Multi-Photodiode Pixel Cell for 2D and 3D Imaging
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Solution Overview
Problem
Current image sensors face challenges in achieving high spatial resolution and efficient power consumption while performing both 2D and 3D imaging, as they require separate pixel cells for different wavelength ranges, leading to lower spatial resolutions and increased form factor and power consumption, and complicate the mapping between 2D and 3D images.
Innovation Solution
An image sensor with an array of pixel cells, each comprising a first and second photodiode and an interface circuit, where the photodiodes form a stack structure to convert different light components to charge, and the interface circuit performs quantization operations to represent light intensities across various intensity ranges, allowing for simultaneous 2D and 3D imaging with improved correspondence between images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate pixel cells are used for different wavelength ranges, then imaging capability for multiple wavelengths is achieved, but spatial resolution decreases and form factor increases
Solution Approach 1:
The patent combines multiple photodiodes (first photodiode for first wavelength range, second photodiode for second wavelength range) within a single pixel cell structure. This merging approach allows the pixel cell to capture multiple wavelength ranges simultaneously while maintaining full spatial resolution, eliminating the need for separate pixel cells for different wavelengths.
Solution Approach 2:
The pixel cell is designed with multi-functional capability to detect both first wavelength range light and second wavelength range light through its multiple photodiodes. This universal design enables a single pixel cell to perform imaging functions across different wavelength ranges, improving both spatial resolution and wavelength adaptability.
2Adaptability or versatility
If separate pixel cells are used for different wavelength ranges, then imaging capability for multiple wavelengths is achieved, but power consumption increases
Solution Approach 1:
The patent merges multiple photodiodes into a single pixel cell, reducing the total number of pixel cells required for multi-wavelength imaging. This consolidation decreases the overall power consumption while maintaining the capability to image across different wavelength ranges.
3Adaptability or versatility
If separate pixel cells are used for different wavelength ranges, then imaging capability for multiple wavelengths is achieved, but mapping between 2D and 3D images becomes complicated
Solution Approach 1:
The patent combines multiple photodiodes within each pixel cell to detect different wavelength ranges simultaneously. This integration simplifies the mapping between 2D and 3D images because corresponding pixels in the two image types originate from the same physical location, eliminating complex registration and mapping procedures.
4Adaptability or versatility
If multi-stage quantization is performed, then dynamic range is expanded, but device complexity increases
Solution Approach 1:
The interface circuit dynamically selects between first quantization and second quantization based on the intensity range of the detected light. This dynamic adaptation allows the system to expand its dynamic range while managing circuit complexity through intelligent control rather than permanently complex hardware.
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 enables full spatial resolution utilization, reduces form factor and power consumption, and expands the dynamic range of the image sensor by performing multi-stage quantization and time-to-saturation measurements, enhancing sensitivity and accuracy in low-light conditions.
Implementation Method 1
a first photodiode configured to convert a first component of light to a first charge
Implementation Method 2
a second photodiode configured to convert a second component of the light to a second charge
Data Source
AI summary
In one example, an apparatus comprises: a first photodiode configured to convert a first component of light to a first charge, second photodiode configured to convert a second component of the light to a second charge; and an interface circuit configured to: perform a first quantization and a second quantization of the first charge to generate, respectively, a first result and a second result, the first quantization and the second quantization being associated with different light intensity ranges; provide one of the first result or the second result to represent an intensity of the first component of a pixel; perform the first quantization and the second quantization of the second charge to generate, respectively, a third result and a fourth result; and provide one of the third result or the fourth result to represent an intensity of the second component of the pixel.