Leaf-Spring Cutter Head for Skin-Adaptive Hair Cutting

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Solution Overview

Problem

Existing hair cutters face challenges in achieving efficient cutting action while adapting to skin contours with minimal skin contact pressure, leading to skin irritations and noise due to the conflicting demands of resilient support structures for self-adaption and rigid driving force transmission.

Innovation Solution

A support structure using an elongated leaf spring that acts as a double cantilever, allowing for micro-diving and micro-tilting of cutter units relative to the cutter head frame, providing elastic adaption to skin contours while maintaining rigid driving efficiency and reducing noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a resilient support structure is used to allow self-adaption of cutter units to skin contour, then adaptability is improved, but driving efficiency deteriorates due to loss of driving force

Engineering Contradiction:
Improveself-adaption to skin contourVSAvoiddriving force transmission
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The support structure is segmented into multiple independent leaf springs, each responsible for supporting individual cutter units. This segmentation allows each spring to independently adapt its cutter unit to skin contours while maintaining rigid driving force transmission along the blade axis, resolving the contradiction between adaptability and driving efficiency.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The leaf springs are designed with non-uniform cross-sections featuring thicker regions for rigidity and thinner regions for flexibility. This local quality variation enables the support structure to provide rigid support for driving force transmission in critical areas while maintaining flexibility for skin contour adaptation in other areas.

Inventive Principle:
Principle #3Local quality

2Adaptability or versatility

If a resilient support structure is used to allow self-adaption of cutter units to skin contour, then adaptability is improved, but skin contact pressure increases causing skin irritations

Engineering Contradiction:
Improveself-adaption to skin contourVSAvoidskin irritation
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The leaf springs provide dynamic support that automatically adjusts to skin contours during shaving. The springs bend and flex to match the skin's surface geometry, distributing contact pressure evenly across the skin surface rather than concentrating it at specific points, thereby preventing irritation while maintaining adaptability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The support structure changes its physical parameters (flexibility and contact pressure distribution) by utilizing the elastic deformation of leaf springs. This allows the cutter units to adapt to varying skin contours while maintaining optimal and distributed contact pressure that prevents skin irritation.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If a resilient support structure is used to allow self-adaption of cutter units to skin contour, then adaptability is improved, but noise increases due to vibrations

Engineering Contradiction:
Improveself-adaption to skin contourVSAvoidnoise and vibrations
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The leaf springs incorporate localized thickening at specific positions to create rigid nodes that serve as vibration dampening points. These thicker regions act as structural reinforcements that reduce unwanted vibrations and noise generation while allowing the thinner regions to maintain flexibility for skin contour adaptation.

Inventive Principle:
Principle #3Local quality

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

The solution enables efficient cutting action with reduced skin contact pressure, minimizing vibrations and noise by allowing self-adaptive movements of cutter units without sacrificing driving efficiency.

Implementation Method 1

an elongated leaf spring holding the at least one cutter unit at the cutter head frame in an elastic way to allow for self-adaption of the cutter unit to the skin contour

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

said leaf spring is rigidly attached, with one end portion, to a first end portion or edge portion of said cutter unit and, with another end portion, to said cutter head frame

Methodology Applied
Scientific EffectRigid connection:

Data Source

PatentEP4484084B1Hair cutter
Publication Date: 2026.01.21 BRAUN GMBH
  • EP4484084B1 patent drawingFigure 1
  • EP4484084B1 patent drawingFigure 2
  • EP4484084B1 patent drawingFigure 3

AI summary

The present invention relates to cutting body hair such as beard stubbles of multidays' beard. More particularly, the present invention relates to a hair cutter such as electric shaver and/or electric trimmer, comprising a handle and a cutter head attached to said handle, and at least one cutter unit including a pair of drivable and stationary cutter elements cooperating with each other, said cutter unit being adjustably supported by means of a support structure including a spring mechanism to allow for elastic self-adaption of the cutter unit to the skin contour in terms of diving and/or tilting of the cutter unit relative to a cutter head frame, said spring mechanism including at least one elongated leaf spring which is rigidly attached, with one end portion, to a first end portion or edge portion of said cutter unit and, with another end portion, to said cutter head frame at a spring support portion thereof adjacent to a second end portion or edge portion of the cutter unit opposite to the first end portion or edge portion thereof. Despite such eccentric attachment of the leaf spring to the cutter unit and the asymmetric layout of the spring mechanism, the elastic support structure of the at least one cutter unit nevertheless may be configured to provide for a symmetric self-adaption, in particular symmetric micro diving and/or micro tilting.