Light Guide Rear Fixing Lugs for Homogeneous Photometry

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Solution Overview

Problem

Existing light guides in optical units, such as vehicle headlights, face challenges in securing the light guide without disturbing photon propagation, especially when the front face has a complex shape, leading to non-homogeneous photometric functions.

Innovation Solution

The light guide features two fixing lugs at its rear end with through holes that induce total internal reflection, allowing for secure attachment without obstructing photon propagation, and these lugs can serve as additional reflectors to enhance the photometric function.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the light guide is secured by additional parts or screws through the rear end, then the fixing is fixed and precise, but the photon propagation towards the front end is disturbed

Engineering Contradiction:
Improvefixing stabilityVSAvoidphotonic function homogeneity
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The light guide is segmented into a central part and rear fixing lugs. The fixing lugs are separated from the central photonic path, allowing independent optimization of mechanical fixing and optical performance. The lugs are positioned at corners of the rear end, away from the central photonic propagation zone.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The fixing lugs act as intermediary elements that provide mechanical attachment functionality without interfering with the main photonic function. They serve as a mediator between the mounting requirement and the photonic integrity, allowing both functions to coexist.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the front face has a complex shape for stylistic reasons or mounting adaptation, then the optical unit can be adapted to various applications, but the photometric function homogeneity deteriorates

Engineering Contradiction:
Improvemounting adaptabilityVSAvoidphotometric function homogeneity
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The light guide is divided into a central part dedicated to photonic function and rear fixing lugs for mechanical attachment. This segmentation allows the central part to maintain optimal geometry for homogeneous light distribution while the rear lugs provide adaptable mounting options without affecting photometric performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different parts of the light guide have different optimized properties: the central part is optimized for photonic propagation with smooth geometry, while the rear lugs are optimized for mechanical attachment with features like through holes and corner positioning. Each zone has local quality tailored to its specific function.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If fixing points are positioned to avoid disturbing photon propagation, then photometric homogeneity is maintained, but the fixing stability may be compromised

Engineering Contradiction:
Improvephotometric function homogeneityVSAvoidfixing stability
Core Design Contradiction:
Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The fixing function is segmented into separate lugs positioned at the rear corners, away from the central photonic path. This allows fixing points to be positioned optimally for both stability and photonic performance, as the lugs are located where they won't interfere with light propagation while still providing robust mechanical attachment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The fixing lugs extend towards the rear from the central part, utilizing the longitudinal dimension to position fixing points away from the transverse photonic propagation path. This dimensional separation allows both functions to coexist without interference.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 design enables homogeneous photometric performance even with complex-shaped front ends, improves stability, and eliminates the need for additional parts, resulting in a modern and efficient optical unit.

Implementation Method 1

having a shape and an external surface which induce at least one total internal reflection of the photons having penetrated through this entry zone towards this central part

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3797242B1Optical unit light guide, with rear end having attachment tabs participating in photon reflection
Publication Date: 2022.08.17 PSA AUTOMOBILES SA
  • EP3797242B1 patent drawingFigure 1~2

AI summary

A light guide (GL) equips an optical unit and comprises a central portion (PC) situated between a rear end (E1), comprising an inlet zone (ZE) supplied with photons by photon sources and having a shape and an external surface inducing at least total internal reflection of the photons having penetrated through the inlet zone (ZE) towards the central portion (PC), and a front end (E2) delivering photons guided by the central portion (PC) and participating in a photometric function. The rear end (E1) also comprises two attachment tabs (PF1-PF2) extending it towards the rear and each comprising a through-hole (T1, T2) delimited by a wall having a portion having a shape and an external surface inducing at least total internal reflection, towards the central portion (PC), of the photons that reach it, in order for them to participate in this photometric function.