Optical Filter Near-Infrared Blocking Composite Structure
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Solution Overview
Problem
Conventional optical filters used in imaging devices face challenges in blocking near-infrared light effectively, leading to issues like ghost images and lens flare, and are difficult to fabricate in thinner forms due to material durability and internal reflection problems.
Innovation Solution
An optical article with a transparent base containing two or more kinds of near-infrared absorbing pigments, having specific absorption peaks in the 650 nm to 750 nm and 980 nm to 1,200 nm ranges, which allows for high transmittance in the visible light region while effectively blocking near-infrared light, thereby reducing lens flare and enabling thinner filter fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a reflective near-infrared blocking filter is used, then near-infrared light blocking is achieved, but ghost phenomenon occurs due to internal reflection between optical filter and microlens
Solution Approach 1:
The patent converts the harmful internal reflection effect into a beneficial one by designing a reflective near-infrared blocking filter where the reflection occurs at the optical filter surface rather than internally. The reflected near-infrared light is directed away from the microlens, preventing ghost image formation while still achieving effective near-infrared blocking. This transforms the potential harmful reflection into a protective mechanism.
2Object-affected harmful factors
If a conventional absorbing near-infrared blocking filter is used, then wavelengths from 800 nm to 1,200 nm are blocked effectively, but the filter is fragile and difficult to fabricate thin due to material durability issues
Solution Approach 1:
The patent employs a composite structure combining a transparent base material with a specifically formulated absorbing layer containing near-infrared absorbing pigments. This composite approach allows the filter to achieve effective near-infrared blocking while maintaining mechanical strength and flexibility. The transparent base provides structural integrity, enabling the filter to be made thinner and more durable compared to conventional absorbing filters made from单一 materials.
3Ease of manufacture
If the optical filter is made thinner to improve imaging device integration, then ease of manufacture increases, but material durability and internal reflection problems worsen
Solution Approach 1:
The composite structure of a robust transparent base combined with a optimized absorbing layer enables the filter to be made thinner while maintaining durability. The transparent base material provides the necessary mechanical strength, allowing reduction of overall filter thickness without compromising reliability.
Solution Approach 2:
By designing the reflective type filter where reflection occurs at the surface rather than internally, the patent eliminates internal reflection problems that would otherwise worsen with thinner filters. The reflected light is directed away from optical components, preventing ghost images even in thin filter configurations.
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 high-resolution imaging with reduced lens flare and ease of fabrication, achieving high transmittance in the visible light region while suppressing near-infrared light transmittance to 0.5% or less, enhancing imaging device performance and productivity.
Implementation Method 1
a transparent base containing two or more kinds of near-infrared absorbing pigments
Implementation Method 2
an absorbance spectrum measured using a spectrophotometer in a wavelength range of 380 nm to 1,200 nm has two or more absorption peaks
Data Source
AI summary
The present invention relates to an optical article and an optical filter including the same. The optical filter: includes an optical article which has at least two absorption peaks, including a first and a second absorption peak, in the wavelength range of 380 nm to 1,200 nm by containing two or more kinds of near-infrared absorbing pigments, and thus shows a high average transmittance of 86% or greater for light having a wavelength in the visible wavelength range; can limit the maximum transmittance of light having a wavelength in the range of 800 nm to 1,100 nm below 0.5%, so as to prevent lens flare; and can reduce assembly defects due to flexure of an optical filter in the process of assembling the optical filter to an image capturing apparatus, thereby improving yield and productivity.