Reflective Sheet Embossing and Air Bubbles for Adhesion Prevention

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Solution Overview

Problem

The existing manufacturing process for reflective sheets in liquid crystal display devices requires a separate bead coating process, leading to high costs and increased manufacturing time due to the need for process line design, manpower, and raw materials, and results in adhesion issues between the reflective sheet and the light guide plate, causing image blurring.

Innovation Solution

A method to form first and second skin layers with embossing surfaces using a reflective sheet fabric manufacturing process without a separate bead coating process, incorporating reflective patterns made from organic and inorganic fillers and beads, and air bubbles to prevent adhesion and enhance light reflection efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate bead coating process is used to form bead layers on the reflective sheet, then adhesion between the reflective sheet and light guide plate is prevented, but manufacturing costs and manufacturing time increase

Engineering Contradiction:
Improveadhesion preventionVSAvoidmanufacturing time
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The bead layer formation process is merged with the reflective sheet manufacturing process. The skin layers containing beads are formed simultaneously with the reflective sheet base layer through a single extrusion and molding operation, eliminating the need for separate coating processes and reducing manufacturing time while maintaining adhesion prevention functionality

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

Beads are incorporated into the skin layers during the initial manufacturing stage of the reflective sheet, before the sheet is assembled with the light guide plate. This preliminary inclusion of beads in the skin layers ensures adhesion prevention is built into the structure from the start, avoiding later coating operations

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a separate bead coating process is used to form bead layers on the reflective sheet, then adhesion between the reflective sheet and light guide plate is prevented, but manufacturing costs increase due to process line design, manpower, and raw materials

Engineering Contradiction:
Improveadhesion preventionVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The bead layer formation process is merged with the reflective sheet manufacturing process. The skin layers containing beads are formed simultaneously with the reflective sheet base layer through a single extrusion and molding operation, eliminating the need for separate coating processes and reducing manufacturing time while maintaining adhesion prevention functionality

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The reflective sheet structure itself provides the adhesion prevention function through beads embedded in the skin layers, rather than requiring external coating processes. The skin layers with integrated beads serve the dual purpose of structural integrity and adhesion prevention, making the system self-sufficient

Inventive Principle:
Principle #25Self-service

3Reliability

If the cover bottom is made non-flat to support the reflective sheet, then adhesion between the reflective sheet and light guide plate is prevented, but light cannot pass through compressed portions of the light guide plate causing image blurring

Engineering Contradiction:
Improveadhesion preventionVSAvoidimage quality
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The skin layers are designed with localized bead structures that provide adhesion prevention only at specific contact points with the light guide plate. This allows the cover bottom to maintain its non-flat supporting structure while the bead-containing skin layers create micro-gaps at adhesion-prone areas, preventing both adhesion and light blockage that would cause image blurring

Inventive Principle:
Principle #3Local quality

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 approach reduces manufacturing costs and prevents adhesion between the reflective sheet and the light guide plate, while improving light reflection efficiency by forming embossing surfaces and air bubbles within the reflective layer, thereby enhancing the display device's performance.

Implementation Method 1

a reflective sheet reflecting light emitted toward a cover bottom disposed below the LEDs toward the light guide plate

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

the reflective layer includes a plurality of air bubbles

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 3

the air bubbles of the air bubble layers have an oval shape having a major axis in a horizontal direction

Methodology Applied
Scientific EffectPhysical separation: Bubble

Data Source

PatentEP2752686B1Display device and method for fabricating reflective sheet for the same
Publication Date: 2021.07.07 LG DISPLAY CO LTD
  • EP2752686B1 patent drawingFigure 1
  • EP2752686B1 patent drawingFigure 2~3A
  • EP2752686B1 patent drawingFigure 3B~3C

AI summary

A method of manufacturing a reflective sheet includes preparing a film comprising first and second skin layers (178, 179) and a reflective layer (166) disposed between the first and second skin layers (178, 179) through a meltextrusion process; injecting CO2 gas into the film and forming (S32) a plurality of air bubble layers (176) in the reflective layer (166) through a foaming process; forming (S34) the first and second skin layers (178, 179) having an embossing surface by pressing the film; and cutting (S36) the reflective sheet (166) comprising the first and second skin layers (178, 179) having an embossing surface using a die cutting process.