Razor Cartridge Variable Inter-Blade Span Design

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Solution Overview

Problem

Conventional razor cartridges often result in aggressive shaving, leading to increased incidents of skin injury, nicks, and irritation due to the exclusive support of the shaving plane by cutting edges, which causes skin bulging and reduced glideness, and the constant inter-blade span can lead to debris blockage during rinsing.

Innovation Solution

A razor cartridge design featuring three or more substantially parallel cutting members with a leading inter-blade span smaller than the trailing inter-blade span, where each cutting member has a blade support with a blade mounting portion on its inner surface facing away from the shaving plane, increasing contact points and reducing pressure on the skin, and allowing for a variable inter-blade span for enhanced glideness and rinsability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the inter-blade span is kept constant in conventional razor cartridges, then the structure is simple and easy to manufacture, but debris blockage occurs during rinsing and skin bulging increases leading to nicks and irritation

Engineering Contradiction:
Improveshaving performanceVSAvoidinter-blade span configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by varying the inter-blade span at different locations along the blade array. The leading inter-blade span is configured to be smaller than the trailing inter-blade span, optimizing each region for its specific function: the leading region for precise cutting with reduced skin bulging, and the trailing region for effective debris ejection during rinsing.

Inventive Principle:
Principle #3Local quality

2Object-affected harmful factors

If the blade support contacts the skin to reduce skin bulging, then skin injuries and irritation are reduced, but the blade mounting complexity increases

Engineering Contradiction:
Improveskin injuryVSAvoidblade support structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent inverts the conventional blade mounting approach by placing the blade mounting portion on the inner surface of the blade support rather than the outer surface. This inversion allows the blade support's outer surface to contact the skin directly, reducing skin bulging and injuries, while the blade remains securely mounted on the opposite side.

Inventive Principle:
Principle #13The other way round (Inversion)

3Ease of operation

If the leading inter-blade span is made smaller to reduce skin bulging, then glideness is improved, but the trailing span must be larger to prevent debris blockage

Engineering Contradiction:
ImproveglidenessVSAvoidinter-blade span variation
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent segments the blade array into distinct regions with different inter-blade span characteristics. The leading portion has a smaller inter-blade span optimized for glideness and skin contact, while the trailing portion has a larger inter-blade span optimized for debris ejection, allowing each segment to perform its specific function effectively.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3744489B1Razor cartridge
Publication Date: 2023.07.19 BIC VIOLEX SINGLE MEMBER SA
  • EP3744489B1 patent drawingFigure 1
  • EP3744489B1 patent drawingFigure 2a~3
  • EP3744489B1 patent drawingFigure 4

AI summary

A razor cartridge (20) comprising three or more substantially parallel cutting members (28a-d) disposed between a leading longitudinal side (24) and a trailing longitudinal side (25) of the razor cartridge in a shaving direction (S) of the razor cartridge. Each of the cutting members (28a-d) comprises a blade support (32) comprising a blade mounting portion (71) disposed on an inner surface (66) of the respective blade support that, in use, faces away from a shaving plane (SH), and a blade (33) attached to the blade mounting portion (71). The cutting members (28a-d) are disposed to define a plurality of inter-blade spans (40, 41, 42) between cutting edges (30) of the blades. A leading inter-blade span (40) that is closer to the leading longitudinal side (24) of the razor cartridge than a trailing inter-blade span (42) is smaller than the trailing inter-blade span (42) that is closer to the trailing longitudinal side (25) of the razor cartridge than the leading inter-blade span.