Backlight Unit With Depressed Layers For Thin Displays

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Solution Overview

Problem

Conventional liquid crystal display (LCD) backlight units face challenges in reducing thickness, preventing particle infiltration, and ensuring uniform light emission, which affects the display's appearance and image quality.

Innovation Solution

A display device with a backlight unit comprising light generating blocks, including a first layer with light source devices, a reflection layer, a second layer with depressed portions, and a third layer for diffusing light, along with a controller for operating the blocks, which reduces thickness, simplifies manufacturing, and provides uniform light emission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a conventional backlight unit structure is used, then light sources can be disposed on the back surface, but the thickness of the display device increases and particle infiltration may occur

Engineering Contradiction:
Improvethickness of display deviceVSAvoidparticle infiltration prevention
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

The patent transitions from a conventional planar backlight structure to a three-dimensional multi-layer structure with depressed portions. The second layer includes recessed areas that allow light sources to be positioned in vertical depth rather than only on the surface plane, reducing overall thickness while maintaining light emission functionality and preventing particle infiltration through the layered design.

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

Solution Approach 2:

The patent implements a nested multi-layer structure where the first layer, second layer with depressed portions, and third layer are stacked vertically. The light sources are nested within the depressed portions of the second layer, allowing compact integration of multiple functional layers in a thin profile that prevents particle infiltration while maintaining light generation and diffusion capabilities.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Length of moving object

If light sources are disposed close together on the back surface, then the backlight unit can be thinner, but light uniformity deteriorates due to adjacent light source interference

Engineering Contradiction:
Improvethickness of backlight unitVSAvoidlight uniformity
Core Design Contradiction:
Length of moving objectVSIllumination intensity

Solution Approach 1:

The patent segments the backlight unit into multiple functional layers: a first layer for light source mounting, a second layer with depressed portions for light propagation, and a third layer for light diffusion. This segmentation allows light sources to be closely spaced while the layered structure with depressed portions separates and redirects light paths, preventing direct interference between adjacent light sources and enabling uniform light distribution across the display surface.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The second layer with depressed portions acts as an intermediary between the light sources in the first layer and the diffusion layer (third layer). The depressed portions redirect light from closely spaced sources at specific angles, and the third diffusion layer further scatters the light, mediating the transition from point sources to uniform illumination and eliminating the negative effects of adjacent light source proximity.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Illumination intensity

If a complex light guiding structure is used to achieve uniform light emission, then light uniformity improves, but manufacturing complexity increases

Engineering Contradiction:
Improvelight uniformityVSAvoidmanufacturing process complexity
Core Design Contradiction:
Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent applies local quality by creating depressed portions only in specific areas of the second layer, rather than using a complex overall light guiding structure. The depressed portions are strategically positioned between adjacent light sources to redirect light locally, while the rest of the structure remains simple. This localized modification achieves light uniformity without requiring complex manufacturing processes throughout the entire backlight unit.

Inventive Principle:
Principle #3Local quality

4Illumination intensity

If multiple layers are added to improve light uniformity, then light distribution improves, but device thickness increases

Engineering Contradiction:
Improvelight uniformityVSAvoidthickness of backlight unit
Core Design Contradiction:
Illumination intensityVSLength of moving object

Solution Approach 1:

The patent uses a dynamic multi-layer design where the second layer includes variable depressed portions that adaptively redirect light from closely spaced sources. The depth and positioning of depressed portions are optimized to redirect light at specific angles, allowing the light to propagate vertically through thin layers rather than requiring thick horizontal light guiding paths. This dynamic light redirection mechanism achieves uniform illumination while maintaining a thin overall profile.

Inventive Principle:
Principle #15Dynamics

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 reduces the display device's thickness, prevents particle infiltration, and ensures uniform light emission, enhancing the external appearance and image quality while simplifying the manufacturing process.

Implementation Method 1

at least one of the light source devices including a light emitting diode for generating the light

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

a reflection layer disposed on the first layer and configured to reflect the light emitted from the light source devices

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 3

a second layer covering the light source devices and the reflection layer and configured to propagate the light reflected by the reflection layer

Methodology Applied
Scientific EffectLight propagation:

Implementation Method 4

at least one third layer disposed on the second layer and configured to diffuse the light propagated by the second layer

Methodology Applied
Scientific EffectLight diffusion: Diffusion

Data Source

PatentEP2470949B1Backlight unit and dipslay device
Publication Date: 2015.11.04 LG ELECTRONICS INC
  • EP2470949B1 patent drawingFigure 1~5
  • EP2470949B1 patent drawingFigure 6~8
  • EP2470949B1 patent drawingFigure 9(a)~11

AI summary

A backlight unit and a display device including the backlight unit are discussed.