Linear Image Sensor Resistive Gate High-Speed Charge Transfer
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Solution Overview
Problem
In linear image sensors, the large-sized photoelectric conversion region leads to delayed charge transfer, making it difficult to achieve a high-speed electronic shutter necessary for precise spectroscopic analysis, as the time delay in charge transfer prevents the efficient removal of background light and detection of element-specific bright-line spectra.
Innovation Solution
The linear image sensor is designed with a potential inclination forming means using a resistive gate electrode to promote high-speed charge transfer in the column direction, and a barrier region with lower impurity concentration to prevent reverse charge flow, allowing for rapid switching of the channel region between ON and OFF states using a high-frequency clock signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the photoelectric conversion region size is increased to improve light-receiving area, then the signal photon incident number increases, but the charge transfer time is delayed
Solution Approach 1:
The photoelectric conversion region is divided into multiple pixel regions (first pixel region and second pixel region) with different impurity concentrations. This segmentation allows each region to have optimized charge transfer characteristics, enabling the large photoelectric conversion area to maintain fast charge transfer by having different regions contribute at different rates.
Solution Approach 2:
Different regions of the photoelectric conversion structure are given different impurity concentrations (first concentration in first pixel region, second concentration in second pixel region). This local quality variation creates different potential gradients and charge transfer speeds in different regions, allowing the system to achieve both large area coverage and fast overall charge transfer by optimizing each local region's contribution.
2Speed
If the impurity concentration is increased to improve charge transfer speed, then the charge transfer time decreases, but the detection precision is reduced
Solution Approach 1:
The photoelectric conversion region is segmented into multiple pixel regions with different impurity concentrations. The first pixel region has higher impurity concentration for faster charge transfer, while the second pixel region has lower impurity concentration for higher detection precision. This segmentation allows the system to achieve both fast charge transfer and high precision detection simultaneously.
Solution Approach 2:
Different local regions are assigned different impurity concentrations optimized for their specific functions. The first pixel region uses higher impurity concentration to provide fast charge transfer capability, while the second pixel region uses lower impurity concentration to provide high signal detection precision. This local optimization resolves the contradiction between speed and precision.
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 design enables a high-speed electronic shutter, allowing for precise analysis by quickly removing background light and enhancing the detection of element-specific spectra, improving the signal-to-noise ratio and analysis accuracy.
Implementation Method 1
converting incident light into electrons (holes) and transferring converted carriers to a terminal portion
Implementation Method 2
a potential inclination forming means using a resistive gate electrode to promote high-speed charge transfer in the column direction
Data Source
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AI summary
An optical detection unit AR is divided so as to have a plurality of pixel regions PX aligned in a column direction. Signals from the plurality of pixel regions PX are integrated for each optical detection unit AR, and output the signal as an electrical signal corresponding to a one-dimensional optical image in time series. Each of the pixel regions PX includes a resistive gate electrode R which promotes transfer of charges in the photoelectric conversion region and a charge accumulation region S2. A drain region ARD is adjacent to the charge accumulation region S2 through a channel region.