Global Shutter Image Sensor With Nested Storage For High Dynamic Range
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Solution Overview
Problem
Conventional image sensors with global shutter schemes face challenges in capturing high-dynamic-range images efficiently due to the need for additional storage, which reduces the space for photosensitive elements and can result in distorted images when used in non-stationary devices.
Innovation Solution
Implementing a global shutter operation with three integration periods of varying durations, allowing for enhanced dynamic range capabilities while maintaining the global shutter scheme, by using a pixel architecture with a photodiode, floating diffusion region, and local storage region, and employing a rolling readout scheme to capture and process image data effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a global shutter scheme is implemented, then image distortion is eliminated, but additional storage space is required which reduces photosensitive element area
Solution Approach 1:
The patent implements a nested storage architecture where a first storage region and a second storage region are nested within the same pixel structure. The first storage region holds charge from a first integration period, and the second storage region holds charge from a second integration period. This nesting allows global shutter operation with multiple integration periods without requiring separate storage structures, thereby preserving photosensitive element area while eliminating image distortion.
Solution Approach 2:
The patent divides the storage function into segmented regions within each pixel - specifically a first storage region and a second storage region. This segmentation allows independent storage of charge from different integration periods, enabling the global shutter scheme to capture multiple exposure levels without requiring a single large storage area, thus maintaining photosensitive element density while achieving distortion-free imaging.
2Stability of the object's composition
If additional storage is provided for global shutter scheme, then image distortion is prevented, but pixel efficiency is reduced
Solution Approach 1:
By nesting the first storage region and second storage region within the pixel structure, the patent achieves global shutter functionality with multiple integration periods without adding external storage components. This nested architecture maintains high pixel efficiency by utilizing space efficiently within each pixel, preventing image distortion while preserving productivity.
Solution Approach 2:
The patent merges the storage functions for different integration periods into a unified pixel structure with interconnected first and second storage regions. This combining approach allows the pixel to simultaneously perform photosensing and multi-period charge storage, eliminating the need for separate storage structures and maintaining high pixel efficiency while achieving distortion-free global shutter imaging.
3Device complexity
If conventional image sensor is used, then device complexity is low, but dynamic range capability is limited
Solution Approach 1:
The patent segments the charge storage function into a first storage region for a first integration period and a second storage region for a second integration period. This segmentation enables the sensor to capture multiple exposure levels within the same scene, significantly expanding dynamic range capability while maintaining relatively simple device architecture through the use of standard semiconductor fabrication processes.
Solution Approach 2:
By nesting multiple storage regions within the pixel structure, the patent achieves enhanced dynamic range capability without substantially increasing device complexity. The nested architecture allows the sensor to store charge from multiple integration periods using space-efficient design, providing adaptability for high-dynamic-range imaging while maintaining manufacturing simplicity.
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 approach enables the capture of high-dynamic-range images with improved luminance ratio, retaining detail in both bright and dark regions without distorting the image, even in moving devices, while optimizing the use of storage circuitry to maintain pixel efficiency.
Implementation Method 1
Each image pixel may include a photosensor, a floating diffusion region, and a local storage region. The floating diffusion region may be used to store an amount of charge accumulated by the photosensor during a first charge integration period.
Data Source
AI summary
High-dynamic-range images may be produced by combining multiple integration periods of varying duration, wherein each integration is obtained using a global shutter operation. Charge accumulated during a first integration period may be stored on a first storage node while charge accumulated during a second and third integration time are carried out. Storage of charges accumulated during the second and third integration periods on a second storage node within a pixel while charge is stored on the first storage node allows capture of a global-shutter-based, high-dynamic-range image. A global-shutter-based image capture base on at least three integration time periods may provide enhanced dynamic range.