Retroreflective Sheet Voids Crushed Under Pressure
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Solution Overview
Problem
Retroreflective sheets with voids between retroreflective elements and dents can experience decreased retroreflectivity when subjected to pressure, such as bending or embossing, leading to compromised performance in applications like vehicle license plates.
Innovation Solution
A retroreflective sheet design featuring a retroreflective layer with retroreflective elements, a resin-based back face layer, and resin particles between the elements and the back face layer, where the particles are sandwiched and bonded to prevent void crushing and enhance bonding strength, ensuring consistent retroreflectivity even under pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If voids are formed between retroreflective elements and dents to improve retroreflectivity, then brightness is improved, but the voids are crushed when pressure is applied in the thickness direction
Solution Approach 1:
The back layer is divided into multiple dent portions that create discrete voids between the retroreflective elements and the back layer. This segmentation allows light reflection while maintaining structural integrity when pressure is applied, as the distributed dent portions prevent complete void collapse.
Solution Approach 2:
The dent portions are pre-formed in the back layer to create voids that cushion and protect the retroreflective elements from pressure. This beforehand cushioning structure prevents the voids from being completely crushed when pressure is applied during use, such as when the retroreflective sheet is bent or embossed.
2Ease of manufacture
If metal vapor-deposited film is used to reduce cost, then manufacturing cost is reduced, but brightness decreases
Solution Approach 1:
The back layer is designed with a porous structure containing multiple dent portions that create voids. This porous structure provides effective light reflection and scattering to maintain brightness without requiring expensive metal vapor-deposited films, achieving both cost reduction and brightness maintenance.
3Adaptability or versatility
If the retroreflective sheet is bent or embossed to fit curved surfaces, then adaptability is improved, but the voids are crushed and retroreflectivity decreases
Solution Approach 1:
The back layer is designed as a flexible thin film structure with dent portions that can deform with the retroreflective sheet when bent or embossed. This flexible structure maintains the voids between the retroreflective elements and back layer even during deformation, preserving retroreflectivity while enabling adaptability to curved surfaces.
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 effectively maintains retroreflectivity and prevents voids from being crushed, enhancing the sheet's reliability and appearance, especially in applications exposed to pressure and environmental factors like water or foreign matter.
Implementation Method 1
Due to the refractive index difference between this gas and the retroreflective elements, the light incident from the retroreflective layer side can be reflected to the retroreflective layer side at an interface between the retroreflective elements and the voids
Data Source
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AI summary
Provided are a retroreflective sheet (100) including: a retroreflective layer (20) including a plurality of retroreflective elements (24) on one surface; a back face layer(40) provided to face the retroreflective elements (24) and having a surface on a retroreflective elements (24) side at least a part of which is made of resin; a plurality of particles (30) disposed between the retroreflective elements (24) and the back face layer (40) and having a surface at least a part of which is made of resin; and voids formed between the retroreflective elements (24) and the back face layer (40), and a method for manufacturing the retroreflective sheet (100).