Projection Device With Light-Guide Edge Masking for Flare Reduction
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Solution Overview
Problem
Existing projection devices in augmented reality (AR) suffer from stray light due to total reflection on the outer surface of light guides, leading to reduced optical performance and flare, and there is a need for miniaturization and improved optical performance.
Innovation Solution
The implementation of a masking layer on the outer surface of the light guide and the addition of guide lenses to prevent total reflection, along with the use of bonding members to enhance optical performance and facilitate manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a masking layer is added to the outer surface of the light guide, then stray light is eliminated and optical performance is improved, but device complexity increases
Solution Approach 1:
A masking layer is introduced as an intermediary component between the light guide and the external environment. This masking layer specifically targets and eliminates stray light caused by total reflection on the outer surface of the light guide, thereby improving optical performance without fundamentally changing the light guide's core structure.
Solution Approach 2:
The masking layer is applied selectively to specific regions of the light guide's outer surface where total reflection occurs. Rather than modifying the entire light guide structure, the masking is localized to the edges and surfaces that generate stray light, improving optical performance while minimizing added complexity.
2Reliability
If guide lenses are added to prevent total reflection, then stray light is eliminated and optical performance is improved, but device complexity increases
Solution Approach 1:
Guide lenses are introduced as intermediary optical elements that couple to the outer surface of the light guide. These lenses modify the light path and prevent total reflection by changing the refractive index interface, thereby eliminating stray light while maintaining the light guide's fundamental structure.
3Volume of moving object
If miniaturization of the light source is achieved through guide lens and aspect ratio, then device size is reduced, but manufacturing difficulty increases
Solution Approach 1:
The aspect ratio of the light source is modified to achieve miniaturization. By changing the geometric parameters of the light source while maintaining its functional characteristics, the device size is reduced without requiring complex manufacturing processes. The guide lens further assists in maintaining optical performance despite the size reduction.
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
Stray light is effectively eliminated, improving optical performance through flare reduction, enabling miniaturization of the light source and facilitating manufacturing processes.
Implementation Method 1
stray light is eliminated by preventing total reflection from occurring on an outer surface of a light guide
Implementation Method 2
addition of a guide lens coupled to the outer surface of the light guide
Data Source
Figure 1
Figure 2~3
Figure 4(a)~4(b)
AI summary
An embodiment discloses a projection device including: a barrel on which a lens group is disposed; a light guide disposed within the barrel; a light source which emits light to the light guide; a lens disposed between the light source and the light guide; and a masking layer disposed between the light guide and the lens or between the light guide and the lens group, wherein the masking layer is disposed along the edge of the outer side of the light guide.