Infrared-absorbing composition for optical filters
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Solution Overview
Problem
Infrared-cut filters face a trade-off between infrared absorption ability and light transmittance in the visible region, with existing compositions either compromising on absorption or transmittance, particularly at wavelengths between 400 nm to 600 nm, and having inadequate cut-off wavelengths.
Innovation Solution
An infrared-absorbing composition comprising a phosphonic acid represented by a specific formula and copper ion, dispersed with a phosphoric acid ester, is used to form an infrared-cut filter with enhanced light transmittance in the visible region and a shortened infrared-side cut-off wavelength of 700 nm or less, achieved by optimizing the molar ratios of the phosphonic acid, copper ion, and phosphoric acid ester.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an infrared-cut filter contains an increased amount of phosphoric acid-based compound and copper ion to improve infrared absorption ability, then the infrared absorption ability increases, but the light transmittance at wavelengths of 400 nm to 600 nm decreases
Solution Approach 1:
The patent optimizes the molar ratio of phosphonic acid to phosphoric acid ester within a specific range (0.3 to 2.0) to achieve the desired balance between infrared absorption and visible light transmittance. By precisely controlling this parameter, the filter accomplishes effective infrared cutoff while maintaining adequate visibility in the 400-600 nm range
Solution Approach 2:
The patent uses a composite system combining phosphonic acid, phosphoric acid ester, and copper ion to create an infrared-absorbing layer. This composite material approach allows the filter to achieve both infrared absorption functionality and improved visible light transmittance properties that neither component could achieve alone
2Manufacturing precision
If the infrared-side cut-off wavelength is shortened to 700 nm or less to improve compatibility with human visual sensitivity, then the optical properties become more compatible with human vision, but the manufacturing precision requirements increase
Solution Approach 1:
The patent controls the cut-off wavelength at 700 nm or less by optimizing the molar ratio of phosphonic acid to phosphoric acid ester and adjusting the concentration of copper ion. These parameter adjustments enable precise control of the infrared-side cut-off wavelength while maintaining manufacturing feasibility
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 composition achieves high light transmittance in the visible region while maintaining effective infrared absorption, with an infrared-side cut-off wavelength of 700 nm or less, enhancing the optical properties of the filter to be compatible with human visual sensitivity.
Implementation Method 1
an infrared absorber formed by a phosphonic acid represented by formula (a) and copper ion
Data Source
AI summary
An infrared-absorbing composition according to the present invention includes: an infrared absorber formed by a phosphonic acid represented by the following formula (a) and copper ion; and a phosphoric acid ester allowing the infrared absorber to be dispersed. The phosphoric acid ester includes at least one of a phosphoric acid diester and a phosphoric acid monoester. R1 is a phenyl group or a phenyl group in which at least one hydrogen atom is substituted by a halogen atom. When molar contents of the phosphonic acid, the copper ion, and the phosphoric acid ester are respectively defined as CA mol, CC mol, and CE mol and a total molar content of reactive hydroxy groups is defined as CH mol, the relations CA/CE<1 and CH/CC>1.95 are satisfied.