Virtual Image Display Device with Dual Light Guiding Units
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Solution Overview
Problem
Existing virtual image display devices face challenges in widening the angle of view while preventing color unevenness, particularly when using diffraction elements for angle conversion, as the wavelength of light changes at the edges, leading to potential color issues and reduced viewing angles.
Innovation Solution
The solution involves a virtual image display device with a dual light guiding unit system, where a first light guiding unit handles a first angle of view and a second light guiding unit handles a second angle of view, both equipped with incident and emission side diffraction elements. This configuration ensures the total reflection condition is maintained, preventing color unevenness and allowing for a wider angle of view by sharing the angle of view among multiple diffraction elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If angle conversion is performed by a diffraction element and light is guided through a light guiding member to obtain a wide angle of view, then the angle of view is widened, but color unevenness occurs due to wavelength changes at the edges
Solution Approach 1:
The patent divides the light guiding function into multiple light guiding members, each handling a specific angular range. By segmenting the overall angle of view into multiple sub-angles and assigning each to a dedicated light guiding member with its own diffraction elements, the system maintains color uniformity within each segment while achieving a wide total angle of view through combination.
2Area of moving object
If the widths of reflecting surfaces are widened to realize a high angle of view in a light guiding plate, then the angle of view is increased, but image light is blocked and image unevenness occurs
Solution Approach 1:
Instead of widening reflecting surfaces in a single light guiding plate which causes image light blocking, the patent segments the function into multiple light guiding members. Each member has optimized reflecting surface widths appropriate for its specific angular range, preventing image light blocking while achieving high overall angle of view through the combination of multiple members.
3Area of moving object
If a single light guiding unit is used to cover a wide angle of view, then the angle of view is widened, but the total reflection condition cannot be satisfied and the angle of view narrows
Solution Approach 1:
The patent segments the wide angle of view into multiple smaller angular ranges, each handled by a separate light guiding member. This allows each member to satisfy the total reflection condition reliably within its specific angular range, while the combination of multiple members achieves the overall wide angle of view that would be impossible for a single member.
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 approach effectively widens the overall angle of view while suppressing color unevenness, even when increasing the angle of view, by ensuring the total reflection condition is met and allowing for uniform luminance across the image.
Implementation Method 1
an incident side diffraction element that takes the image light into the inside
Implementation Method 2
an emission side diffraction element that emits the image light to the outside
Implementation Method 3
it is easy to secure the total reflection condition
Data Source
AI summary
A virtual image display device includes a display light guiding unit, and an image forming unit that emits image light to the display light guiding unit, the display light guiding unit includes a first light guiding unit that guides image light corresponding to a first angle of view, and a second light guiding unit that guides image light corresponding to a second angle of view, among angles of view of image light emitted from the image forming unit, and the first light guiding unit and the second light guiding unit respectively include incident side diffraction elements that take the image light beams into the inside, and emission side diffraction elements that emit the image light beams to the outside.