Solid-State Imaging Device Dual-Wavelength Pixel Arrangement
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Solution Overview
Problem
Conventional solid-state imaging apparatuses face challenges in achieving high-resolution color imaging using visible light and infrared light simultaneously due to insufficient visible light information in rows and columns where half of the pixels detect infrared light, leading to deteriorated resolution and the need for complex operations or large, impractical designs.
Innovation Solution
A solid-state imaging apparatus with a two-dimensional arrangement of pixel cells, where filters are arranged in units that include a combination of filters transmitting visible light and infrared light, with specific configurations to minimize the number of infrared light-detecting pixels and enhance resolution, using multilayer interface filters composed of λ/4 multilayer films and dielectric layers to downsize the device and increase pixel count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If half of the pixels in every row and column detect infrared light, then infrared imaging capability is improved, but visible light information becomes insufficient and resolution deteriorates
Solution Approach 1:
The pixel array is segmented into two distinct types: first pixel cells with filters for visible light wavelengths and second pixel cells with filters for infrared wavelengths. This segmentation allows each type of pixel to specialize in detecting its designated wavelength range, preventing the conflict between infrared and visible light detection while maintaining high resolution in both modes.
Solution Approach 2:
Different regions of the pixel array are assigned different functional qualities - some pixels are optimized for visible light detection while others are optimized for infrared detection. This local differentiation enables the system to maintain high visible light resolution in areas with more visible-light-optimized pixels while preserving infrared imaging capability in areas with infrared-optimized pixels.
2Measurement precision
If an infrared cut filter is used to remove infrared light, then color reproducibility is improved, but visible light transmission decreases by 10-20% and sensitivity deteriorates
Solution Approach 1:
The filter system is segmented into two categories: filters for first pixel cells that transmit visible light while blocking infrared, and filters for second pixel cells that transmit infrared while blocking visible light. This eliminates the need for a single infrared cut filter that would reduce visible light transmission across the entire array, as each pixel type has a filter optimized for its specific function.
Solution Approach 2:
Instead of applying infrared blocking action across the entire pixel array (which would reduce visible light transmission), the infrared blocking function is applied only to the first pixel cells where it is needed for color imaging, while the second pixel cells are dedicated to infrared detection without such blocking.
3Adaptability or versatility
If filters are laminated to transmit both visible and infrared light, then dual imaging capability is improved, but device size increases and pixel count decreases
Solution Approach 1:
Rather than laminating multiple filters together which would increase device volume, the filter system is segmented so that different pixels have different single-layer filters optimized for their specific wavelength ranges. This maintains a compact device structure while achieving dual imaging capability through spatial differentiation of filter types across the pixel array.
4Adaptability or versatility
If filters are switched between visible and infrared modes, then dual imaging capability is improved, but the ability to perform both color imaging and infrared imaging simultaneously deteriorates
Solution Approach 1:
The pixel array is permanently segmented into first pixel cells for visible light and second pixel cells for infrared light, eliminating the need for mechanical or electronic filter switching. Both types of pixels operate simultaneously and independently, enabling the system to capture both visible and infrared images at the same time without sequential switching delays.
Solution Approach 2:
The imaging device achieves multi-functionality by incorporating two types of pixel cells with different filter characteristics within the same array. This universal design allows the device to perform both color imaging and infrared imaging functions simultaneously, rather than requiring mode switching between single-function 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
Enables high-resolution color imaging using visible light and infrared light simultaneously, reduces resolution deterioration, and allows for a compact design with a higher pixel count, while simplifying signal processing through straightforward subtraction methods.
Implementation Method 1
When incident light that has passed through a filter is received by a photodiode, the photodiode receives light in a wavelength region (around 380 nm to 1100 nm) which is wider than the visible region of humans (around 380 nm to 780 nm) to generate signal charge.
Implementation Method 2
for example, it is possible to prevent information about visible light from being insufficient, using a filter that transmits light in a predetermined wavelength region in addition to infrared light
Data Source
AI summary
A solid-state imaging apparatus that performs color imaging using visible light and imaging using infrared light, the solid-state imaging apparatus including a plurality of two-dimensionally arranged pixel cells, in each of which a filter mainly transmits one of visible light and infrared light, wherein filters are arranged such that a first unit of arrangement where a plurality of filters that mainly transmit visible light are arranged and a second unit of arrangement where a filter that mainly transmits visible light and a filter that mainly transmits infrared light are arranged are alternately arranged in both a row direction and a column direction. Also, in the first unit of arrangement are arranged filters including three kinds of filters each transmitting one of red light, green light and blue light and in the second unit of arrangement are arranged four kinds of filters each transmitting one of red light, green light, blue light and infrared light.