Overmolded Thermoplastic Electrodes for Headlight Lens Defrosting
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Solution Overview
Problem
Existing vehicle headlight glass defrosting technologies are either inefficient, costly, or limited in their application, as they often require visible connectors and are not effectively connected for outdoor use, and lack detailed descriptions of electrical connections.
Innovation Solution
A vehicle headlight glass with electrically conductive thermoplastic electrodes integrated into the edges, featuring connectors with insulating engagement devices and a conductive coating that covers the inner surface, allowing for efficient and economical defrosting with hidden connectors for external power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic electrodes are used for defrosting with visible connectors, then electrical connection is achieved, but aesthetic appearance deteriorates due to visible connectors and tracks
Solution Approach 1:
The invention extracts the visible metallic connectors and tracks from the lens structure by using thermoplastic electrodes that are integrated directly into the lens material. The electrodes are made from the same or similar thermoplastic material as the lens, making them visually indistinguishable while maintaining electrical conductivity through conductive fillers.
Solution Approach 2:
The invention applies local quality by creating electrodes with specific electrical conductivity properties only where needed within the lens material. The thermoplastic material contains conductive fillers (such as carbon black, metal particles, or conductive polymers) concentrated in electrode regions, while the rest of the lens maintains its optical transparency and aesthetic appearance.
2Reliability
If complex connection devices are used for electrical supply, then reliable power connection is achieved, but device complexity increases
Solution Approach 1:
The invention merges the electrical connection function with the lens structure itself. The thermoplastic electrodes are integrated directly into the lens material, eliminating the need for separate connectors, terminals, or wiring harnesses. The lens body serves dual purposes: optical function and electrical conduction pathway.
Solution Approach 2:
The lens material serves multiple functions simultaneously: optical transparency, structural integrity, and electrical conduction. The thermoplastic electrodes embedded in the lens perform both mechanical integration and electrical connection functions, reducing the overall system complexity.
3Reliability
If traditional defrosting coatings are applied to outer surface, then defrosting function is achieved, but manufacturing precision is compromised due to coating application variability
Solution Approach 1:
The invention segments the defrosting function from the surface coating and integrates it directly into the lens material structure. Instead of applying a separate coating layer to the outer surface, conductive thermoplastic electrodes are embedded within the lens material during manufacturing, ensuring precise and uniform electrical properties throughout the electrode regions.
Solution Approach 2:
The conductive electrodes are incorporated into the lens material during the injection molding process itself, before the lens is assembled or coated. This preliminary integration ensures precise control over electrode position, shape, and electrical properties, eliminating variability associated with post-manufacturing coating applications.
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 provides effective, economical, and practical defrosting of vehicle headlight glasses by integrating thermoplastic electrodes and conductive coatings within the glass edges, enabling efficient electrical connection and hidden connector placement for reduced visibility and cost.
Implementation Method 1
an electrically conductive coating forming an electrical defrosting resistance
Implementation Method 2
the electrodes are made of electrically conductive thermoplastic material
Data Source
Figure 1~2
AI summary
The invention relates to a lens (6) for a lighting device (2), particularly for a motor vehicle, comprising a main portion (61) made of transparent plastic; at least two edges (62) for attachment to a housing (4) of the lighting device (2); an electrically conductive coating (8) forming an electrical defrosting resistor; and at least two electrodes (10) electrically connected to the conductive coating (8). The electrodes (10) are made of electrically conductive thermoplastic material and are located on the attachment edges (62). They are overmolded by the transparent plastic material. The invention also relates to a lighting device comprising the lens in question and to a method for manufacturing said lens.