Light Extracting Unit Edge Positioning for See-Through Image Clarity
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Solution Overview
Problem
See-through image display apparatuses with half mirror arrays suffer from edge interference, causing distortion in the see-through image when the edge portions of the half mirror array fall within the field range, leading to a compromised viewing experience.
Innovation Solution
The image display apparatus incorporates a light extracting unit with edges positioned outside the see-through visual field range, utilizing a half mirror array with dummy regions and diffraction elements to minimize edge interference and enhance image clarity, while maintaining the angle of view for both virtual and external images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the half mirror array is provided on the light guide plate to guide image light to the observer, then the image light can be extracted toward the exit pupil, but the edge portion of the half mirror array interferes with the see-through image and causes distortion when located within the field range
Solution Approach 1:
The light extracting unit is segmented into a functional region containing the half mirror array for image light extraction and a dummy region without half mirrors at the edges. This segmentation allows the edge portions to be positioned outside the see-through visual field range, eliminating distortion while maintaining effective image light extraction in the central region.
Solution Approach 2:
Different regions of the light extracting unit are assigned different functions: the central region contains half mirrors for efficient image light extraction, while the edge regions are designed as dummy regions without half mirrors to prevent see-through image distortion. This local differentiation optimizes both image extraction and visual comfort.
2Area of stationary object
If the light extracting unit is provided on the second plane (light incident side) to achieve better see-through field, then the see-through visual field range becomes wider, but the light extracting unit requires larger size
Solution Approach 1:
The light extracting unit is positioned on the first plane (exit pupil side) rather than the second plane (light incident side), utilizing the dimensional difference between the two planes. Although the see-through field is inherently wider on the second plane, positioning on the first plane with properly designed dummy regions achieves adequate field of view while significantly reducing the light extracting unit size.
3Object-affected harmful factors
If dummy regions are added to the light extracting unit to position edges outside the visual field, then see-through image distortion is eliminated, but the light extracting unit structure becomes more complex
Solution Approach 1:
The dummy regions are designed with specific dimensional parameters that allow the edge portions to be positioned outside the see-through visual field range. By carefully controlling the size and position of these dummy regions, the patent eliminates edge interference while maintaining a relatively simple overall structure that can be manufactured using conventional processes.
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 users to recognize see-through images without distortion, providing a balanced and comfortable viewing experience by ensuring the edges of the light extracting unit are outside the visual field, thus preventing edge interference and enhancing image quality.
Implementation Method 1
a projection lens configured to project the image light toward a light incident section of the light guide member
Implementation Method 2
a half mirror array that is provided on a surface of the light guide plate and guides the light to an observer's eye
Implementation Method 3
capable of transmitting see-through light having been transmitted in the light guide member from the second plane side to the first plane side toward the exit pupil
Data Source
AI summary
An image display apparatus includes an image display device configured to emit image light, a light guide member, a projection lens configured to project the image light toward the light guide member, and a light extracting unit provided on the light guide member, the light extracting unit being configured to extract the image light guided in the light guide member toward an exit pupil. The light extracting unit includes a first edge located at an end portion of the light extracting unit on the light incident section side and a second edge located at an end portion on the opposite side, and is capable of transmitting see-through light having been transmitted in the light guide member toward the exit pupil, and at least one of the first edge and the second edge is located outside a see-through visual field range in which the see-through light passes through.