Multi-Storage Node Pixel Design for High Dynamic Range Imaging
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Solution Overview
Problem
Conventional global shutter pixels with multiple storage regions for high dynamic range (HDR) imaging result in larger pixels, reducing photodiode area and sensitivity due to the need for simultaneous integration of light across all pixels, which can lead to motion distortion and reduced image quality, especially when capturing moving objects.
Innovation Solution
A multi-storage node pixel design that includes a photosensitive element, a floating diffusion node, and a storage node, with transfer gates controlling charge transfer between these nodes during integration periods, allowing for simultaneous reset and separate exposure periods for each node to minimize motion distortion and enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional global shutter pixels use multiple storage regions for HDR imaging, then HDR capability is improved, but pixel size increases and photodiode area decreases
Solution Approach 1:
The pixel is segmented into multiple independent storage regions (first storage region and second storage region) that can be independently controlled for different exposure periods. This segmentation allows simultaneous integration in both regions during the first exposure period, capturing multiple exposure durations without requiring a larger overall pixel structure, thereby maintaining photodiode area while achieving HDR capability.
Solution Approach 2:
The patent introduces a temporal dimension to the storage regions by enabling simultaneous integration across multiple regions during different exposure periods. This dimensional approach allows the pixel to capture multiple exposure durations (short and long) within the same spatial footprint, achieving HDR without increasing pixel size and preserving photodiode area.
2Adaptability or versatility
If conventional global shutter pixels use multiple storage regions, then HDR imaging is enabled, but sensitivity decreases due to reduced photodiode area
Solution Approach 1:
By segmenting the storage function into multiple independent regions rather than using a single large storage structure, the patent maintains a compact pixel design with sufficient photodiode area. This segmentation allows each region to be optimized for specific exposure durations while preserving overall pixel sensitivity through adequate photodiode surface area.
Solution Approach 2:
The patent implements preliminary action by simultaneously integrating light in both storage regions during the first exposure period before the second exposure period begins. This preliminary simultaneous integration ensures that both regions capture sufficient light signal during their active integration time, maintaining sensitivity while enabling subsequent HDR processing.
3Device complexity
If rolling shutter architecture is used, then device complexity is reduced, but motion distortion increases
Solution Approach 1:
The patent merges the functionality of multiple storage regions with global shutter operation, allowing simultaneous integration across all pixels and regions. This combining approach achieves global shutter-like simultaneous capture without the full complexity of traditional global shutter circuits, reducing motion distortion while maintaining reasonable device complexity through the multi-region architecture.
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 multi-storage node pixel design effectively reduces motion distortion and maintains high sensitivity by allowing for simultaneous integration of light across all pixels, enabling the creation of high-quality HDR images with reduced pixel size while minimizing the impact of rolling shutter effects.
Implementation Method 1
each pixel comprising a photodiode
Data Source
AI summary
Various embodiments of the present technology may comprise a method and apparatus for a pixel array. Each pixel may include multiple storage regions capable of storing pixel signals during integration. The method and apparatus may utilize the floating diffusion region as a storage region during both an integration period and readout period. The method and apparatus may store pixel signals corresponding to a first exposure periods in the floating diffusion region and pixel signals corresponding to a second exposure periods in a separate storage region.