Solid-State Image Sensor with Organic Near-Infrared Layer
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Solution Overview
Problem
Solid-state image capture devices face challenges in capturing images under low light conditions without deteriorating color reproduction and resolution, as existing solutions either require complex switching mechanisms or alter the typical color filter arrangement, leading to insufficient luminance and color resolution.
Innovation Solution
Incorporating an organic photoelectric conversion layer absorptive of near-infrared light alongside traditional photoelectric conversion elements, allowing for enhanced sensitivity by utilizing both visible and near-infrared signal charges without changing the typical color filter arrangement, such as a Bayer arrangement, and enabling grayscale image capture at night while maintaining color image quality during the day.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pixels having sensitivity to near infrared light are arranged in addition to pixels having sensitivity to visible light, then both visible-light signals and near-infrared-light signals can be obtained, but the typical color filter arrangement is changed and the luminance and color resolution become insufficient
Solution Approach 1:
The pixel array is segmented into two distinct types: first photoelectric conversion elements with color filters for visible light capture, and second photoelectric conversion elements without color filters for near-infrared light capture. This segmentation allows each element type to specialize in its respective wavelength range, avoiding the need to compromise the color filter arrangement while still enabling dual-wavelength capture.
Solution Approach 2:
Different regions of the pixel array have different properties: some pixels are equipped with color filters optimized for visible light, while other pixels are left without color filters to capture near-infrared light. This local differentiation of properties allows the system to maintain high color resolution in visible light regions while achieving near-infrared sensitivity in specific regions.
2Illumination intensity
If a switching mechanism is used to create states of presence and absence of an IR cut filter, then bright images can be generated in low light conditions, but operating portions must be manufactured with high accuracy making it difficult to miniaturize and reduce manufacturing cost
Solution Approach 1:
The mechanical switching mechanism is replaced with an electronic control system. The solid-state image capture element electronically switches between capturing visible light and near-infrared light by activating different photoelectric conversion elements, eliminating the need for physical IR cut filter switching mechanisms and their associated mechanical components.
Solution Approach 2:
The solid-state image capture element is designed with multi-functionality, capable of operating in two modes: capturing visible light using first photoelectric conversion elements with color filters, and capturing near-infrared light using second photoelectric conversion elements without color filters. This universal design eliminates the need for separate hardware components for different lighting conditions.
3Adaptability or versatility
If visible-light signals and near-infrared-light signals are used regardless of incident light amount without an IR cut filter, then image capture is possible in various conditions, but color reproduction deteriorates
Solution Approach 1:
The signal processing is segmented to handle visible light and near-infrared light separately. First photoelectric conversion elements process visible light signals to maintain accurate color reproduction, while second photoelectric conversion elements process near-infrared light signals independently. This segmentation prevents near-infrared contamination of color information while still utilizing near-infrared data for brightness enhancement when needed.
Solution Approach 2:
The system dynamically adjusts which photoelectric conversion elements are active based on lighting conditions. In well-lit conditions, only visible light capture is used to maintain color accuracy. In low-light conditions, the system dynamically switches to activate near-infrared sensitive elements to enhance brightness, adapting to environmental conditions optimally.
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 solution allows for high-sensitivity image capture under low light conditions without compromising color reproduction or resolution, enabling compact and cost-effective camera designs that can operate effectively both day and night without the need for mechanical IR cut filters.
Implementation Method 1
photoelectric conversion elements that perform photoelectric conversion on incident light to obtain signal charges; and an organic photoelectric conversion layer provided at light incident sides of the color filter portions
Implementation Method 2
the organic photoelectric conversion layer containing a pigment that is absorptive of near infrared light
Data Source
AI summary
A solid-state image capture device includes photoelectric conversion elements that perform photoelectric conversion on incident light to obtain signal charges, color filter portions provided at light incident sides of the corresponding photoelectric conversion elements, and an organic photoelectric conversion layer provided at light incident sides of the color filter portions. The organic photoelectric conversion layer contains a pigment that is absorptive of near infrared light.