Polarization Beam-Splitting Light Guide Structure for Thin Backlight Modules

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Solution Overview

Problem

Current direct type LED backlight modules suffer from inefficiencies in light energy distribution, leading to significant light loss and increased thickness, which compromises the thinness and energy efficiency of LED liquid crystal display products.

Innovation Solution

A light guide structure incorporating a first and second waveguide layer with polarization beam-splitting and coupling gratings, along with a mesh layer, to split and reflect light efficiently, eliminating the need for extensive light mixing distances and reducing the number of LEDs required.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a direct type LED backlight module uses conventional light mixing methods, then light uniformity can be achieved, but the module thickness increases and light energy loss increases

Engineering Contradiction:
Improvelight uniformityVSAvoidbacklight module thickness
Core Design Contradiction:
Illumination intensityVSLength of stationary object

Solution Approach 1:

The patent divides the backlight module into multiple functional layers including a light guide layer with microlens arrays, a reflection layer, and a diffusion layer. Each layer performs a specific function in light redistribution, eliminating the need for thick light mixing sections while achieving uniform illumination through coordinated action of segmented components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces microlens arrays that redirect light in the vertical dimension through refraction, and reflection layers that bounce light in multiple directions. This dimensional approach to light redistribution replaces conventional horizontal light mixing, achieving uniformity without increasing module thickness.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If conventional direct type LED backlight modules are used, then structure is simple, but light energy distribution is inefficient leading to increased energy loss

Engineering Contradiction:
Improvestructure simplicityVSAvoidlight energy loss
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The patent introduces a light guide layer with microlens arrays as an intermediary component between the LED light sources and the display panel. This intermediary structure efficiently redirects and distributes light energy, reducing loss while maintaining reasonable structural complexity through the addition of functional optical elements.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the optical parameters of light propagation by incorporating microlens arrays that alter light direction through refraction, and reflection layers that change light path through reflection. These parameter changes optimize light energy distribution efficiency without requiring complete structural redesign.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If conventional direct type LED backlight modules are used, then manufacturing is simple, but light uniformity cannot be optimized without increasing thickness

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidlight uniformity
Core Design Contradiction:
Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent segments the backlight module into standardized functional layers (light guide layer with microlens arrays, reflection layer, diffusion layer) that can be manufactured separately and assembled. This segmentation maintains manufacturing simplicity while achieving optimized light uniformity through the coordinated function of each layer.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates a multi-functional light guide layer that simultaneously performs light redirection through microlens arrays, uniform distribution through integrated diffusion structures, and maintains thin profile. This universal component design achieves light uniformity optimization without complicating the overall manufacturing process.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution enhances light uniformity and reduces energy loss, allowing for a thinner and more energy-efficient backlight module design while maintaining image quality and reducing costs.

Implementation Method 1

a polarization beam-splitting structure disposed on the first light exiting surface, and configured to split light emitted from a light source into a first polarized light and a second polarized light

Methodology Applied
Scientific EffectPolarization beam-splitting: Polarisation

Implementation Method 2

a first polarization coupling grating disposed on the first light incident surface and configured to deflect the first polarized light and allow the first polarized light to be totally reflected in the first waveguide layer

Methodology Applied
Scientific EffectTotal reflection: Total Internal Reflection

Implementation Method 3

a first polarization coupling grating disposed on the first light incident surface and configured to deflect the first polarized light

Methodology Applied
Scientific EffectGrating diffraction: Diffraction Grating

Implementation Method 4

a second polarization coupling grating disposed on the polarization beam-splitting structure... allow the second polarized light to be totally reflected in the second waveguide layer

Methodology Applied
Scientific EffectTotal reflection: Total Internal Reflection

Implementation Method 5

a second polarization coupling grating disposed on the polarization beam-splitting structure... configured to deflect the second polarized light

Methodology Applied
Scientific EffectGrating diffraction: Diffraction Grating

Implementation Method 6

the grating structure is used for guiding light incident to the grating structure to the waveguide layer and performing total reflection propagation in the waveguide layer

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3690530B1Light guide structure for a direct type backlight, direct backlight module and display panel
Publication Date: 2023.05.10 BOE TECHNOLOGY GROUP CO LTD
  • EP3690530B1 patent drawingFigure 1~2
  • EP3690530B1 patent drawingFigure 3~4
  • EP3690530B1 patent drawingFigure 5~6

AI summary

The present disclosure relates to the field of display technology, and provides a light guide structure including a first waveguide layer having a first light incident surface and a first light exiting surface; a polarization beam-splitting structure disposed on the first light exiting surface, and configured to split light emitted from a light source into a first polarized light and a second polarized light; a first polarization coupling grating disposed on the first light incident surface and configured to deflect the first polarized light and allow the first polarized light to be totally reflected in the first waveguide layer; a second waveguide layer having a second light incident surface and a second light exiting surface and disposed on the polarization beam-splitting structure; a second polarization coupling grating disposed between the second light incident surface and the polarization beam-splitting structure and configured to deflect the second polarized light and allow the second polarized light to be totally reflected in the second waveguide layer.