Multi-Pivot Safety Razor Blade Unit with Magnetic Return

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Solution Overview

Problem

Safety razors with blade units that pivot about a single axis parallel to the blade edges have limited ability to conform to skin contours, often disengaging during shaving due to restricted movement.

Innovation Solution

A safety razor design featuring a blade unit mounted for pivotal movement about a pivot axis substantially perpendicular to the blade edges, utilizing magnetic return forces to ensure smooth and consistent conformance with skin contours, with multiple sets of magnetic elements generating increasing repulsive forces to guide the blade unit back to rest positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the blade unit pivots about a single axis parallel to the blade edges, then the structure is simple, but the blade unit has limited ability to conform to skin contours and often disengages during shaving

Engineering Contradiction:
Improveability to conform to skin contoursVSAvoidpivotal movement structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent transitions from single-axis pivotal movement to multi-axis pivotal movement, adding another dimension of freedom. The blade unit can now pivot about a first axis substantially parallel to the blade edges and a second axis substantially perpendicular to the blade edges, enabling three-dimensional adaptation to skin contours while maintaining manageable structural complexity through modular magnetic element design

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If the blade unit is allowed to pivot freely to follow skin contours, then conformance improves, but the blade unit may disengage from the skin during shaving

Engineering Contradiction:
Improveconformance to skin contoursVSAvoidblade unit engagement
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements magnetic feedback mechanisms where magnets mounted on the handle interact with magnets on the blade unit to generate restoring forces. As the blade unit pivots away from its rest position to follow skin contours, the magnetic attraction/repulsion provides a feedback force that guides the blade unit back toward engagement, preventing disengagement while maintaining adaptability

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent utilizes changes in magnetic field parameters (strength, direction, distribution) as the blade unit pivots. The magnetic interaction parameters dynamically adjust based on the blade unit's position, providing controlled restoring forces that maintain reliable skin engagement throughout the range of motion

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If magnetic elements are used to generate return force, then smooth and reproducible pivotal movement is achieved, but the device complexity increases

Engineering Contradiction:
Improvesmoothness of pivotal movementVSAvoidmagnetic element configuration
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent divides the magnetic system into segmented components: multiple magnets distributed on the handle and multiple magnets on the blade unit, each serving specific functional zones. This segmentation allows independent optimization of each magnetic element's position and strength, achieving smooth reproducible movement while managing overall system complexity through modular design

Inventive Principle:
Principle #1Segmentation

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 magnetic return forces enable improved conformance to skin contours, ensuring smooth and reproducible pivotal movement, enhancing shaving performance by maintaining blade unit engagement throughout the shaving process.

Implementation Method 1

The return force comprises a magnetic force generated by a set of magnetic elements that are moved relative to each other in response to pivotal movement of the blade unit about the pivot axis

Methodology Applied
Scientific EffectMagnetic force: Magnetism

Data Source

PatentEP2227360B1Safety razor with multi-pivot blade unit
Publication Date: 2012.02.22 THE GILLETTE CO
  • EP2227360B1 patent drawingFigure 1~2
  • EP2227360B1 patent drawingFigure 3~4
  • EP2227360B1 patent drawingFigure 5~6

AI summary

A safety razor blade unit 11 mounted for pivotal movement relative to a razor handle 12 about a pivot axis B substantially perpendicular to a blade 20 mounted in the blade unit. The blade unit is biased to a rest position by a magnetic return force generated by a set of magnetic elements 32, 34, 36. The set of magnetic elements are so disposed that the return force increases as the pivotal displacement of the blade unit from the rest position increases.