Light Projector Module With Folded Beam Path for Slim AR/VR
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Solution Overview
Problem
Existing light projector modules for VR and AR devices are bulky, hindering user comfort and wearability, and there is a need for miniaturization to enhance portability and integration into compact devices.
Innovation Solution
A compact light projector module design featuring a static mirror that folds the beam path about an angle, integrated with a housing enclosing the light source, MEMS mirror, and waveguide, with the beam path running parallel to the temple axis, and a transparent cover supporting the static mirror to maintain an air gap for total internal reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple MEMS mirrors are arranged in series with a reflective surface to couple the light beam into the waveguide, then the light coupling function is achieved, but the device becomes bulky and installation space increases
Solution Approach 1:
The patent combines the light coupling function and beam folding function into a single static mirror component. This mirror is positioned beside the first side of the waveguide and folds the beam path at an angle, eliminating the need for separate MEMS mirrors arranged in series. The merging of functions reduces the overall device volume while maintaining the required light coupling capability.
Solution Approach 2:
The static mirror is positioned beside the first side of the waveguide rather than in the traditional in-line configuration. This spatial repositioning in a different dimension allows the beam path to be folded at an angle, optimizing the light coupling efficiency while minimizing the device's footprint and installation space.
2Device complexity
If the beam path from the light source to the MEMS mirror is not folded, then the optical path is simple, but the module size increases and user comfort decreases
Solution Approach 1:
The static mirror folds the beam path at an angle, changing the spatial arrangement of the optical components. By positioning the mirror beside the waveguide and folding the beam in a different dimension, the optical path remains relatively simple while the module achieves a compact, slim form factor that improves user comfort.
3Device complexity
If the angle of incidence of the light beam onto the MEMS mirror is not minimized, then the beam path is straightforward, but geometrical distortions increase
Solution Approach 1:
The static mirror is positioned and angled to fold the beam path in a way that optimizes the angle of incidence onto the MEMS mirror. This spatial configuration in a different dimension allows the beam to strike the MEMS mirror at a minimized angle, reducing geometrical distortions while maintaining a straightforward optical path.
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 design achieves a slim and tightly integrated module suitable for VR and AR devices, minimizing geometrical distortions and reducing module size without increasing installation space, thus enhancing user comfort and portability.
Implementation Method 1
a static mirror (11) in the beam path from the light source (10) to the MEMS mirror (12) to fold the beam path about an angle of folding
Implementation Method 2
the transparent cover (29), e.g. a thin glass plate used to protect the waveguide while maintaining the air gap necessary for total internal reflection within the waveguide
Implementation Method 3
a micro-electro-mechanical-system (MEMS) mirror supported by the support and configured to deflect the emitted light beam received over the beam path as a deflected light beam
Data Source
Figure 1~2
Figure 3
AI summary
A light projector module (5) comprises a support (9), a light source (10) for emitting in a beam path (P) a light beam (14), a micro-electro-mechanical-system (MEMS) mirror (12) for deflecting the emitted light beam (14), a waveguide (13) having an in-coupling area (25) for receiving the deflected light beam (18) and an out-coupling area (26) for projecting the deflected light beam (19) with enlarged cross section, and a static mirror (11) in the beam path (P) from the light source (10) to the MEMS mirror (12) to fold the beam path (P) about an angle of folding (δ), wherein the static mirror (11) lies beside the first side (24) of the waveguide (13).