techniques.

Innovation Solution

An electric shaver with a detection system to measure user-related parameters, controlling the rotational speed of the external cutting member based on factors like skin sensitivity, hair properties, and shaving motion to optimize hair-catching efficiency and user comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the external cutting member is rotated at a fixed rotational speed, then the hair-catching efficiency is improved, but the user comfort and adaptability to different users deteriorate

Engineering Contradiction:
Improvehair-catching efficiencyVSAvoidadaptability to user-specific factors
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by making the rotational speed of the external cutting member adjustable rather than fixed. The drive system enables the external cutting member to rotate at variable speeds (first rotational speed for internal cutting member, second rotational speed for external cutting member), allowing adaptation to different user needs, skin sensitivities, and hair properties while maintaining effective hair catching.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of rotational speed from a fixed value to a variable parameter. The control system adjusts the rotational speeds of both internal and external cutting members based on detected user-related parameters, enabling optimization of hair-catching efficiency for different individuals while managing skin irritation risks.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the external cutting member is rotated at high speed to improve hair-catching efficiency, then the productivity increases, but the skin irritation and user discomfort increase

Engineering Contradiction:
Improvehair-catching efficiencyVSAvoidskin irritation
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system dynamically adjusts the rotational speed of the external cutting member based on detected user-related parameters. When parameters indicate sensitive skin or specific shaving conditions, the system reduces the rotational speed to minimize skin irritation while maintaining adequate hair-catching efficiency through optimized rotation patterns.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent incorporates a detection system that measures user-related parameters (skin sensitivity, hair properties, shaving motion) and feeds this information back to the control system. The control system then adjusts the rotational speeds of the cutting members accordingly, creating a closed-loop system that balances productivity with user comfort and minimizes harmful effects like skin irritation.

Inventive Principle:
Principle #23Feedback

3Productivity

If the rotational speeds of cutting members are optimized for maximum hair catching, then the productivity increases, but the complexity of the drive system increases

Engineering Contradiction:
Improvehair-catching efficiencyVSAvoiddrive system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The drive system is designed to perform multiple functions: it drives both the internal cutting member and external cutting member, controls their relative rotation, and adjusts their rotational speeds independently based on user parameters. This multi-functional approach, while increasing complexity, enables sophisticated optimization of hair-catching efficiency across different users and conditions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4543644B1Electric shaver with rotatable external cutting member having adjustable rotational speed
Publication Date: 2026.02.18 KONINKLIJKE PHILIPS NV
  • EP4543644B1 patent drawingFigure 1
  • EP4543644B1 patent drawingFigure 2
  • EP4543644B1 patent drawingFigure 3

AI summary

An electric shaver (1) comprises at least one hair-cutting unit (9a, 9b, 9c) having a central axis (11), an external cutting member (13) with hair-entry openings (61), and an internal cutting member (15). The internal and external cutting members are rotated about the central axis, respectively, at a first rotational speed (ω1) and at a second rotational speed (ω2) and such that the internal and external cutting members are rotated relative to each other. The electric shaver further comprises a detection system (87) for measuring at least one user-related parameter (URP) relating to skin or hairs of a user of the electric shaver or relating to manipulation of the electric shaver by the user relative to a body of the user. The electric shaver further comprises a processor (89) for controlling the second rotational speed (ω2) of the external cutting member in dependence on the at least one measured user-related parameter.