Thin Metal Heating Pattern on Adhesive Film for Vehicle Windows
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Solution Overview
Problem
Existing heating elements for vehicle windows face challenges in achieving effective heating while maintaining optical clarity, as methods either result in high resistance at low voltage or visible tungsten lines, and the use of additional films can cause refractive index differences leading to view distortion.
Innovation Solution
A heating element with a conductive heating pattern formed on an adhesive film using a metal plating layer of 10 micrometers or less, directly laminated onto the film without a transparent substrate, allowing for a thin, efficient heating solution without additional films and minimizing refractive index issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent conductive oxide film such as ITO is used to form a conductive thin film on the whole window surface, then optical transparency is improved, but heating value at low voltage deteriorates due to relatively high resistance
Solution Approach 1:
The patent uses a composite structure combining a transparent substrate, adhesive film, and metal heating pattern to achieve both transparency and effective heating. The metal pattern provides low resistance for efficient heating while the transparent substrate and adhesive film maintain optical clarity.
Solution Approach 2:
Instead of covering the entire surface with conductive material, the patent applies heating functionality locally through metal patterns (lines, grids, or shapes) positioned strategically on the adhesive film. This localized approach reduces material usage and maintains transparency in non-heating areas.
2Reliability
If a tungsten wire with diameter of 18 micrometers or greater is inserted to PVB film for heating, then sufficient heating value at low voltage is achieved, but the tungsten line becomes noticeable due to relatively high thickness
Solution Approach 1:
The patent uses a thin metal pattern formed on a flexible adhesive film instead of thick tungsten wire. The metal pattern can be made with much smaller cross-section while maintaining heating effectiveness, and the flexible film allows conformal attachment to the glass surface.
Solution Approach 2:
The heating pattern is created as a thin metal layer copied onto the adhesive film through lamination and etching processes, replacing the need for inserting thick wire elements. This copied pattern achieves the same heating function with minimal visual impact.
3Reliability
If a metal pattern is formed on a PET film through printing or photolithography and inserted between two PVB films, then heating functionality is achieved, but view distortion occurs due to refractive index difference between PET film and PVB film
Solution Approach 1:
The patent extracts the PET film from the structure and directly forms the metal heating pattern on the adhesive film that will be laminated to the glass. This eliminates the refractive index mismatch between PET and PVB films, removing the source of view distortion while preserving heating functionality.
Solution Approach 2:
The heating pattern formation and adhesive film preparation are merged into a single integrated process. The metal pattern is formed directly on the adhesive film that will contact the glass, eliminating intermediate layers and reducing the number of interfaces that could cause optical distortion.
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
This approach enables a thin, efficient heating element with reduced visibility and distortion, offering improved heating performance at low voltage and lower fabrication costs by eliminating the need for additional films and preventing refractive index-related distortions.
Implementation Method 1
forming a metal plating layer having a thickness of 10 micrometers or less on a metal layer
Implementation Method 2
applying electric power to both terminals of the heating line, and thereby increasing a temperature of the glass surface
Data Source
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AI summary
The present specification provides a heating element including an adhesive film; and a conductive heating pattern provided on at least one surface of the adhesive film and having a line height of 10 micrometers or less, and a method for fabricating the same.