Waterproof Handle Unit with Flexure Hinge Seal

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Solution Overview

Problem

Conventional toothbrushes face issues with excessive force application during brushing, leading to health problems like gum irritation and tooth enamel abrasion, and existing pressure sensors in toothbrushes often suffer from sealing failures that allow water and toothpaste to accumulate, promoting mold growth.

Innovation Solution

A handle unit for a personal care implement featuring a light indication and sealing element with a ring structure connected by flexure hinges and filled with transparent elastomeric material, providing a watertight seal and feedback on pressure application through a light ring that surrounds the handle, allowing for independent movement of the pivot lever and preventing dead volumes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a pressure sensor is installed in the toothbrush handle, then the user can receive feedback on brushing force, but sealing elements create dead volumes where water and toothpaste accumulate allowing mold to grow

Engineering Contradiction:
Improvepressure sensingVSAvoidmold growth
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent employs a flexible membrane seal that spans the cavity opening, allowing the pivot lever to move freely while maintaining water-tight sealing. The membrane is supported by a flexible arch structure that prevents it from collapsing into the cavity, thereby eliminating dead volumes where mold could grow while still permitting the pressure sensor's pivot lever to detect brushing forces accurately.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The flexible membrane acts as an intermediary element between the internal cavity containing the pressure sensor and the external environment. It transmits pressure changes from the brushing action to the sensor while blocking water and toothpaste from entering the cavity, thus preventing mold growth without compromising pressure sensing functionality.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If internal sealing elements are used to allow pivot lever movement, then the pressure sensor can function, but the seal creates dead volumes that accumulate water and toothpaste

Engineering Contradiction:
Improvepivot lever movementVSAvoidwater accumulation
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

A flexible membrane formed from elastomeric material is positioned at the cavity opening to seal it. The membrane is supported by a flexible arch structure that prevents collapse, allowing the pivot lever to move freely against the membrane without creating dead volumes where water and toothpaste could accumulate.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The sealing solution is designed to be dynamic rather than static. The flexible membrane and arch structure allow the seal to adapt and move with the pivot lever during operation, maintaining water-tight sealing while enabling the full range of motion required for pressure sensing functionality.

Inventive Principle:
Principle #15Dynamics

3Reliability

If the handle is sealed water-tight, then the housing is protected, but movements of the pressure sensor parts are restricted

Engineering Contradiction:
Improvewater-tight sealingVSAvoidsensor part movement
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent uses a flexible membrane seal that can deform to accommodate the movement of the pressure sensor's pivot lever. The membrane is supported by a flexible arch structure that prevents it from collapsing into the cavity, thereby maintaining water-tight sealing while allowing the necessary movements for pressure sensing.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The sealing system's physical parameters (flexibility, support structure) are optimized to allow movement within a certain range while maintaining sealing integrity. The flexible arch structure provides mechanical support that enables the membrane to flex without collapsing, balancing sealing reliability with movement freedom.

Inventive Principle:
Principle #35Parameter changes

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 effectively prevents water accumulation, reduces health risks by indicating excessive pressure, and enhances the hygiene and durability of the toothbrush by ensuring a reliable, waterproof seal and improved vibration transmission, regardless of how the handle is gripped.

Implementation Method 1

the circular gap being filled with a transparent and/or translucent soft elastomeric material, the transparent and/or translucent soft elastomeric material forming the elastic circular section to seal the ring structure and the housing in a substantially water-tight manner

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the ring structure being connected to the housing at the proximal end by two flexure hinges thereby creating a circular gap between the ring structure and the housing

Methodology Applied
Scientific EffectFlexure: Hinge

Data Source

PatentEP3892233B1Unit for a handle of a personal care implement and personal care implement
Publication Date: 2023.10.11 THE GILLETTE CO
  • EP3892233B1 patent drawingFigure 1~2
  • EP3892233B1 patent drawingFigure 3~4
  • EP3892233B1 patent drawingFigure 5~6

AI summary

A unit for a handle of a personal care implement is provided, the unit comprising a housing having a proximal end closest to a head being repeatably attachable to and detachable from the handle, and a light indication and sealing element, the light indication and sealing element comprising a ring structure and an elastic circular section, the ring structure being connected to the housing at the proximal end by two flexure hinges thereby creating a circular gap between the ring structure and the housing, the circular gap being filled with a transparent and/or translucent soft elastomeric material, the transparent and/or translucent soft elastomeric material forming the elastic circular section to seal the ring structure and the housing in a substantially water-tight manner.