Automotive Head-Up Display Polarization Folding
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Solution Overview
Problem
Existing head-up displays in automobiles are bulky and difficult to miniaturize without compromising optical performance and image quality.
Innovation Solution
The use of a specific optical configuration involving a reflective polarizer, quarter-wave plate, and concave mirror, which converts image light polarization to optimize projection onto a combiner, such as a windshield, allowing for reduced volume and improved picture quality by securing sufficient optical length and reducing aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional optical configurations are used in head-up displays, then optical performance and image quality can be maintained, but the device volume becomes bulky and difficult to miniaturize
Solution Approach 1:
The patent combines multiple optical functions into a single integrated optical system. The optical element performs both reflection and polarization conversion functions that would traditionally require separate components, thereby reducing device volume while maintaining optical performance. The combiner is positioned to receive image light directly from the image light output device, eliminating the need for additional relay optics.
Solution Approach 2:
The patent utilizes the polarization dimension of light to achieve compact optical design. By employing polarization-division multiplexing and polarization- selective optical elements, the system can fold the optical path in the polarization domain, effectively reducing the physical space required for the optical system while maintaining image quality.
2Manufacturing precision
If the optical path length is increased to improve image quality, then picture quality improves, but the device volume increases
Solution Approach 1:
The patent implements a nested optical configuration where the optical path is folded back on itself within a compact volume. The optical element is positioned to reflect light back toward the combiner, creating a nested optical path that achieves sufficient optical length for high picture quality while occupying minimal device volume.
Solution Approach 2:
The patent employs dynamic light control through polarization modulation. The optical system dynamically manipulates the polarization state of light to control its path and interaction with optical elements, enabling compact design while maintaining the effective optical path length needed for high image quality.
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 enables a significant reduction in the volume of the head-up display while maintaining high image quality and reducing exposure to external light, thus extending the device's service life and improving visibility.
Implementation Method 1
The first optical element reflects the image light having a first polarization direction and allowing the image light having a second polarization direction different from the first polarization direction to pass through
Implementation Method 2
The third optical element is disposed between the first optical element and the second optical element, and converts the image light having the first polarization direction to the image light having the second polarization direction by allowing the image light to pass through back and forth
Data Source
AI summary
A head-up display includes an image light output device for outputting image light, a first optical element, a second optical element, and a third optical element. The first optical element is provided to be inclined with respect to the output surface of the image light output device. The first optical element reflects the image light having a first polarization direction and allowing the image light having second polarization direction to pass through. The second optical element reflects the image light from the first optical element to the first optical element. The third optical element is disposed between the first and the second optical element, and converts the image light having the first polarization direction to the image light having the second polarization direction by allowing the image light to pass through back and forth. The image light passing through the first optical element is projected on a combiner.