Elastic Circuit Board Lines for LCD Backlight Thermal Deformation

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Solution Overview

Problem

Liquid Crystal Display (LCD) backlight units face mechanical deformation due to differing heat expansion coefficients between materials, leading to poor picture quality and issues like dark areas and Mura (uniformity defects) due to inadequate mechanical flexibility.

Innovation Solution

A circuit board with elastic second lines connected to a light emitting device and a heat expansion compensating portion is integrated with a light guide plate, allowing for mechanical deformation in response to thermal expansion, thereby maintaining structural adherence and preventing bending or curvature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a circuit board is adhered to a light guide plate using rigid materials, then structural strength is improved, but mechanical deformation occurs due to heat expansion coefficient differences

Engineering Contradiction:

Improvestructural strengthVSAvoidmechanical deformation

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The patent changes the mechanical parameter of the circuit board by introducing an elastic portion that can deform. The rigid portion maintains structural strength while the elastic portion accommodates thermal expansion differences, allowing the circuit board to bend elastically when temperature changes occur, thus preventing mechanical deformation and delamination.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The circuit board is segmented into a rigid portion and an elastic portion. The rigid portion provides structural support and electrical connection functionality, while the elastic portion specifically handles thermal expansion compensation. This segmentation allows each part to perform its specialized function effectively.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the circuit board is made fully elastic to accommodate thermal expansion, then mechanical flexibility is improved, but structural strength and electrical connection stability deteriorate

Engineering Contradiction:

Improvemechanical flexibilityVSAvoidstructural strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The circuit board is divided into a rigid portion and an elastic portion. The rigid portion maintains structural strength and provides stable electrical connections, while the elastic portion provides the necessary mechanical flexibility to accommodate thermal expansion. This segmentation ensures that flexibility is provided only where needed without compromising overall structural integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the circuit board have different mechanical properties: the rigid portion has high stiffness for structural support, while the elastic portion has low stiffness for flexibility. This local differentiation of material properties allows the circuit board to simultaneously maintain strength and provide thermal adaptation.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If rigid materials are used for the circuit board, then manufacturing precision is improved, but picture quality deteriorates due to deformation and bending

Engineering Contradiction:

Improvecircuit board fabrication precisionVSAvoidpicture quality

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent introduces an elastic portion that changes its physical state with temperature, allowing the circuit board to adapt to thermal expansion. This prevents deformation and bending that would otherwise occur with fully rigid materials, thereby maintaining picture quality and eliminating defects like dark areas and Mura while still allowing for precise manufacturing of the rigid portions.

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

This solution enhances the mechanical flexibility of the backlight unit, preventing deformation and maintaining contact with the light guide plate, thus improving picture quality by compensating for heat expansion and contraction.

Implementation Method 1

a plurality of second lines connected to the first line to have elasticity at least at a point connected to the first line

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

for having mechanical deformation in conformity with heat expansion or contraction of the light guide plate owing to elasticity

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS9069206B2Circuit board, backlight unit and liquid crystal display device with the same

Publication Date: 2015.06.30 LG ELECTRONICS INC

AI summary

The present invention relates to a device which comprises a light source of a light emitting device, and more particularly to a circuit board, a backlight unit and a liquid crystal display device with the same. The backlight unit comprises a circuit board having a first line with circuit lines provided thereto, a plurality of second lines connected to the first line each to have elasticity at least at a point connected to the first line, and a light emitting device mounting portion connected to the second line and electrically connected to the circuit line, and a light guide plate positioned on the circuit board.