Combiner Separation Optimization for Head-Up Display Image Visibility
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Solution Overview
Problem
Conventional head-up displays using a light guide and combiners face issues with image visibility due to missing or excessive overlap of virtual images, affecting the display surface size and user experience.
Innovation Solution
The image display device optimizes the separation distance between combiners to prevent image overlap and omission by setting it within a specific range, ensuring that images from different emitting portions of the light guide are either superimposed or aligned correctly, using a light guide with a transparent substrate and multiple emitting portions, and flat plate-like combiners arranged in front of the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the separation distance between combiners is increased to reduce image overlap, then image visibility is improved, but image gaps and missing areas occur in the virtual image
Solution Approach 1:
The patent applies parameter changes by precisely controlling the separation distance between combiners within a specific range. This quantitative parameter adjustment ensures that images from different emitting portions are properly superimposed without excessive overlap or gaps, resolving the contradiction between visibility and completeness
Solution Approach 2:
The patent introduces dynamic adjustment capability by making the combiner separation distance可调 (adjustable). This allows the system to adapt to different viewing conditions and maintain optimal image quality, enabling the display surface to be fully utilized without fixed limitations
2Area of stationary object
If the separation distance between combiners is decreased to ensure complete coverage, then display surface completeness is improved, but excessive image overlap occurs reducing visibility
Solution Approach 1:
The patent uses parameter changes by defining a specific separation distance range that prevents excessive overlap. Within this optimized parameter range, the system achieves both complete coverage and acceptable visibility by controlling the degree of image superposition
Solution Approach 2:
The patent applies partial action by allowing controlled partial overlap of images from different emitting portions. Instead of completely avoiding overlap, the system permits a degree of superposition that ensures complete coverage while maintaining visibility through proper positioning within the specified distance range
3Area of stationary object
If multiple combiners are used to increase display surface size, then display area is improved, but image overlap and missing areas occur affecting image quality
Solution Approach 1:
The patent applies segmentation by dividing the display function across multiple combiners, each handling specific emitting portions. This segmentation allows the system to expand display surface area while maintaining image quality through proper spatial arrangement and separation distance control
Solution Approach 2:
The patent uses merging by superimposing images from multiple combiners at the user's eye position. When the separation distance is properly controlled, these segmented images merge to form a complete virtual image with enhanced display area and maintained 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 enhances the visibility of virtual images by preventing excessive overlap and image gaps, allowing for a larger display surface while maintaining high image quality.
Implementation Method 1
the incident portion guides image light incident from the image emitting unit to an inside of the substrate so as to be totally reflected by the first surface and the second surface
Implementation Method 2
The plurality of outgoing-side reflection surfaces 202a to 202c, like the incident-side reflection surface 201, is perpendicular to the third surface and the fourth surface and is inclined with respect to the first surface 200a and the second surface 200b
Implementation Method 3
the plurality of flat plate-like combiners is configured to reflect a part of the image light emitted from the plurality of emitting portions to guide the part of the image light to the eyes of the user
Data Source
AI summary
Image light that travels between opposed parallel surfaces (100a, 100b) of the light guide (10) while being reflected by the opposed parallel surfaces is partially reflected by the outgoing-side reflection surfaces (102a, 102b) of a beam splitter. The image light took out from the light guide (10) is partially reflected by the two combiners (14, 15) and advances towards eyes of a user (E). The distance D of the combiners (14, 15) is set to be equal to or larger than A1/(2 cos θ·tan θ) and equal to or smaller than A2/(2 cos θ·tan θ), where θ is an incident angle θ of the image light to the combiner (14, 15), A1 is a light flux width of the image light reflected by one outgoing-side reflection surface, and A2 is a light flux width of the image light emitted from all of the outgoing-side reflection surfaces. This makes it possible to reduce the overlapping of images formed when viewed from the user, avoid the generation of partial image omission, and improve visibility.