IR Dye Optical Filter for Angle-Stable Near-Infrared Blocking
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Solution Overview
Problem
Existing optical filters suffer from reduced transparency and increased near-infrared light transmission at large incident angles, affecting the spectral sensitivity of solid-state imaging devices, particularly in camera modules with reduced height.
Innovation Solution
An optical filter design incorporating a substrate with a resin film containing a near-infrared dye and a dielectric multilayer film, optimized to maintain high transparency for visible light and block near-infrared light across various incident angles, meeting specific spectroscopic characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a near-infrared light absorbing dye with maximum absorption wavelength of 800 nm or longer is used, then the blocking ability for near-infrared light is improved, but the transparency in visible range decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the maximum absorption wavelength of the near-infrared light absorbing dye to be within 780-800 nm, and by optimizing the concentration of the dye in the resin film. This parameter optimization allows the filter to achieve high blocking ability for near-infrared light (700 nm or longer) while maintaining high transparency in the visible range (400-700 nm), thus resolving the contradiction between these two requirements.
2Object-affected harmful factors
If a dielectric multilayer film is used to block near-infrared light, then the blocking ability is improved, but the transmittance of near-infrared light increases at large incident angles
Solution Approach 1:
The patent employs composite materials by combining a resin film containing near-infrared light absorbing dye with a dielectric multilayer film. The resin film provides broadband near-infrared absorption that is less sensitive to incident angle, while the dielectric multilayer film enhances visible light transmittance. This composite structure achieves consistent near-infrared blocking performance across various incident angles while maintaining high visible light transmittance.
Solution Approach 2:
The patent applies local quality by assigning different functional characteristics to different layers: the resin film layer is optimized for near-infrared absorption with incident angle insensitivity, while the dielectric multilayer film is optimized for visible light transmittance enhancement. This functional differentiation allows each layer to address specific requirements, resulting in overall consistent performance at large incident angles.
3Volume of moving object
If the camera module height is reduced, then the compactness is improved, but the incident angle of light increases
Solution Approach 1:
The patent applies parameter changes by optimizing the maximum absorption wavelength of the near-infrared light absorbing dye to be within 780-800 nm and controlling its concentration to achieve optimal absorption. This parameter optimization ensures that the filter maintains effective near-infrared blocking even when subjected to large incident angles that occur in compact camera modules, thus resolving the contradiction between miniaturization and optical performance.
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 filter achieves high transparency for visible light and effective blocking of near-infrared light, even at large incident angles, minimizing noise and maintaining consistent spectral sensitivity.
Implementation Method 1
the substrate includes a resin film including a dye (IR) and a resin, the dye (IR) has a maximum absorption wavelength in a wavelength of 680 to 800 nm in the resin
Implementation Method 2
a reflection type filter in which dielectric thin films having different refractive indices are laid alternately on one or both major surfaces of a transparent substrate to form a dielectric multilayer film. This optical filter reflects light to block utilizing light interference.
Data Source
AI summary
An optical filter including: a substrate; and a dielectric multilayer film laid on or above at least one major surface of the substrate as an outermost layer, in which the substrate includes a resin film including a dye (IR) and a resin, the dye (IR) has a maximum absorption wavelength in a wavelength of 680 to 800 nm in the resin, and the optical filter satisfies specific spectroscopic characteristics.