CMOS Image Sensor Readout Circuit Illumination Adaptation
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Solution Overview
Problem
Current solid-state imaging devices face challenges in effectively reading pixels by switching between common-source and source follower readout operations based on illumination levels, as existing technologies do not efficiently adapt to varying light conditions.
Innovation Solution
A solid-state imaging device and method that includes a readout unit capable of performing common-source or source follower operations for each pixel column, adapting the operation based on illumination levels to reset and read electric charges from a floating diffusion region, utilizing transfer gates and a photoelectric transducer to optimize signal reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single readout operation mode (common-source or source follower) is used, then the circuit structure is simple, but the pixel reading effectiveness varies under different illumination levels
Solution Approach 1:
The readout circuit dynamically switches between common-source and source follower operation modes based on illumination levels. The control unit determines the appropriate mode and configures the pixel circuit accordingly, allowing the system to adapt its reading effectiveness to varying light conditions rather than being fixed in a single mode.
Solution Approach 2:
The invention changes the operational parameters of the pixel circuit by switching between two distinct readout modes. By adjusting the circuit configuration parameter (which mode to use) based on illumination conditions, the system optimizes pixel reading effectiveness for both bright and dim environments.
2Productivity
If common-source readout operation is used, then conversion efficiency is high, but the floating diffusion region cannot be effectively reset under certain conditions
Solution Approach 1:
The control unit monitors illumination conditions and provides feedback to determine the appropriate readout mode. Based on this feedback, the system switches between common-source and source follower modes to ensure both effective conversion and reliable floating diffusion region resetting under varying light conditions.
Solution Approach 2:
The system dynamically selects the readout mode based on real-time illumination assessment. When common-source mode cannot effectively reset the floating diffusion region, the system transitions to source follower mode, which provides the necessary resetting capability while maintaining acceptable conversion efficiency.
3Ease of manufacture
If source follower readout operation is used, then the circuit is simple to implement, but signal reading efficiency decreases
Solution Approach 1:
Rather than always using the simpler source follower mode, the system dynamically selects between common-source and source follower modes based on illumination conditions. This allows the system to use the more efficient common-source mode when appropriate while falling back to the simpler source follower mode when needed.
Solution Approach 2:
The invention changes the operational parameter of the pixel circuit by switching readout modes. By adjusting which mode is active based on illumination levels, the system optimizes the balance between manufacturing simplicity and signal reading efficiency for different operating conditions.
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 allows for effective pixel reading across varying illumination levels, enhancing signal reading efficiency by switching between readout operations to suit different lighting conditions, thereby improving the overall performance of the imaging device.
Implementation Method 1
a photoelectric transducer that generates an electric charge according to an amount of incident light and accumulates the electric charge inside
Data Source
AI summary
The present technology relates to a solid-state imaging device, a method of driving the solid-state imaging device, and an electronic apparatus by which pixels can be read effectively. The solid-state imaging device includes a readout unit that performs a common-source operation or a source follower operation with respect to pixels to read a signal for each column. According to a level of illumination, the readout unit performs a common-source readout operation to reset a floating diffusion region and read an electric charge transferred from a photoelectric transducer and held in the floating diffusion region, and performs a source follower readout operation to reset the floating diffusion region and read the electric charge transferred from the photoelectric transducer and held in the floating diffusion region. The present technology is applicable to a solid-state imaging device such as a CMOS image sensor.