Embedded Grating Light Guiding Assembly for Thin Backlight Modules

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Solution Overview

Problem

Current backlight modules, especially bottom-type modules, face issues of excessive thickness and poor light coupling efficiency due to unreasonable structural design of the light guiding assembly, leading to high power consumption and increased cost, as they require a large number of LEDs with significant spacing and suffer from optical energy loss during light propagation.

Innovation Solution

A light guiding assembly with a waveguide layer and a coupling grating structure comprising multiple gratings, where the gratings are arranged to diffract light in a way that higher diffraction orders satisfy total reflection conditions, improving coupling efficiency and reducing module thickness, and including a light guiding dot layer for enhanced light distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If traditional light guiding assembly structure is used, then the backlight module can provide sufficient illumination, but the thickness becomes excessive and light coupling efficiency deteriorates

Engineering Contradiction:

Improvelight coupling efficiencyVSAvoidmodule thickness

Core Design Contradiction:

Illumination intensityVSLength of stationary object

Solution Approach 1:

The patent transitions from traditional surface-level light guiding structures to a three-dimensional grating structure embedded within the waveguide layer. The grating structure comprises multiple layers of gratings at different depths and orientations, creating a volumetric light coupling mechanism that significantly improves coupling efficiency while maintaining thin profile.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The grating structure is nested within the waveguide layer, with multiple grating layers positioned at different depths. The gratings are embedded inside the waveguide material, creating a compact nested arrangement that maximizes light coupling functionality within minimal thickness space.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Illumination intensity

If a large number of LEDs with significant spacing are used, then sufficient light output is achieved, but power consumption increases and cost rises

Engineering Contradiction:

Improvelight outputVSAvoidpower consumption

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The patent replaces the mechanical approach of using multiple spaced LEDs with an optical field-based grating structure. The grating structure manipulates light propagation through diffraction and total internal reflection, creating a more efficient light distribution system that reduces the number of LED sources needed and lowers overall power consumption.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If traditional light guiding structure is used, then manufacturing is straightforward, but light propagation suffers from optical energy loss

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidoptical energy loss

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent optimizes key parameters of the grating structure including grating period, depth, orientation angles, and refractive index contrasts to maximize light coupling efficiency. By carefully tuning these parameters, the structure achieves superior light propagation with minimal energy loss while remaining compatible with existing manufacturing processes.

Inventive Principle:

Principle #35Parameter changes

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 achieves high light coupling efficiency of over 80%, reduces the thickness of the backlight module, decreases the number of LEDs required, and simplifies the manufacturing process, while enabling effective dynamic local dimming technology.

Implementation Method 1

The first grating is configured to diffract the incident light to form first diffracted light such that at least one portion of diffraction orders of the first diffracted light satisfies total reflection conditions in the waveguide layer

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

at least one portion of diffraction orders of the first diffracted light satisfies total reflection conditions in the waveguide layer

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS11237429B2Light guiding assembly and fabricating method thereof, backlight module and display device

Publication Date: 2022.02.01 BOE TECHNOLOGY GROUP CO LTD

AI summary

A light guiding assembly and a fabricating method, a backlight module, and a display device are provided. The light guiding assembly includes a waveguide layer, and a coupling grating structure including at least two gratings, wherein at least one of the at least two gratings is located inside the waveguide layer, and orthographic projections of the at least two gratings on a surface of the waveguide layer at least partially overlap, the coupling grating structure being configured such that incident light propagates in the waveguide layer.