Stacked Multispectral Pixel Layout for Wide Dynamic Range Imaging
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Solution Overview
Problem
Imaging devices face challenges in achieving high pixel density and wide dynamic range due to the miniaturization of pixels, which limits their ability to effectively capture and differentiate between various wavelength regions of light, particularly infrared and visible light, leading to issues like blown highlights and parallax in multi-spectral imaging.
Innovation Solution
The imaging device incorporates multiple photoelectric converters sensitive to different wavelength regions, such as infrared and visible light, with a shared capacitive element that allows for the accumulation of electric charges from these regions, enabling efficient light detection and reduced parallax in multi-spectral imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pixels are miniaturized to increase pixel density, then pixel density is improved, but the ability to differentiate between various wavelength regions deteriorates
Solution Approach 1:
The patent transitions from planar 2D pixel arrangement to 3D stacked photodiode structure, enabling multiple wavelength-sensitive photodiodes to be vertically stacked within a single pixel footprint. This vertical stacking allows simultaneous capture of multiple wavelength regions (e.g., visible and infrared) without increasing lateral pixel density, thereby maintaining wavelength differentiation capability while achieving high pixel density through the third dimension.
2Measurement precision
If multiple photoelectric converters are stacked to capture different wavelength regions, then wavelength differentiation capability is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple photodiodes targeting different wavelength regions into a single integrated stacked structure. Each photodiode layer is directly coupled to a shared readout circuit, eliminating the need for separate readout circuits for each wavelength channel. This merging approach reduces device complexity by consolidating multiple independent systems into one unified structure while maintaining the ability to differentiate between wavelength regions.
3Device complexity
If a shared capacitive element is used to accumulate charges from multiple photodiodes, then device complexity is reduced, but charge accumulation capacity is limited
Solution Approach 1:
The patent implements dynamic control of the shared capacitive element through timing-based charge transfer mechanisms. The capacitive element can selectively accumulate charges from different photodiode layers at different time intervals, with control circuits managing the timing and sequence of charge transfers. This dynamic operation allows a single capacitive element to serve multiple photodiodes effectively, maintaining charge accumulation capacity through temporal multiplexing while keeping the circuit structure simple.
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 enhances the imaging device's ability to capture a wide dynamic range and reduces parallax between infrared and visible light images, improving sensitivity and resolution while maintaining a compact pixel size, suitable for applications like surveillance and autonomous driving.
Implementation Method 1
a first photoelectric converter that converts light having a wavelength in a first wavelength region into first electric charge
Implementation Method 2
a second photoelectric converter that is arranged at a different height from the first photoelectric converter in a thickness direction of the imaging device and that converts light having a wavelength in a second wavelength region into second electric charge
Implementation Method 3
a first capacitive element that accumulates the first electric charge and the second electric charge
Data Source
AI summary
An imaging device includes a first photoelectric converter, a second photoelectric converter, and a first capacitive element. The first photoelectric converter converts light having a wavelength in a first wavelength region into first electric charge. The second photoelectric converter converts light having a wavelength in a second wavelength region into second electric charge. The second photoelectric converter is arranged at a different height from the first photoelectric converter in a thickness direction of the imaging device. The first capacitive element accumulates the first electric charge and the second electric charge.