Hybrid CIS-DVS Pixel Layout for Low-Noise Image Sensors
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Solution Overview
Problem
Conventional image sensors that mix CMOS Image Sensor (CIS) and Dynamic Vision Sensor (DVS) pixels suffer from noise due to varying parasitic capacitance, leading to fixed pattern noise and require color reconstruction to compensate for lost color information.
Innovation Solution
A hybrid image sensor design with heterogeneous CIS and DVS pixels, where CIS pixels generate gray-level image signals and DVS pixels detect changes in brightness, utilizing a specific layout and isolation structure to minimize parasitic capacitance and optimize signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If CIS and DVS pixels are mixed in conventional image sensors, then heterogeneous pixel functionality is achieved, but noise due to varying parasitic capacitance occurs
Solution Approach 1:
The patent applies local quality by making each pixel type (CIS and DVS) electrically independent through separate readout circuits and isolated photodiode regions. This allows each pixel to maintain its specific electrical characteristics without being affected by neighboring pixels, thereby achieving heterogeneous functionality while eliminating fixed pattern noise caused by varying parasitic capacitance across different pixel types.
Solution Approach 2:
The patent segments the pixel array into distinct CIS pixel regions and DVS pixel regions with separate readout circuits. This segmentation isolates the electrical characteristics of each pixel type, preventing noise propagation and allowing independent optimization of each pixel type's performance without interference from the other type.
2Adaptability or versatility
If CIS and DVS pixels are mixed in conventional image sensors, then motion detection capability is improved, but color reconstruction is required
Solution Approach 1:
The patent merges CIS and DVS pixel types within the same image sensor device, allowing simultaneous capture of both absolute brightness information (from CIS pixels) and brightness change information (from DVS pixels). This integration eliminates the need for separate sensors and complex color reconstruction algorithms, as both pixel types contribute directly to the final image output.
3Area of moving object
If photodiodes are arranged in specific regions, then light-receiving area is increased, but parasitic capacitance varies between pixels
Solution Approach 1:
The patent segments the photodiode array into distinct CIS photodiode regions and DVS photodiode regions, each with its own readout circuit. This segmentation ensures that each photodiode type maintains consistent electrical characteristics within its group, eliminating parasitic capacitance variation between different pixel types while allowing each type to optimize its light-receiving area for its specific function.
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 hybrid design effectively reduces fixed pattern noise and minimizes the need for color reconstruction, enabling efficient motion deblurring and uniform signal settling times while maintaining image quality.
Implementation Method 1
a first photodiode in a first region in the substrate; a second photodiode in a second region in the substrate... an image sensing pixel circuit configured to generate a first electrical signal based on charges generated by the first photodiode; an event sensing pixel circuit configured to generate a second electrical signal based on a change in an amount of charges generated by the second photodiode
Data Source
AI summary
An image sensor includes: a first region disposed in a first direction and a second direction in parallel with an upper surface of a substrate, wherein the first direction and the second direction intersect each other; a second region disposed in the first direction and the second direction; a first photodiode in the first region; a second photodiode in the second region; an image sensing pixel circuit configured to generate a first electrical signal based on charges generated by the first photodiode; an event sensing pixel circuit configured to generate a second electrical signal based on a change in an amount of charges generated by the second photodiode; and a logic circuit electrically connected to the image sensing pixel circuit, wherein the first region is disposed diagonally to the second region in a third direction, and wherein the third direction is different from the first and second directions.