CMOS Image Sensor Wide Dynamic Range Pixel Architecture
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Solution Overview
Problem
Conventional CMOS image sensors have limited dynamic range in responding to light brightness, and existing methods to enhance this range are complex and require additional external memories or specific processes.
Innovation Solution
A CMOS image sensor design that outputs multiple signals corresponding to different exposure integration times using a unit pixel with a photodiode, first and second processing units, and an erasing transfer gate transistor, allowing for wide dynamic range without external memories and simple image processing, applicable to both rolling shuttering and global shuttering schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple signals corresponding to different exposure integration times are output simultaneously, then the dynamic range is improved, but the device complexity increases due to multiple processing units and output signal lines
Solution Approach 1:
The pixel is divided into multiple processing units (first processing unit, second processing unit, etc.), each responsible for a specific exposure integration time. This segmentation allows simultaneous output of multiple signals with different exposure times, thereby extending the dynamic range while maintaining manageable complexity through functional division.
Solution Approach 2:
The patent introduces an additional dimension by adding multiple output signal lines (first output signal line, second output signal line, etc.) corresponding to different processing units. This dimensional expansion enables simultaneous transmission of multiple exposure signals, achieving wide dynamic range without requiring sequential processing that would increase time complexity.
2Measurement precision
If additional external memories are used to store signals from multiple photodiodes, then the dynamic range is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the need for additional external memories by designing a system where multiple processing units directly output their signals through dedicated output signal lines. This extraction of the memory requirement simplifies the overall device structure while maintaining the capability to handle multiple exposure integration times simultaneously.
Solution Approach 2:
Each processing unit is designed to be self-sufficient, with its own dedicated output signal line for transmitting signals. This self-service architecture allows each processing unit to independently manage its exposure signal without requiring external memory storage, thereby reducing device complexity while achieving wide dynamic range.
3Measurement precision
If the photodiode structure is modified to enable wide dynamic range, then the dynamic range is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent employs a universal photodiode structure that serves multiple functions by being shared among different processing units. Each processing unit processes different exposure integration times using the same photodiode, eliminating the need for multiple specialized photodiodes and simplifying the manufacturing process while achieving wide dynamic range.
Solution Approach 2:
The patent merges multiple exposure integration time processing capabilities into a single photodiode structure by using transfer gate transistors to control electron transfer to different floating diffusion regions. This combining approach maintains manufacturing simplicity while enabling wide dynamic range through temporal multiplexing of the photodiode's electron storage capability.
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 design significantly improves the dynamic range of the image sensor by integrating electrons over multiple exposure times, enabling parallel output of signals, thus enhancing the sensor's response to light brightness across both shuttering schemes without additional memories or complex processes.
Implementation Method 1
CMOS (Complementary Metal Oxide Semiconductor) image sensor is a sensor produced using a CMOS manufacturing technology, which converts the light incident on each pixel of the sensor into electrons using photodiodes
Data Source
AI summary
Disclosed are a CMOS image sensor having a wide dynamic range and a sensing method thereof. Each unit pixel of the CMOS image sensor of the present invention includes multiple processing units, so that one shuttering section for the image generation of one image frame can be divided into multiple sections to separately shutter and sample the divided sections by each processing unit. Thus, the image sensor of the present invention enables many shuttering actions to be performed in the multiple processing units, respectively, and the multiple processing units to separately sample each floating diffusion voltage caused by the shuttering actions, thereby realizing a wide dynamic range.