Virtual Image Display Device with Variable Reflection Paths
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing virtual image display devices face challenges in achieving a large display size with a simple configuration while securing a large Eyring diameter for a preferable see-through observation, often resulting in blind spots and complex optical systems.
Innovation Solution
A virtual image display device featuring a projective optical system and a light guiding member with reflective surfaces that allow image light to be guided through total reflection, varying the number of reflections for each image light beam, enabling a wide angle of emission and combining them to form a single virtual image, thus securing a large display size without the need for pupil division.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light guiding optical system with emission opening smaller than pupil size is used to realize see-through state, then the see-through state is achieved, but the display size of virtual image cannot be made large and the Eyring diameter cannot be made large
Solution Approach 1:
The invention divides the optical system into multiple optical paths with different numbers of reflections. By segmenting the light guiding function into multiple reflection paths (different reflection counts), the system achieves both see-through capability and large display size simultaneously, resolving the contradiction between reliable see-through state and large virtual image display area
Solution Approach 2:
The invention transitions from a single-dimensional approach (single emission opening size) to multi-dimensional optimization by controlling the number of reflections in different optical paths. This dimensional change in the optical path design allows the emission opening to be larger than the pupil while maintaining see-through quality and achieving large display size
2Reliability
If a light guiding optical system with emission opening smaller than pupil size is used, then see-through state is achieved, but the Eyring diameter cannot be made large to correspond to individual pupil width
Solution Approach 1:
The optical system is segmented into multiple reflection paths that guide light from different regions of the display element through different numbers of reflections to the pupil. This segmentation allows the Eyring diameter to be enlarged to match individual pupil widths while maintaining the see-through state through coordinated optimization of each reflection path
3Device complexity
If the emission opening or casing of light guiding optical system is physically disposed in the vicinity of the pupil, then the structure is compact, but a blind spot is generated and perfect see-through is not achieved
Solution Approach 1:
The invention moves the emission opening away from the pupil vicinity by utilizing multiple reflection paths that extend the optical path length. This dimensional change in the optical path configuration allows the emission opening to be positioned farther from the pupil, eliminating blind spots and achieving perfect see-through while maintaining structural compactness through the folded optical paths
4Adaptability or versatility
If an optical system with multiple light modes and different light guiding angles is used, then display content can be changed by each optical mode, but the device becomes complex and the observed image becomes dark
Solution Approach 1:
The invention applies local quality by assigning different reflection counts to different regions of the display element. Each local region guides light through a specific number of reflections tailored to its position, achieving display content variation without requiring a complex multi-mode optical system. This localized optimization simplifies the overall system while maintaining versatility
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 allows for a large display size and secure Eyring diameter, enabling a preferable see-through observation without increasing the thickness of the light guiding portion and maintaining a simple optical system.
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
Image light reflected by a third reflective surface of a light incidence portion is propagated while being totally reflected by first and second reflective surfaces of a light guiding portion, is reflected by a fourth reflective surface of a light emission portion, and is incident to observer's eye as a virtual image. At this time, the number of times of reflection of first image light, which is emitted from a first partial region of an image display device, in the light guiding portion, and the number of times of reflection of second image light, which is emitted from a second partial region of the image display device in the light guiding portion are different from each other, such that it is possible to take in the image light beams from the different partial regions of the image display device with a relatively wide angle of view.