Electric Shaver Display Foil Sealing Against Moisture

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Solution Overview

Problem

Personal care devices like electric shavers face issues with moisture ingress affecting display visibility and integrity due to misalignment and manufacturing tolerances, leading to impaired illumination and potential damage to the display foil.

Innovation Solution

The display foil is sealed to both inner and outer housing elements using adhesive, with adhesive foam compensating for tolerances and deformations, and laser-treated symbols are applied post-attachment to ensure precise alignment and prevent moisture ingress, while opaque shading fences restrict stray light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the display foil is positioned outside the sealed inner housing to provide brilliant illumination, then the display visibility is improved, but moisture ingress between the inner and outer housings can damage the display foil

Engineering Contradiction:
Improvedisplay visibilityVSAvoidmoisture damage to display foil
Core Design Contradiction:
Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

A sealing layer is introduced as an intermediary element between the inner and outer housings at the display foil position. This sealing layer acts as a moisture barrier while allowing the display foil to remain externally positioned for optimal illumination. The sealing layer specifically blocks moisture ingress paths without interfering with the light transmission needed for display visibility.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The sealing layer is implemented as a thin film structure that conformally seals the interface between housings. This thin film provides effective moisture protection while maintaining the optical properties needed for display foil illumination. The flexible nature of the thin film allows it to accommodate manufacturing tolerances and housing deformations.

Inventive Principle:
Principle #30Flexible shells and thin films

2Reliability

If adhesive is used to seal the display foil to housings, then moisture protection is improved, but manufacturing complexity increases due to additional sealing steps

Engineering Contradiction:
Improvemoisture protectionVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sealing function is merged with the existing adhesive bonding process that attaches the display foil to the housings. The adhesive serves dual purposes: mechanical attachment of the display foil and sealing against moisture ingress. This integration eliminates the need for separate sealing steps, reducing manufacturing complexity while maintaining reliable moisture protection.

Inventive Principle:
Principle #5Merging (Combining)

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

This solution provides a sealed and visually effective display that is resistant to moisture, maintaining clarity and extending the lifespan of the display foil by preventing corrosion and improving handling and aesthetics.

Implementation Method 1

adhesive foam compensating for tolerances and deformations

Methodology Applied
Scientific EffectAdhesive: Adhesive

Implementation Method 2

laser-treated symbols are applied post-attachment

Methodology Applied
Scientific EffectLaser: Laser

Data Source

PatentEP3546155B1Personal care device such as electric shaver
Publication Date: 2022.07.20 BRAUN GMBH
  • EP3546155B1 patent drawingFigure 1
  • EP3546155B1 patent drawingFigure 2~3
  • EP3546155B1 patent drawingFigure 4

AI summary

The present invention relates to a personal care device, in particular an electric shaver, comprising a housing (300) with a working head (3) attached thereto, said housing including an inner housing (301) and an outer housing (302), and a display (500) including a light source (503) accommodated in the inner housing to emit light through transparent portions of said inner and outer housings, said display further including a display foil (502) having portions of different transparency and/or different colors forming display symbols, said display foil being sandwiched between said transparent portions of the inner and outer housings. More particularly, the display foil may be glued to both the inner and outer housing by means of an adhesive on each of opposite sides of the display foil.