Rotary Shaver Cutter Unit with Pivot Case for Skin Contouring

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Solution Overview

Problem

Existing rotary electric shavers face issues with deep shaving and skin burning due to large cutter unit sizes and inadequate movement of outer cutters, leading to poor shaving experiences and potential skin damage.

Innovation Solution

A rotary electric shaver design featuring a disk-shaped outer cutter with an outer cutter ring and pivot case that allows for upward and downward movement and tilting, supported by a return spring, ensuring the outer cutter follows the skin's contour without sinking deeply, and a compact design with reduced spacing between cutter units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the outer cutter is designed to be movable upward and downward and tiltable in an arbitrary direction, then the shaving feeling is improved, but the distance between the outer cutter and the outer cutter holder becomes larger, causing the cutter unit and cutter head to be large in size

Engineering Contradiction:

Improveshaving feelingVSAvoidcutter unit size

Core Design Contradiction:

Ease of operationVSVolume of moving object

Solution Approach 1:

The outer cutter is nested within the outer cutter holder, with the holder forming a cavity that accommodates the cutter. The cutter can move freely within this nested space while maintaining close proximity to the holder, thus achieving both good shaving feeling and compact size.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The outer cutter is designed to move in multiple dimensions (upward/downward and tilting in arbitrary directions) simultaneously, allowing it to adapt to skin contours while remaining within a compact overall structure. This multi-dimensional movement enables good shaving performance without increasing the cutter head size.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If the inner cutter is supported to be rotated only about one axis, then the structure is simplified, but when skin pressure is applied to the rotating axis, the skin supporting rim cannot turn, causing poor shaving operation

Engineering Contradiction:

Improvecutter support structureVSAvoidshaving operation smoothness

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The cutter support structure is designed to be dynamic rather than fixed. The inner cutter can rotate about one axis while the outer cutter and skin supporting rim can tilt in arbitrary directions when skin pressure is applied. This dynamic adaptation allows smooth shaving operation while maintaining relatively simple structure.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The cutter assembly is segmented into independently movable parts: the inner cutter for rotation about one axis, and the outer cutter with skin supporting rim for independent tilting. This segmentation allows each component to perform its specific function without interfering with the other, achieving both structural simplicity and operational smoothness.

Inventive Principle:

Principle #1Segmentation

3Productivity

If the outer cutter presses the skin firmly, then the cutting efficiency is improved, but the outer cutter sinks deeply into the skin, causing deep shaving and potential skin damage

Engineering Contradiction:

Improvecutting efficiencyVSAvoidskin damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The skin supporting rim is designed beforehand to provide cushioning and protection. When the outer cutter presses against the skin, the rim prevents the cutter from sinking too deeply by providing a supporting structure that limits excessive penetration, thus preventing skin damage while maintaining cutting efficiency.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The skin supporting rim acts as an intermediary between the outer cutter and the skin. It provides a protective interface that allows the cutter to press against the skin for efficient cutting while preventing direct deep penetration that would cause damage. The rim mediates the interaction between the cutting tool and the skin surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 design enhances shaving comfort by preventing deep cuts and skin burning, while maintaining a compact cutter head size and improving the overall shaving experience with efficient hair cutting.

Implementation Method 1

a return spring that is compressedly provided between the pivot case and the cutter receiving stage so that the return spring returns the pivot case to a position coaxial with the drive shaft

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS7370420B2Rotary electric shaver

Publication Date: 2008.05.13 IZUMI PROD CO

AI summary

A cutter unit of a rotary shaver including: a cutter receiving stage 90 held by an outer cutter housing 18 and coaxially penetrated by a drive shaft 26, a pivot case holder 50 held by the cutter receiving stage to be movable upward and downward and having a case supporting portion 58 below an outer cutter 14, a bowl-shaped pivot case 48 held by the pivot case holder 50 to make sliding contact with the case supporting portion 58 of the pivot case holder, the pivot case 48 being pivotable in any direction and surrounding the lower portion of an inner cutter 40, an outer cutter ring 76 provided on the pivot case 48 and in which the flange of the outer cutter is secured, and a return spring 70 for returning the pivot case 48 to be coaxial with the drive shaft.