Movable Head-Up Display Image Combiner for Windshield Fogging Prevention
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Solution Overview
Problem
Head-up displays with separate image combiners located close to the windshield can lead to fogging issues due to reduced air flow in the triangular space between the windshield and the combiner, especially in vehicles with sharply-angled windshields, as existing solutions like integrated air distribution ducts are not universally effective.
Innovation Solution
The position of the image combiner is automatically adjusted based on signals from environmental sensors and driver inputs, such as humidity, temperature, and defroster usage, to prevent fogging, allowing the combiner to retract when fogging is likely and extend when conditions are clear, using existing vehicle hardware and climate control systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the image combiner is located close to the windshield to improve virtual image distance and driver comfort, then the virtual image appears farther away reducing eye strain, but the triangular space between the windshield and combiner creates regions with very little air flow causing the windshield to fog up easily
Solution Approach 1:
The image combiner is made movable between an active position (close to the windshield for optimal viewing) and an inactive/retracted position (flush with or housed within the instrument panel). This dynamic positioning allows the system to adapt to different operating conditions, particularly retracting when fogging conditions are detected to maintain clear windshield visibility.
Solution Approach 2:
The system proactively detects conditions that may lead to windshield fogging (such as temperature and humidity signals) and automatically retracts the image combiner before fogging occurs, preventing the harmful effect rather than addressing it after it happens.
2Adaptability or versatility
If a separate image combiner is used in vehicles with sharply-angled windshields to enable proper projection geometry, then direct projection onto the windshield becomes unsuitable and the combiner can provide proper viewing angles, but an intermediate space forms that reduces air flow and creates fogging-prone areas
Solution Approach 1:
The image combiner is designed as a movable component that can be positioned dynamically. In vehicles with sharply-angled windshields, the combiner can be extended to the active position to provide proper projection geometry, and retracted when fogging conditions arise, offering both geometric adaptability and fogging prevention.
Solution Approach 2:
The head-up display system monitors environmental conditions (temperature, humidity) and automatically adjusts the image combiner position to prevent fogging, making the system self-regulating without requiring manual intervention from the driver.
3Reliability
If the image combiner remains in the active position continuously to maintain optimal display performance, then the virtual image remains at the optimal distance, but the windshield may fog up during certain environmental conditions such as high humidity or when defroster is in use
Solution Approach 1:
The system incorporates sensors that continuously monitor environmental conditions (temperature, humidity, defroster status) and provide feedback to the control unit. Based on this feedback, the control unit automatically adjusts the image combiner position to prevent fogging while maintaining optimal display performance when conditions allow.
Solution Approach 2:
The image combiner transitions between static and dynamic states, remaining in the active position for optimal display performance when conditions permit, and automatically retracting to the inactive position when sensor data indicates fogging risk, thus adapting to changing environmental conditions.
Data Source
AI summary
A head-up display in a motor vehicle has an image combiner movable between an active position, in which it is situated in the field of view of a driver of the vehicle, and an inactive position, in which it is situated close to a surface of or within an instrument panel. The position of the image combiner is controlled depending on signals from vehicle devices that indicate a likelihood or probability of a fogging condition of the windshield. The fogging condition may be indicated by a driver actuation of a windshield defogging/heating system.