Selective Readout CMOS Image Sensor for Visible-Infrared Crosstalk
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Solution Overview
Problem
Current image sensors face challenges in capturing both visible and non-visible images efficiently, particularly in reducing crosstalk and maintaining sensitivity, while also mitigating the influence of ambient light and flickering in dynamic scenes.
Innovation Solution
The implementation of a stacked CMOS image sensor with selective readout capabilities, allowing for separate exposure periods for visible and non-visible light, and independent readout of storage nodes to combine long and short exposure data, thereby reducing crosstalk and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single image sensor captures both visible and non-visible light simultaneously, then the sensor can capture multiple types of image data, but crosstalk between visible and non-visible light signals increases
Solution Approach 1:
The image sensor is divided into two separate stacked sensors: a first image sensor for capturing visible light and a second image sensor for capturing non-visible light. This segmentation physically separates the light capture paths, eliminating crosstalk between visible and non-visible light signals while maintaining the capability to capture both types of light simultaneously.
Solution Approach 2:
A stacked architecture acts as an intermediary structure between the visible and non-visible light capture systems. The stacked configuration allows both sensors to share the same optical path and processing infrastructure while maintaining separate photodetector arrays, enabling multi-spectral capture without direct interference.
2Device complexity
If the image sensor uses a single exposure period for both visible and non-visible light, then the imaging process is simplified, but sensitivity for both light types cannot be optimized
Solution Approach 1:
The imaging system employs dynamic control of exposure periods through separate control circuits for each stacked sensor. The first control circuit independently manages the exposure timing for visible light, while the second control circuit independently manages exposure timing for non-visible light. This dynamic, independent control allows optimization of exposure duration for each light type based on scene requirements while maintaining a unified stacked sensor architecture.
3Productivity
If the image sensor captures ambient light during non-visible light exposure, then the sensor utilizes available light, but ambient light influence degrades non-visible light image quality
Solution Approach 1:
The system extracts and separates the non-visible light signal capture from the ambient visible light capture by using dedicated photodetectors in the second stacked sensor that are insensitive to visible light. This extraction allows the non-visible light imaging to proceed independently without contamination from ambient visible light, while the first sensor simultaneously captures the visible ambient light for color information.
4Device complexity
If the image sensor uses a single readout system for both visible and non-visible light, then the system structure is simplified, but selective readout and crosstalk reduction are compromised
Solution Approach 1:
The readout system is segmented into separate readout circuits for each stacked sensor. The first readout circuit is dedicated to reading signals from visible light photodetectors, while the second readout circuit reads signals from non-visible light photodetectors. This segmentation ensures complete signal separation during readout, preventing any crosstalk between light types while maintaining efficient parallel processing through the stacked 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
This approach enables the capture of high-quality images with reduced crosstalk and ambient light influence, maintaining sensitivity and minimizing flickering, particularly beneficial for video capture and high dynamic range imaging.
Implementation Method 1
The image sensor includes an array of pixels having photosensitive elements (e.g., photodiodes) that absorb a portion of the incident image light and generate image charge upon absorption of the image light
Data Source
AI summary
An imaging system including a sensor wafer and a logic wafer. The sensor wafer includes a plurality of pixels arranged in rows and columns, the plurality of pixels arranged in rows and columns and including at least a first pixel and a second pixel positioned in a first row included in the rows. The sensor wafer includes a first transfer control line associated with the first row, the first transfer control line coupled to both a first transfer gate of the first pixel and a second transfer gate of the second pixel. The logic wafer includes a first storage capacitor associated with the first pixel and a second storage capacitor associated with the second pixel, a first storage control line coupled to a first storage gate associated with the first pixel and a second storage control line coupled to a second storage gate associated with the second pixel.