Head-Up Display Optics for Stable Virtual Image Orientation
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Solution Overview
Problem
Conventional field-of-view display apparatuses, such as head-up displays in vehicles, experience an undesired change in the orientation of the virtual image plane when adapting the light beam to different eye positions of users, affecting the perceptibility of the virtual display image.
Innovation Solution
A projection unit with a first adjustment device to tilt the mirror for adapting the beam propagation direction to individual eye positions and a second adjustment device for image-orientation-maintaining tilting of the picture-generating unit or further optical components, ensuring a consistent orientation of the virtual image plane across different eyebox positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the concave mirror is tilted to adapt to different eye positions, then the beam propagation direction is adapted to individual eye positions, but the orientation of the virtual image plane changes undesirably
Solution Approach 1:
The adjustment function is segmented into two independent devices: the first adjustment device tilts the concave mirror for eye position adaptation, while the second adjustment device tilts the picture-generating unit for image orientation maintenance. This segmentation allows each device to perform its specific function without interfering with the other, resolving the contradiction between adaptability and stability.
Solution Approach 2:
The picture-generating unit acts as an intermediary element that can be independently adjusted. By tilting this unit through the second adjustment device, the system compensates for the orientation changes caused by the first adjustment device, thereby maintaining a stable virtual image plane orientation while adapting to different eye positions.
2Ease of operation
If the mirror is tilted for eye position adaptation, then different users can view the display, but the virtual display image appears in differently tilted virtual image planes
Solution Approach 1:
The adjustment system is divided into two independent adjustment devices with distinct functions. The first device handles eye position adaptation to improve ease of operation, while the second device maintains image plane orientation consistency, thereby preserving manufacturing precision. This segmentation allows both usability and precision to be optimized simultaneously.
Solution Approach 2:
The system changes the tilt parameter of the picture-generating unit dynamically through the second adjustment device to compensate for orientation changes. By adjusting this parameter in response to eye position changes, the system maintains consistent virtual image plane orientation across different users while allowing easy adaptation.
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 maintains a predetermined orientation of the virtual image plane, enhancing the stability and clarity of the virtual display image for all users, regardless of their eye positions, thereby improving the usability and readability of the display content.
Implementation Method 1
a picture-generating unit (PGU), which is configured to generate a light beam with a desired display content. It may be any suitable picture-generating apparatus, for example a display such as a liquid crystal display (LCD), LCOS (liquid crystal on silicon) or a self-luminous display on μLED or OLED basis
Implementation Method 2
The imaging and projection optical unit in the beam path downstream of the display typically comprises a folding mirror for space-saving folding of the beam path and furthermore a concave mirror, which serves for example for image magnification and/or compensation of a windshield curvature
Implementation Method 3
The imaging and projection optical unit in the beam path downstream of the display typically comprises a folding mirror for space-saving folding of the beam path
Data Source
AI summary
A projection unit for a field-of-vision display device for a vehicle includes an imaging unit for generating a light beam bundle having a display content; a mirror which is disposed in the beam path of the light beam bundle and has a first adjustment apparatus configured to tilt the mirror for adjustment to different eye-box positions of different users; and a second adjustment apparatus configured to tilt the imaging unit or an additional optical component such that image orientation is maintained. The projection unit is configured to generate a virtual display image in a virtual image plane in the field of vision of the user by outputting the light beam bundle toward a reflective pane, by which the light beam bundle is reflected to the eye-box of the user. The tilt is configured such that the virtual image plane has the same predefined orientation for the different eye-box positions.