Aspheric Light Guide for Variable Automotive Output Spot Size

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Solution Overview

Problem

Existing automotive lighting devices face limitations in achieving a larger output spot size due to manufacturing and design constraints, particularly with flat light guides.

Innovation Solution

A light guide device with aspheric surfaces, including a first and second aspheric surface with a common focal point, and a collimator to control light rays, allowing for adaptable output spot size adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a flat light guide is used, then manufacturing is simplified, but the output spot size is limited

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidoutput spot size
Core Design Contradiction:
Ease of manufactureVSArea of stationary object

Solution Approach 1:

The patent applies curvature by replacing flat light guide surfaces with aspheric surfaces. The light guide includes at least one aspheric surface that enables variable output spot sizes while maintaining manufacturing feasibility. This curvature principle directly resolves the contradiction by allowing larger output spots without sacrificing manufacturing simplicity.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Area of stationary object

If the light guide thickness is increased, then the output spot size can be larger, but manufacturing complexity increases

Engineering Contradiction:
Improveoutput spot sizeVSAvoidlight guide structure complexity
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent changes the geometric parameters of the light guide by introducing aspheric surfaces with specific mathematical definitions (e.g., z = c*r^2 / (1 + sqrt(1 - (1+k)*c^2*r^2))). This allows variable output spot sizes to be achieved through parameter optimization rather than increasing overall thickness, thereby reducing structural complexity while maintaining the desired output area.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If aspheric surfaces are introduced, then output spot size becomes adaptable, but manufacturing precision requirements increase

Engineering Contradiction:
Improveoutput spot size adaptabilityVSAvoidsurface accuracy
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent uses aspheric surfaces defined by well-established mathematical equations that can be precisely manufactured using modern molding or machining techniques. The specific aspheric profiles (parabolic, elliptical, or hyperbolic) provide predictable optical performance, allowing adaptability in output spot size while maintaining achievable manufacturing precision through standardized geometric definitions.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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

Enables variable output spot size while adhering to manufacturing requirements, enhancing flexibility and efficiency in automotive lighting applications.

Implementation Method 1

The two or more aspherical surfaces are configured to maintain total internal reflection in the light guide

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3499113B1Light guide device for automotive lighting
Publication Date: 2026.01.21 VALEO NORTH AMERICA INC(US)
  • EP3499113B1 patent drawingFigure 1
  • EP3499113B1 patent drawingFigure 2~3
  • EP3499113B1 patent drawingFigure 4

AI summary

A device (100), a light guide (102), and a method for automotive lighting are provided. The device (100) includes a light source (104) and a light guide (102). The light source provides light rays. The light guide (102) includes two or more aspheric surfaces (112,114) having at least a common focal point (206). The two or more aspheric surfaces (112,114) are configured to maintain total internal reflection of the light rays in the light guide (102).