Lightguide Recess Design for Uniform Illumination

Solution Overview

Problem

The assembly and cost of lightguide systems with multiple LEDs for illumination can be complex and expensive, especially when using flexible lightguides, due to the need for precise distribution and spacing of LEDs for uniform light output.

Innovation Solution

An optical system featuring a lightguide with an elongated recess that divides the lightguide into sections, allowing for light extraction from one section while maintaining it within the other, enabling the use of a single LED and providing design flexibility for light management through varying recess dimensions and light extractor placement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If multiple LEDs are arranged along the lightguide for light injection, then the total amount of light and spatial uniformity are improved, but the assembly complexity and cost increase

Engineering Contradiction:

Improvetotal amount of lightVSAvoidassembly complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent extracts the light distribution function from multiple LED sources and consolidates it into a single LED combined with a reflective cavity. The reflective cavity extracts and redirects light to achieve uniform distribution along the lightguide, eliminating the need for multiple LEDs and their complex spacing arrangements.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The lightguide is divided into multiple sections along its length, with light extractors positioned at specific locations. The reflective cavity segments the light path, directing light to different sections sequentially, which simplifies the overall system while maintaining uniform illumination across all segments.

Inventive Principle:

Principle #1Segmentation

2Illumination intensity

If multiple LEDs are arranged along the lightguide for light injection, then the spatial uniformity is improved, but the assembly complexity and cost increase

Engineering Contradiction:

Improvespatial uniformityVSAvoidassembly complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent extracts the light distribution function from multiple LED sources and consolidates it into a single LED combined with a reflective cavity. The reflective cavity extracts and redirects light to achieve uniform distribution along the lightguide, eliminating the need for multiple LEDs and their complex spacing arrangements.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a spatial dimension by incorporating a reflective cavity that operates in three-dimensional space. This cavity reflects light at various angles and positions, creating uniform illumination along the length of the lightguide without requiring multiple light sources arranged in specific patterns.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Illumination intensity

If multiple LEDs are used for light injection, then the illumination coverage is improved, but the cost increases

Engineering Contradiction:

Improveillumination coverageVSAvoidcost

Core Design Contradiction:

Illumination intensityVSQuantity of substance

Solution Approach 1:

The patent merges the functions of multiple LEDs into a single LED system equipped with a reflective cavity. This unified structure provides the same illumination coverage that would otherwise require multiple separate light sources, thereby reducing component count and overall system cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the light distribution function from multiple LED sources and consolidates it into a single LED combined with a reflective cavity. The reflective cavity extracts and redirects light to achieve uniform distribution along the lightguide, eliminating the need for multiple LEDs and their complex spacing arrangements.

Inventive Principle:

Principle #2Taking out (Extraction)

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 configuration simplifies the assembly and reduces costs by allowing a single LED to provide uniform illumination, offering greater design flexibility and efficient light distribution within the lightguide.

Implementation Method 1

A non-imaging reflector may be positioned at the bottom of the recess 20 to reflect light into the second lightguide section 40.

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

Light extractors may be disposed in the second, but not the first, lightguide section for extracting light that would otherwise propagate within and along the second lightguide section.

Methodology Applied

Scientific EffectOptical coupling:

Data Source

PatentUS11199654B2Lightguide having recess of varying depth

Publication Date: 2021.12.14 3M INNOVATIVE PROPERTIES CO

AI summary

An optical system comprises a lightguide having an elongated recess formed therein. The recess divides the lightguide into a first lightguide section a second larger lightguide section. Light extractors are disposed in the second, but not the first, lightguide section for extracting light that would otherwise propagate within and along the second lightguide section via total internal reflection (TIR). The depth of the recess varies along its length. The inclusion of a recess having a depth that varies along its length provides design flexibility in the number and location of light source(s) used by the optical system.