Automotive Glazing Optical Quality via Washable Cover Layer
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Solution Overview
Problem
The application of enamel patterns on automotive glazings for masking purposes leads to thermal gradients during bending, causing optical distortion and residual stress due to the uneven heat absorption by black frit, which affects the performance of optical sensors like cameras.
Innovation Solution
A laminated glazing method involving an enamel obscuration mask with a washable cover layer resistant to high temperatures, applied on the glass sheet before bending, to ensure uniform heat distribution and reduce optical distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If enamel patterns are applied to mask unsightly elements on automotive glazing, then aesthetic appearance is improved, but optical distortion occurs during thermal processing due to thermal gradients
Solution Approach 1:
The patent applies a clear frit composition specifically in the camera zone (local area) rather than across the entire glazing surface. This localized application maintains aesthetic appearance in other areas while eliminating thermal gradient effects in the critical camera viewing area, thereby resolving the contradiction between aesthetic appearance and optical quality.
Solution Approach 2:
The glazing surface is segmented into different zones: areas with enamel patterns for aesthetic purposes and a clear frit zone in the camera area for optical quality. This segmentation allows different regions to serve different functions, resolving the contradiction between appearance and optical performance.
2Object-generated harmful factors
If black frit is used for obscuration masking, then masking effectiveness is improved, but thermal gradients cause optical distortion and residual stress
Solution Approach 1:
The patent uses black frit composition in areas where masking is needed while using clear frit composition in the camera zone where optical quality is critical. This local differentiation maintains masking effectiveness where required while eliminating optical distortion in the camera area.
Solution Approach 2:
The clear frit composition acts as an intermediary material in the camera zone, providing the benefits of frit application (adhesion, surface preparation) without the harmful thermal absorption properties of black frit, thus mediating between masking requirements and optical quality needs.
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 method significantly reduces optical distortion by up to 50% in the 'camera zone' by maintaining a uniform heat distribution during the bending process, enhancing the performance of optical sensors.
Implementation Method 1
Radiant heat is the predominant heat source used for glass bending. The black frit areas of the glass run hotter than the adjacent clear areas.
Implementation Method 2
With glass being a poor conductor of heat, gradients in the tens of degrees centigrade can arise over a short distance.
Implementation Method 3
The black frit absorbs more radiant heat than the clear glass.
Implementation Method 4
The application of these enamel compositions is followed by a high-temperature curing which melts the frit and fixes the enamel to the support.
Data Source
AI summary
A method for producing an automotive glazing with an optical sensor device, with the glazing having superior optical qualities, including the steps of applying an enamel obscuration mask on at least one face of at least one glass sheet, where the obscuration mask extends to an area where the at least one optical sensor device will be fixed and includes at least one opening on the automotive interior side so as to be capable of acquiring information through the opening from the optical sensor device intended to be fixed at the at least one opening; drying or firing the enamel obscuration mask; applying a washable cover layer resisting at a temperature of at least 620° C. on the surface of the at least one opening; submitting the glass sheet to a heat treatment above 450° C. during a bending or tempering process; and removing by washing the washable cover layer.