Virtual Image Display Emission Opening Width Optimization
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Solution Overview
Problem
Existing virtual image display devices face challenges in achieving high-quality image display due to partial image deficiencies and variations in brightness, particularly in see-through configurations where the light guiding optical system is smaller than the pupil size, leading to blind spots and complex image formation processes.
Innovation Solution
A virtual image display device incorporating a projective optical system with a light guiding member featuring parallel reflective surfaces and a half mirror, allowing image light to be guided through total reflection, with an emission opening width larger than the third reflective surface, enabling efficient image light incidence and preventing partial deficiencies and brightness variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a light guiding optical system with emission opening smaller than pupil size is used to achieve see-through state, then the see-through function is realized, but the display size of virtual image cannot be made large and blind spots are generated
Solution Approach 1:
The patent introduces a third optical surface (half mirror) at the emission side, creating a three-surface optical system that utilizes multiple dimensions of light reflection. This allows the emission opening to be larger than the pupil size while maintaining see-through functionality, resolving the contradiction between see-through capability and display size.
2Volume of moving object
If a light guiding optical system smaller than pupil size is used, then the device structure is compact, but the effective pupil diameter cannot be made large to correspond to individual pupil width
Solution Approach 1:
The optical system is segmented into three distinct optical surfaces: first and second reflective surfaces for light guiding, and a third reflective surface (half mirror) at the emission side. This segmentation allows each surface to perform its specific function optimally, enabling the effective pupil diameter to match individual pupil widths while maintaining compact device structure.
3Adaptability or versatility
If multiple optical modes with different light guiding angles are used, then the optical system can display content by changing modes, but the device becomes complex and observed image becomes dark
Solution Approach 1:
The patent merges multiple optical modes into a single integrated optical system where the first and second reflective surfaces guide light in different angles simultaneously. This eliminates the need for sequential mode switching and multiple liquid crystal panels, reducing device complexity while maintaining the capability to display content through different optical paths.
4Area of stationary object
If the emission opening width is increased to prevent image deficiency, then the light guiding portion thickness increases
Solution Approach 1:
The patent utilizes a third dimension by introducing the third optical surface (half mirror) at the emission side, perpendicular to the plane of the first and second reflective surfaces. This three-dimensional optical configuration allows the emission opening width to be increased without proportionally increasing the light guiding portion thickness, as the light paths are distributed across multiple spatial dimensions.
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
The solution enables high-quality virtual image display with reduced image deficiencies and brightness variations, allowing for a larger display size and effective see-through observation without increasing the thickness of the light guiding portion, thus enhancing the overall display experience.
Implementation Method 1
the light guiding portion has a first reflective surface and a second reflective surface that are disposed in parallel with each other and allow the image light to be guided through a total reflection
Implementation Method 2
the light incidence portion has a third reflective surface that makes a predetermined angle with respect to the first reflective surface
Implementation Method 3
the light emission portion has a fourth reflective surface that makes a predetermined angle with respect to the first reflective surface
Data Source
AI summary
In regard to a second direction (combination direction) that is turned back by a reflection at the time of light-guiding, a projective optical system has an emission opening width larger than an opening width of a third reflective surface, such that it is possible to prevent a partial deficiency of image light when the image light emitted from the projective optical system is incident to the third reflective surface from occurring, and thereby it is possible to prevent the occurrence of deficiency of an image or a large variation in brightness.