Light Guide Prevention Structure for Virtual Image Display
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Solution Overview
Problem
Virtual image display apparatuses, such as head mount displays, face challenges in suppressing leakage lights due to unintended reflections of outside world lights, especially when the light guide member has curved or narrow shapes, leading to ghost lights and reduced image clarity.
Innovation Solution
Incorporating a light guide prevention structure in the narrow width shape parts of the light guide device, which can be achieved through non-axisymmetric curved surfaces, light shielding members, or application of colored adhesive agents, to prevent the reflection and refraction of outside world lights, thereby maintaining better light guidance for the picture lights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the light guide device uses curved surfaces or narrow width shape parts to guide picture lights, then the light guide condition is improved and the device can be downsized, but the probability of unintended reflection of lights from the outside world increases, generating leakage lights
Solution Approach 1:
The patent applies different surface properties to different regions of the light guide device. Specifically, the light guide surfaces maintain high reflectivity for picture lights, while the narrow width shape parts have reduced reflectivity to prevent leakage light generation. This local differentiation of surface properties resolves the contradiction between compact design and leakage light suppression.
Solution Approach 2:
The patent converts the potentially harmful narrow width shape parts that generate leakage lights into beneficial light-trapping structures. By designing these narrow portions with specific geometric features and reduced reflectivity, incoming leakage lights are trapped and absorbed within these regions, preventing them from reaching the observer while maintaining the compact form factor.
2Shape
If the light guide device has curved surface portions or narrow width shape parts, then the device can be downsized with non-axisymmetric curved surfaces, but the probability of unintended reflection becomes higher
Solution Approach 1:
The patent employs non-axisymmetric curved surfaces in the light guide device, where the curvature and shape vary asymmetrically across different regions. This asymmetric design optimizes the light guide condition for picture lights while creating specific zones (narrow width shape parts) that trap and absorb leakage lights, preventing unintended reflection.
Solution Approach 2:
The patent addresses the reflection problem by transitioning from considering only the primary light guide dimension to incorporating additional dimensional considerations. The narrow width shape parts introduce a secondary dimension of light control, where light rays are trapped through multiple internal reflections within these narrow regions, effectively removing them from the optical path.
3Object-affected harmful factors
If a light shielding member is used to cover the narrow width shape part, then direct incidence of lights from the outside world is suppressed, but the assembly complexity increases
Solution Approach 1:
The patent merges the light shielding function with the existing narrow width shape parts of the light guide device. Instead of adding separate light shielding members, the design integrates light-trapping geometric features directly into the narrow portions of the light guide structure, achieving light shielding through the device's own geometry and reducing assembly complexity.
Solution Approach 2:
The narrow width shape parts of the light guide device serve dual functions: guiding picture lights and trapping leakage lights. The geometric configuration of these narrow portions creates self-trapping effects where leakage lights are automatically confined and absorbed through multiple internal reflections, eliminating the need for additional light shielding components.
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 light guide prevention structure effectively suppresses unintended lights from reaching the observer, enhancing the light guidance condition for picture lights and reducing ghosting effects, while allowing for a downsized and accurately assembled optical system.
Implementation Method 1
a light guide device that guides the picture lights from the picture device by reflection using a plurality of surfaces
Implementation Method 2
superimposes lights from the outside world and the picture lights for visual recognition
Implementation Method 3
the adhesive agent forming the light guide prevention structure is a black UV curing adhesive agent... unintended lights (leakage lights) due to the lights from the outside world are absorbed by the colored adhesive agent
Implementation Method 4
the adhesive agent forming the light guide prevention structure is a black UV curing adhesive agent... light guide prevention structure that can easily perform desired light absorption by UV irradiation
Data Source
AI summary
An apparatus has a see-through configuration that guides picture lights by a light guide device and superimposes lights from the outside world and the picture lights for visual recognition. The light guide device has a light guide prevention structure (light transmission prevention structure) provided in a narrow width shape part having a narrower shape than a surrounding part, and thereby, prevents unintended reflection or the like of lights due to the lights from the outside world and suppresses light guide of the lights toward an observer side.