Asymmetric Stop Opening for Compact Virtual Image Display
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Solution Overview
Problem
Existing virtual image display apparatuses face challenges in reducing size while maintaining optical precision, as design constraints such as total reflection conditions, aberration suppression, and angle of view limit the size reduction of optical systems.
Innovation Solution
The virtual image display apparatus incorporates a light guide member with nonaxisymmetric curved surfaces and a projection system with a stop that forms an asymmetric opening, allowing for further size reduction while maintaining optical precision by adjusting light paths and blocking unnecessary light components effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a light guide member with nonaxisymmetric curved surfaces is used to guide video image light, then the size of the apparatus is reduced, but the optical precision and design conditions (total reflection condition, aberration suppression, angle of view) are compromised
Solution Approach 1:
The patent applies asymmetry by configuring the stop opening to be asymmetric in shape relative to the optical axis. Specifically, the opening has different aperture ratios in the first direction (horizontal) and second direction (vertical), creating an asymmetric structure that allows independent optimization of light control in each direction while maintaining compact apparatus size
Solution Approach 2:
The patent implements local quality by making different portions of the stop opening have different aperture characteristics. The first aperture ratio (in the first direction) and second aperture ratio (in the second direction) are different from each other, allowing localized optimization of light guidance and aberration control in specific regions of the optical system
2Length of stationary object
If the length of the light guide member is shortened to reduce apparatus size, then the overall length is reduced, but the total reflection condition and aberration suppression are compromised
Solution Approach 1:
The asymmetric stop opening configuration allows the optical system to maintain effective light guidance with a shorter light guide member length. By having different aperture ratios in different directions, the system can compensate for the reduced length while maintaining the necessary total reflection conditions and optical performance
3Length of stationary object
If the overall length of the projection system is shortened to reduce apparatus size, then the apparatus becomes more compact, but the angle of view and optical precision are compromised
Solution Approach 1:
The asymmetric stop opening with different aperture ratios in the first and second directions enables the projection system to maintain a satisfactory angle of view while having a reduced overall length. The asymmetric configuration allows independent optimization of light paths in different directions, preserving angular coverage despite the compact size
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 enables a more compact virtual image display apparatus with improved optical precision, resolution, and angle of view, allowing for see-through observation and high-quality image formation.
Implementation Method 1
a light guide member that guides the video image light from the video device based on total reflection that occurs at a plurality of surfaces including a nonaxisymmetric curved surface
Implementation Method 2
the projection system has a stop that forms an opening that is symmetric with respect to a first flat plane including the projection system optical axis and a first axis that extends in parallel to the first direction
Data Source
AI summary
In a projection system, providing a stop that forms an opening that is symmetric with respect to a first flat plane including the projection system optical axis and a first axis that extends in parallel to the first direction and intersects the projection system optical axis but asymmetric with respect to a second flat surface including the projection system optical axis and a second axis that extends in parallel to the second direction and intersects the projection system optical axis allows appropriate light adjustment at the stop even when pencils of light from the points in a video device exit at different angles along a second direction, whereby high-quality video images can be provided with the size of an optical system further reduced and therefore the size of an overall virtual image display apparatus reduced.