Infrared Absorption Layer for Image Pickup Devices
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Solution Overview
Problem
Solid-state image pickup devices face challenges in achieving sufficient infrared absorption without thickening the on-chip lens and color filter, leading to potential deterioration of pixel resolution and color separation, while also requiring heat-resistant materials that maintain infrared absorption ability at elevated temperatures.
Innovation Solution
An image pickup device is designed with an on-chip lens made of high-refractive-index material, a low-refractive-index layer, and an infrared absorption layer formed with an infrared absorption pigment and binder resin, where the infrared absorption layer is laminated above the low-refractive-index layer to prevent light from entering adjacent photoelectric conversion devices and is heat-stable up to 180°C, using pigments with high molar absorption coefficients and antioxidants to prevent oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the on-chip lens and color filter are thickened to achieve sufficient infrared absorption, then infrared absorption ability is improved, but the distance between the lens surface and photoelectric conversion device increases, causing incident light to enter adjacent photoelectric conversion devices and deteriorating pixel resolution and color separation
Solution Approach 1:
The patent divides the infrared absorption function into two separate components: the on-chip lens maintains its original thickness for optimal optical performance, while a dedicated infrared absorption layer is added as a separate functional element. This segmentation allows each component to be optimized independently - the lens for light gathering and the absorption layer for infrared filtering - thereby resolving the contradiction between infrared absorption and image quality.
Solution Approach 2:
The infrared absorption function is extracted from the on-chip lens structure and implemented as a separate layer. This extraction allows the on-chip lens to maintain its original thin design for optimal optical performance while the dedicated infrared absorption layer provides the necessary filtering capability without interfering with the lens's optical path and resolution.
2Object-affected harmful factors
If a large concentration of infrared absorption material is used to achieve sufficient infrared absorption, then infrared absorption ability is improved, but the visible light transmission amount is reduced
Solution Approach 1:
The patent applies local quality by making the infrared absorption layer selectively transparent - it has high absorption capability for infrared wavelengths while maintaining high transmission for visible wavelengths. This is achieved through careful selection of absorption material properties and layer thickness, allowing the layer to perform its filtering function locally for infrared radiation while remaining essentially transparent for visible light.
Solution Approach 2:
The patent optimizes the parameters of the infrared absorption layer, specifically controlling its thickness and material composition to achieve the desired balance between infrared absorption and visible light transmission. By adjusting these parameters, the layer provides sufficient infrared filtering while minimizing impact on visible light throughput.
3Length of stationary object
If the image pickup optical system is thinned to reduce overall thickness, then miniaturization is achieved, but an additional infrared cut filter cannot be mounted, making it difficult to remove infrared components
Solution Approach 1:
The patent merges the infrared absorption layer with the existing on-chip lens structure, integrating the filtering function directly into the lens assembly. This integration eliminates the need for a separate infrared cut filter component, allowing the optical system to be thinned while maintaining infrared removal capability through the combined lens-absorption layer structure.
Solution Approach 2:
The on-chip lens structure is given multi-functionality by incorporating infrared absorption capability directly into it. The lens simultaneously performs its primary light-gathering function and provides infrared filtering through the integrated absorption layer, eliminating the need for separate dedicated infrared filtering components and enabling optical system thinning.
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
This configuration allows for a thinner image pickup optical system without compromising image quality, maintaining high infrared absorption efficiency and durability even at elevated temperatures, thus preventing heat-induced deterioration and light scattering.
Implementation Method 1
an infrared absorption layer formed with an infrared absorption pigment and binder resin, where the infrared absorption layer is laminated above the low-refractive-index layer
Implementation Method 2
an on-chip lens made of high-refractive-index material
Data Source
AI summary
An image pickup device according to the present technique includes an on-chip lens, a low-refractive-index layer, and an infrared absorption layer. The on-chip lens is formed of a high-refractive-index material. The low-refractive-index layer is formed flat on the on-chip lens and formed of a low-refractive-index material. The infrared absorption layer is formed of an infrared absorption material and laminated as a higher layer than the low-refractive-index layer. The infrared absorption material includes an infrared absorption pigment and a binder resin, the binder resin, being a synthetic resin constituted of a siloxane skeleton alone or a synthetic resin constituted of a siloxane skeleton part and a partial skeleton having a low reaction activity in an oxygen part.