Multi-axis mirror for head-up display eyebox expansion
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Solution Overview
Problem
Conventional head-up displays in vehicles have a limited and fixed eyebox, which can cause the virtual image to be out of view for drivers who move their heads or adjust their position while driving, leading to reduced visibility of the HUD.
Innovation Solution
A multi-axis mirror design that rotates about both horizontal and vertical axes, integrated with an eye tracking system or manual control, allowing the mirror to adjust the position of the virtual image to maintain visibility for the driver regardless of head movement or position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed mirror position is used in conventional HUD, then the device structure is simple, but the eyebox size is limited and cannot adapt to driver head movements
Solution Approach 1:
The mirror is transformed from a fixed position to a dynamically adjustable position through a gimbal mounting structure that enables rotation about two perpendicular axes. This allows the mirror to adapt to different driver head positions and movements, effectively increasing the eyebox size while maintaining a manageable structural complexity through the use of standardized gimbal mechanisms.
2Reliability
If the mirror is made fixed and horizontally aligned, then the manufacturing and alignment process is simplified, but the visibility is lost when the driver moves their head out of position
Solution Approach 1:
The mirror mounting structure incorporates two rotational degrees of freedom through the gimbal mechanism, allowing the mirror to dynamically adjust its orientation to maintain virtual image visibility across a range of driver head positions. This dynamic adjustment capability ensures reliable visibility without requiring complex precision alignment during manufacturing, as the system can adapt to positional variations.
Solution Approach 2:
The system integrates eye tracking or head position detection that provides feedback to the control system, which then actuates the gimbal to adjust the mirror orientation accordingly. This closed-loop feedback mechanism ensures the virtual image remains visible to the driver regardless of head movement, while the automated adjustment reduces the burden on manual alignment during manufacturing.
3Area of moving object
If a single-axis horizontally fixed mirror is used, then the device complexity is reduced, but the eyebox remains small and cannot accommodate vertical or lateral head movements
Solution Approach 1:
The gimbal mounting structure provides two rotational degrees of freedom, enabling the mirror to adjust both horizontally and vertically to track driver head movements. This dynamic adjustment effectively expands the eyebox area by accommodating a wider range of head positions, while the modular gimbal design keeps the overall device complexity manageable through the use of established mechanical principles.
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 a larger eyebox, ensuring the virtual image remains visible to the driver over a range of head movements and positions, enhancing the usability and effectiveness of the head-up display.
Implementation Method 1
A mirror reflects the light field such that the reflected light field is again reflected by a windshield of the motor vehicle
Data Source
AI summary
A head up display arrangement presents a virtual image to a human driver of a motor vehicle. A picture generation unit emits a light field. A mirror is mounted on a gimbal such that the mirror is rotatable about both a first axis and a second axis oriented perpendicular to the first axis. The mirror reflects the light field such that the reflected light field is again reflected by a windshield of the motor vehicle and is visible to the human driver as the virtual image. First and second motors rotate the mirror about the first axis and second axis, respectively. An electronic processor controls the first motor and/or the second motor dependent upon a detected position of the eyes of the human driver such that the virtual image remains visible to the human driver over a range of motion of the driver's head.