Asymmetric Razor Blade Geometry for Lower Skin Irritation

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Solution Overview

Problem

Existing razor blades with symmetrical shapes do not fully optimize shaving geometry, leading to suboptimal shaving performance and potential skin irritation.

Innovation Solution

The development of asymmetric razor blades with a split line through the tip, defining asymmetric sections and a bevel shoulder on one section to reduce tip pressure and enhance skin-contacting performance, while maintaining a sharp cutting edge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If symmetrical blade shape is used, then manufacturing is simpler, but shaving performance is suboptimal and skin irritation occurs

Engineering Contradiction:
Improveblade manufacturing simplicityVSAvoidskin irritation
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by designing the blade with a split line that divides the blade into asymmetric sections, creating different facet configurations on each side of the blade. This asymmetric geometry optimizes the interaction between the blade and skin, reducing skin irritation while maintaining manufacturing feasibility through precise geometric control.

Inventive Principle:
Principle #4Asymmetry

2Object-affected harmful factors

If asymmetric blade design is implemented, then shaving performance and skin comfort improve, but manufacturing complexity increases

Engineering Contradiction:
Improveskin irritation reductionVSAvoidblade geometry complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies segmentation by introducing a split line that divides the blade into distinct sections with different facet configurations. This segmentation allows each section to be optimized for specific functions (cutting, skin contact, pressure distribution) while maintaining overall geometric control and manufacturability through modular design principles.

Inventive Principle:
Principle #1Segmentation

3Productivity

If blade exposure is increased, then cutting performance improves, but skin irritation increases

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

Solution Approach 1:

The patent applies local quality by creating different geometric characteristics in different regions of the blade. The asymmetric facets and split line configuration ensure that the cutting edge maintains optimal exposure for efficient hair cutting, while other regions of the blade are designed to minimize skin contact pressure and reduce irritation, achieving both high productivity and low harmful effects.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4135953B1Razor blade
Publication Date: 2026.03.25 THE GILLETTE CO
  • EP4135953B1 patent drawingFigure 1
  • EP4135953B1 patent drawingFigure 2A
  • EP4135953B1 patent drawingFigure 2B

AI summary

A razor blade is provided comprising a substrate comprising a first portion and a second portion. The first portion may comprise first and second generally parallel outer surfaces. The second portion may comprise first and second sections separated by a split line. The first section may comprise a first facet extending directly from the first outer surface of the first portion and an end facet extending directly from the first facet. The second section may comprise an end facet. The end facets of the first and second sections may converge at a tip to define a cutting edge. The split line may pass through the tip and is generally parallel with and extends between the first and second outer surfaces of the first portion.