Off-Axis Light Source for Compact AR Display Engine
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Solution Overview
Problem
Current augmented reality (AR) display devices face challenges in miniaturizing high-resolution display engines to achieve lightweight and thin designs necessary for wearable applications, such as AR glasses, while maintaining effective image projection and virtual image overlay on real-world environments.
Innovation Solution
The AR display device incorporates a display engine with a light source unit, a reflective display panel, and a projection optical system, including an iris and first projection lens group, where the light source unit is positioned off the optical axis to avoid overlapping incident and reflection angles, allowing for a compact design with a light guide or light pipe to facilitate efficient light transmission, and a waveguide that allows real scene light to pass through, enabling a wearable and compact form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the display engine is miniaturized to reduce weight and thickness, then the wearable comfort is improved, but the image projection quality and resolution may deteriorate
Solution Approach 1:
The light source unit is positioned off the optical axis in a direction perpendicular to the optical path, utilizing spatial dimensionality to separate incident light angles from reflected light angles. This off-axis configuration allows the light source to be positioned away from the central optical path, enabling miniaturization while maintaining image quality through optimized optical path design.
Solution Approach 2:
The light source unit is deliberately positioned asymmetrically off the optical axis rather than symmetrically on the axis. This asymmetric positioning creates distinct incident and reflected light paths, preventing angle overlap and enabling compact design. The asymmetric arrangement allows for reduced device volume while maintaining effective image projection.
2Device complexity
If the light source unit is positioned on the optical axis, then the alignment is simplified, but the incident angle range overlaps with the reflection angle range causing optical interference
Solution Approach 1:
The light source unit is positioned asymmetrically off the optical axis, creating distinct incident and reflected light paths. This asymmetric positioning ensures that the incident angle range does not overlap with the reflection angle range, eliminating optical interference while maintaining simplified alignment through the off-axis configuration.
Solution Approach 2:
By positioning the light source in a direction perpendicular to the optical path (off-axis configuration), the system utilizes spatial dimensionality to separate the incident and reflected light paths. This dimensional separation prevents angle overlap and optical interference without complicating the alignment process.
3Volume of moving object
If the display engine volume is reduced for wearable applications, then the portability is improved, but the light transmission efficiency may deteriorate
Solution Approach 1:
The off-axis positioning of the light source unit utilizes spatial dimensionality to optimize the optical path within a compact volume. By arranging components in three-dimensional space rather than linearly, the system achieves efficient light transmission while maintaining a reduced overall device volume suitable for wearable applications.
Solution Approach 2:
The iris and first projection lens group are integrated into a compact arrangement where the iris includes an effective opening that receives light from the display panel. This merging of optical elements into a compact configuration maintains light transmission efficiency while minimizing the display engine volume.
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 reduces the volume, weight, and thickness of the display engine, enhancing the convenience and usability of AR display devices by maintaining image quality and overlay capabilities in a compact, wearable form.
Implementation Method 1
a reflective display panel
Implementation Method 2
a projection optical system, the projection optical system includes an iris and a first projection lens group
Implementation Method 3
a waveguide configured to receive and output light projected from the display engine
Data Source
AI summary
An augmented reality (AR) display device includes a display engine configured to project light of an image, and a waveguide configured to receive and output the projected light. The display engine includes a light source unit, a reflective display panel, and a projection optical system. The projection optical system includes an iris and a projection lens group arranged between the iris and the reflective display panel. The light source unit includes a light source or a light exit end positioned near the iris in a position deviating from an optical axis of the projection optical system, such that an incident angle range of light incident to the display panel does not overlap with a reflection angle range of light reflected from the display panel. The iris includes an effective opening through which light reflected from the display panel passes.