Refrigerator Door AR-Low-E Coating for Clearer Merchandise Display
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Solution Overview
Problem
Current refrigerator doors with multiple glass panes and low-E coatings suffer from reduced visible light transmission, leading to decreased marketing value and impulse sales due to increased visible reflectance and thermal insulation needs.
Innovation Solution
A combination anti-reflective (AR) and low-emissivity (low-E) coating using indium-tin-oxide (ITO) between silicon oxynitride and silicon oxide dielectric layers is applied to the interior surfaces of the glass substrates, enhancing energy efficiency while minimizing visible reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If multiple glass panes and low-E coatings are incorporated to increase thermal insulation, then energy efficiency is improved, but visible light transmission is reduced
Solution Approach 1:
The patent combines the low-E coating and AR coating into a single integrated coating structure. The low-E coating layers (containing silver or aluminum) provide thermal insulation by reflecting infrared radiation, while the AR coating layers (with optimized refractive indices) reduce visible light reflectance. This merging allows both functions to coexist in one coating system, resolving the contradiction between thermal insulation and visible light transmission.
Solution Approach 2:
The patent uses a composite coating structure consisting of multiple layers with different material properties. The low-E coating contains metallic layers (silver/aluminum) for thermal reflection, while the AR coating uses dielectric materials with specific refractive indices (1.38-2.60) to minimize visible light reflectance. This composite structure enables simultaneous achievement of thermal insulation and high visible light transmission.
2Loss of energy
If more low-E coatings are applied to increase thermal insulation, then energy efficiency is improved, but visible reflectance increases making merchandise difficult to see
Solution Approach 1:
The patent applies local quality by differentiating the optical properties of different coating layers. The low-E coating layers are designed with high infrared reflectance but controlled visible reflectance, while the AR coating layers are specifically engineered with refractive indices (1.38-2.60) to minimize visible light reflectance. This local differentiation of optical properties allows thermal insulation without excessive visible reflectance.
Solution Approach 2:
The patent changes the refractive index parameter of the AR coating layers to optimize visible light transmission. By selecting materials with refractive indices between 1.38 and 2.60 and controlling layer thicknesses, the coating minimizes visible light reflectance while maintaining thermal insulation performance. This parameter optimization resolves the contradiction between thermal insulation and visible reflectance.
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 increases energy efficiency and visible light transmission through the doors, making merchandise more visible to customers while maintaining low emissivity, thus addressing the issue of reduced impulse sales and marketing value.
Implementation Method 1
a transparent conductive layer comprising or consisting essentially of indium-tin-oxide (ITO) that reflects IR so as to also function as a low-E coating
Implementation Method 2
a combination anti-reflective and low-E coating... wherein the coating comprises a transparent conductive layer comprising or consisting essentially of indium-tin-oxide (ITO) that is located between at least a dielectric layer comprising or consisting essentially of silicon oxynitride and a dielectric layer comprising or consisting essentially of silicon oxide
Data Source
AI summary
Refrigerator doors (which includes freezer doors) are provided for use in display areas where refrigerated merchandise (e.g., frozen or chilled food) is displayed. It is desired to increase energy efficiency of the doors and thus of the refrigerated display system, while at the same time reducing visible reflectance from the doors to make it easier for customers to see merchandise which is being displayed behind the transparent doors. Refrigerator doors according to certain example embodiments of this invention include one or more AR coatings, some of which may include a transparent conductive layer (e.g., ITO) so as to also function as a low-E coating.