Stacked Light Guide Symbol Display With LED Alignment Assembly

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Solution Overview

Problem

Conventional electronic pixel matrix displays for function displays are expensive, prone to 'burn-in,' high in power consumption, and pose safety risks, particularly in applications like motor vehicles where head impacts are possible, and they require precise alignment of light sources which is challenging due to their design.

Innovation Solution

A function display using a stack of transparent or translucent flat light guides separated by an air gap, with microstructured symbol areas and individually coupled light sources, allowing for precise alignment and energy-efficient operation, and featuring a circuit board with light sources arranged for optimal illumination and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electronic pixel matrix displays are used for function display, then display functionality is achieved, but cost increases, power consumption increases, and safety risks arise

Engineering Contradiction:
ImprovesafetyVSAvoidinjury risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces expensive electronic pixel matrix displays with a simpler, safer light guide-based display system. The light guide stack with microstructured symbol areas and LED light sources provides the same display functionality without the burn-in risk and safety hazards of electronic displays, effectively using a more reliable, long-lasting alternative.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent extracts the display function from electronic pixel matrix technology and implements it through a separate optical system using light guides and microstructured surfaces. This separation eliminates the harmful aspects of electronic displays while maintaining the desired display functionality through pure optical means.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If electronic pixel matrix displays are used, then display functionality is provided, but power consumption increases

Engineering Contradiction:
Improvedisplay stabilityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces power-hungry electronic pixel matrix displays with a passive light guide system that uses LED light sources. The light guides themselves consume no power, and the LED sources are significantly more energy-efficient than electronic pixel matrices, reducing overall power consumption while maintaining stable display functionality.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Adaptability or versatility

If multiple light guides are stacked to display different symbols, then display versatility is improved, but alignment precision of light sources becomes more difficult

Engineering Contradiction:
Improvesymbol display capabilityVSAvoidlight source alignment
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent introduces a light shaft as an intermediary component between the LED light source and the light guides. The light shaft acts as a mechanical guide and optical channel that automatically aligns the light source with the light guide's end face, eliminating the need for precise manual alignment and ensuring optimal optical coupling in the stacked light guide configuration.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The light shaft structure provides self-alignment functionality, where the mechanical fit of the light source into the light shaft automatically positions it correctly relative to the light guide. This self-aligning mechanism ensures precise optical coupling without requiring complex external alignment tools or procedures.

Inventive Principle:
Principle #25Self-service

4Ease of manufacture

If light sources are arranged on a circuit board for efficiency, then manufacturing simplicity is improved, but alignment precision with light guides deteriorates

Engineering Contradiction:
Improvelight source arrangementVSAvoidoptical coupling accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The light shaft serves as an intermediary that bridges the circuit board mounting system and the light guide requiring precise alignment. The light shaft is mounted on the circuit board with the light source, and its structure ensures that when assembled, the light source is automatically positioned at the correct location and orientation relative to the light guide, combining manufacturing simplicity with alignment precision.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

The solution provides a reliable, cost-effective, and energy-efficient function display with precise optical coupling and reduced safety risks, enabling the selective display of symbols and states while maintaining visibility and safety in automotive applications.

Implementation Method 1

a light guide stack which, when the function display is attached as intended, forms a display surface facing a viewer. The light guide stack is formed from at least two transparent or translucent, flat light guides

Methodology Applied
Scientific EffectLight transmission: Light

Implementation Method 2

The light guides each have a main surface facing a viewer and a main surface facing away from the viewer

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 3

a microstructured symbol area which is provided in or on the light guide and which comprises a plurality of light-refractive and/or light-scattering microstructures

Methodology Applied
Scientific EffectLight refraction: Refraction

Implementation Method 4

a microstructured symbol area which is provided in or on the light guide and which comprises a plurality of light-refractive and/or light-scattering microstructures

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 5

arranged superimposed in a stacking direction, which are spaced apart by a transparent or translucent layer made of a material that is optically thinner compared to the adjacent light guides, preferably via an air gap

Methodology Applied
Scientific EffectOptical isolation: Refraction

Data Source

PatentEP4105055B1Function display for selectively displaying a plurality of symbols representing a switching function and / or a plurality of switching states with alignment function of the light sources and corresponding method of assembly
Publication Date: 2023.09.27 PREH GMBH
  • EP4105055B1 patent drawingFigure 1
  • EP4105055B1 patent drawingFigure 2
  • EP4105055B1 patent drawingFigure 3

AI summary

The invention relates to a function display (1) for the selective display of several symbols, each representing a switching function and/or at least two switching states, comprising: a stack of light guides which, when the function display (1) is installed as intended, forms a display surface (8) facing a viewer (B);wherein the optical fiber stack is formed from at least two transparent or translucent planar optical fibers (2, 3) arranged superimposed in a stacking direction, which are spaced apart by a transparent or translucent layer of a material that is optically thinner than the adjacent optical fibers (2, 3), preferably via an air gap (14), such that the optical fibers (2, 3) each have a main surface (H) facing a viewer (B) and a main surface (H') facing away from the viewer (B), and in at least one optical fiber (2) the main surface (H') facing away from the viewer (B) is facing an optical fiber (3) that is nearest to it in the opposite direction to the stacking direction; per optical fiber (2, 3) at least one light source (5, 5') which is arranged such that its light (L, L') is coupled into the respective optical fiber (2, 3) via an end face (11) of an associated optical fiber (2, 3) facing the light source (5, 5');wherein at least one microstructured symbol area (12a, 12b) is provided in or on each light guide (2, 3), which is designed to be luminously visible to the observer (B) by means of the light (L, L') coupled into the light guide (2, 3) when the light source (5, 5') is activated; a printed circuit board (7) on which the multiple light sources (5, 5') are arranged and fixed; an aperture (6) fixed to the light guide stack by a material-bonded and/or force-fit and/or form-fit connection, to which the printed circuit board (7) is fixed by contact with a mounting surface (15), wherein two light sources (5') of the printed circuit board serve as an alignment aid during the fastening of the printed circuit board (7) and aperture (6); and an associated assembly method.