Light Guide Optical Cutoff Edge for Adhesive Overspill Control
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Solution Overview
Problem
Existing light guiding devices face challenges due to imperfect edges and adhesive overspill, leading to scattering and reduced signal-to-noise ratios, as rounded edges and transparent adhesive overspill create unwanted optical paths and distortions.
Innovation Solution
A non-transparent coating is applied to define an optical cutoff edge, with transparent adhesive extending to and overlapping this edge, ensuring controlled light propagation and minimizing scattering by excluding stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If transparent adhesive is used to bond the coupling prism to the light guiding element, then bonding strength and optical transmission are improved, but adhesive overspill creates unwanted optical paths and scattering
Solution Approach 1:
The patent converts the harmful effect of adhesive overspill by applying a non-transparent coating over it. The coating material transforms the scattered light from the adhesive into a defined optical cutoff edge, where the adhesive's presence is no longer harmful but serves as a boundary marker for light propagation control.
Solution Approach 2:
The patent applies a non-transparent coating (changing optical properties from transparent to opaque) over the adhesive overspill area. This coating creates a distinct visual and optical boundary that defines the cutoff edge, preventing light from following unwanted paths through the transparent adhesive.
2Ease of manufacture
If edges of the light guiding element are left uncoated for precise optical cutoff, then manufacturing simplicity is improved, but rounded edges cause scattering and reduced signal-to-noise ratio
Solution Approach 1:
The patent applies the non-transparent coating to the edges of the light guiding element before final assembly. This preliminary coating action ensures that even if edges are rounded or imperfect from manufacturing, the coating creates a sharp optical cutoff boundary, eliminating the need for perfectly sharp edges.
Solution Approach 2:
The patent applies coating selectively to specific regions (edges and surfaces requiring optical cutoff) while leaving other regions uncoated. This localized application provides precise optical control where needed without unnecessarily complicating the entire manufacturing process.
3Manufacturing precision
If non-transparent coating is applied to define optical cutoff edge, then light propagation control is improved, but coating application complexity increases
Solution Approach 1:
The patent merges the coating application process with the assembly process by applying the non-transparent coating to the light guiding element before bonding the coupling prism. This integration reduces the total number of separate manufacturing steps and allows the coating to serve multiple functions: edge definition, scattering prevention, and optical cutoff.
4Reliability
If adhesive is applied generously to ensure complete coverage, then bonding reliability is improved, but excess adhesive creates scattering centers
Solution Approach 1:
The patent converts the harmful effect of excess adhesive by covering it with a non-transparent coating. The coating transforms the scattered light from the adhesive overspill into a defined optical cutoff boundary, allowing generous adhesive application for bonding reliability without the penalty of scattering.
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 enhances optical properties by maintaining internal reflection and providing a clear delineation between desired and undesired light paths, improving signal-to-noise ratios and device quality.
Implementation Method 1
the light guiding element being configured for guiding light by internal reflection at the first and second parallel faces
Implementation Method 2
a non-transparent coating applied to at least part of at least one of the plurality of faces of the light guiding element, the coating defining an edge adjacent to, or overlapping, the coupling surface
Implementation Method 3
a quantity of transparent adhesive deployed between the coupling surface and the interface surface so as to form an optically transmissive interface
Data Source
AI summary
A light-guide device includes a light guiding element (13) with a number of faces, including two parallel faces (26), for guiding light by internal reflection. A transparent optical element (19) has an interface surface for attachment to a coupling surface (14) of the light guiding element, and is configured such that light propagating within the transparent optical element passes through the interface surface and the coupling surface (14) so as to propagate within the light guiding element (13). A non-transparent coating (15) is applied to at least part of one or more faces of the light guiding element (13), defining an edge (17) adjacent to, or overlapping, the coupling surface (14) of the light guiding element (13). A quantity of transparent adhesive is deployed between the coupling surface and the interface surface so as to form an optically transmissive interface. An overspill region 31 of the adhesive extends to, and overlaps, the edge (17).