Shared Input Node Readout Timing for CMOS Image Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing solid-state imaging apparatus experiences deterioration in image quality when reading out signals from a shared input node, due to the reduction of saturated electrons.
Innovation Solution
A photoelectric conversion device with a pixel array comprising multiple rows and columns, where each pixel includes photoelectric conversion elements, amplification transistors, and reset transistors, and output lines are used to manage signal output in specific periods to prevent signal mismatch and fluctuation at the input node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pixel size is reduced by sharing an input node between multiple photoelectric conversion units, then the reduction of saturated electrons is suppressed, but deterioration in image quality occurs when reading out a signal from the shared input node
Solution Approach 1:
The photoelectric conversion units are divided into first and second units, with each having dedicated transfer transistors (first and second transfer transistors) that transfer charges to different regions of the shared input node. This segmentation allows independent charge transfer paths, preventing signal deterioration while maintaining reduced saturated electron levels through shared node architecture.
Solution Approach 2:
The input node serves as an intermediary element that receives charges from multiple photoelectric conversion units through dedicated transfer transistors. By introducing this intermediate structure with separate transfer paths, the patent enables multiple units to share the input node without causing signal deterioration, thus resolving the contradiction between reducing saturated electrons and maintaining image quality.
2Device complexity
If multiple photoelectric conversion units share a common input node, then device complexity is reduced, but signal reading quality deteriorates
Solution Approach 1:
The input node is segmented into multiple charge receiving regions, with each region accessible through a dedicated transfer transistor. This segmentation maintains the simplicity of sharing a common input node structure while improving signal reading quality by providing separate charge transfer paths that prevent signal interference and deterioration.
Solution Approach 2:
The patent employs dynamic control of transfer transistors to manage charge transfer timing and paths. By dynamically controlling which transfer transistor is active at each moment, the system maintains a simple shared input node structure while achieving high-quality signal reading through time-multiplexed charge transfer operations.
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 configuration suppresses image quality deterioration by ensuring consistent signal readout and reducing the influence of parasitic capacitance, allowing for high-speed readout and die shrinkage of pixels.
Implementation Method 1
each pixel including a plurality of photoelectric conversion elements generating charge
Data Source
AI summary
A device of the disclosure comprises pixels including photoelectric converters generating charge, transistors having nodes receiving signals based on the charge, and transistors supplying reset voltage; and lines along the columns, wherein: in a first period, the node is disconnected from the converter, and signals based on the reset voltage is output from a pixel in a first row to a line, in a second period, signals based on the reset voltage and the charge transferred to the node are output from the pixel in the first row to a line, in a third period, signals based on the charge is output from a pixel in a second row to a line, in a fourth period, signals based on the charge is output from a pixel in a third row to a line, and the first period is prior to the second period, and between the third and fourth periods.