Vehicle Light Guide Protuberance Stray Light Control

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Solution Overview

Problem

Vehicle light units experience stray light due to photons passing through mask openings, causing degradation in photometric function quality, particularly due to dimensional variations and manufacturing processes leading to functional clearance.

Innovation Solution

Incorporating protuberances on the light guides perpendicular to the general direction of guidance, which act as barriers to prevent photons from exiting through mask openings, combined with edge features on the mask to enhance photon redirection and minimize stray light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a functional clearance is provided between mask opening and light guide to account for dimensional variations and facilitate passage, then ease of manufacture and assembly are improved, but stray light passes through the clearance causing degradation of photometric function quality

Engineering Contradiction:

Improveease of assemblyVSAvoidstray light

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The light guide is segmented by adding a protuberance that divides the light guide structure into distinct regions: a main body portion and a protuberance portion. This segmentation creates a barrier that blocks stray light paths while preserving the functional clearance for assembly, thus resolving the contradiction between ease of manufacture and stray light prevention.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The protuberance acts as an intermediary element between the light guide and the mask opening. It introduces a light-blocking structure that mediates the interaction between light and the clearance space, preventing stray light from passing through while maintaining the necessary functional clearance for assembly purposes.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the mask opening is made smaller to reduce stray light passage, then stray light is reduced, but the passage of light guides through the mask opening becomes more difficult and vibration prevention is compromised

Engineering Contradiction:

Improvestray lightVSAvoidpassage through mask opening

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The solution applies local quality by adding a protuberance at a specific location on the light guide rather than uniformly reducing the mask opening size. This localized structural modification blocks stray light paths in critical areas while preserving the overall dimensions needed for easy passage and vibration prevention.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If the functional clearance between mask opening and light guide is reduced to prevent stray light, then stray light passage is minimized, but manufacturing dimensional variations cause assembly difficulties

Engineering Contradiction:

Improvestray lightVSAvoiddimensional variations

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The protuberance is designed in advance with predetermined dimensions and positioning to compensate for manufacturing dimensional variations. This preliminary structural feature ensures that even with normal manufacturing tolerances, the stray light blocking function is maintained while the functional clearance for assembly is preserved.

Inventive Principle:

Principle #10Preliminary action

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

Significantly reduces stray light, maintaining photometric function quality by preventing parasitic photons from passing through openings, thus addressing manufacturing defects related to dimensional variations and functional clearance.

Implementation Method 1

at least one light guide comprising a rear end supplied with photons by at least one photon source and a front end having a front face delivering guided photons

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

each light guide comprises on at least one lateral face, in the vicinity of the corresponding aperture and before the latter, at least one protuberance arranged so as to limit the exit of photons through a portion of the aperture which is placed in front of a protuberance

Methodology Applied

Scientific EffectPhysical barrier blocking: Physical Containment

Data Source

PatentEP3453947B1Vehicle optical block with light guide(s) having protuberance(s) for limiting passage of photons parasites

Publication Date: 2021.03.24 PSA AUTOMOBILES SA

Figure 1~2

AI summary

An optical unit (OU) equips a vehicle and comprises a housing delimiting, with a translucent screen (ET), a cavity (CB) in which at least one light guide (G1-G3) is installed. Each light guide has a rear end (E11-E13) supplied with photons by at least one photon source (S1-S3) and a front end (E21-E23) having a front face (FV) delivering guided photons, and a mask (MB) comprising at least one aperture (O1-O3) through which the front end (E21-E23) passes. Each light guide (G1-G3) includes, on at least one lateral face (FL1), in the vicinity of an aperture (O1-O3) and before it, a protrusion (PR) defined perpendicular to the general direction of photon guidance and limiting the exit of photons through a portion of this aperture (O1-O3) located in front of it (PR).