Dual-Gate Sensing Device for Faster Image Readout
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Solution Overview
Problem
The operating time of image sensors increases with the area of the sensing device due to lower electron mobility in thin film transistors made of glass compared to semiconductor devices, necessitating optimization of sensing speed.
Innovation Solution
A sensing device is designed to operate in reset, exposure, and readout periods, comprising specific transistors and a sensing element, which includes an N-type transistor and P-type transistors to manage voltage and signal output efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the area of the sensing device is increased, then the image sensor can cover a larger field of view or capture more light, but the operating time increases due to lower electron mobility in thin film transistors
Solution Approach 1:
The sensing device is divided into multiple sensing units, each with its own pixel circuit. This segmentation allows parallel processing of signals from different regions, reducing the total operating time while maintaining large area coverage.
Solution Approach 2:
The patent introduces a dual-gate transistor structure where the second gate can independently control the transistor operation. This adds a new control dimension that enables faster signal reading and reduces operating time without sacrificing sensing area.
2Ease of manufacture
If thin film transistors made of glass are used, then the sensing device can be manufactured with lower cost and simpler process, but the electron mobility is much lower than semiconductor devices
Solution Approach 1:
The patent changes the electrical parameters of the thin film transistor by introducing a dual-gate structure with independent voltage control. This allows optimization of electron mobility through voltage tuning while maintaining the ease of manufacture of glass-based thin film transistors.
Solution Approach 2:
The invention combines glass-based thin film transistor materials with a dual-gate structure design, creating a composite system that leverages the manufacturing advantages of glass while achieving improved electron mobility through the structural configuration.
3Area of stationary object
If the area of the sensing device is increased, then more pixels can be included for higher resolution, but the pixel circuit operating time increases accordingly
Solution Approach 1:
The pixel circuit is segmented into multiple functional blocks including first and second transfer switches, first and second storage nodes, and dual-gate transistors. This segmentation enables parallel signal processing paths that reduce the overall operating time while supporting high-resolution large-area sensors.
Solution Approach 2:
The dual-gate transistor structure performs preliminary signal conditioning and transfer operations in the first gate before final readout through the second gate. This preliminary action prepares signals for faster subsequent processing, reducing the total pixel circuit operating time.
Data Source
AI summary
A sensing device is provided herein, which operates in a reset period, an exposure period, and a readout period. The sensing device includes a first transistor, a second transistor, a detection device, and a third transistor. The first transistor includes a control terminal and a first terminal. The second transistor is coupled to the first transistor and configured to set the voltage of the control terminal during the exposure period. The sensing device is coupled to the first transistor and configured to change the voltage of the control terminal during the exposure period. The third transistor is coupled to the first transistor and includes an output terminal outputting a sense signal from the first terminal during the readout period. The first transistor is an N-type transistor and the third transistor is a P-type transistor.