Stacked Inorganic Image Sensor for Sterilization
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Solution Overview
Problem
Medical imaging apparatuses, such as endoscopes, require heat resistance to withstand high-pressure steam sterilization, but existing image sensors with organic photoelectric conversion layers are not suitable due to their susceptibility to heat, leading to image quality degradation.
Innovation Solution
A medical imaging system with a stacked solid-state image sensor that uses inorganic photoelectric conversion layers, eliminating the need for organic materials and ensuring heat resistance, and controls light emission to separate wavelength bands, preventing color mixing and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an organic photoelectric conversion layer is used to improve wavelength separation and reduce color mixing, then image quality is improved, but heat resistance deteriorates making the sensor unsuitable for high-pressure steam sterilization
Solution Approach 1:
The patent changes the material parameter from organic to inorganic photoelectric conversion layer, fundamentally altering the thermal stability characteristics while maintaining the stacked multi-layer structure for wavelength separation
Solution Approach 2:
The patent uses composite inorganic photoelectric conversion layers with different bandgap energies (e.g., Si and Ge layers) to achieve both wavelength separation functionality and heat resistance, combining multiple materials with complementary properties
2Adaptability or versatility
If photodiodes are formed at different depths in a silicon substrate to capture different wavelength bands, then color detection is enabled, but wavelength separation properties deteriorate causing color mixing
Solution Approach 1:
The patent segments the photoelectric conversion function into multiple independent inorganic layers with different bandgap energies, where each layer is responsible for detecting specific wavelength bands, thereby achieving both color detection capability and wavelength separation
Solution Approach 2:
The patent extends the solution from a single-plane color filter approach to a multi-layer stacked structure in the depth dimension, using vertical layering to achieve wavelength separation while maintaining color detection versatility
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 system achieves heat resistance and enhanced image quality by using inorganic layers and time-division light emission to separate color signals, preventing color mixing and maintaining high-resolution imaging even under sterilization conditions.
Implementation Method 1
an image sensor (solid-state image sensor) that photoelectrically converts light with different wavelengths by using photodiodes formed at different depths in a silicon substrate
Data Source
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AI summary
There is provided a medical imaging apparatus including a solid-state image sensor that includes a photoelectric converter having at least two photoelectric conversion layers stacked with respect to a light-receiving surface and separating received light into light of different wavelength bands and circuitry configured to control a light source device that illuminates a subject.