Vehicle Head-Up Display Polarization Mirror for Double Image Elimination
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Solution Overview
Problem
Existing head-up displays for vehicles face challenges in achieving compactness while improving image performance, particularly in minimizing double images that deteriorate image quality.
Innovation Solution
The head-up display incorporates a housing with an imaging device that emits linearly polarized light, a polarization mirror with a transmission area and a polarization reflection area, and a phase retardation mirror to create overlapping images, thereby enhancing image clarity and reducing double images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional head-up display uses multiple separate mirrors and optical components to form two virtual images, then the display functionality is achieved, but the device size increases and image quality deteriorates due to double images
Solution Approach 1:
The patent combines multiple optical functions (polarization reflection, phase retardation, and image formation) into a single integrated polarization mirror structure. This mirror has different refractive indices for different polarizations, allowing it to simultaneously perform polarization separation and phase retardation that were previously requiring multiple separate components. This merging reduces the overall device volume while maintaining the dual virtual image formation capability and eliminating double image issues.
Solution Approach 2:
The polarization mirror serves multiple functions simultaneously: it acts as a polarization beam splitter, a phase retarder, and an image forming element. By designing the mirror with specific optical properties (different refractive indices for different polarizations), it can guide different polarization components along different optical paths to form two distinct virtual images, eliminating the need for separate dedicated components for each function.
2Reliability
If a head-up display uses one image source with two optical paths of different total lengths, then two virtual images can be formed, but double images occur that deteriorate image performance
Solution Approach 1:
The patent applies local quality by giving different regions of the polarization mirror different optical properties. The mirror is designed with specific refractive indices for different polarizations in different areas, allowing it to selectively guide s-polarized and p-polarized light along different optical paths. This localized differentiation enables precise control over the two optical paths without requiring complex overall system configuration, thereby forming two clear virtual images without double image deterioration.
3Reliability
If the polarization mirror has parallel front and rear surfaces, then manufacturing is simplified, but double images are generated that reduce image clarity
Solution Approach 1:
The patent introduces asymmetry by designing the polarization mirror with non-parallel front and rear surfaces. This asymmetric geometry is crucial for eliminating double images, as it ensures that light rays reflecting from the front surface and light rays transmitting through to the rear surface converge to form overlapping images rather than separate double images. While this increases manufacturing complexity compared to parallel surfaces, it is necessary to achieve the required image clarity.
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 results in improved image performance by ensuring that at least a portion of the images generated by light reflected from the rear and front surfaces of the polarization mirror overlap, providing clear and reduced double image issues.
Implementation Method 1
an imaging device accommodated in the inner space and emitting first linearly polarized light having a first direction
Implementation Method 2
a polarization mirror having a transmission area through which the first linearly polarized light transmits and a polarization reflection area through which a second linearly polarized light having a second direction perpendicular to the first direction is reflected
Implementation Method 3
a polarization reflection mirror disposed to be spaced apart from the first reflection mirror, reflecting linearly polarized light in the first direction and transmitting linearly polarized light in the second direction
Implementation Method 4
a phase retardation mirror spaced apart from the polarization mirror and phase-converting the first linearly polarized light transmitted through the transmission area into the second linearly polarized light
Implementation Method 5
Image light generated from the display panel may be incident on the windshield of the vehicle by the mirror, and the driver may perceive a virtual image of the position in front of the windshield
Data Source
AI summary
Discussed is a head-up display including, a housing formed with an inner space inside and disposed below a windshield, an imaging device accommodated in the inner space and emitting a first linearly polarized light polarized in a first direction, a polarization mirror having a transmission area through which the first linearly polarized light is transmitted and a polarization reflection area through which a second linearly polarized light polarized in a second direction perpendicular to the first direction is reflected, and a phase retardation mirror spaced apart from the polarization mirror and phase-converting the first linearly polarized light transmitted through the transmission area into the second linearly polarized light, wherein at least a portion of the polarization mirror is located between the imaging device and the phase retardation mirror, and wherein a first surface and a second surface of the polarization mirror are not parallel.