Copper Heating Wire Microstructure for High-Voltage Defrosters
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Solution Overview
Problem
Conventional defrosters using tungsten wires face challenges with rapid temperature rise when subjected to high supply voltages, such as those in mild hybrid vehicles, leading to potential defects.
Innovation Solution
A heating element comprising a copper wire with controlled cross-sectional crystal size of less than 1.5 μm, integrated into a laminated glass structure, which suppresses rapid temperature rise even at high supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional defroster with standard copper wire is applied to high voltage vehicles, then heating performance is improved, but temperature rises rapidly causing defects
Solution Approach 1:
The patent changes the physical parameter of copper crystal grain size to less than 1.5 μm, which fundamentally alters the electrical resistance characteristics of the heating wire. This parameter change enables the wire to withstand high voltage (48V or higher) without excessive temperature rise, resolving the contradiction between heating performance and temperature control reliability.
2Power
If tungsten wire is used as heating wire, then heating efficiency is improved, but wire diameter becomes thick making fining difficult and visibility poor
Solution Approach 1:
The patent replaces expensive tungsten wire with copper wire, which is more cost-effective and can be processed more easily. By controlling copper crystal grain size, the invention achieves both fine wire diameter (improving visibility) and adequate heating efficiency, making copper a superior alternative to tungsten for this application.
3Ease of manufacture
If copper wire with large crystal grains is used, then manufacturing is easier, but temperature rises rapidly at high voltage
Solution Approach 1:
The patent specifies a precise parameter range for copper crystal grain size (less than 1.5 μm) that balances manufacturability with thermal performance. This controlled parameter change ensures the wire can be manufactured with standard processes while preventing rapid temperature rise under high voltage conditions.
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 heating element effectively controls calorific value and resistance, preventing rapid temperature rises and ensuring safe operation at high supply voltages, while maintaining design flexibility and visibility.
Implementation Method 1
When a conventional defroster is applied to such a vehicle in which the supply voltage is high, there is a concern that the temperature of the defroster may rapidly rise to cause a defect. The present inventors have now found that in a heating element comprising a copper wire, controlling the cross-sectional crystal size of copper crystal grains forming the copper wire to less than 1.5 μm makes it possible to suppress the rapid temperature rise even when the supply voltage is high.
Data Source
AI summary
Provided is a heating element capable of suppressing the rapid temperature rise even when the supply voltage is high. The heating element includes a resin film and heating wires provided on at least one surface of the resin film and including a copper wire, wherein copper crystal grains forming the copper wire have a cross-sectional crystal size of less than 1.5 μm.