Solid-State Image Sensor Charge Separation for Quality
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Solution Overview
Problem
Solid-state image sensors with both asynchronous and synchronous circuits sharing a photodiode face challenges in improving image quality due to reduced electron transfer to each circuit, leading to lower image quality and increased mounting area.
Innovation Solution
A solid-state image sensor design where one type of charge (electrons or holes) is used for generating pixel signals, and the other for detecting address events, with specific units arranged on separate chips to reduce circuit scales and enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If both asynchronous and synchronous circuits share a photodiode, then the sensor can provide both high-speed address event detection and synchronous image data acquisition, but the image quality deteriorates because the amount of electrons transferred to each circuit becomes smaller
Solution Approach 1:
The photodiode is divided into a first region and a second region, where the first region generates electrons for the asynchronous circuit and the second region generates holes for the synchronous circuit. This spatial segmentation allows each circuit to receive sufficient charge carriers independently, resolving the image quality deterioration caused by shared photodiode electron transfer.
2Measurement precision
If the area of the photodiode is made large to increase the amount of charge, then the image quality can be improved, but the mounting area is increased which is not desirable
Solution Approach 1:
Different regions of the photodiode are assigned different functions: the first region is optimized for generating electrons for asynchronous detection, while the second region is optimized for generating holes for synchronous imaging. This local quality differentiation allows each region to be optimized for its specific function without requiring a uniformly large photodiode area, thus improving image quality while controlling mounting area.
3Adaptability or versatility
If electrons are transferred to both asynchronous and synchronous circuits, then both functions can be supported, but the amount of electrons to each circuit is reduced leading to lower image quality
Solution Approach 1:
Instead of having the photodiode transfer electrons to both circuits (conventional approach), the invention inverts the charge carrier assignment: the first region transfers electrons to the asynchronous circuit while the second region transfers holes to the synchronous circuit. This inversion allows each circuit to receive sufficient charge carriers independently, maintaining both functionality and image quality.
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 improves image quality by optimizing charge utilization and reducing circuit complexity, allowing for higher-quality image data generation while minimizing the mounting area.
Implementation Method 1
a photodiode configured to generate electrons and holes by photoelectric conversion
Data Source
AI summary
To improve image quality of image data in a solid-state image sensor that detects an address event. The solid-state image sensor includes a photodiode, a pixel signal generation unit, and a detection unit. In the solid-state image sensor, the photodiode generates electrons and holes by photoelectric conversion. The pixel signal generation unit generates a pixel signal having a voltage according to an amount of one of the electrons and the holes. The detection unit detects whether or not a change amount in the other of the electrons and the holes has exceeded a predetermined threshold and outputs a detection signal.