Planar Optical Waveguide Assembly with Intermediate Light Mixing

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Solution Overview

Problem

Existing lighting arrangements with planar light guides experience inhomogeneities in color and brightness due to direct placement of LEDs on narrow sides or end faces, leading to uneven light distribution and emission.

Innovation Solution

Incorporating an additional light guide on the narrow sides or end faces of the planar light guide, with structures for coupling light out of the additional guide into the planar guide, ensuring pre-mixing and uniform distribution of light before entering the planar guide.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If light sources are positioned directly on the narrow sides or end faces of the planar light guide, then the structure is simple and easy to manufacture, but inhomogeneities in color and brightness occur due to uneven light distribution

Engineering Contradiction:
Improveease of manufactureVSAvoiduniformity of light emission
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

An additional light guide is introduced as an intermediary component between the light source and the planar light guide. This intermediate light guide receives light from the light source and distributes it along its length before coupling into the planar light guide, thereby achieving uniform light distribution without complicating the overall manufacturing process

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If different LED types are used to adjust light color or color temperature, then color flexibility is improved, but optimal mixing of light from different LED types is not achieved leading to color inhomogeneity

Engineering Contradiction:
Improvecolor temperature adjustmentVSAvoidcolor uniformity
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The additional light guide performs preliminary mixing of light from different LED types before the light enters the planar light guide. By pre-mixing the light along the length of the additional light guide, uniform color distribution is achieved, enabling color temperature adjustment without compromising color uniformity

Inventive Principle:
Principle #10Preliminary action

3Illumination intensity

If a relatively large distance is chosen between high-power LEDs, then the desired brightness is achieved, but inhomogeneities in brightness occur across the light output

Engineering Contradiction:
ImprovebrightnessVSAvoidbrightness uniformity
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The solution transitions from a point-source arrangement (LEDs positioned at discrete locations) to a linear distribution arrangement (light guide extending along the narrow side). This dimensional change allows light to be distributed continuously along the length of the additional light guide, achieving both high brightness and uniformity simultaneously

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

Achieves homogeneous light emission across the planar light guide by ensuring uniform mixing and distribution of light, reducing inhomogeneities in color and brightness.

Implementation Method 1

The planar light guide is designed such that, due to total internal reflection, the light is guided through the planar light guide and then emitted or coupled out at one or both flat sides of the planar light guide.

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

the light which enters one of the structures for coupling from the further light guide is reflected when it hits the bottom surface of a structure for coupling, and is coupled out when it hits the lateral surface of the structure for coupling

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3350510B1Lighting assembly
Publication Date: 2025.11.05 ZUMTOBEL LIGHTING GMBH
  • EP3350510B1 patent drawingFigure 1
  • EP3350510B1 patent drawingFigure 2~4
  • EP3350510B1 patent drawingFigure 5

AI summary

The invention relates to a lighting assembly (1), comprising at least one light source (4), in particular one LED, and a planar optical waveguide (2) for outputting light via at least one of the 5 flat sides (6) of the planar optical waveguide (2), wherein the lighting assembly (1) has at least one further optical waveguide (3), which is arranged on one of the narrow sides or one of the end faces (7) of the planar optical waveguide (2), wherein the light source (4) is arranged on one of the end faces (9) of the further optical waveguide (3) and wherein a plurality of structures (5) for coupling the light out of the further optical waveguide (3) is provided on the further optical waveguide (3) on the side (8) facing the planar optical waveguide (2).