Light-Guiding Member Curved Surface Matching for AR Displays
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Solution Overview
Problem
Existing virtual image display devices, such as head-mounted displays (HMDs), face issues with light leakage and ghosting due to the shape of the connection surface between reflection surfaces, which also leads to coating failures when a hard coat layer is applied, complicating the mold formation process.
Innovation Solution
A virtual image display device with a light-guiding member featuring a plurality of reflection surfaces, including a first and second reflection surface adjacent to each other, where at least one surface is curved, with the ends matching when projected from a specific direction, eliminating the need for a separate mold for the connection surface and reducing light leakage and coating failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a connection surface is designed to connect reflection surfaces in the light-guiding member, then the reflection surfaces can be properly positioned and aligned, but light leakage and ghosting occur due to the shape of the connection surface
Solution Approach 1:
The invention extracts and eliminates the connection surface from the light-guiding member structure. By removing the separate connection surface that caused light leakage and ghosting, the patent achieves proper positioning of reflection surfaces through direct adjacency without requiring a dedicated connection interface.
Solution Approach 2:
The invention merges the reflection surfaces by making them directly adjacent to each other without a separate connection surface. This consolidation eliminates the harmful connection surface while maintaining the structural integrity and positioning accuracy of the reflection surfaces.
2Strength
If a hard coat layer is applied through dip treatment on the light-guiding member, then surface protection is achieved, but coating failure occurs due to accumulation of hard coat liquid at the connection surface
Solution Approach 1:
The invention removes the connection surface that caused liquid accumulation during dip treatment. By eliminating this geometric feature, the hard coat liquid can flow uniformly across the entire surface without accumulating at connection interfaces, ensuring consistent coating quality.
3Shape
If separate molds are used for each reflection surface and connection surface, then complex shapes can be formed, but the molding process becomes complicated and production efficiency decreases
Solution Approach 1:
The invention combines multiple reflection surfaces and the connection region into a single integrated mold cavity. This allows the light-guiding member to be formed in one molding operation without requiring separate molds for each surface, significantly simplifying the manufacturing process while maintaining complex surface geometries.
Solution Approach 2:
The single mold design serves multiple functions by forming all reflection surfaces and their interconnections in one operation. This universal mold approach eliminates the need for multiple specialized molds, reducing manufacturing complexity and improving production efficiency.
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 enhances visibility by minimizing light leakage and ghosting, while allowing for a more straightforward molding process and preventing hard coat failures, thus maintaining favorable visibility and device miniaturization.
Implementation Method 1
a light-guiding member including a plurality of reflection surfaces and configured to guide image light from the display element by reflecting the image light at an inner surface
Data Source
AI summary
A display element, and a light-guiding member including a plurality of reflection surfaces and configured to guide image light from the display element by reflecting the image light at an inner surface, and cause the image light and external light to be visually recognized in an overlapping manner are provided, wherein at a boundary between a first reflection surface and a second reflection surface adjacent to each other included in the plurality of reflection surfaces of the light-guiding member with at least one of the first reflection surface and the second reflection surface including a curved surface, an end of the first reflection surface and an end of the second reflection surface match when projected from a specific direction.