Glass sheet and method for manufacturing same
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Solution Overview
Problem
Low-E glass systems face issues with warpage during heat treatment and inadequate heat insulating performance due to differences in Low-E film deposition methods and materials on opposing surfaces, leading to high sheet resistance values that hinder temperature reduction and heat shielding effectiveness.
Innovation Solution
A glass plate design with fluorine-doped tin oxide films on both surfaces, each formed using CVD methods under specific conditions, with undercoat layers to prevent diffusion and improve adhesion, ensuring uniform film quality and reduced sheet resistance, thus preventing warpage and enhancing heat insulating properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If different deposition methods (CVD and sputtering) are used on first and second surfaces, then heat insulating property is improved, but warpage occurs during heat treatment due to different film qualities
Solution Approach 1:
The patent applies homogeneity by using the same CVD deposition method for both first and second Low-E films, ensuring identical film qualities and materials on both surfaces. This uniformity prevents differential thermal expansion and contraction during heat treatment, thereby eliminating warpage while maintaining heat insulating properties through consistent emissivity values on both surfaces.
2Ease of manufacture
If spray method is used for second Low-E film, then manufacturing complexity is reduced, but sheet resistance value becomes significantly high reducing heat insulating performance
Solution Approach 1:
The patent applies parameter changes by optimizing the CVD deposition parameters (temperature, pressure, gas flow rates, deposition time) to achieve the desired sheet resistance value on the second surface. By carefully controlling these parameters, the patent maintains low sheet resistance (high electrical conductivity) of the second Low-E film, ensuring sufficient heat insulating performance while using the same reliable CVD method as the first surface.
3Stability of the object's composition
If uniform CVD method is used on both surfaces, then warpage is prevented, but manufacturing time and cost increase
Solution Approach 1:
The patent applies merging by combining both first and second Low-E film depositions into a single continuous CVD process when possible, or using identical CVD equipment and parameters for both surfaces. This unified approach prevents warpage through uniform film properties while improving manufacturing efficiency by eliminating the need for separate deposition processes, reducing handling steps, and simplifying process control.
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 prevents warpage during heat treatment and achieves appropriate sheet resistance values, enabling effective temperature reduction and heat shielding performance in Low-E glass systems, with emissivity of 0.15 or less and transmittance of 75% or more, improving visibility and thermal performance.
Implementation Method 1
a first Low-E film is deposited, by a CVD method, on a first surface of a glass substrate, and depositing a second Low-E film, by a sputtering method, on a second surface of the glass substrate
Implementation Method 2
a film that suppresses a heat transfer by radiation, known as a Low-E film, is arranged on at least one surface of a glass plate
Data Source
Figure 1~2
AI summary
A glass plate includes a first surface provided with a first film; and a second surface provided with a second film and opposite to the first surface. Each of the first film and the second film includes mainly tin oxide and has a sheet resistance value of 20 Ω/□ or less. When film thicknesses of the first and second films are θ1 nm and θ2 nm respectively, and when, in the glass plate, a haze value measured from the first surface side for a configuration provided with the first film only is H1 (%), and a haze value measured from the second surface side for a configuration provided with the second film only is H2 (%), a value of θ1 divided by H1 is 500 or more but 1200 or less, and a value of θ2 divided by H2 is 300 or more but 750 or less.