HUD Imaging Layout for Low-Distortion Eye Detection
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Solution Overview
Problem
Existing head-up display (HUD) devices face challenges in reducing image distortion and improving accuracy in detecting body parts, such as the eye, due to the non-uniform curvature of windshields, which affects the installation position of infrared cameras and leads to increased device size and potential external light interference.
Innovation Solution
The HUD device is configured with a translucent cover that separates display light and imaging light paths, positioning the imaging element closer to the end side of the vehicle to minimize distortion and using a filter unit to block visible light and transmit infrared light, thereby reducing device size and preventing external light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the camera is disposed at a position apart from the optical system for display light, then the arrangement of the camera can be freely determined independently of the optical system, but the housing needs to have a large size
Solution Approach 1:
The patent positions the imaging unit in the width direction (lateral dimension) rather than only in the depth direction, utilizing the windshield's curved surface geometry to achieve optical path separation. This dimensional approach allows independent arrangement freedom while maintaining compact housing dimensions by leveraging the three-dimensional space more efficiently.
2Device complexity
If the camera is disposed at a position apart from the optical system for display light, then the optical element can have a simplified configuration, but the housing needs to have a large size
Solution Approach 1:
The imaging unit is positioned laterally apart from the display optical system, utilizing the windshield's width-direction curvature to achieve optical path separation. This simplifies the optical element configuration by eliminating the need for complex beam splitting elements, while the lateral positioning maintains compact housing size by using available lateral space rather than increasing overall device volume.
3Measurement precision
If the camera is disposed closer to the center side of the vehicle, then the accuracy in detection of the position of a body part is improved, but the distortion of a captured image increases
Solution Approach 1:
The patent positions the imaging unit on the end side in the width direction to utilize the windshield's curved surface geometry, which provides more favorable reflection angles for reducing image distortion. This lateral positioning strategy balances the trade-off between detection accuracy and image quality by leveraging the three-dimensional optical path geometry rather than only adjusting depth position.
4Manufacturing precision
If the camera is disposed on the end side of the vehicle, then the distortion of a captured image is reduced, but the accuracy in detection of the position of a body part decreases
Solution Approach 1:
The imaging unit is positioned laterally on the end side to reduce image distortion by utilizing favorable windshield curvature angles. The patent accepts this positional compromise as necessary to achieve acceptable detection accuracy while maintaining superior image quality, recognizing that lateral positioning offers better overall performance than depth-adjustment alone.
5Ease of manufacture
If the translucent cover is provided at an opening portion of the housing, then external light may enter the HUD device, but the light emitting element and camera can be visually recognized
Solution Approach 1:
The translucent cover is designed with selective transparency properties that allow imaging light (infrared or specific wavelength) to pass through while blocking or filtering external visible light. This optical filtering approach maintains the simplicity of the translucent cover design while effectively preventing external light interference with the imaging function.
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 reduces image distortion, enhances the accuracy of body part detection, and maintains a compact HUD device design while preventing external light from affecting the imaging process.
Implementation Method 1
using a filter unit to block visible light and transmit infrared light
Implementation Method 2
captures an image of a body part of the occupant by irradiating the body part with imaging light and receiving reflected light from the body part via the reflective translucent member
Data Source
AI summary
A head-up display device comprises a housing, a translucent cover, a display unit that displays an image, an optical system, and an imaging unit that is provided outside a path of display light of the image within the housing and has a light emitting element and an imaging element. When seen in plan view from above, the housing is disposed between a display light passing region through which the display light passes, and an imaging element region corresponding to the imaging element located below the translucent cover, and when seen from the occupant, the imaging element region is provided on the end side that is the side opposite to the center side of a vehicle in the width direction of the vehicle with respect to the display light passing region.