Optical Filter Basic Layer with Moisture-Resistant Coating
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Solution Overview
Problem
Conventional optical filters face challenges in achieving high visible light transmittance while effectively blocking ultraviolet and infrared light, particularly due to issues with moisture resistance and heat resistance, especially when using infrared absorption glass substrates, which can lead to a ripple phenomenon affecting color reproducibility in imaging devices.
Innovation Solution
A basic layer for optical filters comprising an infrared absorption substrate with a moisture-resistant layer that maintains low ripple values and excellent durability, featuring a polysilazane or silane compound-based moisture-resistant layer with specific adhesion properties and a dielectric film structure to enhance optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an infrared absorption glass substrate is used to achieve effective infrared light blocking, then the optical filter can block long-wavelength infrared light, but the moisture resistance and heat resistance become inferior
Solution Approach 1:
The patent uses a composite structure combining an infrared absorption glass substrate with a dielectric film layer. The substrate provides infrared absorption through CuO addition, while the dielectric film (composed of multiple layers with different refractive indices) provides moisture resistance and enhances overall durability. This composite approach allows the optical filter to simultaneously achieve infrared blocking and environmental resistance.
2Reliability
If a dielectric film is added to improve moisture resistance, then the durability is enhanced, but the transmittance curve shifts according to incident angle
Solution Approach 1:
The patent carefully controls the optical parameters of the dielectric film, specifically managing its thickness and refractive index characteristics. By optimizing these parameters, the film provides moisture resistance while minimizing the shift in transmittance curve with incident angle. The dielectric film is designed with specific optical properties that balance protection and optical performance.
3Object-affected harmful factors
If the infrared absorption glass composition is adjusted to improve long-wavelength infrared absorption, then the absorption characteristics are enhanced, but the moisture resistance and heat resistance deteriorate further
Solution Approach 1:
The patent separates the functions of infrared absorption and environmental resistance into distinct components. The infrared absorption glass substrate is optimized specifically for infrared absorption through controlled CuO content, while the dielectric film layer is dedicated to providing moisture resistance and structural protection. This functional segmentation allows each component to be optimized for its specific purpose without compromising the other.
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 provides optical filters with improved durability, high visible light transmittance, effective blocking of ultraviolet and infrared light, and minimized ripple phenomena, even when using substrates with poor moisture and heat resistance, ensuring superior color reproducibility and optical performance.
Implementation Method 1
An infrared absorption glass (also called as a blue glass) having near-infrared absorption properties is used for an optical filter and the substrate that becomes the optical filter itself is also known. An infrared absorption glass is a glass filter where CuO or the like is added to the glass to selectively absorb light in the near infrared wavelength region.
Implementation Method 2
A publicly known optical filter comprises an absorption layer containing an absorbent; a dielectric film containing a reflective layer. If the dielectric film is utilized, it is possible to block light in the ultraviolet and/or infrared region.
Implementation Method 3
a moisture-resistant layer formed on one or both surfaces of the infrared absorption substrate where a ripple value in a wavelength range of 450 nm to 560 nm is 7% or less, and an absolute value of ΔTV according to Equation 1 is 30% or less
Data Source
AI summary
The present invention provides a basic layer for an optical filter, an optical filter, and their application for an image capture device. The present invention provides a basic layer for an optical filter and an optical filter having excellent optical properties while exhibiting excellent durability including a moisture-resistant layer.