ITO Infrared Pass Filter for Visible Blocking in Image Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing infrared light pass filters for solid-state image sensors fail to selectively transmit near-infrared light while effectively blocking visible light, leading to reduced detection accuracy and wavelength selectivity.
Innovation Solution
An infrared light pass filter comprising a colorant, indium tin oxide (ITO), and a polymer, with a specific transmittance profile of 30% or less in the 400-800 nm range, 75% or more in the 900-1100 nm range, and 55% or less in the 1300-2500 nm range, and a coloring composition with ITO content between 10% to 30% by weight, enhancing wavelength selectivity and reducing residue area during patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional infrared light pass filters are used, then visible light transmission is blocked, but near-infrared light transmission is insufficient and wavelength selectivity is poor
Solution Approach 1:
The patent uses a composite material consisting of indium tin oxide (ITO) particles dispersed in a transparent resin to create the infrared light pass filter. This composite structure enables selective transmission of near-infrared light while blocking visible light, achieving both high near-infrared transmittance (75% or more at 900-1100 nm) and effective visible light blocking (30% or less at 400-800 nm), thereby resolving the contradiction between illumination intensity and reliability
Solution Approach 2:
The patent optimizes the particle size of ITO particles (0.1 μm to 10 μm) and their concentration (10% to 30% by weight in total solid content) to achieve the desired transmittance characteristics. By changing these parameters, the filter achieves high near-infrared transmission while maintaining visible light blocking, thus improving detection accuracy without sacrificing near-infrared light transmission
2Illumination intensity
If ITO content is increased to improve near-infrared transmission, then visible light blocking improves, but residue area during patterning increases
Solution Approach 1:
The patent optimizes the ITO particle concentration to a specific range (10% to 30% by weight of total solid content) and particle size (0.1 μm to 10 μm). This parameter optimization ensures sufficient near-infrared transmission while keeping the coating composition manageable during patterning, thus achieving high near-infrared transmittance without excessive residue area
Solution Approach 2:
The patent specifies that ITO particles should be uniformly dispersed throughout the transparent resin matrix, creating a homogeneous composite material. This uniform distribution ensures consistent optical properties across the filter while facilitating clean patterning with minimal residue, resolving the contradiction between transmission performance and manufacturing precision
3Ease of manufacture
If the filter structure is simplified, then manufacturing cost decreases, but wavelength selectivity is reduced
Solution Approach 1:
The patent employs a single-layer composite structure consisting of ITO particles in a transparent resin, eliminating the need for complex multi-layer dielectric structures. This simplified structure achieves superior wavelength selectivity (blocking visible light at 400-800 nm while transmitting near-infrared at 900-1100 nm) and is easier to manufacture, thus resolving the contradiction between ease of manufacture and reliability
Solution Approach 2:
The patent achieves high wavelength selectivity by optimizing the ITO particle size (0.1 μm to 10 μm) and concentration (10% to 30% by weight). These parameter optimizations enable a simple single-layer structure to outperform complex multi-layer designs in terms of both wavelength selectivity and manufacturing ease
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 achieves selective transmission of near-infrared light, improving detection accuracy and maintaining high transmittance in the desired wavelength range while minimizing residue area, thus enhancing the performance and accuracy of solid-state image sensors.
Implementation Method 1
an infrared light pass filter structure including a colorant, an indium tin oxide, and a polymer such that the infrared light pass filter structure has an average transmittance of 30% or less in a first wavelength range of 400 nm or more and 800 nm or less, an average transmittance of 75% or more in a second wavelength range of 900 nm or more and 1100 nm or less
Data Source
AI summary
An infrared light pass filter includes a colorant, an indium tin oxide, and a polymer. The infrared light pass filter has an average transmittance of 30% or less in a first wavelength range of 400 nm or greater and 800 nm or less, an average transmittance of 75% or more in a second wavelength range of 900 nm or greater and 1100 nm or less, and an average transmittance of 55% or less in a third wavelength range of 1300 nm or greater and 2500 nm or less.