Eyeglass Temple Hinge With Interference-Fit Spherical Locking

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Solution Overview

Problem

Existing eyeglass hinges require small components like screws, bushings, or spot welds for connection, which are cumbersome, prone to wear, and affect appearance, necessitating specialist assembly and being susceptible to breakage.

Innovation Solution

A hinge design that integrates a spherical element with a hook-shaped temple end, allowing interference fit into a semicircular cavity in the eyeglass front, eliminating the need for screws, rivets, or adhesive bonding, and enabling user-friendly assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If screws, bushings, or rivets are used for connecting the temple to the front, then the connection is secure, but the assembly requires specialist opticians and the components are prone to wear and loss

Engineering Contradiction:

Improveconnection securityVSAvoidassembly complexity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The hinge is designed to be self-contained and self-assembling. The temple end with the curved surface directly engages with the corresponding recess in the front, allowing users to assemble and disassemble the eyeglasses without requiring specialist opticians or additional tools. The hinge structure itself provides the connection function, eliminating the need for separate fastening components.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The hinge is integrated as a single unified component that combines the connection function with the structural elements of both the temple and front. By merging the hinge with the temple end and front recess, the design eliminates the need for separate screws, bushings, or rivets, simplifying both the assembly process and the overall structure.

Inventive Principle:

Principle #5Merging (Combining)

2Strength

If spot welds are used to connect the temple to the front, then the connection is strong, but the surface becomes uneven and affects the appearance

Engineering Contradiction:

Improveconnection strengthVSAvoidsurface uniformity

Core Design Contradiction:

StrengthVSShape

Solution Approach 1:

The design replaces the thermal welding process (spot welding) with a mechanical interference fit system. The curved surface on the temple end engages with the complementary recess in the front through precise geometric shaping, creating a strong connection without heat or deformation. This mechanical approach maintains surface uniformity while providing sufficient connection strength.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the hinge is made robust to withstand stresses from repeated openings and closings, then the connection is reliable, but the hinge dimensions increase and spoil the minimal appearance

Engineering Contradiction:

Improvehinge durabilityVSAvoidtemple diameter

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The hinge design applies local quality by concentrating the structural strength exactly where needed - in the localized interface between the temple end and front recess. The curved surface and corresponding recess are precisely shaped to provide maximum connection strength in a minimal volume, allowing the hinge to withstand repeated stresses without requiring increased overall dimensions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The temple end features a curved surface that engages with a complementary recess in the front. This curved geometry allows for a compact, space-efficient connection that maintains minimal temple diameter while providing robust mechanical engagement. The curvature enables the hinge to accommodate repeated opening and closing motions without requiring excessive material or volume.

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Reliability

If traditional hinge components are used, then the connection is secure, but the components can be lost by the user and require specialist assembly

Engineering Contradiction:

Improveconnection securityVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The hinge is designed as a single integrated component that combines the connection function with the structural elements of both the temple and front. By merging the hinge with the temple end and front recess, the design eliminates the need for separate screws, bushings, or rivets, simplifying both the assembly process and the overall structure.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Inventive Principle:

Principle #25Self-service

Data Source

PatentEP3999900B1Eyeglasses with simplified hinge for temple

Publication Date: 2025.12.17 LUXOTTICA SRL

Figure 1
Figure 2~3
Figure 4~6

AI summary

Eyeglasses (1) with a simplified hinge, comprising a front (2) of the eyeglasses and a pair of temples (3), a cavity (4) is defined in the front for accommodating a retention and locking element (9) which is adapted to be engaged by a hook-shaped portion (6) of one end of each one of the temples, the retention and locking element (9) being adapted to be accommodated in the cavity (4) of the front, when it is coupled to the hook-shaped end (6) of the temple, in order to couple the temple (3) to the front (2).