Virtual Image Display Mirror Layout 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 to the virtual image.
Innovation Solution
A virtual image display device with a projection optical system comprising a first and second concave mirror, where the first concave mirror is oriented along a reference plane and the second concave mirror is oriented intersecting the reference plane, with the display unit positioned at the focal point of a composite optical system within a meridional plane to reduce 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 double image occurrence is reduced, but visibility of the virtual image deteriorates
Solution Approach 1:
The projection optical system is segmented into multiple optical components (projection optical system with specific focal length, windshield with specific curvature radius) that work together to control light paths. This segmentation allows independent optimization of each component to achieve both reduced double images and improved visibility at appropriate viewing distances
Solution Approach 2:
The invention changes key parameters: the focal length of the projection optical system is specifically designed to be 50mm or more, and the curvature radius of the windshield is set to 3000mm or more. These parameter changes enable the system to reduce double image occurrence while maintaining good visibility at practical viewing distances
2Device complexity
If conventional projection systems are used, then device complexity is low, but double image occurrence increases
Solution Approach 1:
The invention achieves reduced double images through careful selection of optical parameters rather than complex structural modifications. The projection optical system uses a focal length of 50mm or more, and the windshield has a curvature radius of 3000mm or more, allowing conventional simple structures to achieve superior performance
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 glasses, thereby improving user experience across various viewing distances.
Implementation Method 1
a first concave mirror that reflects the image display light toward the virtual image presentation plate
Implementation Method 2
a second concave mirror that reflects the image display light toward the first concave mirror
Implementation Method 3
the display unit is provided at a focal point of a composite optical system within a meridional plane... to reduce astigmatism
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
A virtual image display device 310 includes a projection optical system 314 that projects an image display light L toward a virtual image presentation plate 22. The projection optical system 314 includes a first concave mirror 316 that reflects the image display light L toward the virtual image presentation plate 22 and a second concave mirror 318 that reflects the image display light L toward the first concave mirror 316. Defining a plane along both a direction of incidence and a direction of output of the image display light on the virtual image presentation plate 22 as a reference plane, the first concave mirror 316 is oriented such that the image display light L is incident on the first concave mirror in a direction along the reference plane, and the second concave mirror 318 is oriented such that the image display light L is incident on the second concave mirror in a direction intersecting the reference plane. The display unit 12 is provided at a focal point of a composite optical system 320 within a meridional plane, the composite optical system 320 being formed by the virtual image presentation plate 22 and the projection optical system 314.