Asymmetric Light Input Wedge Backlight for Uniform Illumination

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional backlights face inefficiencies in light distribution due to parallel side surfaces and lack of effective reflective layers, leading to suboptimal light extraction and uniformity in illumination.

Innovation Solution

The use of asymmetric light input wedges with a specular reflective layer, where the reflective layer is not in intimate contact with the diverging surfaces, enhances light extraction through direct emission and total internal reflection, improving light distribution and efficiency by utilizing multilayer polymeric mirror films for high reflectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If parallel side surfaces are used in conventional backlights, then manufacturing is simplified, but light extraction efficiency and uniformity deteriorate

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidlight extraction efficiency

Core Design Contradiction:

Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent applies asymmetry by transitioning from parallel side surfaces to asymmetric light input wedges with non-parallel opposing side surfaces. The wedge configuration creates diverging light paths that improve light extraction efficiency and uniformity across the light guide, resolving the contradiction between manufacturing simplicity and illumination performance.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent changes geometric parameters by introducing wedge angles and non-parallel surface configurations. This parameter change transforms the light propagation characteristics, enabling improved light extraction while maintaining manufacturability through standard molding processes.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If reflective layers are placed in intimate contact with diverging surfaces, then device complexity is reduced, but light reflection efficiency deteriorates due to absorption losses

Engineering Contradiction:

Improvestructural simplicityVSAvoidabsorption losses

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent extracts the reflective layer from intimate contact with the diverging surfaces, positioning it instead at the narrow end of the asymmetric wedge. This separation eliminates absorption losses that would occur at the interface, while the light guide structure itself handles light distribution, resolving the contradiction between structural simplicity and energy efficiency.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The light guide portion acts as an intermediary between the light source and the reflective layer. It receives light from the source, performs initial light distribution through its asymmetric geometry, and directs light to the reflective layer, which then reflects light uniformly across the output surface without direct contact losses.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Illumination intensity

If asymmetric light input wedges are implemented, then light distribution uniformity improves, but device complexity increases

Engineering Contradiction:

Improvelight distribution uniformityVSAvoidstructural complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent merges the light guide portion with the asymmetric light input wedges into a single integrated structure. This combination achieves improved light distribution uniformity through the asymmetric wedge geometry while avoiding the complexity of separate components, as the entire structure can be manufactured in one piece using standard molding techniques.

Inventive Principle:

Principle #5Merging (Combining)

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 significantly improves light extraction efficiency and uniformity, achieving greater than 95% reflectivity for visible light, resulting in enhanced illumination performance and reduced absorption losses.

Implementation Method 1

a visible light transmissive body primarily propagating light by TIR with a light input surface and a light output surface

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

achieving greater than 95% reflectivity for visible light

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 3

asymmetric light input wedges with a specular reflective layer, where the reflective layer is not in intimate contact with the diverging surfaces, enhances light extraction through direct emission and total internal reflection

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS9207384B2Backlight asymmetric light input wedge

Publication Date: 2015.12.08 3M INNOVATIVE PROPERTIES CO

AI summary

A backlight is disclosed and includes a visible light transmissive body primarily propagating light by TIR with a light input surface and a light output surface and a light guide portion and a light input portion. The light guide portion has a light reflection surface and a light emission surface. The light input portion has opposing side surfaces that are not parallel. One of the opposing surfaces is co-planar with either the light emission surface or the light reflection surface. A light source is disposed adjacent to the light input surface. The light source emits light into the light input portion. A reflective layer is disposed adjacent to or on the opposing side surfaces.