Image Sensor Charge Transmitter Design for Blooming Prevention
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Solution Overview
Problem
Image sensors experience image distortion due to excess charge overflow and read-out time differences in single frame capture mode, particularly in rolling shutter mode, where charges from incident light overflow into the charge detector, causing blooming and distortion.
Innovation Solution
An image sensor design incorporating a photoelectric converter on a semiconductor substrate with a first charge transmitter and a second charge transmitter, where the second charge transmitter has a width at least half of the photoelectric converter's span, transmitting excess charges to an overflow drain region to prevent overflow into the charge detector, thereby reducing image distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single charge detector is shared by multiple unit pixels in time division mode, then device complexity is reduced, but read-out time difference occurs between pixel units causing image distortion
Solution Approach 1:
The invention divides the charge detection function into multiple independent charge detectors, with each unit pixel having its own dedicated charge detector. This segmentation eliminates the time division multiplexing approach that caused read-out time differences, thereby resolving image distortion while maintaining reasonable device complexity through systematic architecture design
Solution Approach 2:
The invention introduces a dedicated overflow drain region and second charge transmitter as intermediary structures between the photoelectric converter and charge detector. These intermediaries capture and divert excess charges before they can cause blooming or distortion, acting as a buffer that protects the charge detector while maintaining efficient charge management
2Productivity
If optical images are sequentially read by row in rolling shutter mode, then continuous image capture is enabled, but each row is exposed at a different time causing image distortion
Solution Approach 1:
The invention implements preliminary charge overflow prevention by providing a dedicated overflow drain region and second charge transmitter that actively divert excess charges before they can contaminate the charge detector. This preliminary action occurs during the exposure phase itself, ensuring that even when rows are exposed at different times in rolling shutter mode, each row's charge signal remains pure and undistorted by overflow from other rows
Solution Approach 2:
The invention extracts the excess charge management function from the main charge detection path by creating a separate overflow drain region and second charge transmitter pathway. This extraction isolates the problematic overflow charges from the legitimate signal charges, allowing continuous rolling shutter operation without the distortion that would otherwise result from temporal exposure differences
3Illumination intensity
If light is continuously incident on the pixel array in SFCM, then high illumination capability is achieved, but excess charges overflow into the charge detector causing blooming and distortion
Solution Approach 1:
The invention introduces a dedicated overflow drain region and second charge transmitter as intermediary structures between the photoelectric converter and charge detector. These intermediaries capture and divert excess charges before they can cause blooming or distortion, acting as a buffer that protects the charge detector while maintaining efficient charge management
Solution Approach 2:
The invention extracts the excess charge management function from the main charge detection path by creating a separate overflow drain region and second charge transmitter pathway. This extraction isolates the problematic overflow charges from the legitimate signal charges, allowing continuous rolling shutter operation without the distortion that would otherwise result from temporal exposure differences
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 solution effectively prevents image distortion and blooming by efficiently managing excess charges, ensuring stable electrical shutter operation even under high illumination, improving image reproducibility in both single frame capture and rolling shutter modes.
Implementation Method 1
a photoelectric converter formed in a semiconductor substrate to generate charges and integrate the charges resulting from incident light
Data Source
AI summary
An image sensor includes a photoelectric converter formed in a semiconductor substrate to generate and integrate charges resulting from incident light, a first charge transmitter transmitting integrated charges to a charge detector, an overflow drain region discharging excess charges generated by the photoelectric converter, and a second charge transmitter transmitting the excess charges to the overflow drain region and having a width which is at least half of a span of the photoelectric converter.