Backlight Unit Flexibility via Porous Reflective Sheet

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Solution Overview

Problem

Conventional backlight units for vehicle interior trim parts are rigid, prone to cracking, and unsuitable for forming into complex shapes due to their thickness and material properties, leading to issues with flexibility and bubble formation during thermoforming.

Innovation Solution

A backlight unit comprising a polycarbonate light guide panel, a reflective sheet with fibers and pores, and an acrylic adhesive sheet, which allows for improved flexibility and prevents delamination during thermoforming, enabling the formation of three-dimensional curved shapes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional rigid materials are used for backlight units, then structural strength is maintained, but flexibility and ability to form complex shapes deteriorate

Engineering Contradiction:

ImproveflexibilityVSAvoidstructural strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent employs a composite structure consisting of a light guide panel, reflective sheet, and adhesive sheet. This composite material approach allows the combination of materials with different properties to achieve both flexibility for forming complex shapes and sufficient structural strength to prevent cracking during installation and use.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If the light guide panel thickness is increased, then structural strength is improved, but flexibility and ability to be formed into curved shapes deteriorates

Engineering Contradiction:

ImproveformabilityVSAvoidstructural strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent utilizes a thin light guide panel with a thickness of 0.25 to 0.4 mm, which falls within the range of thin films. This thin film structure provides the necessary flexibility to be formed into three-dimensional curved shapes while maintaining sufficient structural strength through the composite construction and proper material selection.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If conventional bonding methods are used without porous structure, then bonding strength is achieved, but bubble formation and delamination during thermoforming occur

Engineering Contradiction:

Improvebonding reliabilityVSAvoidbubble formation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a reflective sheet with a porous structure that has specific pore size and distribution. This porous structure allows trapped air and bubbles to escape during the bonding process and thermoforming, preventing bubble formation and delamination while maintaining bonding reliability between the light guide panel and reflective sheet.

Inventive Principle:

Principle #31Porous materials

4Adaptability or versatility

If the light guide panel is made thinner to improve flexibility, then formability is enhanced, but susceptibility to cracking and structural failure increases

Engineering Contradiction:

ImproveflexibilityVSAvoidcrack resistance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs a composite structure where the thin light guide panel is bonded to a reflective sheet and adhesive sheet. This composite construction provides crack resistance and structural reliability to the thin light guide panel, allowing it to be made thinner for improved flexibility while preventing structural failure through the supporting layers.

Inventive Principle:

Principle #40Composite materials

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 enhances the flexibility and quality of the backlight unit, allowing it to be formed into complex shapes while preventing bubble formation and delamination, resulting in a thinner, more durable, and efficient lighting solution for vehicle interior trim parts.

Implementation Method 1

the reflective sheet includes pores

Methodology Applied

Scientific EffectPorosity: Porosity

Implementation Method 2

a reflective sheet including fibers and provided below the light guide panel to reflect the light dispersed by the light guide panel

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 3

an acrylic adhesive sheet interposed between the light guide panel and the reflective sheet

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 4

a light guide panel including polycarbonate and configured to disperse light received from a light emitting device therein

Methodology Applied

Scientific EffectLight dispersion: Scattering

Data Source

PatentUS10823906B2Backlight unit for planar lighting apparatuses with improved flexibility and manufacturing method thereof

Publication Date: 2020.11.03 KOLON INDUSTRIES INC

AI summary

Disclosed are a backlight unit for planar lighting apparatuses and a manufacturing method thereof. The backlight unit simplifies a layer structure to be formed into the shape of a vehicle interior trim part, and has a thin thickness and improved flexibility. The backlight unit includes a light emitting device configured to emit light; a light guide panel having polycarbonate and configured to disperse the light received from a light emitting device; a reflective sheet having fibers and provided below the light guide panel to reflect the light dispersed by the light guide panel; and an acrylic adhesive sheet interposed between the light guide panel and the reflective sheet. The reflective sheet includes pores.