Low-E Coated Glass Neutral Appearance
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Solution Overview
Problem
Existing low-e coatings for glass do not provide a neutral appearance when viewed from both the glass side and the coating side, and they lack resistance to thermal processes while maintaining optimal visible and solar transmittance.
Innovation Solution
A low-e coating applied onto glass, comprising multiple dielectric and functional layers, including Si x N y, SiAlN x, and TiO x layers, with specific thicknesses and configurations to achieve neutral appearance, high thermal process resistance, and targeted transmittance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional low-e coating structures are used, then infrared reflection and solar transmittance can be controlled, but neutral appearance when viewed from both glass side and coating side cannot be achieved
Solution Approach 1:
The coating is divided into multiple functional layers including first, second and third dielectric layers with specific refractive indices, separated by barrier layers. Each layer segment performs a specific optical function to collectively achieve neutral appearance from both sides while maintaining infrared reflection properties.
Solution Approach 2:
Different regions of the coating have different optical properties - the first dielectric layer has higher refractive index than the second, the barrier layers have specific thickness ranges (0.5-2.0 nm) to control local reflection characteristics, and the silver functional layers are positioned at specific locations to achieve directional optical control for neutral appearance.
2Reliability
If thermal process resistance is improved by adding more barrier layers, then coating stability increases, but manufacturing complexity and production time increase
Solution Approach 1:
Barrier layers comprising NiCr, NiCrOx, TiOx, ZnAlOx, or ZnOx are introduced as intermediary protective layers between the dielectric layers and silver functional layers. These barrier layers prevent thermal degradation and oxidation during thermal processing while maintaining coating performance, achieving thermal process resistance without excessive complexity.
3Illumination intensity
If visible region transmittance is increased to improve daylight transmission, then solar transmittance increases, but thermal insulation performance deteriorates
Solution Approach 1:
The coating parameters are optimized to achieve visible region transmittance between 60-75% and solar transmittance between 23-35%. The refractive indices of dielectric layers, thickness of barrier layers (0.5-2.0 nm), and positioning of silver layers are adjusted to create optical interference that allows visible light passage while blocking infrared thermal radiation, decoupling these two transmittance parameters.
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 coating achieves a neutral appearance with visible region transmittance between 60-75% and solar transmittance between 23-35%, while maintaining high thermal process resistance and ensuring the glass side reflection a* value remains in the negative region at all angles.
Implementation Method 1
low-emission (low-e) coating which transmits daylight and used as thermal insulation glass and with high thermal process resistance and having infrared reflective layers therein
Implementation Method 2
Magnetron sputtering process is a well-known coating application which takes place in vacuum environment
Implementation Method 3
Total solar energy transmittance (g) is also an important parameter in coated glasses... For lowering heating loads inside vehicles in cold climates
Data Source
Figure 1
AI summary
The present invention relates to a low-e coating (20) applied onto a glass (10), in order to provide neutrality at first sight from inside and outside of automotive and architectural glasses.