Interchangeable Spectacle Arms Snap-Fit Coupling

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Solution Overview

Problem

Existing interchangeable coupling systems for spectacles arms lack stability and are prone to deformations and breakages due to complexity and fragility, affecting efficacy and reliability.

Innovation Solution

The spectacles feature a coupling device with a strip-shaped body and a seat, utilizing a snap-fit coupling system with resiliently flexible branches that deform to ensure stable interference engagement, eliminating coupling play and facilitating easy disengagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If quick-fit mechanisms with snap-fit connections are used for interchangeable arms, then ease of operation is improved, but stability of the connection deteriorates due to coupling play

Engineering Contradiction:
Improveease of arm interchangeabilityVSAvoidconnection stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent changes the geometric parameters of the coupling interface by introducing a tapered conical shape instead of a cylindrical shape. This parameter change allows the coupling elements to maintain both ease of quick-fit engagement and stable connection without play, resolving the contradiction between ease of operation and connection stability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies a conical (curved) geometry to the coupling elements rather than a straight cylindrical form. The tapered surfaces enable self-centering and elimination of coupling play while maintaining simple snap-fit operation, thus improving connection stability without sacrificing ease of operation

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Device complexity

If screw type systems of small dimensions are used for coupling arms, then device complexity is reduced, but reliability deteriorates due to risk of deformations and breakages

Engineering Contradiction:
Improvesimplicity of coupling systemVSAvoidresistance to deformations and breakages
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent extracts the fastening function from a screw-type system and implements it through a pure snap-fit mechanism with tapered coupling surfaces. This eliminates the need for threads and fastening elements that are prone to deformation and breakage, while maintaining simplicity of the overall device

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the coupling mechanism from a threaded connection to a tapered snap-fit connection. This parameter change eliminates the weak points associated with small screws and threads, providing a more reliable connection that is equally simple in structure

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

This configuration provides improved stability and ease of use for interchangeable arms, ensuring secure coupling without play and simplifying the quick disengagement process for easy interchangeability.

Implementation Method 1

resiliently flexible branches which deform to ensure stable interference engagement

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3129826B1Spectacles with interchangeable arms
Publication Date: 2025.05.14 SAFILO SPA
  • EP3129826B1 patent drawingFigure 1~2
  • EP3129826B1 patent drawingFigure 3~10
  • EP3129826B1 patent drawingFigure 8~9

AI summary

There is described a pair of spectacles with interchangeable arms (6), comprising a front frame (2) with opposed lateral lugs (7) for the hinged pivoting of the respective lateral arms (6), a device for the removable coupling of each arm (6) to the frame (2), the device comprising a first and a second coupling element (8, 9), engaged in each other so as to be slidable from and towards a position of mutual retention, the elements being configured for quick disengagement from this position, the first coupling element (8) being intended for the hinged connection to the respective lug (7) of the frame (2), and the second element (9) comprises a seat (12) which is provided in the corresponding arm (6) and which can be slidingly engaged by the first element (8), resiliently flexible retaining means being provided between the coupling elements (8, 9) of each arm (6) to fix these elements to each other in a removable manner, by means of a snap-fitting coupling. The first coupling element (8) comprises a strip- shaped body (11) with a first and a second branch (13, 14) of the strip extending from a common portion (15) and having their predominant longitudinal extents in directions parallel with each other, the branches (13, 14) being spaced apart and extending in a first direction (X) substantially perpendicular to the strip plane (P) and in a second direction (Y) substantially parallel with the strip plane (P), in such a manner that the branches (13, 14) of the strip can engage the seat (12) in the arm (6) by bearing against opposing inner surfaces (12a, b; 12c, d) of the seat (12) in both the first direction (X) and the second direction (Y), as a result of a resilient stress created in the branches (13, 14) of the strip in these directions (X, Y).