Modular Backlight Unit for Slim LCDs

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Solution Overview

Problem

The existing back-light units for liquid crystal displays (LCDs) are thick and lack modular design, which hinders the production of slim LCDs with high contrast ratios, as they require complex assembly and higher production costs.

Innovation Solution

A modular back-light unit design utilizing a light guide plate and reflection plate arranged in a tiling fashion, with LEDs positioned on the edges of the light guide plate, allowing for easier assembly, reduced thickness, and improved light distribution, enabling high contrast ratios through local dimming.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a traditional back-light unit is used, then the display device can be assembled, but the thickness of the display device becomes large

Engineering Contradiction:
Improvethickness of display deviceVSAvoidstructure of back-light unit
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The back-light unit is divided into multiple modules, each containing a light guide plate, light source, and reflection plate. These modules can be assembled in a tiling fashion to form the complete back-light unit, reducing overall thickness while maintaining functionality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The light guide plate is designed with a projection that extends in the thickness direction, creating an air layer gap between the light guide plate and the optical sheet. This dimensional change allows for reduced thickness without compromising light distribution.

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

2Length of moving object

If the back-light unit is made into modules, then the thickness can be reduced, but optical unevenness occurs at the boundary of adjacent modules

Engineering Contradiction:
Improvethickness of back-light unitVSAvoidoptical uniformity
Core Design Contradiction:
Length of moving objectVSManufacturing precision

Solution Approach 1:

A reflection plate is positioned between adjacent light guide plate modules to act as an optical intermediary. The reflection plate reflects light from one module toward adjacent modules, compensating for optical unevenness at the boundaries and achieving uniform light distribution across the entire display surface.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If a non-modular back-light unit is used, then assembly is simpler, but production cost increases and contrast ratio is reduced

Engineering Contradiction:
Improveassembly processVSAvoidcontrast ratio
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The back-light unit is segmented into standardized modules that can be easily assembled in a tiling fashion. Each module contains integrated components (light guide plate, light source, reflection plate), simplifying the assembly process while enabling local dimming control for high contrast ratios.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The modular design enables dynamic control of different module groups, allowing local dimming where specific modules can be independently adjusted based on image content. This dynamic control achieves high contrast ratios while maintaining ease of assembly through standardized module interfaces.

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

This design reduces the overall thickness of the display device, simplifies assembly, lowers production costs, and enhances light uniformity and contrast ratios by allowing for modular construction and efficient light management.

Implementation Method 1

a light guide plate having a first side surface receiving light emitted from the LED light source incident thereon and a second side surface facing the first side surface

Methodology Applied
Scientific EffectLight transmission: Light

Implementation Method 2

at least one reflection plate having plural light guide plates thereon

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP2488914B1Liquid crystal display
Publication Date: 2018.02.07 LG ELECTRONICS INC
  • EP2488914B1 patent drawingFigure 1~2
  • EP2488914B1 patent drawingFigure 3~4
  • EP2488914B1 patent drawingFigure 5

AI summary

The present invention relates to a liquid crystal display. The thickness of the back-light unit of the present invention can be reduced and the back-light unit can be driven partially by a module and can provide high contrast ratio. Since the assembly of the plurality of back-light unit modules is made to be easy according to the described structure, a production cost may be reduced.