Vehicle Head-Up Display Using Polarization Control for Virtual Image Spacing
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Solution Overview
Problem
Existing head-up displays for vehicles face challenges in forming multiple virtual images efficiently, as they often require complex structures, increased power consumption, and larger sizes due to multiple image sources or optical paths, with difficulties in precisely controlling the spacing between virtual images based on external conditions.
Innovation Solution
A head-up display system that uses a linearly-polarized light source, a prism, an electric polarization conversion element, and selective reflection/ transmission mirrors to form multiple virtual images with adjustable distances, minimizing the number of components and optimizing compactness, while allowing for dynamic adjustment of virtual image spacing based on external conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two image sources are used to form two virtual images, then the convenience of the head up display is increased, but the structure becomes complicated, power consumption increases, and the overall size increases
Solution Approach 1:
A single image source performs multiple functions by generating different virtual images through different optical paths. The first virtual image is formed through a first reflection mirror, while the second virtual image is formed through a second reflection mirror with a different optical path length, allowing one image source to provide multiple display functions without requiring two separate image sources
Solution Approach 2:
The optical system is segmented into multiple independent optical paths with different lengths. The first optical path includes the first reflection mirror and has a first total length, while the second optical path includes the second reflection mirror and has a second total length different from the first. This segmentation allows a single image source to create multiple virtual images at different distances without increasing the number of image sources
2Device complexity
If a half mirror is used to form two virtual images with one image source, then the number of image sources is reduced, but optical loss becomes large
Solution Approach 1:
Instead of using a single half mirror that causes optical loss, the system segments the optical path into two separate paths with different total lengths. Each path uses full reflection mirrors, avoiding the optical loss associated with half mirrors while still enabling the formation of two virtual images from one image source
3Adaptability or versatility
If multiple flat mirrors are used to obtain a distance difference between virtual images, then two virtual images can be formed, but it is difficult to precisely set the distance between virtual images due to interferences from the sizes of the mirrors
Solution Approach 1:
The optical system is divided into two distinct optical paths with precisely controlled total lengths. The first optical path has a first total length and the second optical path has a second total length, allowing the distance between virtual images to be determined by the difference in these path lengths rather than by mirror sizes, thereby improving precision
Solution Approach 2:
The design changes the controlling parameter for virtual image distance from mirror physical sizes to optical path lengths. By controlling the total length of each optical path (first total length and second total length), the system achieves more precise and flexible control over the distance between virtual images without the interference of mirror dimensions
4Device complexity
If virtual image distances are fixed in prior art, then the structure is simple, but the system cannot control spacing between virtual images based on external traffic situations
Solution Approach 1:
The system enables dynamic control of virtual image distances by adjusting the optical path lengths. The first and second optical paths can be independently configured with different total lengths, allowing the spacing between virtual images to be adapted to external conditions such as traffic situations, transforming a static system into a dynamic one
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 system effectively forms multiple virtual images with different distances using fewer components, enhances image quality by preventing overlap, and allows for real-time adjustment of virtual image spacing, providing more information to the driver while maintaining a compact and efficient design.
Implementation Method 1
a prism for refracting a portion of the linearly-polarized light emitted from the image source
Implementation Method 2
a polarization reflection mirror spaced apart from the first reflection mirror, wherein the polarization reflection mirror reflects the linearly-polarized light in the first direction and transmits the linearly-polarized light in the second direction
Data Source
AI summary
A head-up display for a vehicle, according to one embodiment of the present invention, may comprise: an image source which emits a linearly-polarized light having a first direction; a prism which refracts one portion of the linearly-polarized light emitted from the image source; an electric polarization conversion element which, when turned off, transmits another portion of the linearly-polarized light emitted from the image source, and when turned on, half-wavelength-converts the another portion of the linearly-polarized light emitted from the image source into a linearly-polarized light having a second direction orthogonal to the first direction; a first reflection mirror which reflects light to a windshield of a vehicle; a polarization reflection mirror which is disposed so as to be spaced apart from the first reflection mirror, reflects the linearly-polarized light having the first direction, and transmits the linearly-polarized light having the second direction; and a second reflection mirror which is disposed so as to be spaced apart from the polarization reflection mirror, and reflects the light transmitted through the polarization reflection mirror to the polarization reflection mirror.