Virtual Image Display Optics for Wider Gaze Detection
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Solution Overview
Problem
Existing virtual image display devices have limited line-of-sight detection capabilities, as the separate IR and RGB light sources restrict the range of eye movement detection to be narrower than the viewing angle of image light.
Innovation Solution
The device incorporates a first and second light guide optical system with diffraction elements that deflect image and infrared light to enable wider line-of-sight detection, allowing the infrared light to form a greater angle with respect to the normal line of the incident-side diffraction element than the image light, enhancing detection accuracy while maintaining display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate IR and RGB light sources are provided for line-of-sight detection and image light, then line-of-sight detection function is achieved, but the detection range is limited to be narrower than the viewing angle of image light
Solution Approach 1:
The patent applies multi-functionality by enabling the RGB light source to serve dual purposes: generating image light for display and providing infrared light for line-of-sight detection. This eliminates the need for separate IR and RGB light sources, allowing the same optical path to be used for both imaging and gaze detection, thereby expanding the detection range to match the viewing angle of the image light.
2Volume of moving object
If the size of the IR light source is smaller than that of the RGB light source, then device compactness is improved, but the range in which eye movement can be detected is limited
Solution Approach 1:
The patent makes the RGB light source perform both image generation and infrared detection functions, eliminating the need for a separate smaller IR light source. This multi-functional approach maintains device compactness while expanding the detection range to cover the full viewing angle of the image light.
Solution Approach 2:
The patent merges the functions of separate IR and RGB light sources into a single RGB light source that handles both image light generation and line-of-sight detection. This consolidation maintains compact device size while achieving comprehensive detection coverage across the entire viewing angle.
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 solution enables wider line-of-sight detection and improved accuracy by using diffraction elements to guide both image and infrared light, allowing for dynamic adjustment of display content based on the user's gaze direction.
Implementation Method 1
a first incident-side diffraction element provided on an incident side of the first light guide member, and a first emitting-side diffraction element provided on an emitting side of the first light guide member
Data Source
AI summary
A virtual image display device includes an image light generating device, an infrared light emitting device, an infrared light receiving device, a first light guide optical system, and a second light guide optical system. The first light guide optical system includes a first light guide member, a first incident-side diffraction element, and a first emitting-side diffraction element. The second light guide optical system includes a second light guide member, a second incident-side diffraction element, and a second emitting-side diffraction element. The maximum value of an angle formed between the infrared light that the second incident-side diffraction element deflects toward the infrared light receiving device and a normal line of the second incident-side diffraction element is greater than the maximum value of an angle formed between the image light incident on the first incident-side diffraction element and a normal line of the first incident-side diffraction element.