Head-Up Display Variable Focal Length Lens Array
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Solution Overview
Problem
Current head-up displays cause visual fatigue due to the need for frequent focal adjustments between near and far objects, especially when vehicle speed changes, as they lack adjustable focal length and are difficult to manufacture with complex projector designs.
Innovation Solution
A head-up display with a movable array of lenses between a projector and a magnifier lens module, allowing the position of the virtual image to be adjusted by changing the relative positions of these components, ensuring the image remains clear and visible without significant design changes to the projector or magnifier lens module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a projector with specifically designed structure or change of curvature is used to achieve focal length adjustability, then the focal length can be adjusted, but the projector becomes difficult to manufacture and the yield rate is poor
Solution Approach 1:
The optical system is divided into separate components: a fixed projector and a movable lens array. The lens array consists of multiple independent lens units that can be positioned at different locations, allowing focal length adjustment without modifying the projector structure itself. This segmentation enables easy manufacturing of the projector while achieving adaptability through the separate lens array component.
Solution Approach 2:
A lens array is introduced as an intermediary component between the projector and the display medium. This lens array acts as a mediator that adjusts the focal length of the projected image by changing the position of lens units, thereby achieving focal length adjustability without requiring the projector itself to have complex adjustable structures.
2Ease of manufacture
If LED segment displays are used to project patterns on windshield glasses, then the cost is low and installation is easy, but users experience eye fatigue due to the need to adjust focal point from far pavement to near windshield glass
Solution Approach 1:
The lens array is designed to be movable, allowing dynamic adjustment of the virtual image distance. This enables the display to adapt to different viewing conditions (e.g., changing focal length based on vehicle speed or environmental conditions), keeping the image in focus and reducing eye fatigue while maintaining ease of installation.
3Device complexity
If the projection of the virtual image is not adjustable in response to vehicle speed change, then the system is simple, but visual fatigue to the driver is easily triggered
Solution Approach 1:
The lens array can be moved to different positions to dynamically adjust the focal length of the virtual image. This allows the system to respond to changing vehicle speeds and driving conditions, maintaining image clarity and reducing visual fatigue without requiring complex redesign of the entire projection system.
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 head-up display with variable focal length, reducing visual fatigue by maintaining clear visibility of driving information across varying distances and speeds, with a simple and cost-effective design that prevents severe image deformation and ensures clear image definition under different lighting conditions.
Implementation Method 1
the beam forms an inter-image after passing the array of lens
Implementation Method 2
forms a virtual image after passing the magnifier lens module
Data Source
AI summary
A head-up display with variable focal length includes a projector which provides a beam with image, a magnifier lens module which is disposed on the route of the beam, and an array of lens which is movably disposed between the projector and the magnifier lens module. The beam forms an inter-image after passing the array of lens, then forms a virtual image after passing the magnifier lens module. To change the position of the virtual image, adjust the relative position between the array of lens and the magnifier lens module. A dispersion angle of the array of lens is θd, a magnification of the magnifier lens module is M, a distance between the virtual image and user's eyes is VID, a visible range of user's eyes is Et, and satisfies the relationship as following: θd=M*2*cot−1 (2VID/Et).