Plastic Mirror Mounting Clips for Stress-Free Retention
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Solution Overview
Problem
Conventional glass mirrors for automotive use are heavy, difficult to form into complex shapes, prone to shattering, and suffer from stress-related distortions when plastic substrates are used, which also face issues with UV radiation, heat, and water damage, leading to reflective surface crazing and interference fringes.
Innovation Solution
A plastic mirror with a polycarbonate substrate coated with a hard abrasion-resistant layer, a thin SiO2 layer, and a chromium reflective layer on the front surface, featuring molded clips on the second surface for mounting that reduce stress and provide a stiff structure to prevent distortion and interference fringes, integrated into a motor actuator design for assembly and disassembly without affecting optical quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If clips are pressed against the plastic substrate and the reflective surface, then retention and mounting are achieved, but stress occurs and influences the reflective appearance causing visible distortion
Solution Approach 1:
The mounting system is divided into separate components: a mounting member with mounting clips and a plastic mirror with retention clips. The mounting clips engage with the retention clips through a form-locking connection, distributing the mounting force away from the reflective surface while maintaining secure retention. This segmentation prevents stress-induced distortion of the reflective surface.
Solution Approach 2:
The mounting clips act as an intermediary mechanism between the mounting member and the plastic substrate. Instead of pressing directly against the reflective surface, the clips provide a mechanical interface that transfers mounting forces through the substrate edges, eliminating direct stress on the reflective area while achieving secure retention.
2Reliability
If a hard coating is applied to protect the plastic substrate and reflective coating, then environmental protection and abrasion resistance are improved, but interference bands appear which are cosmetically unacceptable
Solution Approach 1:
A multi-layer coating system is applied to the plastic substrate, consisting of a hard protective layer for abrasion resistance and environmental protection, combined with optical layers that manage light reflection. The composite structure provides both protective function and optical quality by controlling interference effects through precise layer design.
Solution Approach 2:
The optical properties of the coating system are optimized by controlling layer thicknesses and material properties to minimize interference bands. By adjusting the parameters of the coating layers (thickness, refractive index), the system achieves both protection and cosmetic acceptability through destructive interference of unwanted reflections.
3Strength
If the plastic substrate is made softer to improve impact resistance, then durability is improved, but the substrate becomes more susceptible to UV radiation, heat and water damage
Solution Approach 1:
The plastic substrate is combined with protective coating layers that provide UV radiation resistance, heat stability, and water protection. The composite structure allows the substrate to maintain its softness and impact resistance while the outer coating layers protect against environmental degradation factors.
Solution Approach 2:
Protective coating layers serve as intermediary barriers between the plastic substrate and environmental factors (UV radiation, heat, water). These coatings absorb or block harmful effects before they reach the substrate, allowing the substrate to remain soft and impact-resistant without suffering from environmental susceptibility.
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 results in a lightweight, durable plastic mirror that passes automotive tests such as salt spray, thermal cycling, and shock tests, maintaining optical quality and cosmetic acceptability by minimizing stress and distortion, while providing improved abrasion resistance and environmental protection.
Implementation Method 1
a hard coating applied in order to provide environmental exposure protection of the plastic substrate and the reflective coating, whilst providing improved abrasion resistance
Implementation Method 2
a chromium reflective layer on the front surface
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
A plastic mirror mounting system is proposed with a substrate made of plastic material coated with at least one reflective layer on a first surface (5). The plastic material has means to be connected to a mounting structure (9) on the second surface of the plastic glass mirror. The plastic substrate includes at least three plastic mirror clips (7) having at least one shoulder of plastic mirror clip (10) that has a distance from the second surface so that no or almost no stress disturbs the reflective surface.