IR-Absorbing Optical Adhesive for Off-Axis Light Interference
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Solution Overview
Problem
Existing optical articles face challenges in effectively absorbing infrared light at off-axis angles without compromising the adhesive and optical clarity of the layers, particularly in devices like fingerprint sensors where off-axis infrared light interferes with the signal.
Innovation Solution
Incorporating an optically clear adhesive layer with a polymeric adhesive matrix containing infrared light absorbing materials, such as dyes or nanoparticles, to absorb infrared light within the 680-1100 nanometer range while maintaining high visible light transmission and adhesive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If additional layers are added to address off-axis IR light interference, then IR absorption is improved, but device complexity increases
Solution Approach 1:
The patent combines the IR absorption function with the existing adhesive layer by incorporating IR-absorbing materials into the adhesive composition. This merging approach allows the adhesive layer to simultaneously serve as both a bonding medium and an IR filter, eliminating the need for separate dedicated IR blocking layers and thus reducing overall device complexity while maintaining effective off-axis IR light absorption.
Solution Approach 2:
The adhesive layer is designed to perform multiple functions: providing mechanical bonding between layers, maintaining optical clarity for visible light transmission, and absorbing off-axis infrared light. This multi-functionality is achieved by formulating the adhesive with specific IR-absorbing materials that do not compromise its adhesive properties or visible light transmission, thereby consolidating multiple functions into a single layer rather than requiring separate dedicated layers.
2Object-affected harmful factors
If IR-absorbing materials are added to adhesive layers, then IR absorption is improved, but optical clarity may be compromised
Solution Approach 1:
The adhesive layer is designed with spatially selective optical properties: it maintains high optical clarity and transparency in the visible light wavelength range to ensure proper light transmission through the optical device, while simultaneously incorporating IR-absorbing materials that selectively absorb infrared light. This local quality differentiation allows the same adhesive layer to transmit visible light effectively while blocking harmful off-axis IR light.
Solution Approach 2:
The adhesive formulation utilizes parameter changes in material composition to achieve wavelength-selective behavior. By carefully selecting IR-absorbing materials and adjusting their concentration within the adhesive matrix, the layer's optical parameters are optimized to absorb IR light while maintaining visible light transmission. The adhesive composition is engineered with specific molecular characteristics that enable differential absorption across different wavelength ranges.
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 effectively absorbs off-axis infrared light, enhancing the performance of optical devices by reducing interference and maintaining optical clarity and adhesive strength.
Implementation Method 1
at least one infrared light absorbing material that absorbs light having the second wavelength
Implementation Method 2
the plurality of polymeric layers reflects at least 70% of the incident light having the first wavelength for each of a first incident angle (θ) of less than about 5 degrees and a second incident angle of greater than about 45 degrees
Data Source
AI summary
Optical devices include a visible light source, a visible light detector, and a multi-layer film article in the pathway between the visible light source and the visible light detector. The multi-layer film article includes an optical film layer and an optically clear adhesive layer. The optically clear adhesive layer includes a polymeric adhesive matrix, and at least one infrared light absorbing material that absorbs light in the range of 680-1100 nanometers. The infrared light absorbing material is an organic dye.