Virtual Image Display Optics for Double-Image Reduction
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Solution Overview
Problem
Existing virtual image display technologies require a large viewing distance to minimize double images, which is not ideal and affects visibility regardless of the viewing distance.
Innovation Solution
A virtual image display device with a projection optical system that includes a concave mirror and a convex lens, where the image display light is incident and reflected diagonally on a concavely curved surface, and the display unit is positioned at the focal point of a composite optical system within the meridional plane, reducing astigmatism and double images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a large viewing distance is used to reduce double images, then the occurrence of double images is reduced, but the visibility of the virtual image deteriorates
Solution Approach 1:
The patent applies curved surfaces (concave mirrors and cylindrical lenses) to the optical system. The projection mirror has a curved reflective surface, and the virtual image presentation plate has curved surfaces that work together to focus and direct light rays. This curvature enables the system to converge light paths from different angles to the same virtual image position, reducing double images while maintaining visibility at shorter viewing distances.
Solution Approach 2:
The patent changes the optical parameters of the system by using a composite optical system with specific focal lengths and curvature radii. The display unit is positioned at a specific focal point determined by the composite optical system's parameters. By optimizing these parameters (focal lengths, curvature radii, distances between components), the system achieves both double image reduction and improved visibility at various viewing distances.
2Device complexity
If a conventional optical system is used, then the device complexity is low, but the occurrence of double images increases
Solution Approach 1:
The patent merges multiple optical components into an integrated composite optical system. The projection mirror and virtual image presentation plate work together as a combined system, with their curved surfaces coordinated to achieve the desired optical effect. This merging of functions into a unified system reduces double images while maintaining reasonable device complexity through functional integration.
Solution Approach 2:
The virtual image presentation plate acts as an intermediary element between the projection mirror and the user's eye. It receives the projected light, applies additional optical transformation through its curved surfaces, and presents the final virtual image. This intermediary component is essential for reducing double images by correcting the light paths before they reach the user.
3Object-affected harmful factors
If specialized windshield designs (wedge glass) are used to reduce double images, then the occurrence of double images is reduced, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of requiring a specialized physical windshield (wedge glass), the patent creates an optical equivalent effect through the composite optical system. The curved surfaces and focal point arrangement replicate the double image reduction function that wedge glass would provide, but through a configurable optical system that can be installed without modifying the windshield itself.
Solution Approach 2:
The patent replaces the mechanical/structural solution (wedge glass windshield with specific angle) with an optical solution (curved mirrors and lenses arranged in a composite system). This substitution allows the same functional outcome (double image reduction) to be achieved through optical principles rather than mechanical windshield design, simplifying manufacturing and installation.
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 reduces the occurrence of double images and enhances the visibility of the virtual image without the need for specialized windshield designs, such as wedge glass, thereby improving user experience across various viewing distances.
Implementation Method 1
the image display light is incident and reflected on a first concavely curved surface of the virtual image presentation plate diagonally
Implementation Method 2
a projection mirror that projects the image display light toward the virtual image presentation plate such that the image display light is incident and reflected on a first concavely curved surface
Implementation Method 3
the display unit is provided at a focal point of a composite optical system within a meridional plane, the composite optical system being formed by the virtual image presentation plate and the projection optical system, and the focal point of the composite optical system within the meridional plane is a position of convergence of parallel beams
Data Source
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Figure 5A~5B
AI summary
A virtual image display device 10 includes a projection optical system 14 that includes a projection mirror 16 that projects an image display light L toward a virtual image presentation plate 22 such that the image display light L is incident and reflected on a first concavely curved surface of the virtual image presentation plate 22 diagonally. The projection mirror 16 has a second concavely curved surface on which the image display light L is incident and reflected diagonally and is arranged such that a direction orthogonal to both a direction of incidence and a direction of reflection of the image display light on the first concavely curved surface and a direction orthogonal to both a direction of incidence and a direction of reflection of the image display light on the second concavely curved surface are orthogonal to each other. The display unit 12 is provided at a focal point of a composite optical system within a meridional plane, the composite optical system being formed by the virtual image presentation plate 22 and the projection optical system 14.