Light Guide Device Anti-Reflection End Surface Stray Light Suppression
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Solution Overview
Problem
Existing light guide devices in display apparatuses suffer from stray light reflections at the end surface, leading to ghosting issues due to the lack of effective anti-reflection mechanisms.
Innovation Solution
A light guide device with a transparent light guide portion featuring a first and second surface and a third surface with a dielectric multilayer film or metal layer anti-reflection structure, where the third surface is designed as an anti-reflection surface to minimize stray light reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a protective layer is provided on the end surface of the light guide portion, then the light guide structure is protected, but stray light occurs due to reflection at the third surface
Solution Approach 1:
The patent applies different surface treatments to different surfaces of the light guide portion. Specifically, the third surface (end surface) is given an anti-reflection structure while other surfaces maintain their original properties or have different coatings. This local differentiation allows the protective function to be maintained while eliminating the harmful reflection at the critical end surface where stray light problems occur.
Solution Approach 2:
The patent converts the harmful reflection at the third surface into a beneficial anti-reflection property by applying an anti-reflection coating or structure. The same coating technology that reduces reflection is applied to transform the end surface from a source of stray light into a surface that allows light to pass through without unwanted reflections, thereby converting a harmful effect into a beneficial one.
2Illumination intensity
If an anti-reflection coating layer is provided on the first surface and second surface, then light transmission is improved, but the coating layer cannot suppress ghost caused by reflection at the third surface
Solution Approach 1:
The patent extends the anti-reflection treatment specifically to the third surface (end surface) in addition to or instead of the first and second surfaces. This localized application of anti-reflection properties at the critical end surface directly addresses the ghost problem caused by reflection there, while maintaining good light transmission through the light guide portion.
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 anti-reflection structure on the third surface effectively suppresses stray light reflections, reducing ghosting and enhancing image clarity by ensuring that light beams are properly directed without unnecessary reflections.
Implementation Method 1
the third surface is a surface with an anti-reflection structure
Implementation Method 2
a plurality of partial reflection surfaces that are disposed along the first direction between the first surface and the second surface and are inclined at the same angle from a normal direction with respect to the second surface toward the one end side
Data Source
AI summary
A light guide system (light guide device) includes a transparent light guide portion that guides light beams incident from one end side to a light-emitting portion. The light guide portion includes a first surface, a second surface which is parallel to the first surface, and a third surface which is positioned between the first surface and the second surface on another end side. A plurality of obliquely-inclined partial reflection surfaces are disposed between the first surface and the second surface, and the third surface is inclined in the same direction as that of the partial reflection surface. The third surface is configured with an anti-reflection surface for image light beams traveling through the light guide portion, and is covered by an anti-reflection film, a light absorption layer, a moth-eye type roughened surface, or the like. Therefore, occurrence of stray light due to reflection by the third surface can be suppressed.