Head-Mounted HUD Image Display Device with Retro-Reflective Optical Path
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Solution Overview
Problem
Head-mounted HUDs are limited in displaying various information across different regions of the field of view and cannot display multiple images in the depth direction, making it difficult to change the display position of images in mid-air.
Innovation Solution
An image display device with a first and second image projection unit, beam splitters, retro-reflecting units, and image forming optical units that split and redirect light to form images at different positions, allowing multiple images to be displayed in the depth direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a head mounted HUD is used to project light directly to the user's eyes, then the device size and weight are reduced, but the display position is limited in the field of view and cannot display multiple images in the depth direction
Solution Approach 1:
The optical system is divided into multiple independent projection units (first image projection unit, second image projection unit), each capable of projecting images to different depth positions. This segmentation allows multiple images to be displayed in the depth direction simultaneously, resolving the limitation of fixed display position while maintaining a compact head-mounted form factor
Solution Approach 2:
The patent extends the display capability from a single fixed position to multiple positions in the depth direction (z-axis dimension). By utilizing beam splitters and retro-reflecting units, the system creates image paths at different optical distances, enabling three-dimensional spatial distribution of displayed images while keeping the physical device compact
2Device complexity
If a single image projection path is used, then the device structure is simple, but it is not possible to display a plurality of images in the depth direction
Solution Approach 1:
Multiple optical paths are merged through beam splitters. The first beam splitter combines light from the first image projection unit with light from the second image projection unit, allowing both images to be viewed simultaneously through the same optical entrance (user's eye). This merging approach enables multi-image display without requiring separate viewing paths for each image
Solution Approach 2:
Beam splitters and retro-reflecting units act as intermediary optical elements that redirect and combine light paths. These intermediaries enable multiple projection units to share a common viewing path while maintaining distinct image formation at different depths, resolving the contradiction between structural simplicity and multi-image capability
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
Enables the display of multiple images at different depths and positions, enhancing the flexibility and capability of HUDs in presenting information.
Implementation Method 1
a first beam splitter configured to split first projection light emitted from the first image projection unit into first transmitted light and first reflective light
Implementation Method 2
a first retro-reflecting unit configured to cause the first reflective light to incident on the first beam splitter as first retro-reflective light
Implementation Method 3
a first image forming optical unit configured to form the first retro-reflective light transmitted through the first beam splitter into an image
Data Source
AI summary
An image display device includes a first image projection unit configured to project a first image, a first beam splitter configured to split first projection light emitted from the first image projection unit into first transmitted light and first reflective light, a first retro-reflecting unit configured to cause the first reflective light to incident on the first beam splitter as first retro-reflective light, and a first image forming optical unit configured to form the first retro-reflective light transmitted through the first beam splitter into an image.