Global Rolling Shutter Control Circuit for Image Sensors
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Solution Overview
Problem
Current solid-state image sensing devices face challenges in efficiently controlling and processing light signals for both global and rolling shutter operations, particularly in managing the integration and transfer of photoelectrons across multiple sensor pixel image sensors.
Innovation Solution
A control apparatus is introduced that includes a row control circuit and a column clamp, sample, and hold circuit to generate reset control signals, transfer gating signals, and row selecting signals for global and rolling shutter operations, enabling efficient photo-conversion signal processing and digital image signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If global shutter operation is implemented across all rows simultaneously, then measurement precision of light signals is improved, but device complexity increases due to simultaneous control requirements
Solution Approach 1:
The patent segments the pixel array into multiple rows, each with independent control capability. The row control circuit generates separate reset control signals for different rows, allowing sequential or simultaneous operation. This segmentation enables the global shutter to achieve high measurement precision while managing control complexity through modular row-based control architecture.
Solution Approach 2:
The patent implements preliminary reset action by generating reset control signals before the integration period begins. The row control circuit activates reset switches to clear photoelectrons from storage nodes prior to light exposure, ensuring accurate baseline conditions for subsequent measurement. This preliminary action is essential for achieving precise light signal measurement in global shutter mode.
2Device complexity
If rolling shutter operation is used to reduce control complexity, then device complexity decreases, but loss of time increases due to sequential row processing
Solution Approach 1:
The patent implements dynamic control where the row control circuit can adaptively select between global shutter mode (simultaneous row reset) and rolling shutter mode (sequential row reset) based on operational requirements. The control apparatus dynamically adjusts the timing and distribution of reset control signals across rows, enabling flexible optimization between speed and complexity for different imaging scenarios.
3Productivity
If multiple photosensor pixels are controlled simultaneously, then productivity increases through parallel processing, but difficulty of detecting and measuring signals increases
Solution Approach 1:
The patent introduces column clamp, sample, and hold circuits as intermediary components between the photosensor pixels and output circuitry. These intermediary circuits receive signals from multiple pixels simultaneously, perform correlated double sampling to eliminate noise, and buffer the signals before output. This intermediary stage enables parallel processing of multiple pixel signals while simplifying detection through standardized sampling and holding operations.
4Measurement precision
If correlated double sampling is implemented to improve signal accuracy, then measurement precision increases, but device complexity increases due to additional sampling circuitry
Solution Approach 1:
The patent merges the correlated double sampling function into the existing row control and column clamp circuits. The row control circuit generates reset signals that trigger both the pixel reset and the sampling operation, while the column clamp circuits perform the actual sampling and holding. This merging of functions achieves high measurement precision through correlated double sampling while avoiding the need for completely separate sampling circuitry, thus managing device complexity.
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 apparatus effectively performs global and rolling shutter operations by managing photoelectron integration and transfer, enhancing the accuracy and efficiency of light signal processing across arrays of color multiple sensor pixel image sensors.
Implementation Method 1
Each picture element (pixel) of the image includes at least one photo sensor. Light energy emitted or reflected from an object impinges upon the array of photo sensors. The light energy is converted by the photo sensors to an electrical signal.
Implementation Method 2
A transfer gate is connected between the pinned photodiode and the storage node floating diffusion to selectively transfer the photoelectrons to the storage node.
Data Source
AI summary
An apparatus controls operation of an array of color multiple sensor pixel image sensors to provide a global shuttering for one half of the color multiple sensor pixel image sensors and a rolling shuttering for all color multiple sensor pixel image sensors of the array. The apparatus includes a row control circuit and a column clamp, sample, and hold circuit. The row control circuit generates the necessary reset control signals, transfer gating signals, and row selecting signals for providing the global shuttering and the rolling shuttering color multiple sensor pixel image sensors. The column clamp, sample and hold circuit generates an output signal representative of a number of photons impinging upon each color multiple sensor pixel image sensor of the row of selected color multiple sensor pixel image sensors. The control apparatus further includes an analog to digital converter which converts the read out signal to a digital image signal.