Rearview Mirror Assembly With Bonded Wide-Angle Glass Reflector
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Solution Overview
Problem
Existing exterior rearview mirror assemblies do not provide a sufficient wide angle rearward field of view for drivers, and existing auxiliary wide angle reflectors face challenges in bonding due to differences in thermal expansion coefficients between materials.
Innovation Solution
An exterior rearview mirror assembly with a glass wide angle reflector element and a glass mirror substrate, both having matching thermal expansion coefficients, bonded using an optical adhesive with similar thermal expansion properties, and an optional darkened band to demarcate the wide angle reflector portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If auxiliary wide angle reflectors are attached to the mirror reflector, then wide angle rearward field of view is provided, but bonding reliability deteriorates due to differences in thermal expansion coefficients between materials
Solution Approach 1:
The patent applies homogeneity by making both the auxiliary wide angle reflector and the mirror substrate from glass materials with matching thermal expansion coefficients. This eliminates the material incompatibility that causes bonding failure under thermal cycling, while still providing the desired wide angle viewing function through the curved glass reflector surface.
Solution Approach 2:
The patent uses composite construction by bonding a curved glass auxiliary reflector to a flat glass mirror substrate. This composite structure combines the wide angle viewing capability of the curved surface with the structural stability of the flat substrate, achieving both functional and reliability requirements.
2Adaptability or versatility
If add-on curved auxiliary reflectors are attached to the mirror reflector, then wide angle rearward field of view is provided, but manufacturing complexity increases
Solution Approach 1:
The patent segments the mirror assembly into two separate glass components: a flat mirror substrate and a curved auxiliary reflector. This segmentation allows each component to be manufactured independently using standard glass forming techniques, then bonded together, simplifying the overall manufacturing process compared to creating a single complex curved mirror.
Solution Approach 2:
The patent introduces a bonding agent as an intermediary between the auxiliary reflector and mirror substrate. This bonding agent facilitates the attachment of the curved reflector to the flat substrate, enabling the composite structure to be assembled without requiring complex integrated manufacturing processes.
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
Enhances the bonding strength and durability of the wide angle reflector to the mirror substrate, providing a wider angle rearward field of view while minimizing thermal stress and improving visibility for the driver.
Implementation Method 1
bonded using an optical adhesive with similar thermal expansion properties
Implementation Method 2
a curved rear surface with a second reflective coating disposed at the curved rear surface
Data Source
AI summary
A vehicular exterior rearview mirror assembly includes a mirror reflective element assembly. The mirror reflective element assembly includes a main reflective element backing plate and a main reflective element. The main reflective element includes a glass substrate having a mirror reflector coated at a surface thereof. The mirror reflector-coated glass substrate of the main reflective element is attached at the main reflective element backing plate. The mirror reflective element assembly includes an auxiliary reflective element backing plate and an auxiliary wide angle reflective element. The auxiliary wide angle reflective element is positioned on the auxiliary reflective element backing plate. The auxiliary reflective element backing plate is attached to the main reflective element backing plate via an attachment mechanism.