Ribbed Head-Up Display Mirror Design
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Solution Overview
Problem
Current head-up display mirrors in the automotive sector face challenges with low flexural rigidity, leading to increased material costs and cycle times, and require additional processing steps like milling off sprues, due to their design as substantially flat plates with high curvature.
Innovation Solution
A mirror design featuring a ribbed periphery with a mirror layer, where the rib provides increased flexural rigidity, allowing for reduced material thickness and costs, and incorporating anti-reflective microstructures to minimize light reflection, manufactured using injection molding with a hot runner film gate to avoid milling and stress cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the mirror is designed as a substantially flat plate with large curvature, then the optical function is achieved, but the flexural rigidity is low requiring increased material thickness
Solution Approach 1:
The mirror base body is segmented into a planar region and a rib structure. The rib divides the mirror into structural zones, providing reinforcement without requiring uniform thickness increase across the entire mirror surface.
Solution Approach 2:
The solution transitions from a two-dimensional flat plate to a three-dimensional structure with a rib. The rib extends vertically from the base body, adding a third dimension to provide structural support and increase flexural rigidity.
2Strength
If the material thickness is increased to compensate for low flexural rigidity, then the mechanical strength is improved, but the production cycle time increases and material costs increase
Solution Approach 1:
Instead of increasing the thickness of the entire mirror uniformly, the design segments the structure into a planar region and a rib. This localized structural addition provides the necessary rigidity while keeping the overall material volume and production time reduced.
3Ease of manufacture
If the mirror is designed as a substantially flat plate, then the manufacturing is simpler, but additional work steps like milling off sprues are required
Solution Approach 1:
The rib structure is integrated into the mold design during the injection molding process. The hot runner film gate is positioned to feed material directly into the rib, and the sprue is designed to break off automatically at a predetermined location, eliminating the need for subsequent milling operations.
4Device complexity
If the mirror is designed as a substantially flat plate, then the structure is simpler, but the mirror is more sensitive to mechanical influences like vibrations
Solution Approach 1:
The mirror structure is segmented into a planar region and a rib that provides mechanical reinforcement. The rib acts as a structural support that reduces the mirror's sensitivity to vibrations and mechanical influences while maintaining optical functionality.
Solution Approach 2:
The addition of the rib extends the structure into a third dimension, creating a more rigid three-dimensional configuration that resists mechanical disturbances better than a two-dimensional flat plate.
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 ribbed mirror design enhances mechanical robustness, reduces material usage by 30%, minimizes production waste, and maintains optical performance while being less sensitive to mechanical influences like vibrations, making it suitable for automotive head-up displays.
Implementation Method 1
The mirror unit is a partially reflecting, light-transmissive pane. The viewer thus sees the contents represented by the picture generating unit as a virtual image and sees the real world behind the pane at the same time.
Implementation Method 2
This structure causes an increased flexural rigidity, so that the mirror becomes much less sensitive to mechanical influences.
Implementation Method 3
The rib has an anti-reflective structure. There is a risk of light reflection on the side surfaces of the mirror. This may be avoided by an anti-reflective structure.
Data Source
AI summary
A mirror for a head-up display, in particular for a head-up display for transportation is disclosed. A head-up display comprising such a mirror is also disclosed. The mirror has a base body with a planar region and a rib arranged at a periphery of the planar region. A mirror layer is arranged on the planar region wherein the rib has an anti-reflective structure.