AR Image Display Device with Diffractive Optical Element for Variable Focus
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Solution Overview
Problem
In Augmented Reality (AR) applications, fixed image depth optical designs cause eyestrain as users need to switch focus between external and virtual images at different depths.
Innovation Solution
An image display device comprising a first lens set, a diffractive optical element, a second lens set, and a coupler, which converts display images into multiple parallel image beams, diffracts them into sub-beams, and focuses these sub-beams to generate multiple zoomed image sub-beams that form image points on a target plane, allowing adjustment of the distance between viewpoints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed image depth optical design is used, then device structure is simple, but user experience deteriorates due to eyestrain from switching focus
Solution Approach 1:
The patent implements a variable focus length mechanism in the second lens set that allows dynamic adjustment of the optical path. By changing the focus length, the system can adapt the virtual image depth to match different external object distances, enabling the user's eye to maintain a fixed focus plane while viewing both virtual and external images clearly, thereby eliminating eyestrain from constant focus switching.
Solution Approach 2:
The system changes the optical parameter (focus length) of the second lens set to adjust the distance between viewpoints. This parameter adjustment allows the virtual image to be presented at different depths, matching the user's viewing distance for external objects, thus resolving the contradiction between simple fixed-depth optics and comfortable variable-depth viewing.
2Manufacturing precision
If multiple viewpoints are generated, then image display quality is improved, but device complexity increases
Solution Approach 1:
The patent uses a diffractive optical element to split a single image beam into multiple image sub-beams, each corresponding to a different viewpoint. This segmentation approach generates multiple viewpoints for enhanced image quality without requiring multiple complete optical systems, thereby improving display quality while controlling device complexity.
Solution Approach 2:
The diffractive optical element serves as an intermediary component between the first lens set and the second lens set. It efficiently generates multiple image sub-beams from a single image beam, enabling multiple viewpoint generation with a compact intermediate element rather than complex multi-path optical systems.
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 clear simultaneous viewing of external and virtual images by adjusting the distance between viewpoints, reducing eyestrain and improving image display quality.
Implementation Method 1
The diffractive optical element receives the image beams, and diffracts each of the image beams to generate multiple image sub-beams
Implementation Method 2
The second lens set provides a focus length and focuses the image sub-beams according to the focus length to generate multiple zoomed image sub-beams
Implementation Method 3
The coupler receives the zoomed image sub-beam, reflects the zoomed image sub-beam to a target plane, and causes the zoomed image sub-beam to form multiple image imaging points on the target plane
Data Source
AI summary
An image display device including a first lens set, a diffractive optical element (DOE), a second lens set and a coupler. The first lens receives a display image, and converts the display image into multiple image beams parallel to each other. The diffractive optical element receives the image beams, diffracts the image beams and generate multiple image sub-beams. The second lens set receives each of the image sub-beams corresponding to each of the image beams. The second lens set provides a focus length, and focuses the image sub-beams according to the focus length to generate multiple zoomed image sub-beams corresponding to each of the image beams. The coupler receives the zoomed image sub-beams, reflects the zoomed image sub-beams to a target plane, and causes the zoomed image sub-beams to form multiple image imaging points on the target plane.