Stacked Pixel Retention Circuits for Fast High-Resolution Imaging
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Solution Overview
Problem
Conventional imaging devices face limitations in obtaining multiple high-resolution imaging data quickly due to the trade-off between the number of pixels and data retention, resulting in low image resolution and high power consumption.
Innovation Solution
The proposed imaging device employs a stack of layers, including a photoelectric conversion element and retention circuits with transfer transistors, allowing for simultaneous retention and reading of multiple imaging data, utilizing metal oxide transistors with extremely low off-state current to enhance data retention and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple imaging data are retained in different pixels simultaneously, then the number of imaging data obtained increases, but the number of pixels available for each imaging data decreases, resulting in lower image resolution
Solution Approach 1:
The patent introduces a time dimension by stacking multiple pixel circuits vertically, allowing simultaneous retention of multiple imaging data (first imaging data and second imaging data) in different time periods. This vertical stacking enables the system to capture multiple frames without reducing the pixel count per frame, thereby maintaining high resolution while increasing productivity through time-multiplexed operation.
2Manufacturing precision
If the number of pixels is increased to maintain resolution, then image quality improves, but the ability to retain multiple imaging data simultaneously decreases
Solution Approach 1:
The patent implements a nested structure where multiple pixel circuits are stacked vertically, with each pixel circuit containing complete functional elements (photoelectric conversion element, transfer transistor, retention transistor, and capacitor). This nesting allows multiple imaging data to be retained simultaneously in different vertical layers without interfering with each other, enabling high productivity while maintaining full pixel count and resolution in each layer.
3Device complexity
If conventional transistors are used in pixel circuits, then device complexity is reduced, but power consumption increases due to higher off-state current
Solution Approach 1:
The patent changes the material parameter of the transistor from conventional semiconductor to oxide semiconductor, which fundamentally alters the off-state current characteristic. Oxide semiconductor transistors exhibit extremely low off-state current due to their wide bandgap and insulating properties, enabling long-term retention of imaging data without refresh operations and significantly reducing power consumption while maintaining the same circuit structure complexity.
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 imaging device to obtain multiple high-resolution imaging data in a short period while maintaining low power consumption and high sensitivity, achieving both high-speed and high-quality image capture.
Implementation Method 1
a photoelectric conversion element
Implementation Method 2
metal oxide transistors with extremely low off-state current
Data Source
AI summary
An imaging device that can obtain imaging data corresponding to high-resolution images in a short period of time is provided. The imaging device includes a pixel including a photoelectric conversion element and n (n is an integer more than 2 inclusive) retention circuits. The photoelectric conversion element and the n retention circuits are stacked. One electrode of the photoelectric conversion element is electrically connected to the first to n-th retention circuits. The retention circuits include OS transistors with an extremely low off-state current feature, and can retain imaging data for a long time. In the first to n-th periods, the imaging device obtains the first to n-th imaging data and retains it in the first to n-th retention circuits. Then, the first to n-th imaging data retained in the first to n-th retention circuits are read out. The read imaging data is output outside the imaging data through AD conversion.