Rear View Mirror Assembly Thermal Radiation Heating
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Solution Overview
Problem
Conventional surface heating elements in rearview mirror assemblies with liquid crystal cells cause stress due to rigid connections, leading to visible dark or clear spots in the optical image.
Innovation Solution
A surface heating element generating thermal radiation is placed on the carrier plate with a housing gap between the carrier plate and the mirror assembly, where the thermal radiation is absorbed by a radiation-absorbing coating on the reflective surface, avoiding rigid connections and stress on the liquid crystal cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a surface heating element is rigidly connected to the mirror assembly with liquid crystal cell, then heating function is achieved, but stress accumulates causing dark spots in optical image
Solution Approach 1:
The heating function is separated from the mirror assembly structure. The surface heating element is mounted on the carrier plate rather than being integrated with the mirror assembly, creating functional segmentation that prevents stress transmission to the liquid crystal cell while maintaining heating capability.
Solution Approach 2:
The carrier plate serves as an intermediary between the heating element and the mirror assembly. By positioning the heating element on the carrier plate and maintaining a housing gap, the carrier plate mediates the thermal function without transmitting mechanical stress to the optical components.
2Reliability
If a housing gap is introduced between carrier plate and mirror assembly, then stress is eliminated, but thermal radiation efficiency may be reduced
Solution Approach 1:
The radiation-absorbing coating is selectively applied to specific areas of the mirror assembly where thermal radiation needs to be absorbed. This localized treatment maintains thermal efficiency by concentrating absorption where needed while preserving the housing gap for stress relief.
Solution Approach 2:
Direct thermal conduction through rigid contact is replaced with thermal radiation across the housing gap. The radiation-absorbing coating enables efficient thermal energy transfer without mechanical connection, substituting a mechanical heat transfer path with a radiative one.
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 configuration ensures a stress-free operation of the liquid crystal cell, maintaining a clear and uniform optical image without impairments, enhancing visibility and user experience.
Implementation Method 1
a surface heating element is arranged on the carrier plate, which generates thermal radiation
Implementation Method 2
the thermal radiation is transmitted to a radiation-absorbing coating arranged on the reflective coating of the mirror assembly
Implementation Method 3
These optical cells can be in the form of liquid crystal cells, for example. With these mirror arrangements, the reflectivity can be changed when an electric field is applied.
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a rear-view mirror assembly (1) for motor vehicles, said assembly comprising a carrier plate (6) and a mirror sub-assembly (5) held on the carrier plate (6) and comprising a liquid-crystal cell (7), for observing the following traffic. The reflectance of the mirror sub-assembly (5) is designed to be variable by means of a control device and the mirror sub-assembly (5) has a front glass pane (11) and a rear reflective coating (12) facing the carrier plate (6). The object of the invention is to improve the rear-view mirror assembly such that an automatically dimming, heatable rear-view mirror assembly comprising an optical liquid-crystal cell for a motor vehicle can produce a consistently flawless optical image for the vehicle occupant as the user. To achieve this, the rear-view mirror assembly (1) is designed to be heatable, the carrier plate (6) being provided with a planar heating element (15) which generates thermal radiation. A housing gap (S) remains between the carrier plate (6) and the mirror sub-assembly (5) and the thermal radiation (16) is transferred to a radiation-absorbing coating (13) situated on the reflective coating (12) of the mirror sub-assembly (5).